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@node Contributing
@chapter Contributing

This project is a cooperative effort, and we need your help to make it
grow!  Please get in touch with us on @email{guix-devel@@gnu.org} and
@code{#guix} on the Libera Chat IRC network.  We welcome ideas, bug
reports, patches, and anything that may be helpful to the project.  We
particularly welcome help on packaging (@pxref{Packaging Guidelines}).

@cindex code of conduct, of contributors
@cindex contributor covenant
We want to provide a warm, friendly, and harassment-free environment, so
that anyone can contribute to the best of their abilities.  To this end
our project uses a ``Contributor Covenant'', which was adapted from
@url{https://contributor-covenant.org/}.  You can find a local version in
the @file{CODE-OF-CONDUCT} file in the source tree.

Contributors are not required to use their legal name in patches and
on-line communication; they can use any name or pseudonym of their
choice.

@menu
* Requirements::                Software needed to build and run Guix.
* Building from Git::           The latest and greatest.
* Running the Test Suite::      Testing Guix.
* Running Guix Before It Is Installed::  Hacker tricks.
* The Perfect Setup::           The right tools.
* Alternative Setups::          Other possible tools that do the job.
* Source Tree Structure::       Source code guided tour.
* Packaging Guidelines::        Growing the distribution.
* Coding Style::                Hygiene of the contributor.
* Submitting Patches::          Share your work.
* Tracking Bugs and Changes::   Keeping it all organized.
* Teams::                       Coordinating efforts.
* Making Decisions::            Collectively choosing the way forward.
* Commit Access::               Pushing to the official repository.
* Reviewing the Work of Others::  Some guidelines for sharing reviews.
* Updating the Guix Package::   Updating the Guix package definition.
* Deprecation Policy::          Commitments and tools for deprecation.
* Writing Documentation::       Improving documentation in GNU Guix.
* Translating Guix::            Make Guix speak your native language.
* Contributing to Guix's Infrastructure::  Make Guix ecosystem work better.
@end menu

@node Requirements
@section Requirements

You can easily hack on Guix itself using Guix and Git, which we use for
version control (@pxref{Building from Git}).

But when packaging Guix for foreign distros or when bootstrapping on
systems without Guix, and if you decide to not just trust and install
our readily made binary (@pxref{Binary Installation}), you can download
a release version of our reproducible source tarball and read on.

This section lists requirements when building Guix from source.  The
build procedure for Guix is the same as for other GNU software, and is
not covered here.  Please see the files @file{README} and @file{INSTALL}
in the Guix source tree for additional details.

@cindex official website
GNU Guix is available for download from its website at
@url{https://www.gnu.org/software/guix/}.

GNU Guix depends on the following packages:

@itemize
@item @url{https://gnu.org/software/guile/, GNU Guile}, version 3.0.x,
version 3.0.3 or later;
@item @url{https://notabug.org/cwebber/guile-gcrypt, Guile-Gcrypt}, version
0.1.0 or later;
@item
@uref{https://gitlab.com/gnutls/guile/, Guile-GnuTLS} (@pxref{Guile
Preparations, how to install the GnuTLS bindings for Guile,,
gnutls-guile, GnuTLS-Guile})@footnote{The Guile bindings to
@uref{https://gnutls.org/, GnuTLS} were distributed as part of GnuTLS
until version 3.7.8 included.};
@item
@uref{https://notabug.org/guile-sqlite3/guile-sqlite3, Guile-SQLite3}, version 0.1.0
or later;
@item @uref{https://notabug.org/guile-zlib/guile-zlib, Guile-zlib},
version 0.1.0 or later;
@item @uref{https://notabug.org/guile-lzlib/guile-lzlib, Guile-lzlib};
@item @uref{https://www.nongnu.org/guile-avahi/, Guile-Avahi};
@item
@uref{https://gitlab.com/guile-git/guile-git, Guile-Git}, version 0.5.0
or later;
@item @uref{https://git-scm.com, Git} (yes, both!);
@item @uref{https://savannah.nongnu.org/projects/guile-json/, Guile-JSON}
4.3.0 or later;
@item @url{https://www.gnu.org/software/make/, GNU Make}.
@end itemize

The following dependencies are optional:

@itemize
@item
@c Note: We need at least 0.13.0 for #:nodelay.
Support for build offloading (@pxref{Daemon Offload Setup}) and
@command{guix copy} (@pxref{Invoking guix copy}) depends on
@uref{https://github.com/artyom-poptsov/guile-ssh, Guile-SSH},
version 0.13.0 or later.

@item
@uref{https://notabug.org/guile-zstd/guile-zstd, Guile-zstd}, for zstd
compression and decompression in @command{guix publish} and for
substitutes (@pxref{Invoking guix publish}).

@item
@uref{https://ngyro.com/software/guile-semver.html, Guile-Semver} for
the @code{crate} importer (@pxref{Invoking guix import}).

@item
@uref{https://www.nongnu.org/guile-lib/doc/ref/htmlprag/, Guile-Lib} for
the @code{go} importer (@pxref{Invoking guix import}) and for some of
the ``updaters'' (@pxref{Invoking guix refresh}).

@item
When @url{http://www.bzip.org, libbz2} is available,
@command{guix-daemon} can use it to compress build logs.
@end itemize

Unless @option{--disable-daemon} was passed to @command{configure}, the
following packages are also needed:

@itemize
@item @url{https://gnupg.org/, GNU libgcrypt};
@item @url{https://sqlite.org, SQLite 3};
@item @url{https://gcc.gnu.org, GCC's g++}, with support for the
C++11 standard.
@end itemize

@node Building from Git
@section Building from Git

If you want to hack Guix itself, it is recommended to use the latest
version from the Git repository:

@example
git clone https://git.savannah.gnu.org/git/guix.git
@end example

@cindex authentication, of a Guix checkout
How do you ensure that you obtained a genuine copy of the repository?
To do that, run @command{guix git authenticate}, passing it the commit
and OpenPGP fingerprint of the @dfn{channel introduction}
(@pxref{Invoking guix git authenticate}):

@c The commit and fingerprint below must match those of the channel
@c introduction in '%default-channels'.
@example
git fetch origin keyring:keyring
guix git authenticate 9edb3f66fd807b096b48283debdcddccfea34bad \
  "BBB0 2DDF 2CEA F6A8 0D1D  E643 A2A0 6DF2 A33A 54FA"
@end example

@noindent
This command completes with exit code zero on success; it prints an
error message and exits with a non-zero code otherwise.

As you can see, there is a chicken-and-egg problem: you first need to
have Guix installed.  Typically you would install Guix System
(@pxref{System Installation}) or Guix on top of another distro
(@pxref{Binary Installation}); in either case, you would verify the
OpenPGP signature on the installation medium.  This ``bootstraps'' the
trust chain.

The easiest way to set up a development environment for Guix is, of
course, by using Guix!  The following command starts a new shell where
all the dependencies and appropriate environment variables are set up to
hack on Guix:

@example
guix shell -D guix -CPW
@end example

or even, from within a Git worktree for Guix:

@example
guix shell -CPW
@end example

If @option{-C} (short for @option{--container}) is not supported on your
system, try @command{--pure} instead of @option{-CPW}.
@xref{Invoking guix shell}, for more information on that command.

If you are unable to use Guix when building Guix from a checkout, the
following are the required packages in addition to those mentioned in the
installation instructions (@pxref{Requirements}).

@itemize
@item @url{https://gnu.org/software/autoconf/, GNU Autoconf};
@item @url{https://gnu.org/software/automake/, GNU Automake};
@item @url{https://gnu.org/software/gettext/, GNU Gettext};
@item @url{https://gnu.org/software/texinfo/, GNU Texinfo};
@item @url{https://www.graphviz.org/, Graphviz};
@item @url{https://www.gnu.org/software/help2man/, GNU Help2man (optional)}.
@end itemize

On Guix, extra dependencies can be added by instead running @command{guix
shell}:

@example
guix shell -D guix help2man git strace --pure
@end example

From there you can generate the build system infrastructure
using Autoconf and Automake:

@example
./bootstrap
@end example

If you get an error like this one:

@example
configure.ac:46: error: possibly undefined macro: PKG_CHECK_MODULES
@end example

@noindent
it probably means that Autoconf couldn’t find @file{pkg.m4}, which is
provided by pkg-config.  Make sure that @file{pkg.m4} is available.  The
same holds for the @file{guile.m4} set of macros provided by Guile.  For
instance, if you installed Automake in @file{/usr/local}, it wouldn’t
look for @file{.m4} files in @file{/usr/share}.  In that case, you have
to invoke the following command:

@example
export ACLOCAL_PATH=/usr/share/aclocal
@end example

@xref{Macro Search Path,,, automake, The GNU Automake Manual}, for
more information.

@cindex state directory
@cindex localstatedir
@cindex system configuration directory
@cindex sysconfdir
Then, run:

@example
./configure
@end example

@noindent
Optionally, @code{--localstatedir} and @code{--sysconfdir} can also be
provided as arguments.  By default, @code{localstatedir} is @file{/var}
(@pxref{The Store}, for information about this) and @code{sysconfdir} is
@file{/etc}.  Note that you will probably not run @command{make install}
at the end (you don't have to) but it's still important to pass the
right @code{localstatedir} and @code{sysconfdir} values, which get
recorded in the @code{(guix config)} Guile module.

Finally, you can build Guix and, if you feel so inclined, run the tests
(@pxref{Running the Test Suite}):

@example
make
make check
@end example

@noindent
If anything fails, take a look at installation instructions
(@pxref{Installation}) or send a message to the
@email{guix-devel@@gnu.org, mailing list}.

From there on, you can authenticate all the commits included in your
checkout by running:

@example
guix git authenticate \
  9edb3f66fd807b096b48283debdcddccfea34bad \
  "BBB0 2DDF 2CEA F6A8 0D1D  E643 A2A0 6DF2 A33A 54FA"
@end example

The first run takes a couple of minutes, but subsequent runs are faster.
On subsequent runs, you can run the command without any arguments since
the @dfn{introduction} (the commit ID and OpenPGP fingerprints above)
will have been recorded@footnote{This requires a recent version of Guix,
from May 2024 or more recent.}:

@example
guix git authenticate
@end example

When your configuration for your local Git repository doesn't match
the default one, you can provide the reference for the @code{keyring}
branch @i{via} the @option{-k} option.  The following
example assumes that you have a Git remote called @samp{myremote}
pointing to the official repository:

@example
guix git authenticate \
  -k myremote/keyring \
  9edb3f66fd807b096b48283debdcddccfea34bad \
  "BBB0 2DDF 2CEA F6A8 0D1D  E643 A2A0 6DF2 A33A 54FA"
@end example

@xref{Invoking guix git authenticate}, for more information on this
command.

@quotation Note
By default, hooks are installed such that @command{guix git
authenticate} is invoked anytime you run @command{git pull} or
@command{git push}.
@end quotation

After updating the repository, @command{make} might fail with an error
similar to the following example:

@example
error: failed to load 'gnu/packages/linux.scm':
ice-9/eval.scm:293:34: In procedure abi-check: #<record-type <origin>>: record ABI mismatch; recompilation needed
@end example

This means that one of the record types that Guix defines (in this
example, the @code{origin} record) has changed, and all of guix needs
to be recompiled to take that change into account.  To do so, run
@command{make clean-go} followed by @command{make}.

Should @command{make} fail with an Automake error message after
updating, you need to repeat the steps outlined in this section,
commencing with @command{./bootstrap}.

@node Running the Test Suite
@section Running the Test Suite

@cindex test suite
After a successful @command{configure} and @code{make} run, it is a good
idea to run the test suite.  It can help catch issues with the setup or
environment, or bugs in Guix itself---and really, reporting test
failures is a good way to help improve the software.  To run the test
suite, type:

@example
make check
@end example

Test cases can run in parallel: you can use the @code{-j} option of
GNU@tie{}make to speed things up.  The first run may take a few minutes
on a recent machine; subsequent runs will be faster because the store
that is created for test purposes will already have various things in
cache.

It is also possible to run a subset of the tests by defining the
@code{TESTS} makefile variable as in this example:

@example
make check TESTS="tests/store.scm tests/cpio.scm"
@end example

By default, tests results are displayed at a file level.  In order to
see the details of every individual test cases, it is possible to define
the @code{SCM_LOG_DRIVER_FLAGS} makefile variable as in this example:

@example
make check TESTS="tests/base64.scm" SCM_LOG_DRIVER_FLAGS="--brief=no"
@end example

The underlying SRFI 64 custom Automake test driver used for the 'check'
test suite (located at @file{build-aux/test-driver.scm}) also allows
selecting which test cases to run at a finer level, via its
@option{--select} and @option{--exclude} options.  Here's an example, to
run all the test cases from the @file{tests/packages.scm} test file
whose names start with ``transaction-upgrade-entry'':

@example
export SCM_LOG_DRIVER_FLAGS="--select=^transaction-upgrade-entry"
make check TESTS="tests/packages.scm"
@end example

Those wishing to inspect the results of failed tests directly from the
command line can add the @option{--errors-only=yes} option to the
@code{SCM_LOG_DRIVER_FLAGS} makefile variable and set the @code{VERBOSE}
Automake makefile variable, as in:

@example
make check SCM_LOG_DRIVER_FLAGS="--brief=no --errors-only=yes" VERBOSE=1
@end example

The @option{--show-duration=yes} option can be used to print the
duration of the individual test cases, when used in combination with
@option{--brief=no}:

@example
make check SCM_LOG_DRIVER_FLAGS="--brief=no --show-duration=yes"
@end example

@xref{Parallel Test Harness,,,automake,GNU Automake} for more
information about the Automake Parallel Test Harness.

Upon failure, please email @email{bug-guix@@gnu.org} and attach the
@file{test-suite.log} file.  Please specify the Guix version being used
as well as version numbers of the dependencies (@pxref{Requirements}) in
your message.

Guix also comes with a whole-system test suite that tests complete
Guix System instances.  It can only run on systems where
Guix is already installed, using:

@example
make check-system
@end example

@noindent
or, again, by defining @code{TESTS} to select a subset of tests to run:

@example
make check-system TESTS="basic mcron"
@end example

These system tests are defined in the @code{(gnu tests @dots{})}
modules.  They work by running the operating systems under test with
lightweight instrumentation in a virtual machine (VM).  They can be
computationally intensive or rather cheap, depending on whether
substitutes are available for their dependencies (@pxref{Substitutes}).
Some of them require a lot of storage space to hold VM images.

If you encounter an error like:

@example
Compiling Scheme modules...
ice-9/eval.scm:142:16: In procedure compile-top-call:
error: all-system-tests: unbound variable
hint: Did you forget `(use-modules (gnu tests))'?
@end example

@noindent
there may be inconsistencies in the work tree from previous builds.  To
resolve this, try running @command{make clean-go} followed by
@command{make}.

Again in case of test failures, please send @email{bug-guix@@gnu.org}
all the details.

@node Running Guix Before It Is Installed
@section Running Guix Before It Is Installed

In order to keep a sane working environment, you will find it useful to
test the changes made in your local source tree checkout without
actually installing them.  So that you can distinguish between your
``end-user'' hat and your ``motley'' costume.

To that end, all the command-line tools can be used even if you have not
run @code{make install}.  To do that, you first need to have an
environment with all the dependencies available (@pxref{Building from
Git}), and then simply prefix each command with @command{./pre-inst-env}
(the @file{pre-inst-env} script lives in the top build tree of Guix;
@pxref{Building from Git} to generate it).  As an example, here is how you
would build the @code{hello} package as defined in your working tree (this
assumes @command{guix-daemon} is already running on your system; it's OK if
it's a different version):

@example
$ ./pre-inst-env guix build hello
@end example

@noindent
Similarly, an example for a Guile session using the Guix modules:

@example
$ ./pre-inst-env guile -c '(use-modules (guix utils)) (pk (%current-system))'

;;; ("x86_64-linux")
@end example

@noindent
@cindex REPL
@cindex read-eval-print loop
@dots{} and for a REPL (@pxref{Using Guix Interactively}):

@example
$ ./pre-inst-env guile
scheme@@(guile-user)> ,use(guix)
scheme@@(guile-user)> ,use(gnu)
scheme@@(guile-user)> (define snakes
                       (fold-packages
                         (lambda (package lst)
                           (if (string-prefix? "python"
                                               (package-name package))
                               (cons package lst)
                               lst))
                         '()))
scheme@@(guile-user)> (length snakes)
$1 = 361
@end example

If you are hacking on the daemon and its supporting code or if
@command{guix-daemon} is not already running on your system, you can
launch it straight from the build tree@footnote{The @option{-E} flag to
@command{sudo} guarantees that @code{GUILE_LOAD_PATH} is correctly set
such that @command{guix-daemon} and the tools it uses can find the Guile
modules they need.}:

@example
$ sudo -E ./pre-inst-env guix-daemon --build-users-group=guixbuild
@end example

The @command{pre-inst-env} script sets up all the environment variables
necessary to support this, including @env{PATH} and @env{GUILE_LOAD_PATH}.

Note that @command{./pre-inst-env guix pull} does @emph{not} upgrade the
local source tree; it simply updates the @file{~/.config/guix/current}
symlink (@pxref{Invoking guix pull}).  Run @command{git pull} instead if
you want to upgrade your local source tree.

Sometimes, especially if you have recently updated your repository,
running @command{./pre-inst-env} will print a message similar to the
following example:

@example
;;; note: source file /home/user/projects/guix/guix/progress.scm
;;;       newer than compiled /home/user/projects/guix/guix/progress.go
@end example

This is only a note and you can safely ignore it.  You can get rid of
the message by running @command{make -j4}.  Until you do, Guile will run
slightly slower because it will interpret the code instead of using
prepared Guile object (@file{.go}) files.

You can run @command{make} automatically as you work using
@command{watchexec} from the @code{watchexec} package.  For example,
to build again each time you update a package file, run
@samp{watchexec -w gnu/packages -- make -j4}.

@node The Perfect Setup
@section The Perfect Setup

The Perfect Setup to hack on Guix is basically the perfect setup used
for Guile hacking (@pxref{Using Guile in Emacs,,, guile, Guile Reference
Manual}).  First, you need more than an editor, you need
@url{https://www.gnu.org/software/emacs, Emacs}, empowered by the
wonderful @url{https://nongnu.org/geiser/, Geiser}.  To set that up, run:

@example
guix install emacs guile emacs-geiser emacs-geiser-guile
@end example

Geiser allows for interactive and incremental development from within
Emacs: code compilation and evaluation from within buffers, access to
on-line documentation (docstrings), context-sensitive completion,
@kbd{M-.} to jump to an object definition, a REPL to try out your code,
and more (@pxref{Introduction,,, geiser, Geiser User Manual}).  If you
allow Emacs to load the @file{.dir-locals.el} file at the root of the
project checkout, it will cause Geiser to automatically add the local
Guix sources to the Guile load path.

To actually edit the code, Emacs already has a neat Scheme mode.  But in
addition to that, you must not miss
@url{https://www.emacswiki.org/emacs/ParEdit, Paredit}.  It provides
facilities to directly operate on the syntax tree, such as raising an
s-expression or wrapping it, swallowing or rejecting the following
s-expression, etc.

@cindex code snippets
@cindex templates
@cindex reducing boilerplate
We also provide templates for common git commit messages and package
definitions in the @file{etc/snippets} directory.  These templates can
be used to expand short trigger strings to interactive text snippets. If
you use @url{https://joaotavora.github.io/yasnippet/, YASnippet}, you
may want to add the @file{etc/snippets/yas} snippets directory to the
@var{yas-snippet-dirs} variable.  If you use
@url{https://github.com/minad/tempel/, Tempel}, you may want to add the
@file{etc/snippets/tempel/*} path to the @var{tempel-path} variable in
Emacs.

@lisp
;; @r{Assuming the Guix checkout is in ~/src/guix.}
;; @r{Yasnippet configuration}
(with-eval-after-load 'yasnippet
  (add-to-list 'yas-snippet-dirs "~/src/guix/etc/snippets/yas"))
;; @r{Tempel configuration}
(with-eval-after-load 'tempel
   ;; Ensure tempel-path is a list -- it may also be a string.
   (unless (listp 'tempel-path)
     (setq tempel-path (list tempel-path)))
   (add-to-list 'tempel-path "~/src/guix/etc/snippets/tempel/*"))
@end lisp

The commit message snippets depend on @url{https://magit.vc/, Magit} to
display staged files.  When editing a commit message type @code{add}
followed by @kbd{TAB} to insert a commit message template for adding a
package; type @code{update} followed by @kbd{TAB} to insert a template
for updating a package; type @code{https} followed by @kbd{TAB} to
insert a template for changing the home page URI of a package to HTTPS.

The main snippet for @code{scheme-mode} is triggered by typing
@code{package...} followed by @kbd{TAB}.  This snippet also inserts the
trigger string @code{origin...}, which can be expanded further.  The
@code{origin} snippet in turn may insert other trigger strings ending on
@code{...}, which also can be expanded further.

@cindex insert or update copyright
@cindex @code{M-x guix-copyright}
@cindex @code{M-x copyright-update}
We additionally provide insertion and automatic update of a copyright in
@file{etc/copyright.el}.  You may want to set your full name, mail, and
load a file.

@lisp
(setq user-full-name "Alice Doe")
(setq user-mail-address "alice@@mail.org")
;; @r{Assuming the Guix checkout is in ~/src/guix.}
(load-file "~/src/guix/etc/copyright.el")
@end lisp

To insert a copyright at the current line invoke @code{M-x guix-copyright}.

To update a copyright you need to specify a @code{copyright-names-regexp}.

@lisp
(setq copyright-names-regexp
      (format "%s <%s>" user-full-name user-mail-address))
@end lisp

You can check if your copyright is up to date by evaluating @code{M-x
copyright-update}.  If you want to do it automatically after each buffer
save then add @code{(add-hook 'after-save-hook 'copyright-update)} in
Emacs.

@node Viewing Bugs within Emacs
@subsection Viewing Bugs within Emacs

Emacs has a nice minor mode called @code{bug-reference}, which, when
combined with @samp{emacs-debbugs} (the Emacs package), can be used to
open links such as @samp{<https://bugs.gnu.org/58697>} or
@samp{<https://issues.guix.gnu.org/58697>} as bug report buffers.  From
there you can easily consult the email thread via the Gnus interface,
reply or modify the bug status, all without leaving the comfort of
Emacs!  Below is a sample configuration to add to your @file{~/.emacs}
configuration file:

@lisp
;;; Bug references.
(require 'bug-reference)
(add-hook 'prog-mode-hook #'bug-reference-prog-mode)
(add-hook 'gnus-mode-hook #'bug-reference-mode)
(add-hook 'erc-mode-hook #'bug-reference-mode)
(add-hook 'gnus-summary-mode-hook #'bug-reference-mode)
(add-hook 'gnus-article-mode-hook #'bug-reference-mode)

;;; This extends the default expression (the top-most, first expression
;;; provided to 'or') to also match URLs such as
;;; <https://issues.guix.gnu.org/58697> or <https://bugs.gnu.org/58697>.
;;; It is also extended to detect "Fixes: #NNNNN" git trailers.
(setq bug-reference-bug-regexp
      (rx (group (or (seq word-boundary
                          (or (seq (char "Bb") "ug"
                                   (zero-or-one " ")
                                   (zero-or-one "#"))
                              (seq (char "Pp") "atch"
                                   (zero-or-one " ")
                                   "#")
                              (seq (char "Ff") "ixes"
                                   (zero-or-one ":")
                                   (zero-or-one " ") "#")
                              (seq "RFE"
                                   (zero-or-one " ") "#")
                              (seq "PR "
                                   (one-or-more (char "a-z+-")) "/"))
                          (group (one-or-more (char "0-9"))
                                 (zero-or-one
                                  (seq "#" (one-or-more
                                            (char "0-9"))))))
                     (seq (? "<") "https://bugs.gnu.org/"
                          (group-n 2 (one-or-more (char "0-9")))
                          (? ">"))
                     (seq (? "<") "https://issues.guix.gnu.org/"
                          (? "issue/")
                          (group-n 2 (one-or-more (char "0-9")))
                          (? ">"))))))
(setq bug-reference-url-format "https://issues.guix.gnu.org/%s")

(require 'debbugs)
(require 'debbugs-browse)
(add-hook 'bug-reference-mode-hook #'debbugs-browse-mode)
(add-hook 'bug-reference-prog-mode-hook #'debbugs-browse-mode)

;; The following allows Emacs Debbugs user to open the issue directly within
;; Emacs.
(setq debbugs-browse-url-regexp
      (rx line-start
          "http" (zero-or-one "s") "://"
          (or "debbugs" "issues.guix" "bugs")
          ".gnu.org" (one-or-more "/")
          (group (zero-or-one "cgi/bugreport.cgi?bug="))
          (group-n 3 (one-or-more digit))
          line-end))

;; Change the default when run as 'M-x debbugs-gnu'.
(setq debbugs-gnu-default-packages '("guix" "guix-patches"))

;; Show feature requests.
(setq debbugs-gnu-default-severities
 '("serious" "important" "normal" "minor" "wishlist"))
@end lisp

For more information, refer to @ref{Bug Reference,,, emacs, The GNU
Emacs Manual} and @ref{Minor Mode,,, debbugs-ug, The Debbugs User
Guide}.

@node Alternative Setups
@section Alternative Setups

Alternative setups than Emacs may let you work on Guix with a
similar development experience and they might work better with the
tools you currently use or help you make the transition to Emacs.

The options listed below only provide the alternatives to the Emacs
based setup, which is the most widely used in the Guix community. If
you want to really understand how is the perfect setup for Guix
development supposed to work, we encourage you to read the section
before this regardless the editor you choose to use.

@menu
* Guile Studio::                First step in your transition to Emacs.
* Vim and NeoVim::              When you are evil to the root.
@end menu

@node Guile Studio
@subsection Guile Studio

Guile Studio is a pre-configured Emacs with mostly everything you need
to start hacking in Guile. If you are not familiar with Emacs it makes
the transition easier for you.

@example
guix install guile-studio
@end example

Guile Studio comes with Geiser preinstalled and prepared for action.

@node Vim and NeoVim
@subsection Vim and NeoVim


Vim (and NeoVim) are also packaged in Guix, just in case you decided
to go for the evil path.

@example
guix install vim
@end example

If you want to enjoy a similar development experience to that in the perfect
setup, you should install several plugins to configure the editor. Vim (and
NeoVim) have the equivalent to Paredit,
@uref{https://www.vim.org/scripts/script.php?script_id=3998,
@code{paredit.vim}}, that will help you with the structural editing of Scheme
files (the support for very large files is not great, though).

@example
guix install vim-paredit
@end example

We also recommend that you run @code{:set autoindent} so that your code is
automatically indented as you type.

For the interaction with Git,
@uref{https://www.vim.org/scripts/script.php?script_id=2975,
@code{fugitive.vim}} is the most commonly used plugin:

@example
guix install vim-fugitive
@end example

And of course if you want to interact with Guix directly from inside of
vim, using the built-in terminal emulator, we have our very own
@code{guix.vim} package!

@example
guix install vim-guix-vim
@end example

In NeoVim you can even make a similar setup to Geiser using
@url{https://conjure.fun/, Conjure} that lets you connect to a running Guile
process and inject your code there live (sadly it's not packaged in Guix yet).


@node Source Tree Structure
@section Source Tree Structure

@cindex structure, of the source tree
If you're willing to contribute to Guix beyond packages, or if you'd
like to learn how it all fits together, this section provides a guided
tour in the code base that you may find useful.

Overall, the Guix source tree contains almost exclusively Guile
@dfn{modules}, each of which can be seen as an independent library
(@pxref{Modules,,, guile, GNU Guile Reference Manual}).

The following table gives an overview of the main directories and what
they contain.  Remember that in Guile, each module name is derived from
its file name---e.g., the module in file @file{guix/packages.scm} is
called @code{(guix packages)}.

@table @file
@item guix
This is the location of core Guix mechanisms.  To illustrate what is
meant by ``core'', here are a few examples, starting from low-level
tools and going towards higher-level tools:

@table @code
@item (guix store)
Connecting to and interacting with the build daemon (@pxref{The Store}).
@item (guix derivations)
Creating derivations (@pxref{Derivations}).
@item (guix gexps)
Writing G-expressions (@pxref{G-Expressions}).
@item (guix packages)
Defining packages and origins (@pxref{package Reference}).
@item (guix download)
@itemx (guix git-download)
The @code{url-fetch} and @code{git-fetch} origin download methods
(@pxref{origin Reference}).
@item (guix swh)
Fetching source code from the
@uref{https://archive.softwareheritage.org,Software Heritage archive}.
@item (guix search-paths)
Implementing search paths (@pxref{Search Paths}).
@item (guix build-system)
The build system interface (@pxref{Build Systems}).
@item (guix profiles)
Implementing profiles.
@end table

@cindex build system, directory structure
@item guix/build-system
This directory contains specific build system implementations
(@pxref{Build Systems}), such as:

@table @code
@item (guix build-system gnu)
the GNU build system;
@item (guix build-system cmake)
the CMake build system;
@item (guix build-system pyproject)
The Python ``pyproject'' build system.
@end table

@item guix/build
This contains code generally used on the ``build side''
(@pxref{G-Expressions, strata of code}).  This includes code used to
build packages or other operating system components, as well as
utilities:

@table @code
@item (guix build utils)
Utilities for package definitions and more (@pxref{Build Utilities}).
@item (guix build gnu-build-system)
@itemx (guix build cmake-build-system)
@itemx (guix build pyproject-build-system)
Implementation of build systems, and in particular definition of their
build phases (@pxref{Build Phases}).
@item (guix build syscalls)
Interface to the C library and to Linux system calls.
@end table

@cindex command-line tools, as Guile modules
@cindex command modules
@item guix/scripts
This contains modules corresponding to @command{guix} sub-commands.  For
example, the @code{(guix scripts shell)} module exports the
@code{guix-shell} procedure, which directly corresponds to the
@command{guix shell} command (@pxref{Invoking guix shell}).

@cindex importer modules
@item guix/import
This contains supporting code for the importers and updaters
(@pxref{Invoking guix import}, and @pxref{Invoking guix refresh}).  For
example, @code{(guix import pypi)} defines the interface to PyPI, which
is used by the @command{guix import pypi} command.
@end table

The directories we have seen so far all live under @file{guix/}.  The
other important place is the @file{gnu/} directory, which contains
primarily package definitions as well as libraries and tools for Guix
System (@pxref{System Configuration}) and Guix Home (@pxref{Home
Configuration}), all of which build upon functionality provided by
@code{(guix @dots{})} modules@footnote{For this reason, @code{(guix
@dots{})} modules must generally not depend on @code{(gnu @dots{})}
modules, with notable exceptions: @code{(guix build-system @dots{})}
modules may look up packages at run time---e.g., @code{(guix
build-system cmake)} needs to access the @code{cmake} variable at run
time---, @code{(guix scripts @dots{})} often rely on @code{(gnu @dots{})}
modules, and the same goes for some of the @code{(guix import @dots{})}
modules.}.

@table @file
@cindex package modules
@item gnu/packages
This is by far the most crowded directory of the source tree: it
contains @dfn{package modules} that export package definitions
(@pxref{Package Modules}).  A few examples:

@table @code
@item (gnu packages base)
Module providing ``base'' packages: @code{glibc}, @code{coreutils},
@code{grep}, etc.
@item (gnu packages guile)
Guile and core Guile packages.
@item (gnu packages linux)
The Linux-libre kernel and related packages.
@item (gnu packages python)
Python and core Python packages.
@item (gnu packages python-xyz)
Miscellaneous Python packages (we were not very creative).
@end table

In any case, you can jump to a package definition using @command{guix
edit} (@pxref{Invoking guix edit}) and view its location with
@command{guix show} (@pxref{Invoking guix package}).

@findex search-patches
@item gnu/packages/patches
This directory contains patches applied against packages and obtained
using the @code{search-patches} procedure.

@item gnu/services
This contains service definitions, primarily for Guix System
(@pxref{Services}) but some of them are adapted and reused for Guix Home
as we will see below.  Examples:

@table @code
@item (gnu services)
The service framework itself, which defines the service and service type
data types (@pxref{Service Composition}).
@item (gnu services base)
``Base'' services (@pxref{Base Services}).
@item (gnu services desktop)
``Desktop'' services (@pxref{Desktop Services}).
@item (gnu services shepherd)
Support for Shepherd services (@pxref{Shepherd Services}).
@end table

You can jump to a service definition using @command{guix system edit}
and view its location with @command{guix system search} (@pxref{Invoking
guix system}).

@item gnu/system
These are core Guix System modules, such as:

@table @code
@item (gnu system)
Defines @code{operating-system} (@pxref{operating-system Reference}).
@item (gnu system file-systems)
Defines @code{file-system} (@pxref{File Systems}).
@item (gnu system mapped-devices)
Defines @code{mapped-device} (@pxref{Mapped Devices}).
@end table

@item gnu/build
These are modules that are either used on the ``build side'' when
building operating systems or packages, or at run time by operating
systems.

@table @code
@item (gnu build accounts)
Creating @file{/etc/passwd}, @file{/etc/shadow}, etc. (@pxref{User
Accounts}).
@item (gnu build activation)
Activating an operating system at boot time or reconfiguration time.
@item (gnu build file-systems)
Searching, checking, and mounting file systems.
@item (gnu build linux-boot)
@itemx (gnu build hurd-boot)
Booting GNU/Linux and GNU/Hurd operating systems.
@item (gnu build linux-initrd)
Creating a Linux initial RAM disk (@pxref{Initial RAM Disk}).
@end table

@item gnu/home
This contains all things Guix Home (@pxref{Home Configuration});
examples:

@table @code
@item (gnu home services)
Core services such as @code{home-files-service-type}.
@item (gnu home services ssh)
SSH-related services (@pxref{Secure Shell}).
@end table

@item gnu/installer
This contains the text-mode graphical system installer (@pxref{Guided
Graphical Installation}).

@item gnu/machine
These are the @dfn{machine abstractions} used by @command{guix deploy}
(@pxref{Invoking guix deploy}).

@item gnu/tests
This contains system tests---tests that spawn virtual machines to check
that system services work as expected (@pxref{Running the Test Suite}).
@end table

Last, there's also a few directories that contain files that are
@emph{not} Guile modules:

@table @file
@item nix
This is the C++ implementation of @command{guix-daemon}, inherited from
Nix (@pxref{Invoking guix-daemon}).

@item tests
These are unit tests, each file corresponding more or less to one
module, in particular @code{(guix @dots{})} modules (@pxref{Running the
Test Suite}).

@item doc
This is the documentation in the form of Texinfo files: this manual and
the Cookbook.  @xref{Writing a Texinfo File,,, texinfo, GNU Texinfo},
for information on Texinfo markup language.

@item po
This is the location of translations of Guix itself, of package synopses
and descriptions, of the manual, and of the cookbook.  Note that
@file{.po} files that live here are pulled directly from Weblate
(@pxref{Translating Guix}).

@item etc
Miscellaneous files: shell completions, support for systemd and other
init systems, Git hooks, etc.
@end table

With all this, a fair chunk of your operating system is at your
fingertips!  Beyond @command{grep} and @command{git grep}, @pxref{The
Perfect Setup} on how to navigate code from your editor, and
@pxref{Using Guix Interactively} for information on how to use Scheme
modules interactively.  Enjoy!

@node Packaging Guidelines
@section Packaging Guidelines

@cindex packages, creating
The GNU distribution is nascent and may well lack some of your favorite
packages.  This section describes how you can help make the distribution
grow.

Free software packages are usually distributed in the form of
@dfn{source code tarballs}---typically @file{tar.gz} files that contain
all the source files.  Adding a package to the distribution means
essentially two things: adding a @dfn{recipe} that describes how to
build the package, including a list of other packages required to build
it, and adding @dfn{package metadata} along with that recipe, such as a
description and licensing information.

In Guix all this information is embodied in @dfn{package definitions}.
Package definitions provide a high-level view of the package.  They are
written using the syntax of the Scheme programming language; in fact,
for each package we define a variable bound to the package definition,
and export that variable from a module (@pxref{Package Modules}).
However, in-depth Scheme knowledge is @emph{not} a prerequisite for
creating packages.  For more information on package definitions,
@pxref{Defining Packages}.

Once a package definition is in place, stored in a file in the Guix
source tree, it can be tested using the @command{guix build} command
(@pxref{Invoking guix build}).  For example, assuming the new package is
called @code{gnew}, you may run this command from the Guix build tree
(@pxref{Running Guix Before It Is Installed}):

@example
./pre-inst-env guix build gnew --keep-failed
@end example

Using @code{--keep-failed} makes it easier to debug build failures since
it provides access to the failed build tree.  Another useful
command-line option when debugging is @code{--log-file}, to access the
build log.

If the package is unknown to the @command{guix} command, it may be that
the source file contains a syntax error, or lacks a @code{define-public}
clause to export the package variable.  To figure it out, you may load
the module from Guile to get more information about the actual error:

@example
./pre-inst-env guile -c '(use-modules (gnu packages gnew))'
@end example

Once your package builds correctly, please send us a patch
(@pxref{Submitting Patches}).  Well, if you need help, we will be happy to
help you too.  Once the patch is committed in the Guix repository, the
new package automatically gets built on the supported platforms by
@url{https://@value{SUBSTITUTE-SERVER-1}, our continuous integration system}.

@cindex substituter
Users can obtain the new package definition simply by running
@command{guix pull} (@pxref{Invoking guix pull}).  When
@code{@value{SUBSTITUTE-SERVER-1}} is done building the package, installing the
package automatically downloads binaries from there
(@pxref{Substitutes}).  The only place where human intervention is
needed is to review and apply the patch.


@menu
* Software Freedom::            What may go into the distribution.
* Package Naming::              What's in a name?
* Version Numbers::             When the name is not enough.
* Synopses and Descriptions::   Helping users find the right package.
* Snippets versus Phases::      Whether to use a snippet, or a build phase.
* Cyclic Module Dependencies::  Going full circle.
* Emacs Packages::              Your Elisp fix.
* Python Modules::              A touch of British comedy.
* Perl Modules::                Little pearls.
* Java Packages::               Coffee break.
* Rust Crates::                 Beware of oxidation.
* Elm Packages::                Trees of browser code
* Fonts::                       Fond of fonts.
@end menu

@node Software Freedom
@subsection Software Freedom

@c Adapted from http://www.gnu.org/philosophy/philosophy.html.
@cindex free software
The GNU operating system has been developed so that users can have
freedom in their computing.  GNU is @dfn{free software}, meaning that
users have the @url{https://www.gnu.org/philosophy/free-sw.html,four
essential freedoms}: to run the program, to study and change the program
in source code form, to redistribute exact copies, and to distribute
modified versions.  Packages found in the GNU distribution provide only
software that conveys these four freedoms.

In addition, the GNU distribution follow the
@url{https://www.gnu.org/distros/free-system-distribution-guidelines.html,free
software distribution guidelines}.  Among other things, these guidelines
reject non-free firmware, recommendations of non-free software, and
discuss ways to deal with trademarks and patents.

Some otherwise free upstream package sources contain a small and optional
subset that violates the above guidelines, for instance because this subset
is itself non-free code.  When that happens, the offending items are removed
with appropriate patches or code snippets in the @code{origin} form of the
package (@pxref{Defining Packages}).  This way, @code{guix
build --source} returns the ``freed'' source rather than the unmodified
upstream source.


@node Package Naming
@subsection Package Naming

@cindex package name
A package actually has two names associated with it.
First, there is the name of the @emph{Scheme variable}, the one following
@code{define-public}.  By this name, the package can be made known in the
Scheme code, for instance as input to another package.  Second, there is
the string in the @code{name} field of a package definition.  This name
is used by package management commands such as
@command{guix package} and @command{guix build}.

Both are usually the same and correspond to the lowercase conversion of
the project name chosen upstream, with underscores replaced with
hyphens.  For instance, GNUnet is available as @code{gnunet}, and
SDL_net as @code{sdl-net}.

A noteworthy exception to this rule is when the project name is only a
single character, or if an older maintained project with the same name
already exists---regardless of whether it has already been packaged for
Guix.  Use common sense to make such names unambiguous and meaningful.
For example, Guix's package for the shell called ``s'' upstream is
@code{s-shell} and @emph{not} @code{s}.  Feel free to ask your fellow
hackers for inspiration.

We do not add @code{lib} prefixes for library packages, unless these are
already part of the official project name.  But @pxref{Python
Modules} and @ref{Perl Modules} for special rules concerning modules for
the Python and Perl languages.

Font package names are handled differently, @pxref{Fonts}.


@node Version Numbers
@subsection Version Numbers

@cindex package version
We usually package only the latest version of a given free software
project.  But sometimes, for instance for incompatible library versions,
two (or more) versions of the same package are needed.  These require
different Scheme variable names.  We use the name as defined
in @ref{Package Naming}
for the most recent version; previous versions use the same name, suffixed
by @code{-} and the smallest prefix of the version number that may
distinguish the two versions.

The name inside the package definition is the same for all versions of a
package and does not contain any version number.

For instance, the versions 2.24.20 and 3.9.12 of GTK+ may be packaged as follows:

@lisp
(define-public gtk+
  (package
    (name "gtk+")
    (version "3.9.12")
    ...))
(define-public gtk+-2
  (package
    (name "gtk+")
    (version "2.24.20")
    ...))
@end lisp
If we also wanted GTK+ 3.8.2, this would be packaged as
@lisp
(define-public gtk+-3.8
  (package
    (name "gtk+")
    (version "3.8.2")
    ...))
@end lisp

@c See <https://lists.gnu.org/archive/html/guix-devel/2016-01/msg00425.html>,
@c for a discussion of what follows.
@cindex version number, for VCS snapshots
Occasionally, we package snapshots of upstream's version control system
(VCS) instead of formal releases.  This should remain exceptional,
because it is up to upstream developers to clarify what the stable
release is.  Yet, it is sometimes necessary.  So, what should we put in
the @code{version} field?

Clearly, we need to make the commit identifier of the VCS snapshot
visible in the version string, but we also need to make sure that the
version string is monotonically increasing so that @command{guix package
--upgrade} can determine which version is newer.  Since commit
identifiers, notably with Git, are not monotonically increasing, we add
a revision number that we increase each time we upgrade to a newer
snapshot.  The resulting version string looks like this:

@example
2.0.11-3.cabba9e
  ^    ^    ^
  |    |    `-- upstream commit ID
  |    |
  |    `--- Guix package revision
  |
latest upstream version
@end example

It is a good idea to strip commit identifiers in the @code{version}
field to, say, 7 digits.  It avoids an aesthetic annoyance (assuming
aesthetics have a role to play here) as well as problems related to OS
limits such as the maximum shebang length (127 bytes for the Linux
kernel).  There are helper functions for doing this for packages using
@code{git-fetch} or @code{hg-fetch} (see below).  It is best to use the
full commit identifiers in @code{origin}s, though, to avoid ambiguities.
A typical package definition may look like this:


@lisp
(define my-package
  (let ((commit "c3f29bc928d5900971f65965feaae59e1272a3f7")
        (revision "1"))          ;Guix package revision
    (package
      (version (git-version "0.9" revision commit))
      (source (origin
                (method git-fetch)
                (uri (git-reference
                      (url "git://example.org/my-package.git")
                      (commit commit)))
                (sha256 (base32 "1mbikn@dots{}"))
                (file-name (git-file-name name version))))
      ;; @dots{}
      )))
@end lisp

@deffn {Procedure} git-version @var{VERSION} @var{REVISION} @var{COMMIT}
Return the version string for packages using @code{git-fetch}.

@lisp
(git-version "0.2.3" "0" "93818c936ee7e2f1ba1b315578bde363a7d43d05")
@result{} "0.2.3-0.93818c9"
@end lisp
@end deffn

@deffn {Procedure} hg-version @var{VERSION} @var{REVISION} @var{CHANGESET}
Return the version string for packages using @code{hg-fetch}.  It works
in the same way as @code{git-version}.
@end deffn

@node Synopses and Descriptions
@subsection Synopses and Descriptions

@cindex package description
@cindex package synopsis
As we have seen before, each package in GNU@tie{}Guix includes a
synopsis and a description (@pxref{Defining Packages}).  Synopses and
descriptions are important: They are what @command{guix package
--search} searches, and a crucial piece of information to help users
determine whether a given package suits their needs.  Consequently,
packagers should pay attention to what goes into them.

Synopses must start with a capital letter and must not end with a
period.  They must not start with ``a'' or ``the'', which usually does
not bring anything; for instance, prefer ``File-frobbing tool'' over ``A
tool that frobs files''.  The synopsis should say what the package
is---e.g., ``Core GNU utilities (file, text, shell)''---or what it is
used for---e.g., the synopsis for GNU@tie{}grep is ``Print lines
matching a pattern''.

Keep in mind that the synopsis must be meaningful for a very wide
audience.  For example, ``Manipulate alignments in the SAM format''
might make sense for a seasoned bioinformatics researcher, but might be
fairly unhelpful or even misleading to a non-specialized audience.  It
is a good idea to come up with a synopsis that gives an idea of the
application domain of the package.  In this example, this might give
something like ``Manipulate nucleotide sequence alignments'', which
hopefully gives the user a better idea of whether this is what they are
looking for.

Descriptions should take between five and ten lines.  Use full
sentences, and avoid using acronyms without first introducing them.
Please avoid marketing phrases such as ``world-leading'',
``industrial-strength'', and ``next-generation'', and avoid superlatives
like ``the most advanced''---they are not helpful to users looking for a
package and may even sound suspicious.  Instead, try to be factual,
mentioning use cases and features.

@cindex Texinfo markup, in package descriptions
Descriptions can include Texinfo markup, which is useful to introduce
ornaments such as @code{@@code} or @code{@@dfn}, bullet lists, or
hyperlinks (@pxref{Overview,,, texinfo, GNU Texinfo}).  However you
should be careful when using some characters for example @samp{@@} and
curly braces which are the basic special characters in Texinfo
(@pxref{Special Characters,,, texinfo, GNU Texinfo}).  User interfaces
such as @command{guix show} take care of rendering it
appropriately.

Synopses and descriptions are translated by volunteers
@uref{https://translate.fedoraproject.org/projects/guix/packages, at
Weblate} so that as many users as possible can read them in
their native language.  User interfaces search them and display them in
the language specified by the current locale.

To allow @command{xgettext} to extract them as translatable strings,
synopses and descriptions @emph{must be literal strings}.  This means
that you cannot use @code{string-append} or @code{format} to construct
these strings:

@lisp
(package
  ;; @dots{}
  (synopsis "This is translatable")
  (description (string-append "This is " "*not*" " translatable.")))
@end lisp

Translation is a lot of work so, as a packager, please pay even more
attention to your synopses and descriptions as every change may entail
additional work for translators.  In order to help them, it is possible
to make recommendations or instructions visible to them by inserting
special comments like this (@pxref{xgettext Invocation,,, gettext, GNU
Gettext}):

@lisp
;; TRANSLATORS: "X11 resize-and-rotate" should not be translated.
(description "ARandR is designed to provide a simple visual front end
for the X11 resize-and-rotate (RandR) extension. @dots{}")
@end lisp

@node Snippets versus Phases
@subsection Snippets versus Phases

@cindex snippets, when to use
The boundary between using an origin snippet versus a build phase to
modify the sources of a package can be elusive.  Origin snippets are
typically used to remove unwanted files such as bundled libraries,
nonfree sources, or to apply simple substitutions.  The source derived
from an origin should produce a source that can be used to build the
package on any system that the upstream package supports (i.e., act as
the corresponding source).  In particular, origin snippets must not
embed store items in the sources; such patching should rather be done
using build phases.  Refer to the @code{origin} record documentation for
more information (@pxref{origin Reference}).

@node Cyclic Module Dependencies
@subsection Cyclic Module Dependencies

While there cannot be circular dependencies between packages, Guile's
lax module loading mechanism allows circular dependencies between Guile
modules, which doesn't cause problems as long as the following
conditions are followed for two modules part of a dependency cycle:

@cindex rules to cope with circular module dependencies
@enumerate
@item
Macros are not shared between the co-dependent modules
@item
Top-level variables are only referenced in delayed (@i{thunked}) package
fields: @code{arguments}, @code{native-inputs}, @code{inputs},
@code{propagated-inputs} or @code{replacement}
@item
Procedures referencing top-level variables from another module are not
called at the top level of a module themselves.
@end enumerate

Straying away from the above rules may work while there are no
dependency cycles between modules, but given such cycles are confusing
and difficult to troubleshoot, it is best to follow the rules to avoid
introducing problems down the line.

@noindent
Here is a common trap to avoid:

@lisp
(define-public avr-binutils
  (package
    (inherit (cross-binutils "avr"))
    (name "avr-binutils")))
@end lisp

In the above example, the @code{avr-binutils} package was defined in the
module @code{(gnu packages avr)}, and the @code{cross-binutils}
procedure in @code{(gnu packages cross-base)}.  Because the
@code{inherit} field is not delayed (thunked), it is evaluated at the
top level at load time, which is problematic in the presence of module
dependency cycles.  This could be resolved by turning the package into a
procedure instead, like:

@lisp
(define (make-avr-binutils)
  (package
    (inherit (cross-binutils "avr"))
    (name "avr-binutils")))
@end lisp

Care would need to be taken to ensure the above procedure is only ever
used in a package delayed fields or within another procedure also not
called at the top level.

@node Emacs Packages
@subsection Emacs Packages

@cindex emacs, packaging
@cindex elisp, packaging
Emacs packages should preferably use the Emacs build system
(@pxref{emacs-build-system}), for uniformity and the benefits provided
by its build phases, such as the auto-generation of the autoloads file
and the byte compilation of the sources.  Because there is no
standardized way to run a test suite for Emacs packages, tests are
disabled by default.  When a test suite is available, it should be
enabled by setting the @code{#:tests?} argument to @code{#true}.  By
default, the command to run the test is @command{make check}, but any
command can be specified via the @code{#:test-command} argument.  The
@code{#:test-command} argument expects a list containing a command and
its arguments, to be invoked during the @code{check} phase.

The Elisp dependencies of Emacs packages are typically provided as
@code{propagated-inputs} when required at run time.  As for other
packages, build or test dependencies should be specified as
@code{native-inputs}.

Emacs packages sometimes depend on resources directories that should be
installed along the Elisp files.  The @code{#:include} argument can be
used for that purpose, by specifying a list of regexps to match.  The
best practice when using the @code{#:include} argument is to extend
rather than override its default value (accessible via the
@code{%default-include} variable).  As an example, a yasnippet extension
package typically include a @file{snippets} directory, which could be
copied to the installation directory using:

@lisp
#:include (cons "^snippets/" %default-include)
@end lisp

When encountering problems, it is wise to check for the presence of the
@code{Package-Requires} extension header in the package main source
file, and whether any dependencies and their versions listed therein are
satisfied.

@node Python Modules
@subsection Python Modules

@cindex python
We currently package Python 2 and Python 3, under the Scheme variable names
@code{python-2} and @code{python} as explained in @ref{Version Numbers}.
To avoid confusion and naming clashes with other programming languages, it
seems desirable that the name of a package for a Python module contains
the word @code{python}.

Some modules are compatible with only one version of Python, others with
both.  If the package Foo is compiled with Python 3, we name it
@code{python-foo}.  If it is compiled with Python 2, we name it
@code{python2-foo}.  Python 2 packages are being removed from the
distribution; please do no not submit any new Python 2 packages.

If a project already contains the word @code{python}, we drop this;
for instance, the module python-dateutil is packaged under the names
@code{python-dateutil} and @code{python2-dateutil}.  If the project name
starts with @code{py} (e.g.@: @code{pytz}), we keep it and prefix it as
described above.

@quotation Note
Currently there are two different build systems for Python packages in Guix:
@var{python-build-system} and @var{pyproject-build-system}.  For the
longest time, Python packages were built from an informally specified
@file{setup.py} file.  That worked amazingly well, considering Python's
success, but was difficult to build tooling around.  As a result, a host
of alternative build systems emerged and the community eventually settled on a
@url{https://peps.python.org/pep-0517/, formal standard} for specifying build
requirements.  @var{pyproject-build-system} is Guix's implementation of this
standard.  It is considered ``experimental'' in that it does not yet support
all the various PEP-517 @emph{build backends}, but you are encouraged to try
it for new Python packages and report any problems.  It will eventually be
deprecated and merged into @var{python-build-system}.
@end quotation

@subsubsection Specifying Dependencies
@cindex inputs, for Python packages

Dependency information for Python packages is usually available in the
package source tree, with varying degrees of accuracy: in the
@file{pyproject.toml} file, the @file{setup.py} file, in
@file{requirements.txt}, or in @file{tox.ini} (the latter mostly for
test dependencies).

Your mission, when writing a recipe for a Python package, is to map
these dependencies to the appropriate type of ``input'' (@pxref{package
Reference, inputs}).  Although the @code{pypi} importer normally does a
good job (@pxref{Invoking guix import}), you may want to check the
following check list to determine which dependency goes where.

@itemize

@item
We currently package Python with @code{setuptools} and @code{pip}
installed per default.  This is about to change, and users are encouraged
to use @code{python-toolchain} if they want a build environment for Python.

@command{guix lint} will warn if @code{setuptools} or @code{pip} are
added as native-inputs because they are generally not necessary.

@item
Python dependencies required at run time go into
@code{propagated-inputs}.  They are typically defined with the
@code{install_requires} keyword in @file{setup.py}, or in the
@file{requirements.txt} file.

@item
Python packages required only at build time---e.g., those listed under
@code{build-system.requires} in @file{pyproject.toml} or with the
@code{setup_requires} keyword in @file{setup.py}---or dependencies only
for testing---e.g., those in @code{tests_require} or @file{tox.ini}---go into
@code{native-inputs}.  The rationale is that (1) they do not need to be
propagated because they are not needed at run time, and (2) in a
cross-compilation context, it's the ``native'' input that we'd want.

Examples are the @code{pytest}, @code{mock}, and @code{nose} test
frameworks.  Of course if any of these packages is also required at
run-time, it needs to go to @code{propagated-inputs}.

@item
Anything that does not fall in the previous categories goes to
@code{inputs}, for example programs or C libraries required for building
Python packages containing C extensions.

@item
If a Python package has optional dependencies (@code{extras_require}),
it is up to you to decide whether to add them or not, based on their
usefulness/overhead ratio (@pxref{Submitting Patches, @command{guix
size}}).

@end itemize


@node Perl Modules
@subsection Perl Modules

@cindex perl
Perl programs standing for themselves are named as any other package,
using the lowercase upstream name.
For Perl packages containing a single class, we use the lowercase class name,
replace all occurrences of @code{::} by dashes and prepend the prefix
@code{perl-}.
So the class @code{XML::Parser} becomes @code{perl-xml-parser}.
Modules containing several classes keep their lowercase upstream name and
are also prepended by @code{perl-}.  Such modules tend to have the word
@code{perl} somewhere in their name, which gets dropped in favor of the
prefix.  For instance, @code{libwww-perl} becomes @code{perl-libwww}.


@node Java Packages
@subsection Java Packages

@cindex java
Java programs standing for themselves are named as any other package,
using the lowercase upstream name.

To avoid confusion and naming clashes with other programming languages,
it is desirable that the name of a package for a Java package is
prefixed with @code{java-}.  If a project already contains the word
@code{java}, we drop this; for instance, the package @code{ngsjava} is
packaged under the name @code{java-ngs}.

For Java packages containing a single class or a small class hierarchy,
we use the lowercase class name, replace all occurrences of @code{.} by
dashes and prepend the prefix @code{java-}.  So the class
@code{apache.commons.cli} becomes package
@code{java-apache-commons-cli}.


@node Rust Crates
@subsection Rust Crates

@cindex rust
Rust programs standing for themselves are named as any other package, using the
lowercase upstream name.

To prevent namespace collisions we prefix all other Rust packages with the
@code{rust-} prefix.  The name should be changed to lowercase as appropriate and
dashes should remain in place.

In the rust ecosystem it is common for multiple incompatible versions of a
package to be used at any given time, so all package definitions should have a
versioned suffix.  The versioned suffix is the left-most non-zero digit (and
any leading zeros, of course).  This follows the ``caret'' version scheme
intended by Cargo.  Examples@: @code{rust-clap-2}, @code{rust-rand-0.6}.

Because of the difficulty in reusing rust packages as pre-compiled inputs for
other packages the Cargo build system (@pxref{Build Systems,
@code{cargo-build-system}}) presents the @code{#:cargo-inputs} and
@code{cargo-development-inputs} keywords as build system arguments.  It would be
helpful to think of these as similar to @code{propagated-inputs} and
@code{native-inputs}.  Rust @code{dependencies} and @code{build-dependencies}
should go in @code{#:cargo-inputs}, and @code{dev-dependencies} should go in
@code{#:cargo-development-inputs}.  If a Rust package links to other libraries
then the standard placement in @code{inputs} and the like should be used.

Care should be taken to ensure the correct version of dependencies are used; to
this end we try to refrain from skipping the tests or using @code{#:skip-build?}
when possible.  Of course this is not always possible, as the package may be
developed for a different Operating System, depend on features from the Nightly
Rust compiler, or the test suite may have atrophied since it was released.


@node Elm Packages
@subsection Elm Packages

@cindex Elm
Elm applications can be named like other software: their names need not
mention Elm.

Packages in the Elm sense (see @code{elm-build-system} under @ref{Build
Systems}) are required use names of the format
@var{author}@code{/}@var{project}, where both the @var{author} and the
@var{project} may contain hyphens internally, and the @var{author} sometimes
contains uppercase letters.

To form the Guix package name from the upstream name, we follow a convention
similar to Python packages (@pxref{Python Modules}), adding an @code{elm-}
prefix unless the name would already begin with @code{elm-}.

In many cases we can reconstruct an Elm package's upstream name heuristically,
but, since conversion to a Guix-style name involves a loss of information,
this is not always possible.  Care should be taken to add the
@code{'upstream-name} property when necessary so that @samp{guix import elm}
will work correctly (@pxref{Invoking guix import}). The most notable scenarios
when explicitly specifying the upstream name is necessary are:

@enumerate
@item
When the @var{author} is @code{elm} and the @var{project} contains one or more
hyphens, as with @code{elm/virtual-dom}; and

@item
When the @var{author} contains hyphens or uppercase letters, as with
@code{Elm-Canvas/raster-shapes}---unless the @var{author} is
@code{elm-explorations}, which is handled as a special case, so packages like
@code{elm-explorations/markdown} do @emph{not} need to use the
@code{'upstream-name} property.
@end enumerate

The module @code{(guix build-system elm)} provides the following utilities for
working with names and related conventions:

@deffn {Procedure} elm-package-origin @var{elm-name} @var{version} @
  @var{hash}
Returns a Git origin using the repository naming and tagging regime required
for a published Elm package with the upstream name @var{elm-name} at version
@var{version} with sha256 checksum @var{hash}.

For example:
@lisp
(package
  (name "elm-html")
  (version "1.0.0")
  (source
   (elm-package-origin
    "elm/html"
    version
    (base32 "15k1679ja57vvlpinpv06znmrxy09lbhzfkzdc89i01qa8c4gb4a")))
  ...)
@end lisp
@end deffn

@deffn {Procedure} elm->package-name @var{elm-name}
Returns the Guix-style package name for an Elm package with upstream name
@var{elm-name}.

Note that there is more than one possible @var{elm-name} for which
@code{elm->package-name} will produce a given result.
@end deffn

@deffn {Procedure} guix-package->elm-name @var{package}
Given an Elm @var{package}, returns the possibly-inferred upstream name, or
@code{#f} the upstream name is not specified via the @code{'upstream-name}
property and can not be inferred by @code{infer-elm-package-name}.
@end deffn

@deffn {Procedure} infer-elm-package-name @var{guix-name}
Given the @var{guix-name} of an Elm package, returns the inferred upstream
name, or @code{#f} if the upstream name can't be inferred.  If the result is
not @code{#f}, supplying it to @code{elm->package-name} would produce
@var{guix-name}.
@end deffn

@node Fonts
@subsection Fonts

@cindex fonts
For fonts that are in general not installed by a user for typesetting
purposes, or that are distributed as part of a larger software package,
we rely on the general packaging rules for software; for instance, this
applies to the fonts delivered as part of the X.Org system or fonts that
are part of TeX Live.

To make it easier for a user to search for fonts, names for other packages
containing only fonts are constructed as follows, independently of the
upstream package name.

The name of a package containing only one font family starts with
@code{font-}; it is followed by the foundry name and a dash @code{-}
if the foundry is known, and the font family name, in which spaces are
replaced by dashes (and as usual, all upper case letters are transformed
to lower case).
For example, the Gentium font family by SIL is packaged under the name
@code{font-sil-gentium}.

For a package containing several font families, the name of the collection
is used in the place of the font family name.
For instance, the Liberation fonts consist of three families,
Liberation Sans, Liberation Serif and Liberation Mono.
These could be packaged separately under the names
@code{font-liberation-sans} and so on; but as they are distributed together
under a common name, we prefer to package them together as
@code{font-liberation}.

In the case where several formats of the same font family or font collection
are packaged separately, a short form of the format, prepended by a dash,
is added to the package name.  We use @code{-ttf} for TrueType fonts,
@code{-otf} for OpenType fonts and @code{-type1} for PostScript Type 1
fonts.


@node Coding Style
@section Coding Style

In general our code follows the GNU Coding Standards (@pxref{Top,,,
standards, GNU Coding Standards}).  However, they do not say much about
Scheme, so here are some additional rules.

@menu
* Programming Paradigm::        How to compose your elements.
* Modules::                     Where to store your code?
* Data Types and Pattern Matching::  Implementing data structures.
* Formatting Code::             Writing conventions.
@end menu

@node Programming Paradigm
@subsection Programming Paradigm

Scheme code in Guix is written in a purely functional style.  One
exception is code that involves input/output, and procedures that
implement low-level concepts, such as the @code{memoize} procedure.

@node Modules
@subsection Modules
@cindex build-side modules
@cindex host-side modules
Guile modules that are meant to be used on the builder side must live in
the @code{(guix build @dots{})} name space.  They must not refer to
other Guix or GNU modules.  However, it is OK for a ``host-side'' module
to use a build-side module.  As an example, the @code{(guix
search-paths)} module should not be imported and used by a package since
it isn't meant to be used as a ``build-side'' module.  It would also
couple the module with the package's dependency graph, which is
undesirable.

Modules that deal with the broader GNU system should be in the
@code{(gnu @dots{})} name space rather than @code{(guix @dots{})}.

@node Data Types and Pattern Matching
@subsection Data Types and Pattern Matching

The tendency in classical Lisp is to use lists to represent everything,
and then to browse them ``by hand'' using @code{car}, @code{cdr},
@code{cadr}, and co.  There are several problems with that style,
notably the fact that it is hard to read, error-prone, and a hindrance
to proper type error reports.

@findex define-record-type*
@findex match-record
@cindex pattern matching
Guix code should define appropriate data types (for instance, using
@code{define-record-type*}) rather than abuse lists.  In addition, it
should use pattern matching, via Guile’s @code{(ice-9 match)} module,
especially when matching lists (@pxref{Pattern Matching,,, guile, GNU
Guile Reference Manual}); pattern matching for records is better done
using @code{match-record} from @code{(guix records)}, which, unlike
@code{match}, verifies field names at macro-expansion time.

When defining a new record type, keep the @dfn{record type descriptor}
(RTD) private (@pxref{Records,,, guile, GNU Guile Reference Manual}, for
more on records and RTDs).  As an example, the @code{(guix packages)}
module defines @code{<package>} as the RTD for package records but it
does not export it; instead, it exports a type predicate, a constructor,
and field accessors.  Exporting RTDs would make it harder to change the
application binary interface (because code in other modules might be
matching fields by position) and would make it trivial for users to
forge records of that type, bypassing any checks we may have in the
official constructor (such as ``field sanitizers'').

@node Formatting Code
@subsection Formatting Code

@cindex formatting code
@cindex coding style
When writing Scheme code, we follow common wisdom among Scheme
programmers.  In general, we follow the
@url{https://mumble.net/~campbell/scheme/style.txt, Riastradh's Lisp
Style Rules}.  This document happens to describe the conventions mostly
used in Guile’s code too.  It is very thoughtful and well written, so
please do read it.

Some special forms introduced in Guix, such as the @code{substitute*}
macro, have special indentation rules.  These are defined in the
@file{.dir-locals.el} file, which Emacs automatically uses.  Also note
that Emacs-Guix provides @code{guix-devel-mode} mode that indents and
highlights Guix code properly (@pxref{Development,,, emacs-guix, The
Emacs-Guix Reference Manual}).

@cindex indentation, of code
@cindex formatting, of code
If you do not use Emacs, please make sure to let your editor knows these
rules.  To automatically indent a package definition, you can also run:

@example
./pre-inst-env guix style @var{package}
@end example

@noindent
@xref{Invoking guix style}, for more information.

We require all top-level procedures to carry a docstring.  This
requirement can be relaxed for simple private procedures in the
@code{(guix build @dots{})} name space, though.

Procedures should not have more than four positional parameters.  Use
keyword parameters for procedures that take more than four parameters.


@node Submitting Patches
@section Submitting Patches

Development is done using the Git distributed version control system.
Thus, access to the repository is not strictly necessary.  We welcome
contributions in the form of patches as produced by @code{git
format-patch} sent to the @email{guix-patches@@gnu.org} mailing list
(@pxref{Submitting patches to a project,,, git, Git User Manual}).
Contributors are encouraged to take a moment to set some Git repository
options (@pxref{Configuring Git}) first, which can improve the
readability of patches.  Seasoned Guix developers may also want to look
at the section on commit access (@pxref{Commit Access}).

This mailing list is backed by a Debbugs instance, which allows us to
keep track of submissions (@pxref{Tracking Bugs and Changes}).
Each message sent to that mailing list gets a new tracking number
assigned; people can then follow up on the submission by sending email
to @code{@var{ISSUE_NUMBER}@@debbugs.gnu.org}, where @var{ISSUE_NUMBER}
is the tracking number (@pxref{Sending a Patch Series}).

Please write commit logs in the ChangeLog format (@pxref{Change Logs,,,
standards, GNU Coding Standards}); you can check the commit history for
examples.

You can help make the review process more efficient, and increase the
chance that your patch will be reviewed quickly, by describing the
context of your patch and the impact you expect it to have.  For
example, if your patch is fixing something that is broken, describe the
problem and how your patch fixes it.  Tell us how you have tested your
patch.  Will users of the code changed by your patch have to adjust
their workflow at all?  If so, tell us how.  In general, try to imagine
what questions a reviewer will ask, and answer those questions in
advance.

Before submitting a patch that adds or modifies a package definition,
please run through this check list:

@enumerate
@item
If the authors of the packaged software provide a cryptographic
signature for the release tarball, make an effort to verify the
authenticity of the archive.  For a detached GPG signature file this
would be done with the @code{gpg --verify} command.

@item
Take some time to provide an adequate synopsis and description for the
package.  @xref{Synopses and Descriptions}, for some guidelines.

@item
Run @command{guix lint @var{package}}, where @var{package} is the
name of the new or modified package, and fix any errors it reports
(@pxref{Invoking guix lint}).

@item
Run @command{guix style @var{package}} to format the new package definition
according to the project's conventions (@pxref{Invoking guix style}).

@item
Make sure the package builds on your platform, using @command{guix build
@var{package}}.  Also build at least its direct dependents with
@command{guix build --dependents=1 @var{package}}
(@pxref{build-dependents, @command{guix build}}).

@item
We recommend you also try building the package on other supported
platforms.  As you may not have access to actual hardware platforms, we
recommend using the @code{qemu-binfmt-service-type} to emulate them.  In
order to enable it, add the @code{virtualization} service module and the
following service to the list of services in your @code{operating-system}
configuration:

@lisp
(service qemu-binfmt-service-type
 (qemu-binfmt-configuration
   (platforms (lookup-qemu-platforms "arm" "aarch64"))))
@end lisp

Then reconfigure your system.

You can then build packages for different platforms by specifying the
@code{--system} option.  For example, to build the "hello" package for
the armhf or aarch64 architectures, you would run the following
commands, respectively:
@example
guix build --system=armhf-linux --rounds=2 hello
guix build --system=aarch64-linux --rounds=2 hello
@end example

@item
@cindex bundling
Make sure the package does not use bundled copies of software already
available as separate packages.

Sometimes, packages include copies of the source code of their
dependencies as a convenience for users.  However, as a distribution, we
want to make sure that such packages end up using the copy we already
have in the distribution, if there is one.  This improves resource usage
(the dependency is built and stored only once), and allows the
distribution to make transverse changes such as applying security
updates for a given software package in a single place and have them
affect the whole system---something that bundled copies prevent.

@item
Take a look at the profile reported by @command{guix size}
(@pxref{Invoking guix size}).  This will allow you to notice references
to other packages unwillingly retained.  It may also help determine
whether to split the package (@pxref{Packages with Multiple Outputs}),
and which optional dependencies should be used.  In particular, avoid
adding @code{texlive} as a dependency: because of its extreme size, use
@code{texlive-updmap.cfg} procedure instead.

@item
Check that dependent packages (if applicable) are not affected by the
change; @command{guix refresh --list-dependent @var{package}} will help you
do that (@pxref{Invoking guix refresh}).

@item
@cindex determinism, of build processes
@cindex reproducible builds, checking
Check whether the package's build process is deterministic.  This
typically means checking whether an independent build of the package
yields the exact same result that you obtained, bit for bit.

A simple way to do that is by building the same package several times in
a row on your machine (@pxref{Invoking guix build}):

@example
guix build --rounds=2 my-package
@end example

This is enough to catch a class of common non-determinism issues, such
as timestamps or randomly-generated output in the build result.

Another option is to use @command{guix challenge} (@pxref{Invoking guix
challenge}).  You may run it once the package has been committed and
built by @code{@value{SUBSTITUTE-SERVER-1}} to check whether it obtains the same
result as you did.  Better yet: Find another machine that can build it
and run @command{guix publish}.  Since the remote build machine is
likely different from yours, this can catch non-determinism issues
related to the hardware---e.g., use of different instruction set
extensions---or to the operating system kernel---e.g., reliance on
@code{uname} or @file{/proc} files.

@item
When writing documentation, please use gender-neutral wording when
referring to people, such as
@uref{https://en.wikipedia.org/wiki/Singular_they, singular
``they''@comma{} ``their''@comma{} ``them''}, and so forth.

@item
Verify that your patch contains only one set of related changes.
Bundling unrelated changes together makes reviewing harder and slower.

Examples of unrelated changes include the addition of several packages,
or a package update along with fixes to that package.

@item
Please follow our code formatting rules, possibly running
@command{guix style} script to do that automatically for you
(@pxref{Formatting Code}).

@item
When possible, use mirrors in the source URL (@pxref{Invoking guix download}).
Use reliable URLs, not generated ones.  For instance, GitHub archives are not
necessarily identical from one generation to the next, so in this case it's
often better to clone the repository.  Don't use the @code{name} field in
the URL: it is not very useful and if the name changes, the URL will probably
be wrong.

@item
Check if Guix builds (@pxref{Building from Git}) and address the
warnings, especially those about use of undefined symbols.

@item
Make sure your changes do not break Guix and simulate a @command{guix pull}
with:
@example
guix pull --url=/path/to/your/checkout --profile=/tmp/guix.master
@end example

@end enumerate

When posting a patch to the mailing list, use @samp{[PATCH] @dots{}} as
a subject, if your patch is to be applied on a branch other than
@code{master}, say @code{core-updates}, specify it in the subject like
@samp{[PATCH core-updates] @dots{}}.

You may use your email client, the @command{git send-email} command
(@pxref{Sending a Patch Series}) or the @command{mumi send-email}
command (@pxref{Debbugs User Interfaces}).  We prefer to get patches in
plain text messages, either inline or as MIME attachments.  You are
advised to pay attention if your email client changes anything like line
breaks or indentation which could potentially break the patches.

Expect some delay when you submit your very first patch to
@email{guix-patches@@gnu.org}. You have to wait until you get an
acknowledgement with the assigned tracking number. Future acknowledgements
should not be delayed.

When a bug is resolved, please close the thread by sending an email to
@email{@var{ISSUE_NUMBER}-done@@debbugs.gnu.org}.

@menu
* Configuring Git::
* Sending a Patch Series::
@end menu

@node Configuring Git
@subsection Configuring Git
@cindex git configuration
@cindex @code{git format-patch}
@cindex @code{git send-email}

If you have not done so already, you may wish to set a name and email
that will be associated with your commits (@pxref{telling git your name,
, Telling Git your name, git, Git User Manual}).  If you wish to use a
different name or email just for commits in this repository, you can
use @command{git config --local}, or edit @file{.git/config} in the
repository instead of @file{~/.gitconfig}.

@cindex commit-msg hook
Other important Git configuration will automatically be configured when
building the project (@pxref{Building from Git}).  A
@file{.git/hooks/commit-msg} hook will be installed that embeds
@samp{Change-Id} Git @emph{trailers} in your commit messages for
traceability purposes.  It is important to preserve these when editing
your commit messages, particularly if a first version of your proposed
changes was already submitted for review.  If you have a
@file{commit-msg} hook of your own you would like to use with Guix, you
can place it under the @file{.git/hooks/commit-msg.d/} directory.

@node Sending a Patch Series
@subsection Sending a Patch Series
@cindex patch series
@cindex @code{git send-email}
@cindex @code{git format-patch}

@unnumberedsubsubsec Single Patches
@anchor{Single Patches}
The @command{git send-email} command is the best way to send both single
patches and patch series (@pxref{Multiple Patches}) to the Guix mailing
list.  Sending patches as email attachments may make them difficult to
review in some mail clients, and @command{git diff} does not store commit
metadata.

@quotation Note
The @command{git send-email} command is provided by the @code{send-email}
output of the @code{git} package, i.e. @code{git:send-email}.
@end quotation

The following command will create a patch email from the latest commit,
open it in your @var{EDITOR} or @var{VISUAL} for editing, and send it to
the Guix mailing list to be reviewed and merged.  Assuming you have
already configured Git according to @xref{Configuring Git}, you can
simply use:

@example
$ git send-email --annotate -1
@end example

@quotation Tip
To add a prefix to the subject of your patch, you may use the
@option{--subject-prefix} option.  The Guix project uses this to
specify that the patch is intended for a branch or repository
other than the @code{master} branch of
@url{https://git.savannah.gnu.org/cgit/guix.git}.

@example
git send-email --annotate --subject-prefix='PATCH core-updates' -1
@end example
@end quotation

The patch email contains a three-dash separator line after the commit
message.  You may ``annotate'' the patch with explanatory text by adding
it under this line.  If you do not wish to annotate the email, you may
drop the @option{--annotate} option.

If you need to send a revised patch, don't resend it like this or send
a ``fix'' patch to be applied on top of the last one; instead, use
@command{git commit --amend} or @url{https://git-rebase.io,
@command{git rebase}} to modify the commit, and use the
@email{@var{ISSUE_NUMBER}@@debbugs.gnu.org} address and the @option{-v}
flag with @command{git send-email}.

@example
$ git commit --amend
$ git send-email --annotate -v@var{REVISION} \
      --to=@var{ISSUE_NUMBER}@@debbugs.gnu.org -1
@end example

@quotation Note
Due to an apparent bug in @command{git send-email},
@option{-v @var{REVISION}} (with the space) will not work; you
@emph{must} use @option{-v@var{REVISION}}.
@end quotation

You can find out @var{ISSUE_NUMBER} either by searching on the mumi
interface at @url{https://issues.guix.gnu.org} for the name of your patch or
reading the acknowledgement email sent automatically by Debbugs in
reply to incoming bugs and patches, which contains the bug number.

@unnumberedsubsubsec Notifying Teams
@anchor{Notifying Teams}
@cindex teams
If your git checkout has been correctly configured (@pxref{Configuring
Git}), the @command{git send-email} command will automatically notify
the appropriate team members, based on the scope of your changes.  This
relies on the @file{etc/teams.scm} script, which can also be invoked
manually if you do not use the preferred @command{git send-email}
command to submit patches.  To list the available actions of the script,
you can invoke it via the @command{etc/teams.scm help} command.  For
more information regarding teams, @pxref{Teams}.

@quotation Note
On foreign distros, you might have to use @command{./pre-inst-env git
send-email} for @file{etc/teams.scm} to work.
@end quotation

@unnumberedsubsubsec Multiple Patches
@anchor{Multiple Patches}
@cindex cover letter
While @command{git send-email} alone will suffice for a single
patch, an unfortunate flaw in Debbugs means you need to be more
careful when sending multiple patches: if you send them all to the
@email{guix-patches@@gnu.org} address, a new issue will be created
for each patch!

When sending a series of patches, it's best to send a Git ``cover
letter'' first, to give reviewers an overview of the patch series.
We can create a directory called @file{outgoing} containing both
our patch series and a cover letter called @file{0000-cover-letter.patch}
with @command{git format-patch}.

@example
$ git format-patch -@var{NUMBER_COMMITS} -o outgoing \
      --cover-letter
@end example

@quotation Note
@code{git format-patch} accepts a wide range of
@uref{https://git-scm.com/docs/gitrevisions, revision range} specifiers.
For example, if you are working in a branch, you could select all commits
in your branch starting at @code{master}.

@example
$ git format-patch master..@var{MY_BRANCH} -o outgoing \
      --cover-letter
@end example
@end quotation

We can now send @emph{just} the cover letter to the
@email{guix-patches@@gnu.org} address, which will create an issue
that we can send the rest of the patches to.

@example
$ git send-email outgoing/0000-cover-letter.patch --annotate
$ rm outgoing/0000-cover-letter.patch # we don't want to resend it!
@end example

Ensure you edit the email to add an appropriate subject line and
blurb before sending it.  Note the automatically generated shortlog
and diffstat below the blurb.

Once the Debbugs mailer has replied to your cover letter email, you
can send the actual patches to the newly-created issue address.

@example
$ git send-email outgoing/*.patch --to=@var{ISSUE_NUMBER}@@debbugs.gnu.org
$ rm -rf outgoing # we don't need these anymore
@end example

Thankfully, this @command{git format-patch} dance is not necessary
to send an amended patch series, since an issue already exists for
the patchset.

@example
$ git send-email -@var{NUMBER_COMMITS} -v@var{REVISION} \
      --to=@var{ISSUE_NUMBER}@@debbugs.gnu.org
@end example

If need be, you may use @option{--cover-letter --annotate} to send
another cover letter, e.g. for explaining what's changed since the last
revision, and these changes are necessary.

@node Tracking Bugs and Changes
@section Tracking Bugs and Changes

This section describes how the Guix project tracks its bug reports,
patch submissions and topic branches.

@menu
* The Issue Tracker::           The official bug and patch tracker.
* Managing Patches and Branches::  How changes to Guix are managed.
* Debbugs User Interfaces::     Ways to interact with Debbugs.
* Debbugs Usertags::            Tag reports with custom labels.
* Cuirass Build Notifications::  Be alerted of any breakage via RSS feeds.
@end menu

@node The Issue Tracker
@subsection The Issue Tracker

@cindex bug reports, tracking
@cindex patch submissions, tracking
@cindex issue tracking
@cindex Debbugs, issue tracking system
Bug reports and patch submissions are currently tracked using the
Debbugs instance at @uref{https://bugs.gnu.org}.  Bug reports are filed
against the @code{guix} ``package'' (in Debbugs parlance), by sending
email to @email{bug-guix@@gnu.org}, while patch submissions are filed
against the @code{guix-patches} package by sending email to
@email{guix-patches@@gnu.org} (@pxref{Submitting Patches}).

@node Managing Patches and Branches
@subsection Managing Patches and Branches
@cindex branching strategy
@cindex rebuild scheduling strategy

Changes should be posted to @email{guix-patches@@gnu.org}.  This mailing
list fills the patch-tracking database (@pxref{The Issue Tracker}).  It
also allows patches to be picked up and tested by the quality assurance
tooling; the result of that testing eventually shows up on the dashboard
at @indicateurl{https://qa.guix.gnu.org/issue/@var{ISSUE_NUMBER}}, where
@var{ISSUE_NUMBER} is the number assigned by the issue tracker.  Leave
time for a review, without committing anything.

As an exception, some changes considered ``trivial'' or ``obvious'' may
be pushed directly to the @code{master} branch.  This includes changes
to fix typos and reverting commits that caused immediate problems.  This
is subject to being adjusted, allowing individuals to commit directly on
non-controversial changes on parts they’re familiar with.

Changes which affect more than 300 dependent packages (@pxref{Invoking
guix refresh}) should first be pushed to a topic branch other than
@code{master}; the set of changes should be consistent---e.g., ``GNOME
update'', ``NumPy update'', etc.  This allows for testing: the branch
will automatically show up at
@indicateurl{https://qa.guix.gnu.org/branch/@var{branch}}, with an
indication of its build status on various platforms.

@cindex feature branches, coordination
To help coordinate the merging of branches, you must create a new
guix-patches issue each time you create a branch (@pxref{The Issue
Tracker}).  The title of the issue requesting to merge a branch should
have the following format:

@cindex merge requests, template
@example
Request for merging "@var{name}" branch
@end example

The @url{https://qa.guix.gnu.org/, QA infrastructure} recognizes such
issues and lists the merge requests on its main page.  The following
points apply to managing these branches:

@enumerate
@item
The commits on the branch should be a combination of the patches
relevant to the branch.  Patches not related to the topic of the branch
should go elsewhere.

@item
Any changes that can be made on the master branch, should be made on the
master branch.  If a commit can be split to apply part of the changes on
master, this is good to do.

@item
It should be possible to re-create the branch by starting from master
and applying the relevant patches.

@item
Avoid merging master in to the branch.  Prefer rebasing or re-creating
the branch on top of an updated master revision.

@item
Minimise the changes on master that are missing on the branch prior to
merging the branch in to master.  This means that the state of the
branch better reflects the state of master should the branch be merged.

@item
If you don't have commit access, create the ``Request for merging''
issue and request that someone creates the branch.  Include a list of
issues/patches to include on the branch.
@end enumerate

Normally branches will be merged in a ``first come, first merged''
manner, tracked through the guix-patches issues.  If you agree on a
different order with those involved, you can track this by updating
which issues block@footnote{You can mark an issue as blocked by another
by emailing @email{control@@debbugs.gnu.org} with the following line in
the body of the email: @code{block XXXXX by YYYYY}.  Where @code{XXXXX}
is the number for the blocked issue, and @code{YYYYY} is the number for
the issue blocking it.} which other issues.  Therefore, to know which
branch is at the front of the queue, look for the oldest issue, or the
issue that isn't @dfn{blocked} by any other branch merges.  An ordered
list of branches with the open issues is available at
@url{https://qa.guix.gnu.org}.

Once a branch is at the front of the queue, wait until sufficient time
has passed for the build farms to have processed the changes, and for
the necessary testing to have happened.  For example, you can check
@indicateurl{https://qa.guix.gnu.org/branch/@var{branch}} to see
information on some builds and substitute availability.

Once the branch has been merged, the issue should be closed and the
branch deleted.

@cindex work-in-progress branches, wip
@cindex wip branches
Sometimes, a branch may be a work in progress, for example for larger
efforts such as updating the GNOME desktop.  In these cases, the branch
name should reflect this by having the @samp{wip-} prefix.  The QA
infrastructure will avoid building work-in-progress branches, so that
the available resources can be better focused on building the branches
that are ready to be merged.  When the branch is no longer a work in
progress, it should be renamed, with the @samp{wip-} prefix removed, and
only then should the merge requests be created, as documented earlier.

@node Debbugs User Interfaces
@subsection Debbugs User Interfaces

@subsubsection Web interface

@cindex mumi, web interface for issues
A web interface (actually @emph{two} web interfaces!) are available to
browse issues:

@itemize
@item
@url{https://issues.guix.gnu.org} provides a pleasant interface powered
by mumi@footnote{Mumi is a nice piece of software written in Guile, and
you can help!  See
@url{https://git.savannah.gnu.org/cgit/guix/mumi.git}.} to browse bug
reports and patches, and to participate in discussions; mumi also has a
command-line interface as we will see below;
@item
@url{https://bugs.gnu.org/guix} lists bug reports;
@item
@url{https://bugs.gnu.org/guix-patches} lists patch submissions.
@end itemize

To view discussions related to issue number @var{n}, go to
@indicateurl{https://issues.guix.gnu.org/@var{n}} or
@indicateurl{https://bugs.gnu.org/@var{n}}.

@subsubsection Command-Line Interface

@cindex mumi command-line interface
@cindex mumi am
@cindex mumi compose
@cindex mumi send-email
@cindex mumi www
Mumi also comes with a command-line interface that can be used to search
existing issues, open new issues, compose replies, apply and send
patches.  You do not need to use Emacs to use the mumi command-line
client.  You interact with it only on the command-line.

To use the mumi command-line interface, navigate to a local clone of the
Guix git repository, and drop into a shell with mumi, git and
git:send-email installed.

@example
$ cd guix
~/guix$ guix shell mumi git git:send-email
@end example

To search for issues, say all open issues about "zig", run

@example
~/guix [env]$ mumi search zig is:open

#60889 Add zig-build-system
opened on 17 Jan 17:37 Z by Ekaitz Zarraga
#61036 [PATCH 0/3] Update zig to 0.10.1
opened on 24 Jan 09:42 Z by Efraim Flashner
#39136 [PATCH] gnu: services: Add endlessh.
opened on 14 Jan 2020 21:21 by Nicol? Balzarotti
#60424 [PATCH] gnu: Add python-online-judge-tools
opened on 30 Dec 2022 07:03 by gemmaro
#45601 [PATCH 0/6] vlang 0.2 update
opened on  1 Jan 2021 19:23 by Ryan Prior
@end example

Pick an issue and make it the "current" issue.

@example
~/guix [env]$ mumi current 61036

#61036 [PATCH 0/3] Update zig to 0.10.1
opened on 24 Jan 09:42 Z by Efraim Flashner
@end example

Once an issue is the current issue, you can open the issue in a web
browser, compose replies, apply patches, send patches, etc. with short
succinct commands.

Open the issue in your web browser using

@example
~/guix [env]$ mumi www
@end example

Compose a reply using

@example
~/guix [env]$ mumi compose
@end example

Compose a reply and close the issue using

@example
~/guix [env]$ mumi compose --close
@end example

@command{mumi compose} opens your mail client by passing @samp{mailto:}
URIs to @command{xdg-open}.  So, you need to have @command{xdg-open} set
up to open your mail client correctly.

Apply the latest patchset from the issue using

@example
~/guix [env]$ mumi am
@end example

You may also apply a patchset of a specific version (say, v3) using

@example
~/guix [env]$ mumi am v3
@end example

Or, you may apply a patch from a specific e-mail message.  For example,
to apply the patch from the 4th message (message index starts from 0),
run

@example
~/guix [env]$ mumi am @@4
@end example

@command{mumi am} is a wrapper around @command{git am}.  You can pass
@command{git am} arguments to it after a @samp{--}.  For example, to add
a Signed-off-by trailer, run

@example
~/guix [env]$ mumi am -- -s
@end example

Create and send patches to the issue using

@example
~/guix [env]$ git format-patch origin/master
~/guix [env]$ mumi send-email foo.patch bar.patch
@end example

Note that you do not have to pass in @samp{--to} or @samp{--cc}
arguments to @command{git format-patch}.  @command{mumi send-email} will
put them in correctly when sending the patches.

To open a new issue, run

@example
~/guix [env]$ mumi new
@end example

and send an email (using @command{mumi compose}) or patches (using
@command{mumi send-email}).

@command{mumi send-email} is really a wrapper around @command{git
send-email} that automates away all the nitty-gritty of sending patches.
It uses the current issue state to automatically figure out the correct
@samp{To} address to send to, other participants to @samp{Cc}, headers
to add, etc.

Also note that, unlike @command{git send-email}, @command{mumi
send-email} works perfectly well with single and multiple patches alike.
It automates away the debbugs dance of sending the first patch, waiting
for a response from debbugs and sending the remaining patches.  It does
so by sending the first patch, polling the server for a response, and
then sending the remaining patches.  This polling can unfortunately take
a few minutes.  So, please be patient.

@subsubsection Emacs Interface

If you use Emacs, you may find it more convenient to interact with
issues using @file{debbugs.el}, which you can install with:

@example
guix install emacs-debbugs
@end example

For example, to list all open issues on @code{guix-patches}, hit:

@example
@kbd{C-u} @kbd{M-x} debbugs-gnu @kbd{RET} @kbd{RET} guix-patches @kbd{RET} n y
@end example

For a more convenient (shorter) way to access both the bugs and patches
submissions, you may want to configure the
@code{debbugs-gnu-default-packages} and
@code{debbugs-gnu-default-severities} Emacs variables (@pxref{Viewing
Bugs within Emacs}).

To search for bugs, @samp{@kbd{M-x} debbugs-gnu-guix-search} can be
used.

@xref{Top,,, debbugs-ug, Debbugs User Guide}, for more information on
this nifty tool!

@node Debbugs Usertags
@subsection Debbugs Usertags

@cindex usertags, for debbugs
@cindex Debbugs usertags
Debbugs provides a feature called @dfn{usertags} that allows any user to
tag any bug with an arbitrary label.  Bugs can be searched by usertag,
so this is a handy way to organize bugs@footnote{The list of usertags is
public information, and anyone can modify any user's list of usertags,
so keep that in mind if you choose to use this feature.}.  If you use
Emacs Debbugs, the entry-point to consult existing usertags is the
@samp{C-u M-x debbugs-gnu-usertags} procedure.  To set a usertag, press
@samp{C} while consulting a bug within the *Guix-Patches* buffer opened
with @samp{C-u M-x debbugs-gnu-bugs} buffer, then select @code{usertag}
and follow the instructions.

For example, to view all the bug reports (or patches, in the case of
@code{guix-patches}) tagged with the usertag @code{powerpc64le-linux}
for the user @code{guix}, open a URL like the following in a web
browser:
@url{https://debbugs.gnu.org/cgi-bin/pkgreport.cgi?tag=powerpc64le-linux;users=guix}.

For more information on how to use usertags, please refer to the
documentation for Debbugs or the documentation for whatever tool you use
to interact with Debbugs.

In Guix, we are experimenting with usertags to keep track of
architecture-specific issues, as well as reviewed ones.  To facilitate
collaboration, all our usertags are associated with the single user
@code{guix}.  The following usertags currently exist for that user:

@table @code

@item powerpc64le-linux
The purpose of this usertag is to make it easy to find the issues that
matter most for the @code{powerpc64le-linux} system type.  Please assign
this usertag to bugs or patches that affect @code{powerpc64le-linux} but
not other system types.  In addition, you may use it to identify issues
that for some reason are particularly important for the
@code{powerpc64le-linux} system type, even if the issue affects other
system types, too.

@item reproducibility
For issues related to reproducibility.  For example, it would be
appropriate to assign this usertag to a bug report for a package that
fails to build reproducibly.

@item reviewed-looks-good
You have reviewed the series and it looks good to you (LGTM).

@end table

If you're a committer and you want to add a usertag, just start using it
with the @code{guix} user.  If the usertag proves useful to you,
consider updating this section of the manual so that others will know
what your usertag means.

@node Cuirass Build Notifications
@subsection Cuirass Build Notifications

@cindex build event notifications, RSS feed
@cindex notifications, build events
Cuirass includes @acronym{RSS, Really Simple Syndication} feeds as one
of its features (@pxref{Notifications,,,cuirass}).  Since
@url{https://ci.guix.gnu.org/, Berlin} runs an instance of Cuirass, this
feature can be used to keep track of recently broken or fixed packages
caused by changes pushed to the Guix git repository.  Any RSS client can
be used.  A good one, included with Emacs, is @xref{Gnus,,,gnus}.  To
register the feed, copy its URL, then from the main Gnus buffer,
@samp{*Group*}, do the following:

@cindex Gnus, configuration to read CI RSS feeds
@cindex RSS feeds, Gnus configuration
@example
@kbd{G R} https://ci.guix.gnu.org/events/rss/?specification=master RET
Guix CI - master RET Build events for specification master. RET
@end example

@noindent
Then, back at the @samp{*Group*} buffer, press @kbd{s} to save the newly
added RSS group.  As for any other Gnus group, you can update its
content by pressing the @kbd{g} key.  You should now receive
notifications that read like:

@example
 . [ ?: Cuirass ] Build tree-sitter-meson.aarch64-linux on master is fixed.
 . [ ?: Cuirass ] Build rust-pbkdf2.aarch64-linux on master is fixed.
 . [ ?: Cuirass ] Build rust-pbkdf2.x86_64-linux on master is fixed.
@end example

@noindent
where each RSS entry contains a link to the Cuirass build details page
of the associated build.

@node Teams
@section Teams
@cindex teams

To organize work on Guix, including but not just development efforts,
the project has a set of @dfn{teams}.  Each team has its own focus and
interests and is the primary contact point for questions and
contributions in those areas.  A team's primary mission is to coordinate
and review the work of individuals in its scope (@pxref{Reviewing the
Work of Others}); it can make decisions within its scope, in agreement
with other teams whenever there is overlap or a close connection, and in
accordance with other project rules such as seeking consensus
(@pxref{Making Decisions}).

As an example, the Python team is responsible for core Python packaging
matters; it can decide to upgrade core Python packages in a dedicated
@code{python-team} branch, in collaboration with any team whose scope is
directly dependent on Python---e.g., the Science team---and following
branching rules (@pxref{Managing Patches and Branches}).  The
Documentation team helps review changes to the documentation and can
initiate overarching documentation changes.  The Translations team
organizes translation of Guix and its manual and coordinates efforts in
that area.  The Core team is responsible for the development of core
functionality and interfaces of Guix; because of its central nature,
some of its work may require soliciting input from the community at
large and seeking consensus before enacting decisions that would affect
the entire community.

Teams are defined in the @file{etc/teams.scm} file in the Guix
repository.  The scope of each team is defined, when applicable, as a
set of files or as a regular expression matching file names.

@cindex team membership
Anyone with interest in a team's domain and willing to contribute to its
work can apply to become a member by contacting current members by
email; commit access is not a precondition.  Membership is formalized by
adding the person's name and email address to @file{etc/teams.scm}.
Members who have not been participating in the team's work for one year
or more may be removed; they are free to reapply for membership later.

@cindex team creation
One or more people may propose the creation of a new team by reaching
out to the community by email at @email{guix-devel@@gnu.org}, clarifying
the intended scope and purpose.  When consensus is reached on the
creation of this team, someone with commit access formalizes its
creation by adding it and its initial members to @file{etc/teams.scm}.

To list existing teams, run the following command from a Guix checkout:

@example
$ ./etc/teams.scm list-teams
id: mentors
name: Mentors
description: A group of mentors who chaperone contributions by newcomers.
members:
+ Charlie Smith <charlie@@example.org>
@dots{}
@end example

@cindex mentoring
You can run the following command to have the Mentors team put in
CC of a patch series:

@example
$ git send-email --to=@var{ISSUE_NUMBER}@@debbugs.gnu.org \
  --header-cmd='etc/teams.scm cc-mentors-header-cmd' *.patch
@end example

The appropriate team or teams can also be inferred from the modified
files.  For instance, if you want to send the two latest commits of the
current Git repository to review, you can run:

@example
$ guix shell -D guix
[env]$ git send-email --to=@var{ISSUE_NUMBER}@@debbugs.gnu.org -2
@end example

@node Making Decisions
@section Making Decisions

@cindex decision making
@cindex consensus seeking
It is expected from all contributors, and even more so from committers,
to help build consensus and make decisions based on consensus.  By using
consensus, we are committed to finding solutions that everyone can live
with.  It implies that no decision is made against significant concerns
and these concerns are actively resolved with proposals that work for
everyone.

A contributor (who may or may not have commit access) wishing to block
a proposal bears a special responsibility for finding alternatives,
proposing ideas/code or explain the rationale for the status quo to
resolve the deadlock.  To learn what consensus decision making means and
understand its finer details, you are encouraged to read
@url{https://www.seedsforchange.org.uk/consensus}.

@node Commit Access
@section Commit Access

@cindex commit access, for developers
Everyone can contribute to Guix without having commit access
(@pxref{Submitting Patches}).  However, for frequent contributors,
having write access to the repository can be convenient.  As a rule of
thumb, a contributor should have accumulated fifty (50) reviewed commits
to be considered as a committer and have sustained their activity in the
project for at least 6 months.  This ensures enough interactions with
the contributor, which is essential for mentoring and assessing whether
they are ready to become a committer.  Commit access should not be
thought of as a ``badge of honor'' but rather as a responsibility a
contributor is willing to take to help the project.

Committers are in a position where they enact technical decisions.  Such
decisions must be made by @emph{actively building consensus} among
interested parties and stakeholders.  @xref{Making Decisions}, for more
on that.

The following sections explain how to get commit access, how to be ready
to push commits, and the policies and community expectations for commits
pushed upstream.

@subsection Applying for Commit Access

When you deem it necessary, consider applying for commit
access by following these steps:

@enumerate
@item
Find three committers who would vouch for you.  You can view the list of
committers at
@url{https://savannah.gnu.org/project/memberlist.php?group=guix}.  Each
of them should email a statement to @email{guix-maintainers@@gnu.org} (a
private alias for the collective of maintainers), signed with their
OpenPGP key.

Committers are expected to have had some interactions with you as a
contributor and to be able to judge whether you are sufficiently
familiar with the project's practices.  It is @emph{not} a judgment on
the value of your work, so a refusal should rather be interpreted as
``let's try again later''.

@item
Send @email{guix-maintainers@@gnu.org} a message stating your intent,
listing the three committers who support your application, signed with
the OpenPGP key you will use to sign commits, and giving its fingerprint
(see below).  See @uref{https://emailselfdefense.fsf.org/en/}, for an
introduction to public-key cryptography with GnuPG.

@c See <https://sha-mbles.github.io/>.
Set up GnuPG such that it never uses the SHA1 hash algorithm for digital
signatures, which is known to be unsafe since 2019, for instance by
adding the following line to @file{~/.gnupg/gpg.conf} (@pxref{GPG
Esoteric Options,,, gnupg, The GNU Privacy Guard Manual}):

@example
digest-algo sha512
@end example

@item
Maintainers ultimately decide whether to grant you commit access,
usually following your referrals' recommendation.

@item
@cindex OpenPGP, signed commits
If and once you've been given access, please send a message to
@email{guix-devel@@gnu.org} to say so, again signed with the OpenPGP key
you will use to sign commits (do that before pushing your first commit).
That way, everyone can notice and ensure you control that OpenPGP key.

@quotation Important
Before you can push for the first time, maintainers must:

@enumerate
@item
add your OpenPGP key to the @code{keyring} branch;
@item
add your OpenPGP fingerprint to the @file{.guix-authorizations} file of
the branch(es) you will commit to.
@end enumerate
@end quotation

@item
Make sure to read the rest of this section and... profit!
@end enumerate

@quotation Note
Maintainers are happy to give commit access to people who have been
contributing for some time and have a track record---don't be shy and
don't underestimate your work!

However, note that the project is working towards a more automated patch
review and merging system, which, as a consequence, may lead us to have
fewer people with commit access to the main repository.  Stay tuned!
@end quotation

All commits that are pushed to the central repository on Savannah must
be signed with an OpenPGP key, and the public key should be uploaded to
your user account on Savannah and to public key servers, such as
@code{keys.openpgp.org}.  To configure Git to automatically sign
commits, run:

@example
git config commit.gpgsign true

# Substitute the fingerprint of your public PGP key.
git config user.signingkey CABBA6EA1DC0FF33
@end example

To check that commits are signed with correct key, use:

@example
guix git authenticate
@end example

@xref{Building from Git} for running the first authentication of a Guix
checkout.

To avoid accidentally pushing unsigned or signed with the wrong key
commits to Savannah, make sure to configure Git according to
@xref{Configuring Git}.

@subsection Commit Policy

If you get commit access, please make sure to follow the policy below
(discussions of the policy can take place on
@email{guix-devel@@gnu.org}).

Ensure you're aware of how the changes should be handled
(@pxref{Managing Patches and Branches}) prior to being pushed to the
repository, especially for the @code{master} branch.

If you're committing and pushing your own changes, try and wait at least
one week (two weeks for more significant changes, up to one month for
changes such as removing a package---@pxref{package-removal-policy,
Package Removal}) after you send them for review.  After this, if no one
else is available to review them and if you're confident about the
changes, it's OK to commit.

When pushing a commit on behalf of somebody else, please add a
@code{Signed-off-by} line at the end of the commit log message---e.g.,
with @command{git am --signoff}.  This improves tracking of who did
what.

When adding channel news entries (@pxref{Channels, Writing Channel
News}), make sure they are well-formed by running the following command
right before pushing:

@example
make check-channel-news
@end example

@subsection Addressing Issues

Peer review (@pxref{Submitting Patches}) and tools such as
@command{guix lint} (@pxref{Invoking guix lint}) and the test suite
(@pxref{Running the Test Suite}) should catch issues before they are
pushed.  Yet, commits that ``break'' functionality might occasionally
go through.  When that happens, there are two priorities: mitigating
the impact, and understanding what happened to reduce the chance of
similar incidents in the future.  The responsibility for both these
things primarily lies with those involved, but like everything this is
a group effort.

Some issues can directly affect all users---for instance because they
make @command{guix pull} fail or break core functionality, because they
break major packages (at build time or run time), or because they
introduce known security vulnerabilities.

@cindex reverting commits
The people involved in authoring, reviewing, and pushing such
commit(s) should be at the forefront to mitigate their impact in a
timely fashion: by pushing a followup commit to fix it (if possible),
or by reverting it to leave time to come up with a proper fix, and by
communicating with other developers about the problem.

If these persons are unavailable to address the issue in time, other
committers are entitled to revert the commit(s), explaining in the
commit log and on the mailing list what the problem was, with the goal
of leaving time to the original committer, reviewer(s), and author(s)
to propose a way forward.

Once the problem has been dealt with, it is the responsibility of
those involved to make sure the situation is understood.  If you are
working to understand what happened, focus on gathering information
and avoid assigning any blame.  Do ask those involved to describe what
happened, do not ask them to explain the situation---this would
implicitly blame them, which is unhelpful.  Accountability comes from
a consensus about the problem, learning from it and improving
processes so that it's less likely to reoccur.

@subsection Commit Revocation

In order to reduce the possibility of mistakes, committers will have
their Savannah account removed from the Guix Savannah project and their
key removed from @file{.guix-authorizations} after 12 months of
inactivity; they can ask to regain commit access by emailing the
maintainers, without going through the vouching process.

Maintainers@footnote{See @uref{https://guix.gnu.org/en/about} for the
current list of maintainers.  You can email them privately at
@email{guix-maintainers@@gnu.org}.} may also revoke an individual's
commit rights, as a last resort, if cooperation with the rest of the
community has caused too much friction---even within the bounds of the
project's code of conduct (@pxref{Contributing}).  They would only do so
after public or private discussion with the individual and a clear
notice.  Examples of behavior that hinders cooperation and could lead to
such a decision include:

@itemize
@item repeated violation of the commit policy stated above;
@item repeated failure to take peer criticism into account;
@item breaching trust through a series of grave incidents.
@end itemize

When maintainers resort to such a decision, they notify developers on
@email{guix-devel@@gnu.org}; inquiries may be sent to
@email{guix-maintainers@@gnu.org}.  Depending on the situation, the
individual may still be welcome to contribute.

@subsection Helping Out

One last thing: the project keeps moving forward because committers not
only push their own awesome changes, but also offer some of their time
@emph{reviewing} and pushing other people's changes.  As a committer,
you're welcome to use your expertise and commit rights to help other
contributors, too!

@node Reviewing the Work of Others
@section Reviewing the Work of Others

Perhaps the biggest action you can do to help GNU Guix grow as a project
is to review the work contributed by others.  You do not need to be a
committer to do so; applying, reading the source, building, linting and
running other people's series and sharing your comments about your
experience will give some confidence to committers.  You must
ensure the check list found in the @ref{Submitting Patches} section has
been correctly followed.  A reviewed patch series should give the best
chances for the proposed change to be merged faster, so if a change you
would like to see merged hasn't yet been reviewed, this is the most
appropriate thing to do!  If you would like to review changes in a
specific area and to receive notifications for incoming patches relevant
to that domain, consider joining the relevant team(s) (@pxref{Teams}).

@cindex reviewing, guidelines
Review comments should be unambiguous; be as clear and explicit as you
can about what you think should be changed, ensuring the author can take
action on it.  Please try to keep the following guidelines in mind
during review:

@enumerate
@item
@emph{Be clear and explicit about changes you are suggesting}, ensuring
the author can take action on it.  In particular, it is a good idea to
explicitly ask for new revisions when you want it.

@item
@emph{Remain focused: do not change the scope of the work being
reviewed.}  For example, if the contribution touches code that follows a
pattern deemed unwieldy, it would be unfair to ask the submitter to fix
all occurrences of that pattern in the code; to put it simply, if a
problem unrelated to the patch at hand was already there, do not ask the
submitter to fix it.

@item
@emph{Ensure progress.}  As they respond to review, submitters may
submit new revisions of their changes; avoid requesting changes that you
did not request in the previous round of comments.  Overall, the
submitter should get a clear sense of progress; the number of items open
for discussion should clearly decrease over time.

@item
@emph{Aim for finalization.}  Reviewing code is time-consuming.  Your
goal as a reviewer is to put the process on a clear path towards
integration, possibly with agreed-upon changes, or rejection, with a
clear and mutually-understood reasoning.  Avoid leaving the review
process in a lingering state with no clear way out.

@item
@emph{Review is a discussion.}  The submitter's and reviewer's views on
how to achieve a particular change may not always be aligned.  To lead
the discussion, remain focused, ensure progress and aim for
finalization, spending time proportional to the stakes@footnote{The
tendency to discuss minute details at length is often referred to as
``bikeshedding'', where much time is spent discussing each one's
preference for the color of the shed at the expense of progress made on
the project to keep bikes dry.}.  As a reviewer, try hard to explain the
rationale for suggestions you make, and to understand and take into
account the submitter's motivation for doing things in a certain way.
In other words, build consensus with everyone involved (@pxref{Making
Decisions}).
@end enumerate

@cindex LGTM, Looks Good To Me
@cindex review tags
@cindex Reviewed-by, git trailer
When you deem the proposed change adequate and ready for inclusion
within Guix, the following well understood/codified
@samp{Reviewed-by:@tie{}Your@tie{}Name@tie{}<your-email@@example.com>}
@footnote{The @samp{Reviewed-by} Git trailer is used by other projects
such as Linux, and is understood by third-party tools such as the
@samp{b4 am} sub-command, which is able to retrieve the complete
submission email thread from a public-inbox instance and add the Git
trailers found in replies to the commit patches.} line should be used to
sign off as a reviewer, meaning you have reviewed the change and that it
looks good to you:

@itemize
@item
If the @emph{whole} series (containing multiple commits) looks good to
you, reply with
@samp{Reviewed-by:@tie{}Your@tie{}Name@tie{}<your-email@@example.com>}
to the cover page if it has one, or to the last patch of the series
otherwise, adding another @samp{(for the whole series)} comment on the
line below to explicit this fact.

@item
If you instead want to mark a @emph{single commit} as reviewed (but not
the whole series), simply reply with
@samp{Reviewed-by:@tie{}Your@tie{}Name@tie{}<your-email@@example.com>}
to that commit message.
@end itemize

If you are not a committer, you can help others find a @emph{series} you
have reviewed more easily by adding a @code{reviewed-looks-good} usertag
for the @code{guix} user (@pxref{Debbugs Usertags}).

@node Updating the Guix Package
@section Updating the Guix Package

@cindex update-guix-package, updating the guix package
It is sometimes desirable to update the @code{guix} package itself (the
package defined in @code{(gnu packages package-management)}), for
example to make new daemon features available for use by the
@code{guix-service-type} service type.  In order to simplify this task,
the following command can be used:

@example
make update-guix-package
@end example

The @code{update-guix-package} make target will use the last known
@emph{commit} corresponding to @code{HEAD} in your Guix checkout,
compute the hash of the Guix sources corresponding to that commit and
update the @code{commit}, @code{revision} and hash of the @code{guix}
package definition.

To validate that the updated @code{guix} package hashes are correct and
that it can be built successfully, the following command can be run from
the directory of your Guix checkout:

@example
./pre-inst-env guix build guix
@end example

To guard against accidentally updating the @code{guix} package to a
commit that others can't refer to, a check is made that the commit used
has already been pushed to the Savannah-hosted Guix git repository.

This check can be disabled, @emph{at your own peril}, by setting the
@code{GUIX_ALLOW_ME_TO_USE_PRIVATE_COMMIT} environment variable.  When
this variable is set, the updated package source is also added to the
store.  This is used as part of the release process of Guix.

@node Deprecation Policy
@section Deprecation Policy

@cindex deprecation policy
As any lively project with a broad scope, Guix changes all the time and
at all levels.  Because it's user-extensible and programmable,
incompatible changes can directly impact users and make their life
harder.  It is thus important to reduce user-visible incompatible
changes to a minimum and, when such changes are deemed necessary, to
clearly communicate them through a @dfn{deprecation period} so everyone
can adapt with minimum hassle.  This section defines the project's
commitments for smooth deprecation and describes procedures and
mechanisms to honor them.

There are several ways to use Guix; how to handle deprecation will
depend on each use case.  Those can be roughly categorized like this:

@itemize
@item
package management exclusively through the command line;

@item
advanced package management using the manifest and package interfaces;

@item
Home and System management, using the @code{operating-system} and/or
@code{home-environment} interfaces together with the service interfaces;

@item
development or use of external tools that use programming interfaces
such as the @code{(guix ...)} modules.
@end itemize

These use cases form a spectrum with varying degrees of coupling---from
``distant'' to tightly coupled.  Based on this insight, we define the
following @dfn{deprecation policies} that we consider suitable for each
of these levels.

@table @asis
@item Command-line tools
Guix sub-commands should be thought of as remaining available
``forever''.  Once a Guix sub-command is to be removed, it should be
deprecated first, and then remain available for @b{at least one year}
after the first release that deprecated it.

Deprecation should first be announced in the manual and as an entry in
@file{etc/news.scm}; additional communication such as a blog post
explaining the rationale is welcome.  Months before the scheduled
removal date, the command should print a warning explaining how to
migrate.  An example of this is the replacement of @command{guix
environment} by @command{guix shell}, started in October
2021@footnote{For more details on the @command{guix shell} transition,
see
@uref{https://guix.gnu.org/en/blog/2021/from-guix-environment-to-guix-shell/}.}.

Because of the broad impact of such a change, we recommend conducting a
user survey before enacting a plan.

@cindex package deprecation
@item Package name changes
When a package name changes, it must remain available under its old name
for @b{at least one year}.  For example, @code{go-ipfs} was renamed to
@code{kubo} following a decision made upstream; to communicate the name
change to users, the package module provided this definition:

@findex deprecated-package
@lisp
(define-public go-ipfs
  (deprecated-package "go-ipfs" kubo))
@end lisp

That way, someone running @command{guix install go-ipfs} or similar sees
a deprecation warning mentioning the new name.

@cindex package removal policy
@anchor{package-removal-policy}
@item Package removal
Packages whose upstream developers have declared as having reached ``end
of life'' or being unmaintained may be removed; likewise, packages that
have been @b{failing to build for two months or more} may be removed.

There is no formal deprecation mechanism for this case, unless a
replacement exists, in which case the @code{deprecated-package}
procedure mentioned above can be used.

If the package being removed is a ``leaf'' (no other packages depend on
it), it may be removed after a @b{one-month review period} of the patch
removing it (this applies even when the removal has additional
motivations such as security problems affecting the package).

If it has many dependent packages---as is the case for example with
Python version@tie{}2---the relevant team must propose a deprecation
removal agenda and seek consensus with other packagers for @b{at least
one month}.  It may also invite feedback from the broader user
community, for example through a survey.  Removal of all impacted
packages may be gradual, spanning multiple months, to accommodate all
use cases.

When the package being removed is considered popular, whether or not it
is a leaf, its deprecation must be announced as an entry in
@code{etc/news.scm}.

@item Package upgrade
In the case of packages with many dependents and/or many users, an
upgrade may be treated like the @emph{removal} of the previous version.

Examples include major version upgrades of programming language
implementations, as we've seen above with Python, and major upgrades of
``big'' libraries such as Qt or GTK.

@cindex service deprecation
@item Services
Changes to services for Guix Home and Guix System have a direct impact
on user configuration.  For a user, adjusting to interface changes is
rarely rewarding, which is why any such change must be clearly
communicated in advance through deprecation warnings and documentation.

Renaming of variables related to service, home, or system configuration
must be communicated for at least six months before removal using the
@code{(guix deprecation)} mechanisms.  For example, renaming of
@code{murmur-configuration} to @code{mumble-server-configuration} was
communicated through a series of definitions like this one:

@findex define-deprecated/public-alias
@lisp
(define-deprecated/public-alias
  murmur-configuration
  mumble-server-configuration)
@end lisp

Procedures slated for removal may be defined like this:

@findex define-deprecated
@lisp
(define-deprecated (elogind-service #:key (config (elogind-configuration)))
  elogind-service-type
  (service elogind-service-type config))
@end lisp

Record fields, notably fields of service configuration records, must
follow a similar deprecation period.  This is usually achieved through
@i{ad hoc} means though.  For example, the @code{hosts-file} field of
@code{operating-system} was deprecated by adding a @code{sanitized}
property that would emit a warning:

@lisp
(define-record-type* <operating-system>
  ;; @dots{}
  (hosts-file %operating-system-hosts-file         ;deprecated
              (default #f)
              (sanitize warn-hosts-file-field-deprecation)))

(define-deprecated (operating-system-hosts-file os)
  hosts-service-type
  (%operating-system-hosts-file os))
@end lisp

When deprecating interfaces in @code{operating-system},
@code{home-environment}, @code{(gnu services)}, or any popular service,
the deprecation must come with an entry in @code{etc/news.scm}.

@cindex deprecation of programming interfaces
@item Core interfaces
Core programming interfaces, in particular the @code{(guix ...)}
modules, may be relied on by a variety of external tools and channels.
Any incompatible change must be formally deprecated with
@code{define-deprecated}, as shown above, for @b{at least one year}
before removal.  The manual must clearly document the new interface and,
except in obvious cases, explain how to migrate from the old one.

As an example, the @code{build-expression->derivation} procedure was
superseded by @code{gexp->derivation} and remained available as a
deprecated symbol:

@lisp
(define-deprecated (build-expression->derivation store name exp
                                                 #:key @dots{})
  gexp->derivation
  @dots{})
@end lisp

Sometimes bindings are moved from one module to another.  In those
cases, bindings must be reexported from the original module for at least
one year.
@end table

This section does not cover all possible situations but hopefully allows
users to know what to expect and developers to stick to its spirit.
Please email @email{guix-devel@@gnu.org} for any questions.

@cindex documentation
@node Writing Documentation
@section Writing Documentation

Guix is documented using the Texinfo system.  If you are not yet
familiar with it, we accept contributions for documentation in most
formats.  That includes plain text, Markdown, Org, etc.

Documentation contributions can be sent to
@email{guix-patches@@gnu.org}.  Prepend @samp{[DOCUMENTATION]} to the
subject.

When you need to make more than a simple addition to the documentation,
we prefer that you send a proper patch as opposed to sending an email
as described above.  @xref{Submitting Patches} for more information on
how to send your patches.

To modify the documentation, you need to edit @file{doc/guix.texi} and
@file{doc/contributing.texi} (which contains this documentation
section), or @file{doc/guix-cookbook.texi} for the cookbook.  If
you compiled the Guix repository before, you will have
many more @file{.texi} files that are translations of these
documents.  Do not modify them, the translation is managed through
@uref{https://translate.fedoraproject.org/projects/guix, Weblate}.
@xref{Translating Guix} for more information.

To render documentation, you must first make sure that you ran
@command{./configure} in your source tree (@pxref{Running Guix Before
It Is Installed}).  After that you can run one of the following
commands:

@itemize
@item @samp{make doc/guix.info} to compile the Info manual.
      You can check it with @command{info doc/guix.info}.
@item @samp{make doc/guix.html} to compile the HTML version.
      You can point your browser to the relevant file in the
      @file{doc/guix.html} directory.
@item @samp{make doc/guix-cookbook.info} for the cookbook Info manual.
@item @samp{make doc/guix-cookbook.html} for the cookbook HTML version.
@end itemize

@cindex translation
@cindex l10n
@cindex i18n
@cindex native language support
@node Translating Guix
@section Translating Guix

Writing code and packages is not the only way to provide a meaningful
contribution to Guix.  Translating to a language you speak is another
example of a valuable contribution you can make.  This section is designed
to describe the translation process.  It gives you advice on how you can
get involved, what can be translated, what mistakes you should avoid and
what we can do to help you!

Guix is a big project that has multiple components that can be translated.
We coordinate the translation effort on a
@uref{https://translate.fedoraproject.org/projects/guix/,Weblate instance}
hosted by our friends at Fedora.  You will need an account to submit
translations.

Some of the software packaged in Guix also contain translations.  We do not
host a translation platform for them.  If you want to translate a package
provided by Guix, you should contact their developers or find the information
on their website.  As an example, you can find the homepage of the
@code{hello} package by typing @command{guix show hello}.  On the ``homepage''
line, you will see @url{https://www.gnu.org/software/hello/} as the homepage.

Many GNU and non-GNU packages can be translated on the
@uref{https://translationproject.org,Translation Project}.  Some projects
with multiple components have their own platform.  For instance, GNOME has
its own platform, @uref{https://l10n.gnome.org/,Damned Lies}.

Guix has five components hosted on Weblate.

@itemize
@item @code{guix} contains all the strings from the Guix software (the
      guided system installer, the package manager, etc), excluding packages.
@item @code{packages} contains the synopsis (single-sentence description
      of a package) and description (longer description) of packages in Guix.
@item @code{website} contains the official Guix website, except for
      blog posts and multimedia content.
@item @code{documentation-manual} corresponds to this manual.
@item @code{documentation-cookbook} is the component for the cookbook.
@end itemize

@subsubheading General Directions

Once you get an account, you should be able to select a component from
@uref{https://translate.fedoraproject.org/projects/guix/,the guix project},
and select a language.  If your language does not appear in the list, go
to the bottom and click on the ``Start new translation'' button.  Select
the language you want to translate to from the list, to start your new
translation.

Like lots of other free software packages, Guix uses
@uref{https://www.gnu.org/software/gettext,GNU Gettext} for its translations,
with which translatable strings are extracted from the source code to so-called
PO files.

Even though PO files are text files, changes should not be made with a text
editor but with PO editing software.  Weblate integrates PO editing
functionality.  Alternatively, translators can use any of various
free-software tools for filling in translations, of which
@uref{https://poedit.net/,Poedit} is one example, and (after logging in)
@uref{https://docs.weblate.org/en/latest/user/files.html,upload} the changed
file.  There is also a special
@uref{https://www.emacswiki.org/emacs/PoMode,PO editing mode} for users of GNU
Emacs.  Over time translators find out what software they are happy with and
what features they need.

On Weblate, you will find various links to the editor, that will show various
subsets (or all) of the strings.  Have a look around and at the
@uref{https://docs.weblate.org/en/latest/,documentation} to familiarize
yourself with the platform.

@subsubheading Translation Components

In this section, we provide more detailed guidance on the translation
process, as well as details on what you should or should not do.  When in
doubt, please contact us, we will be happy to help!

@table @asis
@item guix
Guix is written in the Guile programming language, and some strings contain
special formatting that is interpreted by Guile.  These special formatting
should be highlighted by Weblate.  They start with @code{~} followed by one
or more characters.

When printing the string, Guile replaces the special formatting symbols with
actual values.  For instance, the string @samp{ambiguous package specification
`~a'} would be substituted to contain said package specification instead of
@code{~a}.  To properly translate this string, you must keep the formatting
code in your translation, although you can place it where it makes sense in
your language.  For instance, the French translation says @samp{spécification
du paquet « ~a » ambiguë} because the adjective needs to be placed in the
end of the sentence.

If there are multiple formatting symbols, make sure to respect the order.
Guile does not know in which order you intended the string to be read, so it
will substitute the symbols in the same order as the English sentence.

As an example, you cannot translate @samp{package '~a' has been superseded by
'~a'} by @samp{'~a' superseeds package '~a'}, because the meaning would be
reversed.  If @var{foo} is superseded by @var{bar}, the translation would read
@samp{'foo' superseeds package 'bar'}.  To work around this problem, it
is possible to use more advanced formatting to select a given piece of data,
instead of following the default English order.  @xref{Formatted Output,,,
guile, GNU Guile Reference Manual}, for more information on formatting in Guile.

@item packages

Package descriptions occasionally contain Texinfo markup (@pxref{Synopses
and Descriptions}).   Texinfo markup looks like @samp{@@code@{rm -rf@}},
@samp{@@emph@{important@}}, etc.  When translating, please leave markup as is.

The characters after ``@@'' form the name of the markup, and the text between
``@{'' and ``@}'' is its content.  In general, you should not translate the
content of markup like @code{@@code}, as it contains literal code that do not
change with language.  You can translate the content of formatting markup such
as @code{@@emph}, @code{@@i}, @code{@@itemize}, @code{@@item}.  However, do
not translate the name of the markup, or it will not be recognized.  Do
not translate the word after @code{@@end}, it is the name of the markup that
is closed at this position (e.g.@: @code{@@itemize ... @@end itemize}).

@item documentation-manual and documentation-cookbook

The first step to ensure a successful translation of the manual is to find
and translate the following strings @emph{first}:

@itemize
@item @code{version.texi}: Translate this string as @code{version-xx.texi},
      where @code{xx} is your language code (the one shown in the URL on
      weblate).
@item @code{contributing.texi}: Translate this string as
      @code{contributing.xx.texi}, where @code{xx} is the same language code.
@item @code{Top}: Do not translate this string, it is important for Texinfo.
      If you translate it, the document will be empty (missing a Top node).
      Please look for it, and register @code{Top} as its translation.
@end itemize

Translating these strings first ensure we can include your translation in
the guix repository without breaking the make process or the
@command{guix pull} machinery.

The manual and the cookbook both use Texinfo.  As for @code{packages}, please
keep Texinfo markup as is.  There are more possible markup types in the manual
than in the package descriptions.  In general, do not translate the content
of @code{@@code}, @code{@@file}, @code{@@var}, @code{@@value}, etc.  You
should translate the content of formatting markup such as @code{@@emph},
@code{@@i}, etc.

The manual contains sections that can be referred to by name by @code{@@ref},
@code{@@xref} and @code{@@pxref}.  We have a mechanism in place so you do
not have to translate their content.  If you keep the English title, we will
automatically replace it with your translation of that title.  This ensures
that Texinfo will always be able to find the node. If you decide to change
the translation of the title, the references will automatically be updated
and you will not have to update them all yourself.

When translating references from the cookbook to the manual, you need to
replace the name of the manual and the name of the section.  For instance,
to translate @code{@@pxref@{Defining Packages,,, guix, GNU Guix Reference
Manual@}}, you would replace @code{Defining Packages} with the title of that
section in the translated manual @emph{only} if that title is translated.
If the title is not translated in your language yet, do not translate it here,
or the link will be broken.  Replace @code{guix} with @code{guix.xx} where
@code{xx} is your language code.  @code{GNU Guix Reference Manual} is the
text of the link.  You can translate it however you wish.

@item website

The website pages are written using SXML, an s-expression version of HTML,
the basic language of the web.  We have a process to extract translatable
strings from the source, and replace complex s-expressions with a more familiar
XML markup, where each markup is numbered.  Translators can arbitrarily change
the ordering, as in the following example.

@example
#. TRANSLATORS: Defining Packages is a section name
#. in the English (en) manual.
#: apps/base/templates/about.scm:64
msgid "Packages are <1>defined<1.1>en</1.1><1.2>Defining-Packages.html</1.2></1> as native <2>Guile</2> modules."
msgstr "Pakete werden als reine <2>Guile</2>-Module <1>definiert<1.1>de</1.1><1.2>Pakete-definieren.html</1.2></1>."
@end example

Note that you need to include the same markups.  You cannot skip any.
@end table

In case you make a mistake, the component might fail to build properly with your
language, or even make guix pull fail.  To prevent that, we have a process
in place to check the content of the files before pushing to our repository.
We will not be able to update the translation for your language in Guix, so
we will notify you (through weblate and/or by email) so you get a chance to
fix the issue.

@subsubheading Outside of Weblate

Currently, some parts of Guix cannot be translated on Weblate, help wanted!

@itemize
@item @command{guix pull} news can be translated in @file{news.scm}, but is not
      available from Weblate.  If you want to provide a translation, you
      can prepare a patch as described above, or simply send us your
      translation with the name of the news entry you translated and your
      language. @xref{Writing Channel News}, for more information about
      channel news.
@item Guix blog posts cannot currently be translated.
@item The installer script (for foreign distributions) is entirely in English.
@item Some of the libraries Guix uses cannot be translated or are translated
      outside of the Guix project.  Guile itself is not internationalized.
@item Other manuals linked from this manual or the cookbook might not be
      translated.
@end itemize

@subsubheading Conditions for Inclusion

There are no conditions for adding new translations of the @code{guix} and
@code{guix-packages} components, other than they need at least one translated
string.  New languages will be added to Guix as soon as possible.  The
files may be removed if they fall out of sync and have no more translated
strings.

Given that the web site is dedicated to new users, we want its translation
to be as complete as possible before we include it in the language menu.
For a new language to be included, it needs to reach at least 80% completion.
When a language is included, it may be removed in the future if it stays
out of sync and falls below 60% completion.

The manual and cookbook are automatically added in the default compilation
target.  Every time we synchronize translations, developers need to
recompile all the translated manuals and cookbooks.  This is useless for what
is essentially the English manual or cookbook.  Therefore, we will only
include a new language when it reaches 10% completion in the component.
When a language is included, it may be removed in the future if it stays
out of sync and falls below 5% completion.

@subsubheading Translation Infrastructure

Weblate is backed by a git repository from which it discovers new strings to
translate and pushes new and updated translations.  Normally, it would be
enough to give it commit access to our repositories.  However, we decided
to use a separate repository for two reasons.  First, we would have to give
Weblate commit access and authorize its signing key, but we do not trust it
in the same way we trust guix developers, especially since we do not manage
the instance ourselves.  Second, if translators mess something up, it can
break the generation of the website and/or guix pull for all our users,
independently of their language.

For these reasons, we use a dedicated repository to host translations, and we
synchronize it with our guix and artworks repositories after checking no issue
was introduced in the translation.

Developers can download the latest PO files from weblate in the Guix
repository by running the @command{make download-po} command.  It will
automatically download the latest files from weblate, reformat them to a
canonical form, and check they do not contain issues.  The manual needs to be
built again to check for additional issues that might crash Texinfo.

Before pushing new translation files, developers should add them to the
make machinery so the translations are actually available.  The process
differs for the various components.

@itemize
@item New po files for the @code{guix} and @code{packages} components must
      be registered by adding the new language to @file{po/guix/LINGUAS} or
      @file{po/packages/LINGUAS}.
@item New po files for the @code{documentation-manual} component must be
      registered by adding the file name to @code{DOC_PO_FILES} in
      @file{po/doc/local.mk}, the generated @file{%D%/guix.xx.texi} manual to
      @code{info_TEXINFOS} in @file{doc/local.mk} and the generated
      @file{%D%/guix.xx.texi} and @file{%D%/contributing.xx.texi} to
      @code{TRANSLATED_INFO} also in @file{doc/local.mk}.
@item New po files for the @code{documentation-cookbook} component must be
      registered by adding the file name to @code{DOC_COOKBOOK_PO_FILES} in
      @file{po/doc/local.mk}, the generated @file{%D%/guix-cookbook.xx.texi}
      manual to @code{info_TEXINFOS} in @file{doc/local.mk} and the generated
      @file{%D%/guix-cookbook.xx.texi} to @code{TRANSLATED_INFO} also
      in @file{doc/local.mk}.
@item New po files for the @code{website} component must be added to the
      @code{guix-artwork} repository, in @file{website/po/}.
      @file{website/po/LINGUAS} and @file{website/po/ietf-tags.scm} must
      be updated accordingly (see @file{website/i18n-howto.txt} for more
      information on the process).
@end itemize


@cindex infrastructure
@node Contributing to Guix's Infrastructure
@section Contributing to Guix's Infrastructure

Since its inception, the Guix project has always valued its autonomy, and that
reflects in its infrastructure: our servers run Guix System and exclusively
free software, and are administered by volunteers.

Of course this comes at a cost and this is why we need contributions.  Our hope
is to make infrastructure-related activity more legible so that maybe you can
picture yourself helping in one of these areas.


@menu
* Coding::
* System Administration::
* Day-to-Day System Administration::
* On-Site Intervention::
* Hosting::
* Administrative Tasks::
@end menu

@node Coding
@subsection Coding

The project runs many Guix-specific services; this is all lovely Scheme code
but it tends to receive less attention than Guix itself:

@itemize
@item
Build Farm Front-End: @url{https://git.cbaines.net/guix/bffe, bffe}
@item
Cuirass: @url{https://guix.gnu.org/cuirass/, Cuirass}
@item
Goggles (IRC logger):
@url{https://git.savannah.gnu.org/cgit/guix/maintenance.git/tree/hydra/goggles.scm,
Goggles}
@item
Guix Build Coordinator:
@url{https://git.savannah.gnu.org/cgit/guix/build-coordinator.git/,
Build-Coordinator}
@item
Guix Data Service:
@url{https://git.savannah.gnu.org/git/guix/data-service.git/, Data-Service}
@item
Guix Packages Website:
@url{https://codeberg.org/luis-felipe/guix-packages-website.git,
Guix-Packages-Website}
@item
mumi: @url{https://git.savannah.gnu.org/cgit/guix/mumi.git/, Mumi}
@item
nar-herder: @url{https://git.savannah.gnu.org/cgit/guix/nar-herder.git/,
Nar-Herder}
@item
QA Frontpage:
@url{https://git.savannah.gnu.org/git/guix/qa-frontpage.git, QA-Frontpage}
@end itemize

There is no time constraint on this coding activity: any improvement is
welcome, whenever it comes.  Most of these code bases are relatively small,
which should make it easier to get started.

Prerequisites: Familiarity with Guile, HTTP, and databases.

If you wish to get started, check out the README of the project of your choice
and get in touch with guix-devel and the primary developer(s) of the tool as
per @code{git shortlog -s | sort -k1 -n}.

@node System Administration
@subsection System Administration

Guix System configuration for all our systems is held in this repository:

@url{https://git.savannah.gnu.org/cgit/guix/maintenance.git/tree/hydra/}

The two front-ends are @file{berlin.scm} (the machine behind ci.guix.gnu.org)
and @file{bayfront.scm} (the machine behind bordeaux.guix.gnu.org,
guix.gnu.org, hpc.guix.info, qa.guix.gnu.org, and more).  Both connect to a
number of build machines and helpers.

Without even having SSH access to the machine, you can help by posting patches
to improve the configuration (you can test it with @code{guix system vm}).
Here are ways you can help:

@itemize
@item
Improve infra monitoring: set up a dashboard to monitor all the infrastructure,
and an out-of-band channel to communicate about downtime.

@item
Implement web site redundancy: guix.gnu.org should be backed by several
machines on different sites.  Get in touch with us and/or send a patch!

@item
Implement substitute redundancy: likewise, bordeaux.guix.gnu.org and
ci.guix.gnu.org should be backed by several head nodes.

@item
Improve backup: there's currently ad-hoc backup of selected pieces over rsync
between the two head nodes; we can improve on that, for example with a
dedicated backup site and proper testing of recoverability.

@item
Support mirroring: We'd like to make it easy for others to mirror substitutes
from ci.guix and bordeaux.guix, perhaps by offering public rsync access.

@item
Optimize our web services: Monitor the performance of our services and tweak
nginx config or whatever it takes to improve it.

There is no time constraint on this activity: any improvement is welcome,
whenever you can work on it.

Prerequisite: Familiarity with Guix System administration and ideally with the
infrastructure handbook:

@url{https://git.savannah.gnu.org/cgit/guix/maintenance.git/tree/doc/infra-handbook.org,
Infra-Handbook}

@end itemize

@node Day-to-Day System Administration
@subsection Day-to-Day System Administration

We're also looking for people who'd be willing to have SSH access to some of
the infrastructure to help with day-to-day maintenance: restarting a build,
restarting the occasional service that has gone wild (that can happen),
reconfiguring/upgrading a machine, rebooting, etc.

This day-to-day activity requires you to be available some of the time (during
office hours or not, during the week-end or not), whenever is convenient for
you, so you can react to issues reported on IRC, on the mailing list, or
elsewhere, and synchronize with other sysadmins.

Prerequisite: Being a ``known'' member of the community, familiarity with Guix
System administration, with some of the services/web sites being run, and with
the infrastructure handbook:

@url{https://git.savannah.gnu.org/cgit/guix/maintenance.git/tree/doc/infra-handbook.org,
Infra-Handbook}

@node On-Site Intervention
@subsection On-Site Intervention

The first front-end is currently generously hosted by the Max Delbrück Center
(MDC), a research institute in Berlin, Germany. Only authorized personnel can
physically access it.

The second one, bordeaux.guix.gnu.org, is hosted in Bordeaux, France, in a
professional data center shared with non-profit ISP Aquilenet.  If you live in
the region of Bordeaux and would like to help out when we need to go on-site,
please make yourself known by emailing @email{guix-sysadmin@@gnu.org}.

On-site interventions are rare, but they're usually in response to an
emergency.

@node Hosting
@subsection Hosting

We're looking for people who can host machines and help out whenever
physical access is needed.  More specifically:

@itemize
@item
We need hosting of ``small'' machines such as single-board computers (AArch64,
RISC-V) for use as build machines.

@item
We need hosting for front-ends and x86_64 build machines in a data center where
they can be racked and where, ideally, several local Guix sysadmins can
physically access them.
@end itemize

The machines should be accessible over Wireguard VPN most of the
time, so longer power or network interruptions should be the
exception.

Prerequisites: Familiarity with installing and remotely administering Guix
System.

@node Administrative Tasks
@subsection Administrative Tasks

The infra remains up and running thanks to crucial administrative tasks, which
includes:

@itemize
@item
Selecting and purchasing hardware, for example build machines.
@item
Renewing domain names.

@item
Securing funding, in particular via the Guix Foundation:
@url{https://foundation.guix.info, Guix Foundation}
@end itemize

Prerequisites: Familiarity with hardware, and/or DNS registrars,
and/or sponsorship, and/or crowdfunding.
rget. One way to help is by publishing the software you build using @command{guix publish} so that others have one more choice of server to download substitutes from (@pxref{Invoking guix publish}). Guix has the foundations to maximize build reproducibility (@pxref{Features}). In most cases, independent builds of a given package or derivation should yield bit-identical results. Thus, through a diverse set of independent package builds, we can strengthen the integrity of our systems. The @command{guix challenge} command aims to help users assess substitute servers, and to assist developers in finding out about non-deterministic package builds (@pxref{Invoking guix challenge}). Similarly, the @option{--check} option of @command{guix build} allows users to check whether previously-installed substitutes are genuine by rebuilding them locally (@pxref{build-check, @command{guix build --check}}). In the future, we want Guix to have support to publish and retrieve binaries to/from other users, in a peer-to-peer fashion. If you would like to discuss this project, join us on @email{guix-devel@@gnu.org}. @node Packages with Multiple Outputs @section Packages with Multiple Outputs @cindex multiple-output packages @cindex package outputs @cindex outputs Often, packages defined in Guix have a single @dfn{output}---i.e., the source package leads to exactly one directory in the store. When running @command{guix install glibc}, one installs the default output of the GNU libc package; the default output is called @code{out}, but its name can be omitted as shown in this command. In this particular case, the default output of @code{glibc} contains all the C header files, shared libraries, static libraries, Info documentation, and other supporting files. Sometimes it is more appropriate to separate the various types of files produced from a single source package into separate outputs. For instance, the GLib C library (used by GTK+ and related packages) installs more than 20 MiB of reference documentation as HTML pages. To save space for users who do not need it, the documentation goes to a separate output, called @code{doc}. To install the main GLib output, which contains everything but the documentation, one would run: @example guix install glib @end example @cindex documentation The command to install its documentation is: @example guix install glib:doc @end example While the colon syntax works for command-line specification of package outputs, it will not work when using a package @emph{variable} in Scheme code. For example, to add the documentation of @code{glib} to the globally installed packages of an @code{operating-system} (see @ref{operating-system Reference}), a list of two items, the first one being the package @emph{variable} and the second one the name of the output to select (a string), must be used instead: @lisp (use-modules (gnu packages glib)) ;; glib-with-documentation is the Guile symbol for the glib package (operating-system ... (packages (append (list (list glib-with-documentation "doc")) %base-packages))) @end lisp Some packages install programs with different ``dependency footprints''. For instance, the WordNet package installs both command-line tools and graphical user interfaces (GUIs). The former depend solely on the C library, whereas the latter depend on Tcl/Tk and the underlying X libraries. In this case, we leave the command-line tools in the default output, whereas the GUIs are in a separate output. This allows users who do not need the GUIs to save space. The @command{guix size} command can help find out about such situations (@pxref{Invoking guix size}). @command{guix graph} can also be helpful (@pxref{Invoking guix graph}). There are several such multiple-output packages in the GNU distribution. Other conventional output names include @code{lib} for libraries and possibly header files, @code{bin} for stand-alone programs, and @code{debug} for debugging information (@pxref{Installing Debugging Files}). The outputs of a package are listed in the third column of the output of @command{guix package --list-available} (@pxref{Invoking guix package}). @node Invoking guix locate @section Invoking @command{guix locate} @cindex file, searching in packages @cindex file search @cindex searching for packages There's so much free software out there that sooner or later, you will need to search for packages. The @command{guix search} command that we've seen before (@pxref{Invoking guix package}) lets you search by keywords: @example guix search video editor @end example @cindex searching for packages, by file name Sometimes, you instead want to find which package provides a given file, and this is where @command{guix locate} comes in. Here is how you can find which package provides the @command{ls} command: @example $ guix locate ls coreutils@@9.1 /gnu/store/@dots{}-coreutils-9.1/bin/ls @end example Of course the command works for any file, not just commands: @example $ guix locate unistr.h icu4c@@71.1 /gnu/store/@dots{}/include/unicode/unistr.h libunistring@@1.0 /gnu/store/@dots{}/include/unistr.h @end example You may also specify @dfn{glob patterns} with wildcards. For example, here is how you would search for packages providing @file{.service} files: @example $ guix locate -g '*.service' man-db@@2.11.1 @dots{}/lib/systemd/system/man-db.service wpa-supplicant@@2.10 @dots{}/system-services/fi.w1.wpa_supplicant1.service @end example The @command{guix locate} command relies on a database that maps file names to package names. By default, it automatically creates that database if it does not exist yet by traversing packages available @emph{locally}, which can take a few minutes (depending on the size of your store and the speed of your storage device). @quotation Note For now, @command{guix locate} builds its database based on purely local knowledge---meaning that you will not find packages that never reached your store. Eventually it will support downloading a pre-built database so you can potentially find more packages. @end quotation By default, @command{guix locate} first tries to look for a system-wide database, usually under @file{/var/cache/guix/locate}; if it does not exist or is too old, it falls back to the per-user database, by default under @file{~/.cache/guix/locate}. On a multi-user system, administrators may want to periodically update the system-wide database so that all users can benefit from it, for instance by setting up @code{package-database-service-type} (@pxref{File Search Services, @code{package-database-service-type}}). The general syntax is: @example guix locate [@var{options}@dots{}] @var{file}@dots{} @end example @noindent ... where @var{file} is the name of a file to search for (specifically, the ``base name'' of the file: files whose parent directories are called @var{file} are not matched). The available options are as follows: @table @code @item --glob @item -g Interpret @var{file}@dots{} as @dfn{glob patterns}---patterns that may include wildcards, such as @samp{*.scm} to denote all files ending in @samp{.scm}. @item --stats Display database statistics. @item --update @itemx -u Update the file database. By default, the database is automatically updated when it is too old. @item --clear Clear the database and re-populate it. This option lets you start anew, ensuring old data is removed from the database, which also avoids having an endlessly growing database. By default @command{guix locate} automatically does that periodically, though infrequently. @item --database=@var{file} Use @var{file} as the database, creating it if necessary. By default, @command{guix locate} picks the database under @file{~/.cache/guix} or @file{/var/cache/guix}, whichever is the most recent one. @item --method=@var{method} @itemx -m @var{method} Use @var{method} to select the set of packages to index. Possible values are: @table @code @item manifests This is the default method: it works by traversing profiles on the machine and recording packages it encounters---packages you or other users of the machine installed, directly or indirectly. It is fast but it can miss other packages available in the store but not referred to by any profile. @item store This is a slower but more exhaustive method: it checks among all the existing packages those that are available in the store and records them. @end table @end table @node Invoking guix gc @section Invoking @command{guix gc} @cindex garbage collector @cindex disk space @cindex @command{guix gc} Packages that are installed, but not used, may be @dfn{garbage-collected}. The @command{guix gc} command allows users to explicitly run the garbage collector to reclaim space from the @file{/gnu/store} directory. It is the @emph{only} way to remove files from @file{/gnu/store}---removing files or directories manually may break it beyond repair! @cindex GC roots @cindex garbage collector roots The garbage collector has a set of known @dfn{roots}: any file under @file{/gnu/store} reachable from a root is considered @dfn{live} and cannot be deleted; any other file is considered @dfn{dead} and may be deleted. The set of garbage collector roots (``GC roots'' for short) includes default user profiles; by default, the symlinks under @file{/var/guix/gcroots} represent these GC roots. New GC roots can be added with @command{guix build --root}, for example (@pxref{Invoking guix build}). The @command{guix gc --list-roots} command lists them. Prior to running @code{guix gc --collect-garbage} to make space, it is often useful to remove old generations from user profiles; that way, old package builds referenced by those generations can be reclaimed. This is achieved by running @code{guix package --delete-generations} (@pxref{Invoking guix package}). Our recommendation is to run a garbage collection periodically, or when you are short on disk space. For instance, to guarantee that at least 5@tie{}GB are available on your disk, simply run: @example guix gc -F 5G @end example It is perfectly safe to run as a non-interactive periodic job (@pxref{Scheduled Job Execution}, for how to set up such a job). Running @command{guix gc} with no arguments will collect as much garbage as it can, but that is often inconvenient: you may find yourself having to rebuild or re-download software that is ``dead'' from the GC viewpoint but that is necessary to build other pieces of software---e.g., the compiler tool chain. The @command{guix gc} command has three modes of operation: it can be used to garbage-collect any dead files (the default), to delete specific files (the @option{--delete} option), to print garbage-collector information, or for more advanced queries. The garbage collection options are as follows: @table @code @item --collect-garbage[=@var{min}] @itemx -C [@var{min}] Collect garbage---i.e., unreachable @file{/gnu/store} files and sub-directories. This is the default operation when no option is specified. When @var{min} is given, stop once @var{min} bytes have been collected. @var{min} may be a number of bytes, or it may include a unit as a suffix, such as @code{MiB} for mebibytes and @code{GB} for gigabytes (@pxref{Block size, size specifications,, coreutils, GNU Coreutils}). When @var{min} is omitted, collect all the garbage. @item --free-space=@var{free} @itemx -F @var{free} Collect garbage until @var{free} space is available under @file{/gnu/store}, if possible; @var{free} denotes storage space, such as @code{500MiB}, as described above. When @var{free} or more is already available in @file{/gnu/store}, do nothing and exit immediately. @item --delete-generations[=@var{duration}] @itemx -d [@var{duration}] Before starting the garbage collection process, delete all the generations older than @var{duration}, for all the user profiles and home environment generations; when run as root, this applies to all the profiles @emph{of all the users}. For example, this command deletes all the generations of all your profiles that are older than 2 months (except generations that are current), and then proceeds to free space until at least 10 GiB are available: @example guix gc -d 2m -F 10G @end example @item --delete @itemx -D Attempt to delete all the store files and directories specified as arguments. This fails if some of the files are not in the store, or if they are still live. @item --list-failures List store items corresponding to cached build failures. This prints nothing unless the daemon was started with @option{--cache-failures} (@pxref{Invoking guix-daemon, @option{--cache-failures}}). @item --list-roots List the GC roots owned by the user; when run as root, list @emph{all} the GC roots. @item --list-busy List store items in use by currently running processes. These store items are effectively considered GC roots: they cannot be deleted. @item --clear-failures Remove the specified store items from the failed-build cache. Again, this option only makes sense when the daemon is started with @option{--cache-failures}. Otherwise, it does nothing. @item --list-dead Show the list of dead files and directories still present in the store---i.e., files and directories no longer reachable from any root. @item --list-live Show the list of live store files and directories. @end table In addition, the references among existing store files can be queried: @table @code @item --references @itemx --referrers @cindex package dependencies List the references (respectively, the referrers) of store files given as arguments. @item --requisites @itemx -R @cindex closure List the requisites of the store files passed as arguments. Requisites include the store files themselves, their references, and the references of these, recursively. In other words, the returned list is the @dfn{transitive closure} of the store files. @xref{Invoking guix size}, for a tool to profile the size of the closure of an element. @xref{Invoking guix graph}, for a tool to visualize the graph of references. @item --derivers @cindex derivation Return the derivation(s) leading to the given store items (@pxref{Derivations}). For example, this command: @example guix gc --derivers $(guix package -I ^emacs$ | cut -f4) @end example @noindent returns the @file{.drv} file(s) leading to the @code{emacs} package installed in your profile. Note that there may be zero matching @file{.drv} files, for instance because these files have been garbage-collected. There can also be more than one matching @file{.drv} due to fixed-output derivations. @end table Lastly, the following options allow you to check the integrity of the store and to control disk usage. @table @option @item --verify[=@var{options}] @cindex integrity, of the store @cindex integrity checking Verify the integrity of the store. By default, make sure that all the store items marked as valid in the database of the daemon actually exist in @file{/gnu/store}. When provided, @var{options} must be a comma-separated list containing one or more of @code{contents} and @code{repair}. When passing @option{--verify=contents}, the daemon computes the content hash of each store item and compares it against its hash in the database. Hash mismatches are reported as data corruptions. Because it traverses @emph{all the files in the store}, this command can take a long time, especially on systems with a slow disk drive. @cindex repairing the store @cindex corruption, recovering from Using @option{--verify=repair} or @option{--verify=contents,repair} causes the daemon to try to repair corrupt store items by fetching substitutes for them (@pxref{Substitutes}). Because repairing is not atomic, and thus potentially dangerous, it is available only to the system administrator. A lightweight alternative, when you know exactly which items in the store are corrupt, is @command{guix build --repair} (@pxref{Invoking guix build}). @item --optimize @cindex deduplication Optimize the store by hard-linking identical files---this is @dfn{deduplication}. The daemon performs deduplication after each successful build or archive import, unless it was started with @option{--disable-deduplication} (@pxref{Invoking guix-daemon, @option{--disable-deduplication}}). Thus, this option is primarily useful when the daemon was running with @option{--disable-deduplication}. @item --vacuum-database @cindex vacuum the store database @comment Avoid words like 'repair,' 'compress,' and 'optimize.' Guix uses an sqlite database to keep track of the items in the store (@pxref{The Store}). Over time it is possible that the database may grow to a large size and become fragmented. As a result, one may wish to clear the freed space and join the partially used pages in the database left behind from removed packages or after running the garbage collector. Running @command{sudo guix gc --vacuum-database} will lock the database and @code{VACUUM} the store, defragmenting the database and purging freed pages, unlocking the database when it finishes. @end table @node Invoking guix pull @section Invoking @command{guix pull} @cindex upgrading Guix @cindex updating Guix @cindex @command{guix pull} @cindex pull @cindex security, @command{guix pull} @cindex authenticity, of code obtained with @command{guix pull} Packages are installed or upgraded to the latest version available in the distribution currently available on your local machine. To update that distribution, along with the Guix tools, you must run @command{guix pull}: the command downloads the latest Guix source code and package descriptions, and deploys it. Source code is downloaded from a @uref{https://git-scm.com/book/en/, Git} repository, by default the official GNU@tie{}Guix repository, though this can be customized. @command{guix pull} ensures that the code it downloads is @emph{authentic} by verifying that commits are signed by Guix developers. Specifically, @command{guix pull} downloads code from the @dfn{channels} (@pxref{Channels}) specified by one of the following, in this order: @enumerate @item the @option{--channels} option; @item the user's @file{~/.config/guix/channels.scm} file, unless @option{-q} is passed; @item the system-wide @file{/etc/guix/channels.scm} file, unless @option{-q} is passed (on Guix System, this file can be declared in the operating system configuration, @pxref{guix-configuration-channels, @code{channels} field of @code{guix-configuration}}); @item the built-in default channels specified in the @code{%default-channels} variable. @end enumerate On completion, @command{guix package} will use packages and package versions from this just-retrieved copy of Guix. Not only that, but all the Guix commands and Scheme modules will also be taken from that latest version. New @command{guix} sub-commands added by the update also become available. Any user can update their Guix copy using @command{guix pull}, and the effect is limited to the user who ran @command{guix pull}. For instance, when user @code{root} runs @command{guix pull}, this has no effect on the version of Guix that user @code{alice} sees, and vice versa. The result of running @command{guix pull} is a @dfn{profile} available under @file{~/.config/guix/current} containing the latest Guix. The @option{--list-generations} or @option{-l} option lists past generations produced by @command{guix pull}, along with details about their provenance: @example $ guix pull -l Generation 1 Jun 10 2018 00:18:18 guix 65956ad repository URL: https://git.savannah.gnu.org/git/guix.git branch: origin/master commit: 65956ad3526ba09e1f7a40722c96c6ef7c0936fe Generation 2 Jun 11 2018 11:02:49 guix e0cc7f6 repository URL: https://git.savannah.gnu.org/git/guix.git branch: origin/master commit: e0cc7f669bec22c37481dd03a7941c7d11a64f1d Generation 3 Jun 13 2018 23:31:07 (current) guix 844cc1c repository URL: https://git.savannah.gnu.org/git/guix.git branch: origin/master commit: 844cc1c8f394f03b404c5bb3aee086922373490c @end example @xref{Invoking guix describe, @command{guix describe}}, for other ways to describe the current status of Guix. This @code{~/.config/guix/current} profile works exactly like the profiles created by @command{guix package} (@pxref{Invoking guix package}). That is, you can list generations, roll back to the previous generation---i.e., the previous Guix---and so on: @example $ guix pull --roll-back switched from generation 3 to 2 $ guix pull --delete-generations=1 deleting /var/guix/profiles/per-user/charlie/current-guix-1-link @end example You can also use @command{guix package} (@pxref{Invoking guix package}) to manage the profile by naming it explicitly: @example $ guix package -p ~/.config/guix/current --roll-back switched from generation 3 to 2 $ guix package -p ~/.config/guix/current --delete-generations=1 deleting /var/guix/profiles/per-user/charlie/current-guix-1-link @end example The @command{guix pull} command is usually invoked with no arguments, but it supports the following options: @table @code @item --url=@var{url} @itemx --commit=@var{commit} @itemx --branch=@var{branch} Download code for the @code{guix} channel from the specified @var{url}, at the given @var{commit} (a valid Git commit ID represented as a hexadecimal string or the name of a tag), or @var{branch}. @cindex @file{channels.scm}, configuration file @cindex configuration file for channels These options are provided for convenience, but you can also specify your configuration in the @file{~/.config/guix/channels.scm} file or using the @option{--channels} option (see below). @item --channels=@var{file} @itemx -C @var{file} Read the list of channels from @var{file} instead of @file{~/.config/guix/channels.scm} or @file{/etc/guix/channels.scm}. @var{file} must contain Scheme code that evaluates to a list of channel objects. @xref{Channels}, for more information. @item --no-channel-files @itemx -q Inhibit loading of the user and system channel files, @file{~/.config/guix/channels.scm} and @file{/etc/guix/channels.scm}. @cindex channel news @item --news @itemx -N Display news written by channel authors for their users for changes made since the previous generation (@pxref{Channels, Writing Channel News}). When @option{--details} is passed, additionally display new and upgraded packages. You can view that information for previous generations with @command{guix pull -l}. @item --list-generations[=@var{pattern}] @itemx -l [@var{pattern}] List all the generations of @file{~/.config/guix/current} or, if @var{pattern} is provided, the subset of generations that match @var{pattern}. The syntax of @var{pattern} is the same as with @code{guix package --list-generations} (@pxref{Invoking guix package}). By default, this prints information about the channels used in each revision as well as the corresponding news entries. If you pass @option{--details}, it will also print the list of packages added and upgraded in each generation compared to the previous one. @item --details Instruct @option{--list-generations} or @option{--news} to display more information about the differences between subsequent generations---see above. @item --roll-back @cindex rolling back @cindex undoing transactions @cindex transactions, undoing Roll back to the previous @dfn{generation} of @file{~/.config/guix/current}---i.e., undo the last transaction. @item --switch-generation=@var{pattern} @itemx -S @var{pattern} @cindex generations Switch to a particular generation defined by @var{pattern}. @var{pattern} may be either a generation number or a number prefixed with ``+'' or ``-''. The latter means: move forward/backward by a specified number of generations. For example, if you want to return to the latest generation after @option{--roll-back}, use @option{--switch-generation=+1}. @item --delete-generations[=@var{pattern}] @itemx -d [@var{pattern}] When @var{pattern} is omitted, delete all generations except the current one. This command accepts the same patterns as @option{--list-generations}. When @var{pattern} is specified, delete the matching generations. When @var{pattern} specifies a duration, generations @emph{older} than the specified duration match. For instance, @option{--delete-generations=1m} deletes generations that are more than one month old. If the current generation matches, it is @emph{not} deleted. Note that deleting generations prevents rolling back to them. Consequently, this command must be used with care. @xref{Invoking guix describe}, for a way to display information about the current generation only. @item --profile=@var{profile} @itemx -p @var{profile} Use @var{profile} instead of @file{~/.config/guix/current}. @item --dry-run @itemx -n Show which channel commit(s) would be used and what would be built or substituted but do not actually do it. @item --allow-downgrades Allow pulling older or unrelated revisions of channels than those currently in use. @cindex downgrade attacks, protection against By default, @command{guix pull} protects against so-called ``downgrade attacks'' whereby the Git repository of a channel would be reset to an earlier or unrelated revision of itself, potentially leading you to install older, known-vulnerable versions of software packages. @quotation Note Make sure you understand its security implications before using @option{--allow-downgrades}. @end quotation @item --disable-authentication Allow pulling channel code without authenticating it. @cindex authentication, of channel code By default, @command{guix pull} authenticates code downloaded from channels by verifying that its commits are signed by authorized developers, and raises an error if this is not the case. This option instructs it to not perform any such verification. @quotation Note Make sure you understand its security implications before using @option{--disable-authentication}. @end quotation @item --system=@var{system} @itemx -s @var{system} Attempt to build for @var{system}---e.g., @code{i686-linux}---instead of the system type of the build host. @item --bootstrap Use the bootstrap Guile to build the latest Guix. This option is only useful to Guix developers. @end table The @dfn{channel} mechanism allows you to instruct @command{guix pull} which repository and branch to pull from, as well as @emph{additional} repositories containing package modules that should be deployed. @xref{Channels}, for more information. In addition, @command{guix pull} supports all the common build options (@pxref{Common Build Options}). @node Invoking guix time-machine @section Invoking @command{guix time-machine} @cindex @command{guix time-machine} @cindex pinning, channels @cindex replicating Guix @cindex reproducibility, of Guix The @command{guix time-machine} command provides access to other revisions of Guix, for example to install older versions of packages, or to reproduce a computation in an identical environment. The revision of Guix to be used is defined by a commit or by a channel description file created by @command{guix describe} (@pxref{Invoking guix describe}). Let's assume that you want to travel to those days of November 2020 when version 1.2.0 of Guix was released and, once you're there, run the @command{guile} of that time: @example guix time-machine --commit=v1.2.0 -- \ environment -C --ad-hoc guile -- guile @end example The command above fetches Guix@tie{}1.2.0 (and possibly other channels specified by your @file{channels.scm} configuration files---see below) and runs its @command{guix environment} command to spawn an environment in a container running @command{guile} (@command{guix environment} has since been subsumed by @command{guix shell}; @pxref{Invoking guix shell}). It's like driving a DeLorean@footnote{If you don't know what a DeLorean is, consider traveling back to the 1980's. (@uref{https://www.imdb.com/title/tt0088763/, Back to the Future (1985)})}! The first @command{guix time-machine} invocation can be expensive: it may have to download or even build a large number of packages; the result is cached though and subsequent commands targeting the same commit are almost instantaneous. As for @command{guix pull}, in the absence of any options, @command{time-machine} fetches the latest commits of the channels specified in @file{~/.config/guix/channels.scm}, @file{/etc/guix/channels.scm}, or the default channels; the @option{-q} option lets you ignore these configuration files. The command: @example guix time-machine -q -- build hello @end example will thus build the package @code{hello} as defined in the main branch of Guix, without any additional channel, which is in general a newer revision of Guix than you have installed. Time travel works in both directions! @quotation Note The history of Guix is immutable and @command{guix time-machine} provides the exact same software as they are in a specific Guix revision. Naturally, no security fixes are provided for old versions of Guix or its channels. A careless use of @command{guix time-machine} opens the door to security vulnerabilities. @xref{Invoking guix pull, @option{--allow-downgrades}}. @end quotation @c Keep this paragraph in sync with 'time-machine.scm'. @command{guix time-machine} raises an error when attempting to travel to commits older than ``v0.16.0'' (commit @samp{4a0b87f0}), dated Dec.@: 2018. This is one of the oldest commits supporting the channel mechanism that makes ``time travel'' possible. @quotation Note Although it should technically be possible to travel to such an old commit, the ease to do so will largely depend on the availability of binary substitutes. When traveling to a distant past, some packages may not easily build from source anymore. One such example are old versions of OpenSSL whose tests would fail after a certain date. This particular problem can be worked around by running a @dfn{virtual build machine} with its clock set to the right time (@pxref{build-vm, Virtual Build Machines}). @end quotation The general syntax is: @example guix time-machine @var{options}@dots{} -- @var{command} @var {arg}@dots{} @end example where @var{command} and @var{arg}@dots{} are passed unmodified to the @command{guix} command of the specified revision. The @var{options} that define this revision are the same as for @command{guix pull} (@pxref{Invoking guix pull}): @table @code @item --url=@var{url} @itemx --commit=@var{commit} @itemx --branch=@var{branch} Use the @code{guix} channel from the specified @var{url}, at the given @var{commit} (a valid Git commit ID represented as a hexadecimal string or the name of a tag), or @var{branch}. @item --channels=@var{file} @itemx -C @var{file} Read the list of channels from @var{file}. @var{file} must contain Scheme code that evaluates to a list of channel objects. @xref{Channels} for more information. @item --no-channel-files @itemx -q Inhibit loading of the user and system channel files, @file{~/.config/guix/channels.scm} and @file{/etc/guix/channels.scm}. Thus, @command{guix time-machine -q} is equivalent to the following Bash command, using the ``process substitution'' syntax (@pxref{Process Substitution,,, bash, The GNU Bash Reference Manual}): @example guix time-machine -C <(echo %default-channels) @dots{} @end example @end table Note that @command{guix time-machine} can trigger builds of channels and their dependencies, and these are controlled by the standard build options (@pxref{Common Build Options}). If @command{guix time-machine} is executed without any command, it prints the file name of the profile that would be used to execute the command. This is sometimes useful if you need to get store file name of the profile---e.g., when you want to @command{guix copy} it. @node Inferiors @section Inferiors @c TODO: Remove this once we're more confident about API stability. @quotation Note The functionality described here is a ``technology preview'' as of version @value{VERSION}. As such, the interface is subject to change. @end quotation @cindex inferiors @cindex composition of Guix revisions Sometimes you might need to mix packages from the revision of Guix you're currently running with packages available in a different revision of Guix. Guix @dfn{inferiors} allow you to achieve that by composing different Guix revisions in arbitrary ways. @cindex inferior packages Technically, an ``inferior'' is essentially a separate Guix process connected to your main Guix process through a REPL (@pxref{Invoking guix repl}). The @code{(guix inferior)} module allows you to create inferiors and to communicate with them. It also provides a high-level interface to browse and manipulate the packages that an inferior provides---@dfn{inferior packages}. When combined with channels (@pxref{Channels}), inferiors provide a simple way to interact with a separate revision of Guix. For example, let's assume you want to install in your profile the current @code{guile} package, along with the @code{guile-json} as it existed in an older revision of Guix---perhaps because the newer @code{guile-json} has an incompatible API and you want to run your code against the old API@. To do that, you could write a manifest for use by @code{guix package --manifest} (@pxref{Writing Manifests}); in that manifest, you would create an inferior for that old Guix revision you care about, and you would look up the @code{guile-json} package in the inferior: @lisp (use-modules (guix inferior) (guix channels) (srfi srfi-1)) ;for 'first' (define channels ;; This is the old revision from which we want to ;; extract guile-json. (list (channel (name 'guix) (url "https://git.savannah.gnu.org/git/guix.git") (commit "65956ad3526ba09e1f7a40722c96c6ef7c0936fe")))) (define inferior ;; An inferior representing the above revision. (inferior-for-channels channels)) ;; Now create a manifest with the current "guile" package ;; and the old "guile-json" package. (packages->manifest (list (first (lookup-inferior-packages inferior "guile-json")) (specification->package "guile"))) @end lisp On its first run, @command{guix package --manifest} might have to build the channel you specified before it can create the inferior; subsequent runs will be much faster because the Guix revision will be cached. The @code{(guix inferior)} module provides the following procedures to open an inferior: @deffn {Procedure} inferior-for-channels channels [#:cache-directory] [#:ttl] Return an inferior for @var{channels}, a list of channels. Use the cache at @var{cache-directory}, where entries can be reclaimed after @var{ttl} seconds. This procedure opens a new connection to the build daemon. As a side effect, this procedure may build or substitute binaries for @var{channels}, which can take time. @end deffn @deffn {Procedure} open-inferior directory [#:command "bin/guix"] Open the inferior Guix in @var{directory}, running @code{@var{directory}/@var{command} repl} or equivalent. Return @code{#f} if the inferior could not be launched. @end deffn @cindex inferior packages The procedures listed below allow you to obtain and manipulate inferior packages. @deffn {Procedure} inferior-packages inferior Return the list of packages known to @var{inferior}. @end deffn @deffn {Procedure} lookup-inferior-packages inferior name [version] Return the sorted list of inferior packages matching @var{name} in @var{inferior}, with highest version numbers first. If @var{version} is true, return only packages with a version number prefixed by @var{version}. @end deffn @deffn {Procedure} inferior-package? obj Return true if @var{obj} is an inferior package. @end deffn @deffn {Procedure} inferior-package-name package @deffnx {Procedure} inferior-package-version package @deffnx {Procedure} inferior-package-synopsis package @deffnx {Procedure} inferior-package-description package @deffnx {Procedure} inferior-package-home-page package @deffnx {Procedure} inferior-package-location package @deffnx {Procedure} inferior-package-inputs package @deffnx {Procedure} inferior-package-native-inputs package @deffnx {Procedure} inferior-package-propagated-inputs package @deffnx {Procedure} inferior-package-transitive-propagated-inputs package @deffnx {Procedure} inferior-package-native-search-paths package @deffnx {Procedure} inferior-package-transitive-native-search-paths package @deffnx {Procedure} inferior-package-search-paths package These procedures are the counterpart of package record accessors (@pxref{package Reference}). Most of them work by querying the inferior @var{package} comes from, so the inferior must still be live when you call these procedures. @end deffn Inferior packages can be used transparently like any other package or file-like object in G-expressions (@pxref{G-Expressions}). They are also transparently handled by the @code{packages->manifest} procedure, which is commonly used in manifests (@pxref{Invoking guix package, the @option{--manifest} option of @command{guix package}}). Thus you can insert an inferior package pretty much anywhere you would insert a regular package: in manifests, in the @code{packages} field of your @code{operating-system} declaration, and so on. @node Invoking guix describe @section Invoking @command{guix describe} @cindex reproducibility @cindex replicating Guix @cindex @command{guix describe} Often you may want to answer questions like: ``Which revision of Guix am I using?'' or ``Which channels am I using?'' This is useful information in many situations: if you want to @emph{replicate} an environment on a different machine or user account, if you want to report a bug or to determine what change in the channels you are using caused it, or if you want to record your system state for reproducibility purposes. The @command{guix describe} command answers these questions. When run from a @command{guix pull}ed @command{guix}, @command{guix describe} displays the channel(s) that it was built from, including their repository URL and commit IDs (@pxref{Channels}): @example $ guix describe Generation 10 Sep 03 2018 17:32:44 (current) guix e0fa68c repository URL: https://git.savannah.gnu.org/git/guix.git branch: master commit: e0fa68c7718fffd33d81af415279d6ddb518f727 @end example If you're familiar with the Git version control system, this is similar in spirit to @command{git describe}; the output is also similar to that of @command{guix pull --list-generations}, but limited to the current generation (@pxref{Invoking guix pull, the @option{--list-generations} option}). Because the Git commit ID shown above unambiguously refers to a snapshot of Guix, this information is all it takes to describe the revision of Guix you're using, and also to replicate it. To make it easier to replicate Guix, @command{guix describe} can also be asked to return a list of channels instead of the human-readable description above: @example $ guix describe -f channels (list (channel (name 'guix) (url "https://git.savannah.gnu.org/git/guix.git") (commit "e0fa68c7718fffd33d81af415279d6ddb518f727") (introduction (make-channel-introduction "9edb3f66fd807b096b48283debdcddccfea34bad" (openpgp-fingerprint "BBB0 2DDF 2CEA F6A8 0D1D E643 A2A0 6DF2 A33A 54FA"))))) @end example @noindent You can save this to a file and feed it to @command{guix pull -C} on some other machine or at a later point in time, which will instantiate @emph{this exact Guix revision} (@pxref{Invoking guix pull, the @option{-C} option}). From there on, since you're able to deploy the same revision of Guix, you can just as well @emph{replicate a complete software environment}. We humbly think that this is @emph{awesome}, and we hope you'll like it too! The details of the options supported by @command{guix describe} are as follows: @table @code @item --format=@var{format} @itemx -f @var{format} Produce output in the specified @var{format}, one of: @table @code @item human produce human-readable output; @item channels produce a list of channel specifications that can be passed to @command{guix pull -C} or installed as @file{~/.config/guix/channels.scm} (@pxref{Invoking guix pull}); @item channels-sans-intro like @code{channels}, but omit the @code{introduction} field; use it to produce a channel specification suitable for Guix version 1.1.0 or earlier---the @code{introduction} field has to do with channel authentication (@pxref{Channels, Channel Authentication}) and is not supported by these older versions; @item json @cindex JSON produce a list of channel specifications in JSON format; @item recutils produce a list of channel specifications in Recutils format. @end table @item --list-formats Display available formats for @option{--format} option. @item --profile=@var{profile} @itemx -p @var{profile} Display information about @var{profile}. @end table @node Invoking guix archive @section Invoking @command{guix archive} @cindex @command{guix archive} @cindex archive @cindex exporting files from the store @cindex importing files to the store The @command{guix archive} command allows users to @dfn{export} files from the store into a single archive, and to later @dfn{import} them on a machine that runs Guix. In particular, it allows store files to be transferred from one machine to the store on another machine. @quotation Note If you're looking for a way to produce archives in a format suitable for tools other than Guix, @pxref{Invoking guix pack}. @end quotation @cindex exporting store items To export store files as an archive to standard output, run: @example guix archive --export @var{options} @var{specifications}... @end example @var{specifications} may be either store file names or package specifications, as for @command{guix package} (@pxref{Invoking guix package}). For instance, the following command creates an archive containing the @code{gui} output of the @code{git} package and the main output of @code{emacs}: @example guix archive --export git:gui /gnu/store/...-emacs-24.3 > great.nar @end example If the specified packages are not built yet, @command{guix archive} automatically builds them. The build process may be controlled with the common build options (@pxref{Common Build Options}). To transfer the @code{emacs} package to a machine connected over SSH, one would run: @example guix archive --export -r emacs | ssh the-machine guix archive --import @end example @noindent Similarly, a complete user profile may be transferred from one machine to another like this: @example guix archive --export -r $(readlink -f ~/.guix-profile) | \ ssh the-machine guix archive --import @end example @noindent However, note that, in both examples, all of @code{emacs} and the profile as well as all of their dependencies are transferred (due to @option{-r}), regardless of what is already available in the store on the target machine. The @option{--missing} option can help figure out which items are missing from the target store. The @command{guix copy} command simplifies and optimizes this whole process, so this is probably what you should use in this case (@pxref{Invoking guix copy}). @cindex nar, archive format @cindex normalized archive (nar) @cindex nar bundle, archive format Each store item is written in the @dfn{normalized archive} or @dfn{nar} format (described below), and the output of @command{guix archive --export} (and input of @command{guix archive --import}) is a @dfn{nar bundle}. The nar format is comparable in spirit to `tar', but with differences that make it more appropriate for our purposes. First, rather than recording all Unix metadata for each file, the nar format only mentions the file type (regular, directory, or symbolic link); Unix permissions and owner/group are dismissed. Second, the order in which directory entries are stored always follows the order of file names according to the C locale collation order. This makes archive production fully deterministic. That nar bundle format is essentially the concatenation of zero or more nars along with metadata for each store item it contains: its file name, references, corresponding derivation, and a digital signature. When exporting, the daemon digitally signs the contents of the archive, and that digital signature is appended. When importing, the daemon verifies the signature and rejects the import in case of an invalid signature or if the signing key is not authorized. @c FIXME: Add xref to daemon doc about signatures. The main options are: @table @code @item --export Export the specified store files or packages (see below). Write the resulting archive to the standard output. Dependencies are @emph{not} included in the output, unless @option{--recursive} is passed. @item -r @itemx --recursive When combined with @option{--export}, this instructs @command{guix archive} to include dependencies of the given items in the archive. Thus, the resulting archive is self-contained: it contains the closure of the exported store items. @item --import Read an archive from the standard input, and import the files listed therein into the store. Abort if the archive has an invalid digital signature, or if it is signed by a public key not among the authorized keys (see @option{--authorize} below). @item --missing Read a list of store file names from the standard input, one per line, and write on the standard output the subset of these files missing from the store. @item --generate-key[=@var{parameters}] @cindex signing, archives Generate a new key pair for the daemon. This is a prerequisite before archives can be exported with @option{--export}. This operation is usually instantaneous but it can take time if the system's entropy pool needs to be refilled. On Guix System, @code{guix-service-type} takes care of generating this key pair the first boot. The generated key pair is typically stored under @file{/etc/guix}, in @file{signing-key.pub} (public key) and @file{signing-key.sec} (private key, which must be kept secret). When @var{parameters} is omitted, an ECDSA key using the Ed25519 curve is generated, or, for Libgcrypt versions before 1.6.0, it is a 4096-bit RSA key. Alternatively, @var{parameters} can specify @code{genkey} parameters suitable for Libgcrypt (@pxref{General public-key related Functions, @code{gcry_pk_genkey},, gcrypt, The Libgcrypt Reference Manual}). @item --authorize @cindex authorizing, archives Authorize imports signed by the public key passed on standard input. The public key must be in ``s-expression advanced format''---i.e., the same format as the @file{signing-key.pub} file. The list of authorized keys is kept in the human-editable file @file{/etc/guix/acl}. The file contains @url{https://people.csail.mit.edu/rivest/Sexp.txt, ``advanced-format s-expressions''} and is structured as an access-control list in the @url{https://theworld.com/~cme/spki.txt, Simple Public-Key Infrastructure (SPKI)}. @item --extract=@var{directory} @itemx -x @var{directory} Read a single-item archive as served by substitute servers (@pxref{Substitutes}) and extract it to @var{directory}. This is a low-level operation needed in only very narrow use cases; see below. For example, the following command extracts the substitute for Emacs served by @code{@value{SUBSTITUTE-SERVER-1}} to @file{/tmp/emacs}: @example $ wget -O - \ https://@value{SUBSTITUTE-SERVER-1}/nar/gzip/@dots{}-emacs-24.5 \ | gunzip | guix archive -x /tmp/emacs @end example Single-item archives are different from multiple-item archives produced by @command{guix archive --export}; they contain a single store item, and they do @emph{not} embed a signature. Thus this operation does @emph{no} signature verification and its output should be considered unsafe. The primary purpose of this operation is to facilitate inspection of archive contents coming from possibly untrusted substitute servers (@pxref{Invoking guix challenge}). @item --list @itemx -t Read a single-item archive as served by substitute servers (@pxref{Substitutes}) and print the list of files it contains, as in this example: @example $ wget -O - \ https://@value{SUBSTITUTE-SERVER-1}/nar/lzip/@dots{}-emacs-26.3 \ | lzip -d | guix archive -t @end example @end table @c ********************************************************************* @node Channels @chapter Channels @cindex channels @cindex @file{channels.scm}, configuration file @cindex configuration file for channels @cindex @command{guix pull}, configuration file @cindex configuration of @command{guix pull} Guix and its package collection are updated by running @command{guix pull}. By default @command{guix pull} downloads and deploys Guix itself from the official GNU@tie{}Guix repository. This can be customized by providing a file specifying the set of @dfn{channels} to pull from (@pxref{Invoking guix pull}). A channel specifies the URL and branch of a Git repository to be deployed, and @command{guix pull} can be instructed to pull from one or more channels. In other words, channels can be used to @emph{customize} and to @emph{extend} Guix, as we will see below. Guix is able to take into account security concerns and deal with authenticated updates. @menu * Specifying Additional Channels:: Extending the package collection. * Using a Custom Guix Channel:: Using a customized Guix. * Replicating Guix:: Running the @emph{exact same} Guix. * Customizing the System-Wide Guix:: Default channels on Guix System. * Channel Authentication:: How Guix verifies what it fetches. * Channels with Substitutes:: Using channels with available substitutes. * Creating a Channel:: How to write your custom channel. * Package Modules in a Sub-directory:: Specifying the channel's package modules location. * Declaring Channel Dependencies:: How to depend on other channels. * Specifying Channel Authorizations:: Defining channel authors authorizations. * Primary URL:: Distinguishing mirror to original. * Writing Channel News:: Communicating information to channel's users. @end menu @node Specifying Additional Channels @section Specifying Additional Channels @cindex extending the package collection (channels) @cindex variant packages (channels) You can specify @emph{additional channels} to pull from. To use a channel, write @code{~/.config/guix/channels.scm} to instruct @command{guix pull} to pull from it @emph{in addition} to the default Guix channel(s): @vindex %default-channels @lisp ;; Add variant packages to those Guix provides. (cons (channel (name 'variant-packages) (url "https://example.org/variant-packages.git")) %default-channels) @end lisp @noindent Note that the snippet above is (as always!)@: Scheme code; we use @code{cons} to add a channel the list of channels that the variable @code{%default-channels} is bound to (@pxref{Pairs, @code{cons} and lists,, guile, GNU Guile Reference Manual}). With this file in place, @command{guix pull} builds not only Guix but also the package modules from your own repository. The result in @file{~/.config/guix/current} is the union of Guix with your own package modules: @example $ guix describe Generation 19 Aug 27 2018 16:20:48 guix d894ab8 repository URL: https://git.savannah.gnu.org/git/guix.git branch: master commit: d894ab8e9bfabcefa6c49d9ba2e834dd5a73a300 variant-packages dd3df5e repository URL: https://example.org/variant-packages.git branch: master commit: dd3df5e2c8818760a8fc0bd699e55d3b69fef2bb @end example @noindent The output of @command{guix describe} above shows that we're now running Generation@tie{}19 and that it includes both Guix and packages from the @code{variant-packages} channel (@pxref{Invoking guix describe}). @node Using a Custom Guix Channel @section Using a Custom Guix Channel The channel called @code{guix} specifies where Guix itself---its command-line tools as well as its package collection---should be downloaded. For instance, suppose you want to update from another copy of the Guix repository at @code{example.org}, and specifically the @code{super-hacks} branch, you can write in @code{~/.config/guix/channels.scm} this specification: @lisp ;; Tell 'guix pull' to use another repo. (list (channel (name 'guix) (url "https://example.org/another-guix.git") (branch "super-hacks"))) @end lisp @noindent From there on, @command{guix pull} will fetch code from the @code{super-hacks} branch of the repository at @code{example.org}. The authentication concern is addressed below (@pxref{Channel Authentication}). Note that you can specify a local directory on the @code{url} field above if the channel that you intend to use resides on a local file system. However, in this case @command{guix} checks said directory for ownership before any further processing. This means that if the user is not the directory owner, but wants to use it as their default, they will then need to set it as a safe directory in their global git configuration file. Otherwise, @command{guix} will refuse to even read it. Supposing your system-wide local directory is at @code{/src/guix.git}, you would then create a git configuration file at @code{~/.gitconfig} with the following contents: @example [safe] directory = /src/guix.git @end example @noindent This also applies to the root user unless when called with @command{sudo} by the directory owner. @node Replicating Guix @section Replicating Guix @cindex pinning, channels @cindex replicating Guix @cindex reproducibility, of Guix The @command{guix describe} command shows precisely which commits were used to build the instance of Guix we're using (@pxref{Invoking guix describe}). We can replicate this instance on another machine or at a different point in time by providing a channel specification ``pinned'' to these commits that looks like this: @lisp ;; Deploy specific commits of my channels of interest. (list (channel (name 'guix) (url "https://git.savannah.gnu.org/git/guix.git") (commit "6298c3ffd9654d3231a6f25390b056483e8f407c")) (channel (name 'variant-packages) (url "https://example.org/variant-packages.git") (commit "dd3df5e2c8818760a8fc0bd699e55d3b69fef2bb"))) @end lisp To obtain this pinned channel specification, the easiest way is to run @command{guix describe} and to save its output in the @code{channels} format in a file, like so: @example guix describe -f channels > channels.scm @end example The resulting @file{channels.scm} file can be passed to the @option{-C} option of @command{guix pull} (@pxref{Invoking guix pull}) or @command{guix time-machine} (@pxref{Invoking guix time-machine}), as in this example: @example guix time-machine -C channels.scm -- shell python -- python3 @end example Given the @file{channels.scm} file, the command above will always fetch the @emph{exact same Guix instance}, then use that instance to run the exact same Python (@pxref{Invoking guix shell}). On any machine, at any time, it ends up running the exact same binaries, bit for bit. @cindex lock files Pinned channels address a problem similar to ``lock files'' as implemented by some deployment tools---they let you pin and reproduce a set of packages. In the case of Guix though, you are effectively pinning the entire package set as defined at the given channel commits; in fact, you are pinning all of Guix, including its core modules and command-line tools. You're also getting strong guarantees that you are, indeed, obtaining the exact same software. This gives you super powers, allowing you to track the provenance of binary artifacts with very fine grain, and to reproduce software environments at will---some sort of ``meta reproducibility'' capabilities, if you will. @xref{Inferiors}, for another way to take advantage of these super powers. @node Customizing the System-Wide Guix @section Customizing the System-Wide Guix @cindex system-wide Guix, customization @cindex channels, for the default Guix If you're running Guix System or building system images with it, maybe you will want to customize the system-wide @command{guix} it provides---specifically, @file{/run/current-system/profile/bin/guix}. For example, you might want to provide additional channels or to pin its revision. This can be done using the @code{guix-for-channels} procedure, which returns a package for the given channels, and using it as part of your operating system configuration, as in this example: @lisp (use-modules (gnu packages package-management) (guix channels)) (define my-channels ;; Channels that should be available to ;; /run/current-system/profile/bin/guix. (append (list (channel (name 'guix-science) (url "https://github.com/guix-science/guix-science") (branch "master"))) %default-channels)) (operating-system ;; @dots{} (services ;; Change the package used by 'guix-service-type'. (modify-services %base-services (guix-service-type config => (guix-configuration (inherit config) (channels my-channels) (guix (guix-for-channels my-channels))))))) @end lisp The resulting operating system will have both the @code{guix} and the @code{guix-science} channels visible by default. The @code{channels} field of @code{guix-configuration} above further ensures that @file{/etc/guix/channels.scm}, which is used by @command{guix pull}, specifies the same set of channels (@pxref{guix-configuration-channels, @code{channels} field of @code{guix-configuration}}). The @code{(gnu packages package-management)} module exports the @code{guix-for-channels} procedure, described below. @deffn {Procedure} guix-for-channels @var{channels} Return a package corresponding to @var{channels}. The result is a ``regular'' package, which can be used in @code{guix-configuration} as shown above or in any other place that expects a package. @end deffn @node Channel Authentication @section Channel Authentication @anchor{channel-authentication} @cindex authentication, of channel code The @command{guix pull} and @command{guix time-machine} commands @dfn{authenticate} the code retrieved from channels: they make sure each commit that is fetched is signed by an authorized developer. The goal is to protect from unauthorized modifications to the channel that would lead users to run malicious code. As a user, you must provide a @dfn{channel introduction} in your channels file so that Guix knows how to authenticate its first commit. A channel specification, including its introduction, looks something along these lines: @lisp (channel (name 'some-channel) (url "https://example.org/some-channel.git") (introduction (make-channel-introduction "6f0d8cc0d88abb59c324b2990bfee2876016bb86" (openpgp-fingerprint "CABB A931 C0FF EEC6 900D 0CFB 090B 1199 3D9A EBB5")))) @end lisp The specification above shows the name and URL of the channel. The call to @code{make-channel-introduction} above specifies that authentication of this channel starts at commit @code{6f0d8cc@dots{}}, which is signed by the OpenPGP key with fingerprint @code{CABB A931@dots{}}. For the main channel, called @code{guix}, you automatically get that information from your Guix installation. For other channels, include the channel introduction provided by the channel authors in your @file{channels.scm} file. Make sure you retrieve the channel introduction from a trusted source since that is the root of your trust. If you're curious about the authentication mechanics, read on! @node Channels with Substitutes @section Channels with Substitutes When running @command{guix pull}, Guix will first compile the definitions of every available package. This is an expensive operation for which substitutes (@pxref{Substitutes}) may be available. The following snippet in @file{channels.scm} will ensure that @command{guix pull} uses the latest commit with available substitutes for the package definitions: this is done by querying the continuous integration server at @url{https://ci.guix.gnu.org}. @lisp (use-modules (guix ci)) (list (channel-with-substitutes-available %default-guix-channel "https://ci.guix.gnu.org")) @end lisp Note that this does not mean that all the packages that you will install after running @command{guix pull} will have available substitutes. It only ensures that @command{guix pull} will not try to compile package definitions. This is particularly useful when using machines with limited resources. @node Creating a Channel @section Creating a Channel @cindex personal packages (channels) @cindex channels, for personal packages Let's say you have a bunch of custom package variants or personal packages that you think would make little sense to contribute to the Guix project, but would like to have these packages transparently available to you at the command line. By creating a @dfn{channel}, you can use and publish such a package collection. This involves the following steps: @enumerate @item A channel lives in a Git repository so the first step, when creating a channel, is to create its repository: @example mkdir my-channel cd my-channel git init @end example @item The next step is to create files containing package modules (@pxref{Package Modules}), each of which will contain one or more package definitions (@pxref{Defining Packages}). A channel can provide things other than packages, such as build systems or services; we're using packages as it's the most common use case. For example, Alice might want to provide a module called @code{(alice packages greetings)} that will provide her favorite ``hello world'' implementations. To do that Alice will create a directory corresponding to that module name. @example mkdir -p alice/packages $EDITOR alice/packages/greetings.scm git add alice/packages/greetings.scm @end example You can name your package modules however you like; the main constraint to keep in mind is to avoid name clashes with other package collections, which is why our hypothetical Alice wisely chose the @code{(alice packages @dots{})} name space. Note that you can also place modules in a sub-directory of the repository; @pxref{Package Modules in a Sub-directory}, for more info on that. @item With this first module in place, the next step is to test the packages it provides. This can be done with @command{guix build}, which needs to be told to look for modules in the Git checkout. For example, assuming @code{(alice packages greetings)} provides a package called @code{hi-from-alice}, Alice will run this command from the Git checkout: @example guix build -L. hi-from-alice @end example @noindent ... where @code{-L.} adds the current directory to Guile's load path (@pxref{Load Paths,,, guile, GNU Guile Reference Manual}). @item It might take Alice a few iterations to obtain satisfying package definitions. Eventually Alice will commit this file: @example git commit @end example As a channel author, consider bundling authentication material with your channel so that users can authenticate it. @xref{Channel Authentication}, and @ref{Specifying Channel Authorizations}, for info on how to do it. @item To use Alice's channel, anyone can now add it to their channel file (@pxref{Specifying Additional Channels}) and run @command{guix pull} (@pxref{Invoking guix pull}): @example $EDITOR ~/.config/guix/channels.scm guix pull @end example Guix will now behave as if the root directory of that channel's Git repository had been permanently added to the Guile load path. In this example, @code{(alice packages greetings)} will automatically be found by the @command{guix} command. @end enumerate Voilà! @c What follows stems from discussions at @c <https://debbugs.gnu.org/cgi/bugreport.cgi?bug=22629#134> as well as @c earlier discussions on guix-devel@gnu.org. @quotation Warning Before you publish your channel, we would like to share a few words of caution: @itemize @item Before publishing a channel, please consider contributing your package definitions to Guix proper (@pxref{Contributing}). Guix as a project is open to free software of all sorts, and packages in Guix proper are readily available to all Guix users and benefit from the project's quality assurance process. @item Package modules and package definitions are Scheme code that uses various programming interfaces (APIs). We, Guix developers, never change APIs gratuitously, but we do @emph{not} commit to freezing APIs either. When you maintain package definitions outside Guix, we consider that @emph{the compatibility burden is on you}. @item Corollary: if you're using an external channel and that channel breaks, please @emph{report the issue to the channel authors}, not to the Guix project. @end itemize You've been warned! Having said this, we believe external channels are a practical way to exert your freedom to augment Guix' package collection and to share your improvements, which are basic tenets of @uref{https://www.gnu.org/philosophy/free-sw.html, free software}. Please email us at @email{guix-devel@@gnu.org} if you'd like to discuss this. @end quotation @node Package Modules in a Sub-directory @section Package Modules in a Sub-directory @cindex subdirectory, channels As a channel author, you may want to keep your channel modules in a sub-directory. If your modules are in the sub-directory @file{guix}, you must add a meta-data file @file{.guix-channel} that contains: @lisp (channel (version 0) (directory "guix")) @end lisp The modules must be @b{underneath} the specified directory, as the @code{directory} changes Guile's @code{load-path}. For example, if @file{.guix-channel} has @code{(directory "base")}, then a module defined as @code{(define-module (gnu packages fun))} must be located at @code{base/gnu/packages/fun.scm}. Doing this allows for only parts of a repository to be used as a channel, as Guix expects valid Guile modules when pulling. For instance, @command{guix deploy} machine configuration files are not valid Guile modules, and treating them as such would make @command{guix pull} fail. @node Declaring Channel Dependencies @section Declaring Channel Dependencies @cindex dependencies, channels @cindex meta-data, channels Channel authors may decide to augment a package collection provided by other channels. They can declare their channel to be dependent on other channels in a meta-data file @file{.guix-channel}, which is to be placed in the root of the channel repository. The meta-data file should contain a simple S-expression like this: @lisp (channel (version 0) (dependencies (channel (name some-collection) (url "https://example.org/first-collection.git") ;; The 'introduction' bit below is optional: you would ;; provide it for dependencies that can be authenticated. (introduction (channel-introduction (version 0) (commit "a8883b58dc82e167c96506cf05095f37c2c2c6cd") (signer "CABB A931 C0FF EEC6 900D 0CFB 090B 1199 3D9A EBB5")))) (channel (name some-other-collection) (url "https://example.org/second-collection.git") (branch "testing")))) @end lisp In the above example this channel is declared to depend on two other channels, which will both be fetched automatically. The modules provided by the channel will be compiled in an environment where the modules of all these declared channels are available. For the sake of reliability and maintainability, you should avoid dependencies on channels that you don't control, and you should aim to keep the number of dependencies to a minimum. @node Specifying Channel Authorizations @section Specifying Channel Authorizations @cindex channel authorizations @anchor{channel-authorizations} As we saw above, Guix ensures the source code it pulls from channels comes from authorized developers. As a channel author, you need to specify the list of authorized developers in the @file{.guix-authorizations} file in the channel's Git repository. The authentication rule is simple: each commit must be signed by a key listed in the @file{.guix-authorizations} file of its parent commit(s)@footnote{Git commits form a @dfn{directed acyclic graph} (DAG). Each commit can have zero or more parents; ``regular'' commits have one parent and merge commits have two parent commits. Read @uref{https://eagain.net/articles/git-for-computer-scientists/, @i{Git for Computer Scientists}} for a great overview.} The @file{.guix-authorizations} file looks like this: @lisp ;; Example '.guix-authorizations' file. (authorizations (version 0) ;current file format version (("AD17 A21E F8AE D8F1 CC02 DBD9 F8AE D8F1 765C 61E3" (name "alice")) ("2A39 3FFF 68F4 EF7A 3D29 12AF 68F4 EF7A 22FB B2D5" (name "bob")) ("CABB A931 C0FF EEC6 900D 0CFB 090B 1199 3D9A EBB5" (name "charlie")))) @end lisp Each fingerprint is followed by optional key/value pairs, as in the example above. Currently these key/value pairs are ignored. This authentication rule creates a chicken-and-egg issue: how do we authenticate the first commit? Related to that: how do we deal with channels whose repository history contains unsigned commits and lack @file{.guix-authorizations}? And how do we fork existing channels? @cindex channel introduction Channel introductions answer these questions by describing the first commit of a channel that should be authenticated. The first time a channel is fetched with @command{guix pull} or @command{guix time-machine}, the command looks up the introductory commit and verifies that it is signed by the specified OpenPGP key. From then on, it authenticates commits according to the rule above. Authentication fails if the target commit is neither a descendant nor an ancestor of the introductory commit. Additionally, your channel must provide all the OpenPGP keys that were ever mentioned in @file{.guix-authorizations}, stored as @file{.key} files, which can be either binary or ``ASCII-armored''. By default, those @file{.key} files are searched for in the branch named @code{keyring} but you can specify a different branch name in @code{.guix-channel} like so: @lisp (channel (version 0) (keyring-reference "my-keyring-branch")) @end lisp To summarize, as the author of a channel, there are three things you have to do to allow users to authenticate your code: @enumerate @item Export the OpenPGP keys of past and present committers with @command{gpg --export} and store them in @file{.key} files, by default in a branch named @code{keyring} (we recommend making it an @dfn{orphan branch}). @item Introduce an initial @file{.guix-authorizations} in the channel's repository. Do that in a signed commit (@pxref{Commit Access}, for information on how to sign Git commits). @item Advertise the channel introduction, for instance on your channel's web page. The channel introduction, as we saw above, is the commit/key pair---i.e., the commit that introduced @file{.guix-authorizations}, and the fingerprint of the OpenPGP used to sign it. @end enumerate Before pushing to your public Git repository, you can run @command{guix git authenticate} to verify that you did sign all the commits you are about to push with an authorized key: @example guix git authenticate @var{commit} @var{signer} @end example @noindent where @var{commit} and @var{signer} are your channel introduction. @xref{Invoking guix git authenticate}, for details. Publishing a signed channel requires discipline: any mistake, such as an unsigned commit or a commit signed by an unauthorized key, will prevent users from pulling from your channel---well, that's the whole point of authentication! Pay attention to merges in particular: merge commits are considered authentic if and only if they are signed by a key present in the @file{.guix-authorizations} file of @emph{both} branches. @node Primary URL @section Primary URL @cindex primary URL, channels Channel authors can indicate the primary URL of their channel's Git repository in the @file{.guix-channel} file, like so: @lisp (channel (version 0) (url "https://example.org/guix.git")) @end lisp This allows @command{guix pull} to determine whether it is pulling code from a mirror of the channel; when that is the case, it warns the user that the mirror might be stale and displays the primary URL@. That way, users cannot be tricked into fetching code from a stale mirror that does not receive security updates. This feature only makes sense for authenticated repositories, such as the official @code{guix} channel, for which @command{guix pull} ensures the code it fetches is authentic. @node Writing Channel News @section Writing Channel News @cindex news, for channels Channel authors may occasionally want to communicate to their users information about important changes in the channel. You'd send them all an email, but that's not convenient. Instead, channels can provide a @dfn{news file}; when the channel users run @command{guix pull}, that news file is automatically read and @command{guix pull --news} can display the announcements that correspond to the new commits that have been pulled, if any. To do that, channel authors must first declare the name of the news file in their @file{.guix-channel} file: @lisp (channel (version 0) (news-file "etc/news.txt")) @end lisp The news file itself, @file{etc/news.txt} in this example, must look something like this: @lisp (channel-news (version 0) (entry (tag "the-bug-fix") (title (en "Fixed terrible bug") (fr "Oh la la")) (body (en "@@emph@{Good news@}! It's fixed!") (eo "Certe ĝi pli bone funkcias nun!"))) (entry (commit "bdcabe815cd28144a2d2b4bc3c5057b051fa9906") (title (en "Added a great package") (ca "Què vol dir guix?")) (body (en "Don't miss the @@code@{hello@} package!")))) @end lisp While the news file is using the Scheme syntax, avoid naming it with a @file{.scm} extension or else it will get picked up when building the channel and yield an error since it is not a valid module. Alternatively, you can move the channel module to a subdirectory and store the news file in another directory. The file consists of a list of @dfn{news entries}. Each entry is associated with a commit or tag: it describes changes made in this commit, possibly in preceding commits as well. Users see entries only the first time they obtain the commit the entry refers to. The @code{title} field should be a one-line summary while @code{body} can be arbitrarily long, and both can contain Texinfo markup (@pxref{Overview,,, texinfo, GNU Texinfo}). Both the title and body are a list of language tag/message tuples, which allows @command{guix pull} to display news in the language that corresponds to the user's locale. If you want to translate news using a gettext-based workflow, you can extract translatable strings with @command{xgettext} (@pxref{xgettext Invocation,,, gettext, GNU Gettext Utilities}). For example, assuming you write news entries in English first, the command below creates a PO file containing the strings to translate: @example xgettext -o news.po -l scheme -ken etc/news.txt @end example To sum up, yes, you could use your channel as a blog. But beware, this is @emph{not quite} what your users might expect. @c ********************************************************************* @node Development @chapter Development @cindex software development If you are a software developer, Guix provides tools that you should find helpful---independently of the language you're developing in. This is what this chapter is about. The @command{guix shell} command provides a convenient way to set up one-off software environments, be it for development purposes or to run a command without installing it in your profile. The @command{guix pack} command allows you to create @dfn{application bundles} that can be easily distributed to users who do not run Guix. @menu * Invoking guix shell:: Spawning one-off software environments. * Invoking guix environment:: Setting up development environments. * Invoking guix pack:: Creating software bundles. * The GCC toolchain:: Working with languages supported by GCC. * Invoking guix git authenticate:: Authenticating Git repositories. @end menu @node Invoking guix shell @section Invoking @command{guix shell} @cindex reproducible build environments @cindex development environments @cindex @command{guix environment} @cindex @command{guix shell} @cindex environment, package build environment The purpose of @command{guix shell} is to make it easy to create one-off software environments, without changing one's profile. It is typically used to create development environments; it is also a convenient way to run applications without ``polluting'' your profile. @quotation Note The @command{guix shell} command was recently introduced to supersede @command{guix environment} (@pxref{Invoking guix environment}). If you are familiar with @command{guix environment}, you will notice that it is similar but also---we hope!---more convenient. @end quotation The general syntax is: @example guix shell [@var{options}] [@var{package}@dots{}] @end example Sometimes an interactive shell session is not desired. An arbitrary command may be invoked by placing the @code{--} token to separate the command from the rest of the arguments. The following example creates an environment containing Python and NumPy, building or downloading any missing package, and runs the @command{python3} command in that environment: @example guix shell python python-numpy -- python3 @end example Note that it is necessary to include the main @code{python} package in this command even if it is already installed into your environment. This is so that the shell environment knows to set @env{PYTHONPATH} and other related variables. The shell environment cannot check the previously installed environment, because then it would be non-deterministic. This is true for most libraries: their corresponding language package should be included in the shell invocation. @quotation Note @cindex shebang, for @command{guix shell} @command{guix shell} can be also be used as a script interpreter, also known as @dfn{shebang}. Here is an example self-contained Python script making use of this feature: @example #!/usr/bin/env -S guix shell python python-numpy -- python3 import numpy print("This is numpy", numpy.version.version) @end example You may pass any @command{guix shell} option, but there's one caveat: the Linux kernel has a limit of 127 bytes on shebang length. @end quotation Development environments can be created as in the example below, which spawns an interactive shell containing all the dependencies and environment variables needed to work on Inkscape: @example guix shell --development inkscape @end example Exiting the shell places the user back in the original environment before @command{guix shell} was invoked. The next garbage collection (@pxref{Invoking guix gc}) may clean up packages that were installed in the environment and that are no longer used outside of it. As an added convenience, @command{guix shell} will try to do what you mean when it is invoked interactively without any other arguments as in: @example guix shell @end example If it finds a @file{manifest.scm} in the current working directory or any of its parents, it uses this manifest as though it was given via @code{--manifest}. Likewise, if it finds a @file{guix.scm} in the same directories, it uses it to build a development profile as though both @code{--development} and @code{--file} were present. In either case, the file will only be loaded if the directory it resides in is listed in @file{~/.config/guix/shell-authorized-directories}. This provides an easy way to define, share, and enter development environments. By default, the shell session or command runs in an @emph{augmented} environment, where the new packages are added to search path environment variables such as @code{PATH}. You can, instead, choose to create an @emph{isolated} environment containing nothing but the packages you asked for. Passing the @option{--pure} option clears environment variable definitions found in the parent environment@footnote{Be sure to use the @option{--check} option the first time you use @command{guix shell} interactively to make sure the shell does not undo the effect of @option{--pure}.}; passing @option{--container} goes one step further by spawning a @dfn{container} isolated from the rest of the system: @example guix shell --container emacs gcc-toolchain @end example The command above spawns an interactive shell in a container where nothing but @code{emacs}, @code{gcc-toolchain}, and their dependencies is available. The container lacks network access and shares no files other than the current working directory with the surrounding environment. This is useful to prevent access to system-wide resources such as @file{/usr/bin} on foreign distros. This @option{--container} option can also prove useful if you wish to run a security-sensitive application, such as a web browser, in an isolated environment. For example, the command below launches Ungoogled-Chromium in an isolated environment, which: @itemize @item shares network access with the host @item inherits host's environment variables @code{DISPLAY} and @code{XAUTHORITY} @item has access to host's authentication records from the @code{XAUTHORITY} file @item has no information about host's current directory @end itemize @example guix shell --container --network --no-cwd ungoogled-chromium \ --preserve='^XAUTHORITY$' --expose="$@{XAUTHORITY@}" \ --preserve='^DISPLAY$' -- chromium @end example @vindex GUIX_ENVIRONMENT @command{guix shell} defines the @env{GUIX_ENVIRONMENT} variable in the shell it spawns; its value is the file name of the profile of this environment. This allows users to, say, define a specific prompt for development environments in their @file{.bashrc} (@pxref{Bash Startup Files,,, bash, The GNU Bash Reference Manual}): @example if [ -n "$GUIX_ENVIRONMENT" ] then export PS1="\u@@\h \w [dev]\$ " fi @end example @noindent ...@: or to browse the profile: @example $ ls "$GUIX_ENVIRONMENT/bin" @end example The available options are summarized below. @table @code @item --check Set up the environment and check whether the shell would clobber environment variables. It's a good idea to use this option the first time you run @command{guix shell} for an interactive session to make sure your setup is correct. For example, if the shell modifies the @env{PATH} environment variable, report it since you would get a different environment than what you asked for. Such problems usually indicate that the shell startup files are unexpectedly modifying those environment variables. For example, if you are using Bash, make sure that environment variables are set or modified in @file{~/.bash_profile} and @emph{not} in @file{~/.bashrc}---the former is sourced only by log-in shells. @xref{Bash Startup Files,,, bash, The GNU Bash Reference Manual}, for details on Bash start-up files. @anchor{shell-development-option} @item --development @itemx -D Cause @command{guix shell} to include in the environment the dependencies of the following package rather than the package itself. This can be combined with other packages. For instance, the command below starts an interactive shell containing the build-time dependencies of GNU@tie{}Guile, plus Autoconf, Automake, and Libtool: @example guix shell -D guile autoconf automake libtool @end example @item --expression=@var{expr} @itemx -e @var{expr} Create an environment for the package or list of packages that @var{expr} evaluates to. For example, running: @example guix shell -D -e '(@@ (gnu packages maths) petsc-openmpi)' @end example starts a shell with the environment for this specific variant of the PETSc package. Running: @example guix shell -e '(@@ (gnu) %base-packages)' @end example starts a shell with all the base system packages available. The above commands only use the default output of the given packages. To select other outputs, two element tuples can be specified: @example guix shell -e '(list (@@ (gnu packages bash) bash) "include")' @end example @xref{package-development-manifest, @code{package->development-manifest}}, for information on how to write a manifest for the development environment of a package. @item --file=@var{file} @itemx -f @var{file} Create an environment containing the package or list of packages that the code within @var{file} evaluates to. As an example, @var{file} might contain a definition like this (@pxref{Defining Packages}): @lisp @verbatiminclude environment-gdb.scm @end lisp With the file above, you can enter a development environment for GDB by running: @example guix shell -D -f gdb-devel.scm @end example @anchor{shell-manifest} @item --manifest=@var{file} @itemx -m @var{file} Create an environment for the packages contained in the manifest object returned by the Scheme code in @var{file}. This option can be repeated several times, in which case the manifests are concatenated. This is similar to the same-named option in @command{guix package} (@pxref{profile-manifest, @option{--manifest}}) and uses the same manifest files. @xref{Writing Manifests}, for information on how to write a manifest. See @option{--export-manifest} below on how to obtain a first manifest. @cindex manifest, exporting @anchor{shell-export-manifest} @item --export-manifest Write to standard output a manifest suitable for @option{--manifest} corresponding to given command-line options. This is a way to ``convert'' command-line arguments into a manifest. For example, imagine you are tired of typing long lines and would like to get a manifest equivalent to this command line: @example guix shell -D guile git emacs emacs-geiser emacs-geiser-guile @end example Just add @option{--export-manifest} to the command line above: @example guix shell --export-manifest \ -D guile git emacs emacs-geiser emacs-geiser-guile @end example @noindent ... and you get a manifest along these lines: @lisp (concatenate-manifests (list (specifications->manifest (list "git" "emacs" "emacs-geiser" "emacs-geiser-guile")) (package->development-manifest (specification->package "guile")))) @end lisp You can store it into a file, say @file{manifest.scm}, and from there pass it to @command{guix shell} or indeed pretty much any @command{guix} command: @example guix shell -m manifest.scm @end example Voilà, you've converted a long command line into a manifest! That conversion process honors package transformation options (@pxref{Package Transformation Options}) so it should be lossless. @item --profile=@var{profile} @itemx -p @var{profile} Create an environment containing the packages installed in @var{profile}. Use @command{guix package} (@pxref{Invoking guix package}) to create and manage profiles. @item --pure Unset existing environment variables when building the new environment, except those specified with @option{--preserve} (see below). This has the effect of creating an environment in which search paths only contain package inputs. @item --preserve=@var{regexp} @itemx -E @var{regexp} When used alongside @option{--pure}, preserve the environment variables matching @var{regexp}---in other words, put them on a ``white list'' of environment variables that must be preserved. This option can be repeated several times. @example guix shell --pure --preserve=^SLURM openmpi @dots{} \ -- mpirun @dots{} @end example This example runs @command{mpirun} in a context where the only environment variables defined are @env{PATH}, environment variables whose name starts with @samp{SLURM}, as well as the usual ``precious'' variables (@env{HOME}, @env{USER}, etc.). @item --search-paths Display the environment variable definitions that make up the environment. @item --system=@var{system} @itemx -s @var{system} Attempt to build for @var{system}---e.g., @code{i686-linux}. @item --container @itemx -C @cindex container Run @var{command} within an isolated container. The current working directory outside the container is mapped inside the container. Additionally, unless overridden with @option{--user}, a dummy home directory is created that matches the current user's home directory, and @file{/etc/passwd} is configured accordingly. The spawned process runs as the current user outside the container. Inside the container, it has the same UID and GID as the current user, unless @option{--user} is passed (see below). @item --network @itemx -N For containers, share the network namespace with the host system. Containers created without this flag only have access to the loopback device. @item --link-profile @itemx -P For containers, link the environment profile to @file{~/.guix-profile} within the container and set @code{GUIX_ENVIRONMENT} to that. This is equivalent to making @file{~/.guix-profile} a symlink to the actual profile within the container. Linking will fail and abort the environment if the directory already exists, which will certainly be the case if @command{guix shell} was invoked in the user's home directory. Certain packages are configured to look in @file{~/.guix-profile} for configuration files and data;@footnote{For example, the @code{fontconfig} package inspects @file{~/.guix-profile/share/fonts} for additional fonts.} @option{--link-profile} allows these programs to behave as expected within the environment. @item --user=@var{user} @itemx -u @var{user} For containers, use the username @var{user} in place of the current user. The generated @file{/etc/passwd} entry within the container will contain the name @var{user}, the home directory will be @file{/home/@var{user}}, and no user GECOS data will be copied. Furthermore, the UID and GID inside the container are 1000. @var{user} need not exist on the system. Additionally, any shared or exposed path (see @option{--share} and @option{--expose} respectively) whose target is within the current user's home directory will be remapped relative to @file{/home/USER}; this includes the automatic mapping of the current working directory. @example # will expose paths as /home/foo/wd, /home/foo/test, and /home/foo/target cd $HOME/wd guix shell --container --user=foo \ --expose=$HOME/test \ --expose=/tmp/target=$HOME/target @end example While this will limit the leaking of user identity through home paths and each of the user fields, this is only one useful component of a broader privacy/anonymity solution---not one in and of itself. @item --no-cwd For containers, the default behavior is to share the current working directory with the isolated container and immediately change to that directory within the container. If this is undesirable, @option{--no-cwd} will cause the current working directory to @emph{not} be automatically shared and will change to the user's home directory within the container instead. See also @option{--user}. @item --expose=@var{source}[=@var{target}] @itemx --share=@var{source}[=@var{target}] For containers, @option{--expose} (resp. @option{--share}) exposes the file system @var{source} from the host system as the read-only (resp. writable) file system @var{target} within the container. If @var{target} is not specified, @var{source} is used as the target mount point in the container. The example below spawns a Guile REPL in a container in which the user's home directory is accessible read-only via the @file{/exchange} directory: @example guix shell --container --expose=$HOME=/exchange guile -- guile @end example @cindex symbolic links, guix shell @item --symlink=@var{spec} @itemx -S @var{spec} For containers, create the symbolic links specified by @var{spec}, as documented in @ref{pack-symlink-option}. @cindex file system hierarchy standard (FHS) @cindex FHS (file system hierarchy standard) @item --emulate-fhs @itemx -F When used with @option{--container}, emulate a @uref{https://refspecs.linuxfoundation.org/fhs.shtml, Filesystem Hierarchy Standard (FHS)} configuration within the container, providing @file{/bin}, @file{/lib}, and other directories and files specified by the FHS. As Guix deviates from the FHS specification, this option sets up the container to more closely mimic that of other GNU/Linux distributions. This is useful for reproducing other development environments, testing, and using programs which expect the FHS specification to be followed. With this option, the container will include a version of glibc that will read @file{/etc/ld.so.cache} within the container for the shared library cache (contrary to glibc in regular Guix usage) and set up the expected FHS directories: @file{/bin}, @file{/etc}, @file{/lib}, and @file{/usr} from the container's profile. @cindex nested containers, for @command{guix shell} @cindex container nesting, for @command{guix shell} @item --nesting @itemx -W When used with @option{--container}, provide Guix @emph{inside} the container and arrange so that it can interact with the build daemon that runs outside the container. This is useful if you want, within your isolated container, to create other containers, as in this sample session: @example $ guix shell -CW coreutils [env]$ guix shell -C guile -- guile -c '(display "hello!\n")' hello! [env]$ exit @end example The session above starts a container with @code{coreutils} programs available in @env{PATH}. From there, we spawn @command{guix shell} to create a @emph{nested} container that provides nothing but Guile. Another example is evaluating a @file{guix.scm} file that is untrusted, as shown here: @example guix shell -CW -- guix build -f guix.scm @end example The @command{guix build} command as executed above can only access the current directory. Under the hood, the @option{-W} option does several things: @itemize @item map the daemon's socket (by default @file{/var/guix/daemon-socket/socket}) inside the container; @item map the whole store (by default @file{/gnu/store}) inside the container such that store items made available by nested @command{guix} invocations are visible; @item add the currently-used @command{guix} command to the profile in the container, such that @command{guix describe} returns the same state inside and outside the container; @item share the cache (by default @file{~/.cache/guix}) with the host, to speed up operations such as @command{guix time-machine} and @command{guix shell}. @end itemize @item --rebuild-cache @cindex caching, of profiles @cindex caching, in @command{guix shell} In most cases, @command{guix shell} caches the environment so that subsequent uses are instantaneous. Least-recently used cache entries are periodically removed. The cache is also invalidated, when using @option{--file} or @option{--manifest}, anytime the corresponding file is modified. The @option{--rebuild-cache} forces the cached environment to be refreshed. This is useful when using @option{--file} or @option{--manifest} and the @command{guix.scm} or @command{manifest.scm} file has external dependencies, or if its behavior depends, say, on environment variables. @item --root=@var{file} @itemx -r @var{file} @cindex persistent environment @cindex garbage collector root, for environments Make @var{file} a symlink to the profile for this environment, and register it as a garbage collector root. This is useful if you want to protect your environment from garbage collection, to make it ``persistent''. When this option is omitted, @command{guix shell} caches profiles so that subsequent uses of the same environment are instantaneous---this is comparable to using @option{--root} except that @command{guix shell} takes care of periodically removing the least-recently used garbage collector roots. In some cases, @command{guix shell} does not cache profiles---e.g., if transformation options such as @option{--with-latest} are used. In those cases, the environment is protected from garbage collection only for the duration of the @command{guix shell} session. This means that next time you recreate the same environment, you could have to rebuild or re-download packages. @xref{Invoking guix gc}, for more on GC roots. @end table @command{guix shell} also supports all of the common build options that @command{guix build} supports (@pxref{Common Build Options}) as well as package transformation options (@pxref{Package Transformation Options}). @node Invoking guix environment @section Invoking @command{guix environment} @cindex @command{guix environment} The purpose of @command{guix environment} is to assist in creating development environments. @quotation Deprecation warning The @command{guix environment} command is deprecated in favor of @command{guix shell}, which performs similar functions but is more convenient to use. @xref{Invoking guix shell}. Being deprecated, @command{guix environment} is slated for eventual removal, but the Guix project is committed to keeping it until May 1st, 2023. Please get in touch with us at @email{guix-devel@@gnu.org} if you would like to discuss it. @end quotation The general syntax is: @example guix environment @var{options} @var{package}@dots{} @end example The following example spawns a new shell set up for the development of GNU@tie{}Guile: @example guix environment guile @end example If the needed dependencies are not built yet, @command{guix environment} automatically builds them. The environment of the new shell is an augmented version of the environment that @command{guix environment} was run in. It contains the necessary search paths for building the given package added to the existing environment variables. To create a ``pure'' environment, in which the original environment variables have been unset, use the @option{--pure} option@footnote{Users sometimes wrongfully augment environment variables such as @env{PATH} in their @file{~/.bashrc} file. As a consequence, when @command{guix environment} launches it, Bash may read @file{~/.bashrc}, thereby introducing ``impurities'' in these environment variables. It is an error to define such environment variables in @file{.bashrc}; instead, they should be defined in @file{.bash_profile}, which is sourced only by log-in shells. @xref{Bash Startup Files,,, bash, The GNU Bash Reference Manual}, for details on Bash start-up files.}. Exiting from a Guix environment is the same as exiting from the shell, and will place the user back in the old environment before @command{guix environment} was invoked. The next garbage collection (@pxref{Invoking guix gc}) will clean up packages that were installed from within the environment and are no longer used outside of it. @vindex GUIX_ENVIRONMENT @command{guix environment} defines the @env{GUIX_ENVIRONMENT} variable in the shell it spawns; its value is the file name of the profile of this environment. This allows users to, say, define a specific prompt for development environments in their @file{.bashrc} (@pxref{Bash Startup Files,,, bash, The GNU Bash Reference Manual}): @example if [ -n "$GUIX_ENVIRONMENT" ] then export PS1="\u@@\h \w [dev]\$ " fi @end example @noindent ...@: or to browse the profile: @example $ ls "$GUIX_ENVIRONMENT/bin" @end example Additionally, more than one package may be specified, in which case the union of the inputs for the given packages are used. For example, the command below spawns a shell where all of the dependencies of both Guile and Emacs are available: @example guix environment guile emacs @end example Sometimes an interactive shell session is not desired. An arbitrary command may be invoked by placing the @code{--} token to separate the command from the rest of the arguments: @example guix environment guile -- make -j4 @end example In other situations, it is more convenient to specify the list of packages needed in the environment. For example, the following command runs @command{python} from an environment containing Python@tie{}3 and NumPy: @example guix environment --ad-hoc python-numpy python -- python3 @end example Furthermore, one might want the dependencies of a package and also some additional packages that are not build-time or runtime dependencies, but are useful when developing nonetheless. Because of this, the @option{--ad-hoc} flag is positional. Packages appearing before @option{--ad-hoc} are interpreted as packages whose dependencies will be added to the environment. Packages appearing after are interpreted as packages that will be added to the environment directly. For example, the following command creates a Guix development environment that additionally includes Git and strace: @example guix environment --pure guix --ad-hoc git strace @end example @cindex container Sometimes it is desirable to isolate the environment as much as possible, for maximal purity and reproducibility. In particular, when using Guix on a host distro that is not Guix System, it is desirable to prevent access to @file{/usr/bin} and other system-wide resources from the development environment. For example, the following command spawns a Guile REPL in a ``container'' where only the store and the current working directory are mounted: @example guix environment --ad-hoc --container guile -- guile @end example @quotation Note The @option{--container} option requires Linux-libre 3.19 or newer. @end quotation @cindex certificates Another typical use case for containers is to run security-sensitive applications such as a web browser. To run Eolie, we must expose and share some files and directories; we include @code{nss-certs} and expose @file{/etc/ssl/certs/} for HTTPS authentication; finally we preserve the @env{DISPLAY} environment variable since containerized graphical applications won't display without it. @example guix environment --preserve='^DISPLAY$' --container --network \ --expose=/etc/machine-id \ --expose=/etc/ssl/certs/ \ --share=$HOME/.local/share/eolie/=$HOME/.local/share/eolie/ \ --ad-hoc eolie nss-certs dbus -- eolie @end example The available options are summarized below. @table @code @item --check Set up the environment and check whether the shell would clobber environment variables. @xref{Invoking guix shell, @option{--check}}, for more info. @item --root=@var{file} @itemx -r @var{file} @cindex persistent environment @cindex garbage collector root, for environments Make @var{file} a symlink to the profile for this environment, and register it as a garbage collector root. This is useful if you want to protect your environment from garbage collection, to make it ``persistent''. When this option is omitted, the environment is protected from garbage collection only for the duration of the @command{guix environment} session. This means that next time you recreate the same environment, you could have to rebuild or re-download packages. @xref{Invoking guix gc}, for more on GC roots. @item --expression=@var{expr} @itemx -e @var{expr} Create an environment for the package or list of packages that @var{expr} evaluates to. For example, running: @example guix environment -e '(@@ (gnu packages maths) petsc-openmpi)' @end example starts a shell with the environment for this specific variant of the PETSc package. Running: @example guix environment --ad-hoc -e '(@@ (gnu) %base-packages)' @end example starts a shell with all the base system packages available. The above commands only use the default output of the given packages. To select other outputs, two element tuples can be specified: @example guix environment --ad-hoc -e '(list (@@ (gnu packages bash) bash) "include")' @end example @item --load=@var{file} @itemx -l @var{file} Create an environment for the package or list of packages that the code within @var{file} evaluates to. As an example, @var{file} might contain a definition like this (@pxref{Defining Packages}): @lisp @verbatiminclude environment-gdb.scm @end lisp @item --manifest=@var{file} @itemx -m @var{file} Create an environment for the packages contained in the manifest object returned by the Scheme code in @var{file}. This option can be repeated several times, in which case the manifests are concatenated. This is similar to the same-named option in @command{guix package} (@pxref{profile-manifest, @option{--manifest}}) and uses the same manifest files. @xref{shell-export-manifest, @command{guix shell --export-manifest}}, for information on how to ``convert'' command-line options into a manifest. @item --ad-hoc Include all specified packages in the resulting environment, as if an @i{ad hoc} package were defined with them as inputs. This option is useful for quickly creating an environment without having to write a package expression to contain the desired inputs. For instance, the command: @example guix environment --ad-hoc guile guile-sdl -- guile @end example runs @command{guile} in an environment where Guile and Guile-SDL are available. Note that this example implicitly asks for the default output of @code{guile} and @code{guile-sdl}, but it is possible to ask for a specific output---e.g., @code{glib:bin} asks for the @code{bin} output of @code{glib} (@pxref{Packages with Multiple Outputs}). This option may be composed with the default behavior of @command{guix environment}. Packages appearing before @option{--ad-hoc} are interpreted as packages whose dependencies will be added to the environment, the default behavior. Packages appearing after are interpreted as packages that will be added to the environment directly. @item --profile=@var{profile} @itemx -p @var{profile} Create an environment containing the packages installed in @var{profile}. Use @command{guix package} (@pxref{Invoking guix package}) to create and manage profiles. @item --pure Unset existing environment variables when building the new environment, except those specified with @option{--preserve} (see below). This has the effect of creating an environment in which search paths only contain package inputs. @item --preserve=@var{regexp} @itemx -E @var{regexp} When used alongside @option{--pure}, preserve the environment variables matching @var{regexp}---in other words, put them on a ``white list'' of environment variables that must be preserved. This option can be repeated several times. @example guix environment --pure --preserve=^SLURM --ad-hoc openmpi @dots{} \ -- mpirun @dots{} @end example This example runs @command{mpirun} in a context where the only environment variables defined are @env{PATH}, environment variables whose name starts with @samp{SLURM}, as well as the usual ``precious'' variables (@env{HOME}, @env{USER}, etc.). @item --search-paths Display the environment variable definitions that make up the environment. @item --system=@var{system} @itemx -s @var{system} Attempt to build for @var{system}---e.g., @code{i686-linux}. @item --container @itemx -C @cindex container Run @var{command} within an isolated container. The current working directory outside the container is mapped inside the container. Additionally, unless overridden with @option{--user}, a dummy home directory is created that matches the current user's home directory, and @file{/etc/passwd} is configured accordingly. The spawned process runs as the current user outside the container. Inside the container, it has the same UID and GID as the current user, unless @option{--user} is passed (see below). @item --network @itemx -N For containers, share the network namespace with the host system. Containers created without this flag only have access to the loopback device. @item --link-profile @itemx -P For containers, link the environment profile to @file{~/.guix-profile} within the container and set @code{GUIX_ENVIRONMENT} to that. This is equivalent to making @file{~/.guix-profile} a symlink to the actual profile within the container. Linking will fail and abort the environment if the directory already exists, which will certainly be the case if @command{guix environment} was invoked in the user's home directory. Certain packages are configured to look in @file{~/.guix-profile} for configuration files and data;@footnote{For example, the @code{fontconfig} package inspects @file{~/.guix-profile/share/fonts} for additional fonts.} @option{--link-profile} allows these programs to behave as expected within the environment. @item --user=@var{user} @itemx -u @var{user} For containers, use the username @var{user} in place of the current user. The generated @file{/etc/passwd} entry within the container will contain the name @var{user}, the home directory will be @file{/home/@var{user}}, and no user GECOS data will be copied. Furthermore, the UID and GID inside the container are 1000. @var{user} need not exist on the system. Additionally, any shared or exposed path (see @option{--share} and @option{--expose} respectively) whose target is within the current user's home directory will be remapped relative to @file{/home/USER}; this includes the automatic mapping of the current working directory. @example # will expose paths as /home/foo/wd, /home/foo/test, and /home/foo/target cd $HOME/wd guix environment --container --user=foo \ --expose=$HOME/test \ --expose=/tmp/target=$HOME/target @end example While this will limit the leaking of user identity through home paths and each of the user fields, this is only one useful component of a broader privacy/anonymity solution---not one in and of itself. @item --no-cwd For containers, the default behavior is to share the current working directory with the isolated container and immediately change to that directory within the container. If this is undesirable, @option{--no-cwd} will cause the current working directory to @emph{not} be automatically shared and will change to the user's home directory within the container instead. See also @option{--user}. @item --expose=@var{source}[=@var{target}] @itemx --share=@var{source}[=@var{target}] For containers, @option{--expose} (resp. @option{--share}) exposes the file system @var{source} from the host system as the read-only (resp. writable) file system @var{target} within the container. If @var{target} is not specified, @var{source} is used as the target mount point in the container. The example below spawns a Guile REPL in a container in which the user's home directory is accessible read-only via the @file{/exchange} directory: @example guix environment --container --expose=$HOME=/exchange --ad-hoc guile -- guile @end example @item --emulate-fhs @item -F For containers, emulate a Filesystem Hierarchy Standard (FHS) configuration within the container, see @uref{https://refspecs.linuxfoundation.org/fhs.shtml, the official specification}. As Guix deviates from the FHS specification, this option sets up the container to more closely mimic that of other GNU/Linux distributions. This is useful for reproducing other development environments, testing, and using programs which expect the FHS specification to be followed. With this option, the container will include a version of @code{glibc} which will read @code{/etc/ld.so.cache} within the container for the shared library cache (contrary to @code{glibc} in regular Guix usage) and set up the expected FHS directories: @code{/bin}, @code{/etc}, @code{/lib}, and @code{/usr} from the container's profile. @end table @command{guix environment} also supports all of the common build options that @command{guix build} supports (@pxref{Common Build Options}) as well as package transformation options (@pxref{Package Transformation Options}). @node Invoking guix pack @section Invoking @command{guix pack} @cindex @command{guix pack} Occasionally you want to pass software to people who are not (yet!) lucky enough to be using Guix. You'd tell them to run @command{guix package -i @var{something}}, but that's not possible in this case. This is where @command{guix pack} comes in. @quotation Note If you are looking for ways to exchange binaries among machines that already run Guix, @pxref{Invoking guix copy}, @ref{Invoking guix publish}, and @ref{Invoking guix archive}. @end quotation @cindex pack @cindex bundle @cindex application bundle @cindex software bundle The @command{guix pack} command creates a shrink-wrapped @dfn{pack} or @dfn{software bundle}: it creates a tarball or some other archive containing the binaries of the software you're interested in, and all its dependencies. The resulting archive can be used on any machine that does not have Guix, and people can run the exact same binaries as those you have with Guix. The pack itself is created in a bit-reproducible fashion, so anyone can verify that it really contains the build results that you pretend to be shipping. For example, to create a bundle containing Guile, Emacs, Geiser, and all their dependencies, you can run: @example $ guix pack guile emacs emacs-geiser @dots{} /gnu/store/@dots{}-pack.tar.gz @end example The result here is a tarball containing a @file{/gnu/store} directory with all the relevant packages. The resulting tarball contains a @dfn{profile} with the three packages of interest; the profile is the same as would be created by @command{guix package -i}. It is this mechanism that is used to create Guix's own standalone binary tarball (@pxref{Binary Installation}). Users of this pack would have to run @file{/gnu/store/@dots{}-profile/bin/guile} to run Guile, which you may find inconvenient. To work around it, you can create, say, a @file{/opt/gnu/bin} symlink to the profile: @example guix pack -S /opt/gnu/bin=bin guile emacs emacs-geiser @end example @noindent That way, users can happily type @file{/opt/gnu/bin/guile} and enjoy. @cindex relocatable binaries, with @command{guix pack} What if the recipient of your pack does not have root privileges on their machine, and thus cannot unpack it in the root file system? In that case, you will want to use the @option{--relocatable} option (see below). This option produces @dfn{relocatable binaries}, meaning they can be placed anywhere in the file system hierarchy: in the example above, users can unpack your tarball in their home directory and directly run @file{./opt/gnu/bin/guile}. @cindex Docker, build an image with guix pack Alternatively, you can produce a pack in the Docker image format using the following command: @example guix pack -f docker -S /bin=bin guile guile-readline @end example @noindent The result is a tarball that can be passed to the @command{docker load} command, followed by @code{docker run}: @example docker load < @var{file} docker run -ti guile-guile-readline /bin/guile @end example @noindent where @var{file} is the image returned by @command{guix pack}, and @code{guile-guile-readline} is its ``image tag''. See the @uref{https://docs.docker.com/engine/reference/commandline/load/, Docker documentation} for more information. @cindex Singularity, build an image with guix pack @cindex SquashFS, build an image with guix pack Yet another option is to produce a SquashFS image with the following command: @example guix pack -f squashfs bash guile emacs emacs-geiser @end example @noindent The result is a SquashFS file system image that can either be mounted or directly be used as a file system container image with the @uref{https://www.sylabs.io/docs/, Singularity container execution environment}, using commands like @command{singularity shell} or @command{singularity exec}. @cindex AppImage, create an AppImage file with @command{guix pack} Another format internally based on SquashFS is @uref{https://appimage.org/, AppImage}. An AppImage file can be created and executed without any special privileges: @example file=$(guix pack -f appimage --entry-point=bin/guile guile) $file --help @end example Several command-line options allow you to customize your pack: @table @code @item --format=@var{format} @itemx -f @var{format} Produce a pack in the given @var{format}. The available formats are: @table @code @item tarball This is the default format. It produces a tarball containing all the specified binaries and symlinks. @item docker This produces a tarball that follows the @uref{https://github.com/docker/docker/blob/master/image/spec/v1.2.md, Docker Image Specification}. By default, the ``repository name'' as it appears in the output of the @command{docker images} command is computed from package names passed on the command line or in the manifest file. Alternatively, the ``repository name'' can also be configured via the @option{--image-tag} option. Refer to @option{--help-docker-format} for more information on such advanced options. @item squashfs This produces a SquashFS image containing all the specified binaries and symlinks, as well as empty mount points for virtual file systems like procfs. @quotation Note Singularity @emph{requires} you to provide @file{/bin/sh} in the image. For that reason, @command{guix pack -f squashfs} always implies @code{-S /bin=bin}. Thus, your @command{guix pack} invocation must always start with something like: @example guix pack -f squashfs bash @dots{} @end example If you forget the @code{bash} (or similar) package, @command{singularity run} and @command{singularity exec} will fail with an unhelpful ``no such file or directory'' message. @end quotation @item deb @cindex Debian, build a .deb package with guix pack This produces a Debian archive (a package with the @samp{.deb} file extension) containing all the specified binaries and symbolic links, that can be installed on top of any dpkg-based GNU(/Linux) distribution. Advanced options can be revealed via the @option{--help-deb-format} option. They allow embedding control files for more fine-grained control, such as activating specific triggers or providing a maintainer configure script to run arbitrary setup code upon installation. @example guix pack -f deb -C xz -S /usr/bin/hello=bin/hello hello @end example @quotation Note Because archives produced with @command{guix pack} contain a collection of store items and because each @command{dpkg} package must not have conflicting files, in practice that means you likely won't be able to install more than one such archive on a given system. You can nonetheless pack as many Guix packages as you want in one such archive. @end quotation @quotation Warning @command{dpkg} will assume ownership of any files contained in the pack that it does @emph{not} know about. It is unwise to install Guix-produced @samp{.deb} files on a system where @file{/gnu/store} is shared by other software, such as a Guix installation or other, non-deb packs. @end quotation @item rpm @cindex RPM, build an RPM archive with guix pack This produces an RPM archive (a package with the @samp{.rpm} file extension) containing all the specified binaries and symbolic links, that can be installed on top of any RPM-based GNU/Linux distribution. The RPM format embeds checksums for every file it contains, which the @command{rpm} command uses to validate the integrity of the archive. Advanced RPM-related options are revealed via the @option{--help-rpm-format} option. These options allow embedding maintainer scripts that can run before or after the installation of the RPM archive, for example. The RPM format supports relocatable packages via the @option{--prefix} option of the @command{rpm} command, which can be handy to install an RPM package to a specific prefix. @example guix pack -f rpm -R -C xz -S /usr/bin/hello=bin/hello hello @end example @example sudo rpm --install --prefix=/opt /gnu/store/...-hello.rpm @end example @quotation Note Contrary to Debian packages, conflicting but @emph{identical} files in RPM packages can be installed simultaneously, which means multiple @command{guix pack}-produced RPM packages can usually be installed side by side without any problem. @end quotation @quotation Warning @command{rpm} assumes ownership of any files contained in the pack, which means it will remove @file{/gnu/store} upon uninstalling a Guix-generated RPM package, unless the RPM package was installed with the @option{--prefix} option of the @command{rpm} command. It is unwise to install Guix-produced @samp{.rpm} packages on a system where @file{/gnu/store} is shared by other software, such as a Guix installation or other, non-rpm packs. @end quotation @item appimage @cindex AppImage, create an AppImage file with @command{guix pack} This produces an @uref{https://appimage.org/, AppImage file} with the @samp{.AppImage} extension. AppImage is a SquashFS volume prefixed with a runtime that mounts the SquashFS file system and executes the binary provided with @option{--entry-point}. This results in a self-contained archive that bundles the software and all its requirements into a single file. When the file is made executable it runs the packaged software. @example guix pack -f appimage --entry-point=bin/vlc vlc @end example The runtime used by AppImages invokes the @command{fusermount3} command to mount the image quickly. If that command is unavailable, the AppImage fails to run, but it can still be started by passing the @option{--appimage-extract-and-run} flag. @quotation Warning When building an AppImage, always @emph{pass} the @option{--relocatable} option (or @option{-R}, or @option{-RR}) to make sure the image can be used on systems where Guix is not installed. A warning is printed when this option is not used. @end quotation @example guix pack -f appimage --entry-point=bin/hello --relocatable hello @end example @quotation Note The resulting AppImage does not conform to the complete standard as it currently does not contain a @file{.DirIcon} file. This does not impact functionality of the AppImage itself, but possibly that of software used to manage AppImages. @end quotation @quotation Note As the generated AppImage packages the complete dependency graph, it will be larger than comparable AppImage files found online, which depend on host system libraries. @end quotation @end table @cindex relocatable binaries @item --relocatable @itemx -R Produce @dfn{relocatable binaries}---i.e., binaries that can be placed anywhere in the file system hierarchy and run from there. When this option is passed once, the resulting binaries require support for @dfn{user namespaces} in the kernel Linux; when passed @emph{twice}@footnote{Here's a trick to memorize it: @code{-RR}, which adds PRoot support, can be thought of as the abbreviation of ``Really Relocatable''. Neat, isn't it?}, relocatable binaries fall to back to other techniques if user namespaces are unavailable, and essentially work anywhere---see below for the implications. For example, if you create a pack containing Bash with: @example guix pack -RR -S /mybin=bin bash @end example @noindent ...@: you can copy that pack to a machine that lacks Guix, and from your home directory as a normal user, run: @example tar xf pack.tar.gz ./mybin/sh @end example @noindent In that shell, if you type @code{ls /gnu/store}, you'll notice that @file{/gnu/store} shows up and contains all the dependencies of @code{bash}, even though the machine actually lacks @file{/gnu/store} altogether! That is probably the simplest way to deploy Guix-built software on a non-Guix machine. @quotation Note By default, relocatable binaries rely on the @dfn{user namespace} feature of the kernel Linux, which allows unprivileged users to mount or change root. Old versions of Linux did not support it, and some GNU/Linux distributions turn it off. To produce relocatable binaries that work even in the absence of user namespaces, pass @option{--relocatable} or @option{-R} @emph{twice}. In that case, binaries will try user namespace support and fall back to another @dfn{execution engine} if user namespaces are not supported. The following execution engines are supported: @table @code @item default Try user namespaces and fall back to PRoot if user namespaces are not supported (see below). @item performance Try user namespaces and fall back to Fakechroot if user namespaces are not supported (see below). @item userns Run the program through user namespaces and abort if they are not supported. @item proot Run through PRoot. The @uref{https://proot-me.github.io/, PRoot} program provides the necessary support for file system virtualization. It achieves that by using the @code{ptrace} system call on the running program. This approach has the advantage to work without requiring special kernel support, but it incurs run-time overhead every time a system call is made. @item fakechroot Run through Fakechroot. @uref{https://github.com/dex4er/fakechroot/, Fakechroot} virtualizes file system accesses by intercepting calls to C library functions such as @code{open}, @code{stat}, @code{exec}, and so on. Unlike PRoot, it incurs very little overhead. However, it does not always work: for example, some file system accesses made from within the C library are not intercepted, and file system accesses made @i{via} direct syscalls are not intercepted either, leading to erratic behavior. @end table @vindex GUIX_EXECUTION_ENGINE When running a wrapped program, you can explicitly request one of the execution engines listed above by setting the @env{GUIX_EXECUTION_ENGINE} environment variable accordingly. @end quotation @cindex entry point, for Docker and Singularity images @item --entry-point=@var{command} Use @var{command} as the @dfn{entry point} of the resulting pack, if the pack format supports it---currently @code{docker}, @code{appimage}, and @code{squashfs} (Singularity) support it. @var{command} must be relative to the profile contained in the pack. The entry point specifies the command that tools like @code{docker run} or @code{singularity run} automatically start by default. For example, you can do: @example guix pack -f docker --entry-point=bin/guile guile @end example The resulting pack can easily be loaded and @code{docker run} with no extra arguments will spawn @code{bin/guile}: @example docker load -i pack.tar.gz docker run @var{image-id} @end example @cindex entry point arguments, for docker images @item --entry-point-argument=@var{command} @itemx -A @var{command} Use @var{command} as an argument to @dfn{entry point} of the resulting pack. This option is only valid in conjunction with @code{--entry-point} and can appear multiple times on the command line. @example guix pack -f docker --entry-point=bin/guile --entry-point-argument="--help" guile @end example @cindex maximum layers argument, for docker images @item --max-layers=@code{n} Specifies the maximum number of Docker image layers allowed when building an image. @example guix pack -f docker --max-layers=100 guile @end example This option allows you to limit the number of layers in a Docker image. Docker images are comprised of multiple layers, and each layer adds to the overall size and complexity of the image. By setting a maximum number of layers, you can control the following effects: @itemize @item Disk Usage: Increasing the number of layers can help optimize the disk space required to store multiple images built with a similar package graph. @item Pulling: When transferring images between different nodes or systems, having more layers can reduce the time required to pull the image. @end itemize @item --expression=@var{expr} @itemx -e @var{expr} Consider the package @var{expr} evaluates to. This has the same purpose as the same-named option in @command{guix build} (@pxref{Additional Build Options, @option{--expression} in @command{guix build}}). @item --file=@var{file} Build a pack containing the package or other object the code within @var{file} evaluates to. This has the same purpose as the same-named option in @command{guix build} (@pxref{Additional Build Options, @option{--file} in @command{guix build}}), but it has no shorthand, because @option{-f} already means @option{--format}. @anchor{pack-manifest} @item --manifest=@var{file} @itemx -m @var{file} Use the packages contained in the manifest object returned by the Scheme code in @var{file}. This option can be repeated several times, in which case the manifests are concatenated. This has a similar purpose as the same-named option in @command{guix package} (@pxref{profile-manifest, @option{--manifest}}) and uses the same manifest files. It allows you to define a collection of packages once and use it both for creating profiles and for creating archives for use on machines that do not have Guix installed. Note that you can specify @emph{either} a manifest file @emph{or} a list of packages, but not both. @xref{Writing Manifests}, for information on how to write a manifest. @xref{shell-export-manifest, @command{guix shell --export-manifest}}, for information on how to ``convert'' command-line options into a manifest. @item --system=@var{system} @itemx -s @var{system} Attempt to build for @var{system}---e.g., @code{i686-linux}---instead of the system type of the build host. @item --target=@var{triplet} @cindex cross-compilation Cross-build for @var{triplet}, which must be a valid GNU triplet, such as @code{"aarch64-linux-gnu"} (@pxref{Specifying target triplets, GNU configuration triplets,, autoconf, Autoconf}). @item --compression=@var{tool} @itemx -C @var{tool} Compress the resulting tarball using @var{tool}---one of @code{gzip}, @code{zstd}, @code{bzip2}, @code{xz}, @code{lzip}, or @code{none} for no compression. @anchor{pack-symlink-option} @item --symlink=@var{spec} @itemx -S @var{spec} Add the symlinks specified by @var{spec} to the pack. This option can appear several times. @var{spec} has the form @code{@var{source}=@var{target}}, where @var{source} is the symlink that will be created and @var{target} is the symlink target. For instance, @code{-S /opt/gnu/bin=bin} creates a @file{/opt/gnu/bin} symlink pointing to the @file{bin} sub-directory of the profile. @item --save-provenance Save provenance information for the packages passed on the command line. Provenance information includes the URL and commit of the channels in use (@pxref{Channels}). Provenance information is saved in the @file{/gnu/store/@dots{}-profile/manifest} file in the pack, along with the usual package metadata---the name and version of each package, their propagated inputs, and so on. It is useful information to the recipient of the pack, who then knows how the pack was (supposedly) obtained. This option is not enabled by default because, like timestamps, provenance information contributes nothing to the build process. In other words, there is an infinity of channel URLs and commit IDs that can lead to the same pack. Recording such ``silent'' metadata in the output thus potentially breaks the source-to-binary bitwise reproducibility property. @item --root=@var{file} @itemx -r @var{file} @cindex garbage collector root, for packs Make @var{file} a symlink to the resulting pack, and register it as a garbage collector root. @item --localstatedir @itemx --profile-name=@var{name} Include the ``local state directory'', @file{/var/guix}, in the resulting pack, and notably the @file{/var/guix/profiles/per-user/root/@var{name}} profile---by default @var{name} is @code{guix-profile}, which corresponds to @file{~root/.guix-profile}. @file{/var/guix} contains the store database (@pxref{The Store}) as well as garbage-collector roots (@pxref{Invoking guix gc}). Providing it in the pack means that the store is ``complete'' and manageable by Guix; not providing it in the pack means that the store is ``dead'': items cannot be added to it or removed from it after extraction of the pack. One use case for this is the Guix self-contained binary tarball (@pxref{Binary Installation}). @item --derivation @itemx -d Print the name of the derivation that builds the pack. @item --bootstrap Use the bootstrap binaries to build the pack. This option is only useful to Guix developers. @end table In addition, @command{guix pack} supports all the common build options (@pxref{Common Build Options}) and all the package transformation options (@pxref{Package Transformation Options}). @node The GCC toolchain @section The GCC toolchain @cindex GCC @cindex ld-wrapper @cindex linker wrapper @cindex toolchain, for C development @cindex toolchain, for Fortran development If you need a complete toolchain for compiling and linking C or C++ source code, use the @code{gcc-toolchain} package. This package provides a complete GCC toolchain for C/C++ development, including GCC itself, the GNU C Library (headers and binaries, plus debugging symbols in the @code{debug} output), Binutils, and a linker wrapper. The wrapper's purpose is to inspect the @code{-L} and @code{-l} switches passed to the linker, add corresponding @code{-rpath} arguments, and invoke the actual linker with this new set of arguments. You can instruct the wrapper to refuse to link against libraries not in the store by setting the @env{GUIX_LD_WRAPPER_ALLOW_IMPURITIES} environment variable to @code{no}. The package @code{gfortran-toolchain} provides a complete GCC toolchain for Fortran development. For other languages, please use @samp{guix search gcc toolchain} (@pxref{guix-search,, Invoking guix package}). @node Invoking guix git authenticate @section Invoking @command{guix git authenticate} @cindex @command{guix git authenticate} @cindex authentication, of Git checkouts @cindex Git checkout authentication The @command{guix git authenticate} command authenticates a Git checkout following the same rule as for channels (@pxref{channel-authentication, channel authentication}). That is, starting from a given commit, it ensures that all subsequent commits are signed by an OpenPGP key whose fingerprint appears in the @file{.guix-authorizations} file of its parent commit(s). You will find this command useful if you maintain a channel. But in fact, this authentication mechanism is useful in a broader context, so you might want to use it for Git repositories that have nothing to do with Guix. The general syntax is: @example guix git authenticate @var{commit} @var{signer} [@var{options}@dots{}] @end example @cindex introduction, for Git authentication By default, this command authenticates the Git checkout in the current directory; it outputs nothing and exits with exit code zero on success and non-zero on failure. @var{commit} above denotes the first commit where authentication takes place, and @var{signer} is the OpenPGP fingerprint of public key used to sign @var{commit}. Together, they form a @dfn{channel introduction} (@pxref{channel-authentication, channel introduction}). On your first successful run, the introduction is recorded in the @file{.git/config} file of your checkout, allowing you to omit them from subsequent invocations: @example guix git authenticate [@var{options}@dots{}] @end example Should you have branches that require different introductions, you can specify them directly in @file{.git/config}. For example, if the branch called @code{personal-fork} has a different introduction than other branches, you can extend @file{.git/config} along these lines: @smallexample [guix "authentication-personal-fork"] introduction-commit = cabba936fd807b096b48283debdcddccfea3900d introduction-signer = C0FF EECA BBA9 E6A8 0D1D E643 A2A0 6DF2 A33A 54FA keyring = keyring @end smallexample The first run also attempts to install pre-push and post-merge hooks, such that @command{guix git authenticate} is invoked as soon as you run @command{git push}, @command{git pull}, and related commands; it does not overwrite preexisting hooks though. The command-line options described below allow you to fine-tune the process. @table @code @item --repository=@var{directory} @itemx -r @var{directory} Open the Git repository in @var{directory} instead of the current directory. @item --keyring=@var{reference} @itemx -k @var{reference} Load OpenPGP keyring from @var{reference}, the reference of a branch such as @code{origin/keyring} or @code{my-keyring}. The branch must contain OpenPGP public keys in @file{.key} files, either in binary form or ``ASCII-armored''. By default the keyring is loaded from the branch named @code{keyring}. @item --end=@var{commit} Authenticate revisions up to @var{commit}. @item --stats Display commit signing statistics upon completion. @item --cache-key=@var{key} Previously-authenticated commits are cached in a file under @file{~/.cache/guix/authentication}. This option forces the cache to be stored in file @var{key} in that directory. @item --historical-authorizations=@var{file} By default, any commit whose parent commit(s) lack the @file{.guix-authorizations} file is considered inauthentic. In contrast, this option considers the authorizations in @var{file} for any commit that lacks @file{.guix-authorizations}. The format of @var{file} is the same as that of @file{.guix-authorizations} (@pxref{channel-authorizations, @file{.guix-authorizations} format}). @end table @c ********************************************************************* @node Programming Interface @chapter Programming Interface GNU Guix provides several Scheme programming interfaces (APIs) to define, build, and query packages. The first interface allows users to write high-level package definitions. These definitions refer to familiar packaging concepts, such as the name and version of a package, its build system, and its dependencies. These definitions can then be turned into concrete build actions. Build actions are performed by the Guix daemon, on behalf of users. In a standard setup, the daemon has write access to the store---the @file{/gnu/store} directory---whereas users do not. The recommended setup also has the daemon perform builds in chroots, under specific build users, to minimize interference with the rest of the system. @cindex derivation Lower-level APIs are available to interact with the daemon and the store. To instruct the daemon to perform a build action, users actually provide it with a @dfn{derivation}. A derivation is a low-level representation of the build actions to be taken, and the environment in which they should occur---derivations are to package definitions what assembly is to C programs. The term ``derivation'' comes from the fact that build results @emph{derive} from them. This chapter describes all these APIs in turn, starting from high-level package definitions. @xref{Source Tree Structure}, for a more general overview of the source code. @menu * Package Modules:: Packages from the programmer's viewpoint. * Defining Packages:: Defining new packages. * Defining Package Variants:: Customizing packages. * Writing Manifests:: The bill of materials of your environment. * Build Systems:: Specifying how packages are built. * Build Phases:: Phases of the build process of a package. * Build Utilities:: Helpers for your package definitions and more. * Search Paths:: Declaring search path environment variables. * The Store:: Manipulating the package store. * Derivations:: Low-level interface to package derivations. * The Store Monad:: Purely functional interface to the store. * G-Expressions:: Manipulating build expressions. * Invoking guix repl:: Programming Guix in Guile * Using Guix Interactively:: Fine-grain interaction at the REPL. @end menu @node Package Modules @section Package Modules From a programming viewpoint, the package definitions of the GNU distribution are provided by Guile modules in the @code{(gnu packages @dots{})} name space@footnote{Note that packages under the @code{(gnu packages @dots{})} module name space are not necessarily ``GNU packages''. This module naming scheme follows the usual Guile module naming convention: @code{gnu} means that these modules are distributed as part of the GNU system, and @code{packages} identifies modules that define packages.} (@pxref{Modules, Guile modules,, guile, GNU Guile Reference Manual}). For instance, the @code{(gnu packages emacs)} module exports a variable named @code{emacs}, which is bound to a @code{<package>} object (@pxref{Defining Packages}). The @code{(gnu packages @dots{})} module name space is automatically scanned for packages by the command-line tools. For instance, when running @code{guix install emacs}, all the @code{(gnu packages @dots{})} modules are scanned until one that exports a package object whose name is @code{emacs} is found. This package search facility is implemented in the @code{(gnu packages)} module. @cindex customization, of packages @cindex package module search path Users can store package definitions in modules with different names---e.g., @code{(my-packages emacs)}@footnote{Note that the file name and module name must match. For instance, the @code{(my-packages emacs)} module must be stored in a @file{my-packages/emacs.scm} file relative to the load path specified with @option{--load-path} or @env{GUIX_PACKAGE_PATH}. @xref{Modules and the File System,,, guile, GNU Guile Reference Manual}, for details.}. There are two ways to make these package definitions visible to the user interfaces: @enumerate @item By adding the directory containing your package modules to the search path with the @code{-L} flag of @command{guix package} and other commands (@pxref{Common Build Options}), or by setting the @env{GUIX_PACKAGE_PATH} environment variable described below. @item By defining a @dfn{channel} and configuring @command{guix pull} so that it pulls from it. A channel is essentially a Git repository containing package modules. @xref{Channels}, for more information on how to define and use channels. @end enumerate @env{GUIX_PACKAGE_PATH} works similarly to other search path variables: @defvr {Environment Variable} GUIX_PACKAGE_PATH This is a colon-separated list of directories to search for additional package modules. Directories listed in this variable take precedence over the own modules of the distribution. @end defvr The distribution is fully @dfn{bootstrapped} and @dfn{self-contained}: each package is built based solely on other packages in the distribution. The root of this dependency graph is a small set of @dfn{bootstrap binaries}, provided by the @code{(gnu packages bootstrap)} module. For more information on bootstrapping, @pxref{Bootstrapping}. @node Defining Packages @section Defining Packages The high-level interface to package definitions is implemented in the @code{(guix packages)} and @code{(guix build-system)} modules. As an example, the package definition, or @dfn{recipe}, for the GNU Hello package looks like this: @lisp (define-module (gnu packages hello) #:use-module (guix packages) #:use-module (guix download) #:use-module (guix build-system gnu) #:use-module (guix licenses) #:use-module (gnu packages gawk)) (define-public hello (package (name "hello") (version "2.10") (source (origin (method url-fetch) (uri (string-append "mirror://gnu/hello/hello-" version ".tar.gz")) (sha256 (base32 "0ssi1wpaf7plaswqqjwigppsg5fyh99vdlb9kzl7c9lng89ndq1i")))) (build-system gnu-build-system) (arguments '(#:configure-flags '("--enable-silent-rules"))) (inputs (list gawk)) (synopsis "Hello, GNU world: An example GNU package") (description "Guess what GNU Hello prints!") (home-page "https://www.gnu.org/software/hello/") (license gpl3+))) @end lisp @noindent Without being a Scheme expert, the reader may have guessed the meaning of the various fields here. This expression binds the variable @code{hello} to a @code{<package>} object, which is essentially a record (@pxref{SRFI-9, Scheme records,, guile, GNU Guile Reference Manual}). This package object can be inspected using procedures found in the @code{(guix packages)} module; for instance, @code{(package-name hello)} returns---surprise!---@code{"hello"}. With luck, you may be able to import part or all of the definition of the package you are interested in from another repository, using the @code{guix import} command (@pxref{Invoking guix import}). In the example above, @code{hello} is defined in a module of its own, @code{(gnu packages hello)}. Technically, this is not strictly necessary, but it is convenient to do so: all the packages defined in modules under @code{(gnu packages @dots{})} are automatically known to the command-line tools (@pxref{Package Modules}). There are a few points worth noting in the above package definition: @itemize @item The @code{source} field of the package is an @code{<origin>} object (@pxref{origin Reference}, for the complete reference). Here, the @code{url-fetch} method from @code{(guix download)} is used, meaning that the source is a file to be downloaded over FTP or HTTP. The @code{mirror://gnu} prefix instructs @code{url-fetch} to use one of the GNU mirrors defined in @code{(guix download)}. The @code{sha256} field specifies the expected SHA256 hash of the file being downloaded. It is mandatory, and allows Guix to check the integrity of the file. The @code{(base32 @dots{})} form introduces the base32 representation of the hash. You can obtain this information with @code{guix download} (@pxref{Invoking guix download}) and @code{guix hash} (@pxref{Invoking guix hash}). @cindex patches When needed, the @code{origin} form can also have a @code{patches} field listing patches to be applied, and a @code{snippet} field giving a Scheme expression to modify the source code. @item @cindex GNU Build System The @code{build-system} field specifies the procedure to build the package (@pxref{Build Systems}). Here, @code{gnu-build-system} represents the familiar GNU Build System, where packages may be configured, built, and installed with the usual @code{./configure && make && make check && make install} command sequence. When you start packaging non-trivial software, you may need tools to manipulate those build phases, manipulate files, and so on. @xref{Build Utilities}, for more on this. @item The @code{arguments} field specifies options for the build system (@pxref{Build Systems}). Here it is interpreted by @code{gnu-build-system} as a request run @file{configure} with the @option{--enable-silent-rules} flag. @cindex quote @cindex quoting @findex ' @findex quote @cindex backquote (quasiquote) @findex ` @findex quasiquote @cindex comma (unquote) @findex , @findex unquote What about these quote (@code{'}) characters? They are Scheme syntax to introduce a literal list; @code{'} is synonymous with @code{quote}. Sometimes you'll also see @code{`} (a backquote, synonymous with @code{quasiquote}) and @code{,} (a comma, synonymous with @code{unquote}). @xref{Expression Syntax, quoting,, guile, GNU Guile Reference Manual}, for details. Here the value of the @code{arguments} field is a list of arguments passed to the build system down the road, as with @code{apply} (@pxref{Fly Evaluation, @code{apply},, guile, GNU Guile Reference Manual}). The hash-colon (@code{#:}) sequence defines a Scheme @dfn{keyword} (@pxref{Keywords,,, guile, GNU Guile Reference Manual}), and @code{#:configure-flags} is a keyword used to pass a keyword argument to the build system (@pxref{Coding With Keywords,,, guile, GNU Guile Reference Manual}). @item The @code{inputs} field specifies inputs to the build process---i.e., build-time or run-time dependencies of the package. Here, we add an input, a reference to the @code{gawk} variable; @code{gawk} is itself bound to a @code{<package>} object. Note that GCC, Coreutils, Bash, and other essential tools do not need to be specified as inputs here. Instead, @code{gnu-build-system} takes care of ensuring that they are present (@pxref{Build Systems}). However, any other dependencies need to be specified in the @code{inputs} field. Any dependency not specified here will simply be unavailable to the build process, possibly leading to a build failure. @end itemize @xref{package Reference}, for a full description of possible fields. @quotation Going further @cindex Scheme programming language, getting started Intimidated by the Scheme language or curious about it? The Cookbook has a short section to get started that recaps some of the things shown above and explains the fundamentals. @xref{A Scheme Crash Course,,, guix-cookbook, GNU Guix Cookbook}, for more information. @end quotation Once a package definition is in place, the package may actually be built using the @code{guix build} command-line tool (@pxref{Invoking guix build}), troubleshooting any build failures you encounter (@pxref{Debugging Build Failures}). You can easily jump back to the package definition using the @command{guix edit} command (@pxref{Invoking guix edit}). @xref{Packaging Guidelines}, for more information on how to test package definitions, and @ref{Invoking guix lint}, for information on how to check a definition for style conformance. @vindex GUIX_PACKAGE_PATH Lastly, @pxref{Channels}, for information on how to extend the distribution by adding your own package definitions in a ``channel''. Finally, updating the package definition to a new upstream version can be partly automated by the @command{guix refresh} command (@pxref{Invoking guix refresh}). Behind the scenes, a derivation corresponding to the @code{<package>} object is first computed by the @code{package-derivation} procedure. That derivation is stored in a @file{.drv} file under @file{/gnu/store}. The build actions it prescribes may then be realized by using the @code{build-derivations} procedure (@pxref{The Store}). @deffn {Procedure} package-derivation store package [system] Return the @code{<derivation>} object of @var{package} for @var{system} (@pxref{Derivations}). @var{package} must be a valid @code{<package>} object, and @var{system} must be a string denoting the target system type---e.g., @code{"x86_64-linux"} for an x86_64 Linux-based GNU system. @var{store} must be a connection to the daemon, which operates on the store (@pxref{The Store}). @end deffn @noindent @cindex cross-compilation Similarly, it is possible to compute a derivation that cross-builds a package for some other system: @deffn {Procedure} package-cross-derivation store package target [system] Return the @code{<derivation>} object of @var{package} cross-built from @var{system} to @var{target}. @var{target} must be a valid GNU triplet denoting the target hardware and operating system, such as @code{"aarch64-linux-gnu"} (@pxref{Specifying Target Triplets,,, autoconf, Autoconf}). @end deffn Once you have package definitions, you can easily define @emph{variants} of those packages. @xref{Defining Package Variants}, for more on that. @menu * package Reference:: The package data type. * origin Reference:: The origin data type. @end menu @node package Reference @subsection @code{package} Reference This section summarizes all the options available in @code{package} declarations (@pxref{Defining Packages}). @deftp {Data Type} package This is the data type representing a package recipe. @table @asis @item @code{name} The name of the package, as a string. @item @code{version} The version of the package, as a string. @xref{Version Numbers}, for guidelines. @item @code{source} An object telling how the source code for the package should be acquired. Most of the time, this is an @code{origin} object, which denotes a file fetched from the Internet (@pxref{origin Reference}). It can also be any other ``file-like'' object such as a @code{local-file}, which denotes a file from the local file system (@pxref{G-Expressions, @code{local-file}}). @item @code{build-system} The build system that should be used to build the package (@pxref{Build Systems}). @item @code{arguments} (default: @code{'()}) The arguments that should be passed to the build system (@pxref{Build Systems}). This is a list, typically containing sequential keyword-value pairs, as in this example: @lisp (package (name "example") ;; several fields omitted (arguments (list #:tests? #f ;skip tests #:make-flags #~'("VERBOSE=1") ;pass flags to 'make' #:configure-flags #~'("--enable-frobbing")))) @end lisp The exact set of supported keywords depends on the build system (@pxref{Build Systems}), but you will find that almost all of them honor @code{#:configure-flags}, @code{#:make-flags}, @code{#:tests?}, and @code{#:phases}. The @code{#:phases} keyword in particular lets you modify the set of build phases for your package (@pxref{Build Phases}). The REPL has dedicated commands to interactively inspect values of some of these arguments, as a convenient debugging aid (@pxref{Using Guix Interactively}). @quotation Compatibility Note Until version 1.3.0, the @code{arguments} field would typically use @code{quote} (@code{'}) or @code{quasiquote} (@code{`}) and no G-expressions, like so: @lisp (package ;; several fields omitted (arguments ;old-style quoted arguments '(#:tests? #f #:configure-flags '("--enable-frobbing")))) @end lisp To convert from that style to the one shown above, you can run @code{guix style -S arguments @var{package}} (@pxref{Invoking guix style}). @end quotation @item @code{inputs} (default: @code{'()}) @itemx @code{native-inputs} (default: @code{'()}) @itemx @code{propagated-inputs} (default: @code{'()}) @cindex inputs, of packages These fields list dependencies of the package. Each element of these lists is either a package, origin, or other ``file-like object'' (@pxref{G-Expressions}); to specify the output of that file-like object that should be used, pass a two-element list where the second element is the output (@pxref{Packages with Multiple Outputs}, for more on package outputs). For example, the list below specifies three inputs: @lisp (list libffi libunistring `(,glib "bin")) ;the "bin" output of GLib @end lisp In the example above, the @code{"out"} output of @code{libffi} and @code{libunistring} is used. @quotation Compatibility Note Until version 1.3.0, input lists were a list of tuples, where each tuple has a label for the input (a string) as its first element, a package, origin, or derivation as its second element, and optionally the name of the output thereof that should be used, which defaults to @code{"out"}. For example, the list below is equivalent to the one above, but using the @dfn{old input style}: @lisp ;; Old input style (deprecated). `(("libffi" ,libffi) ("libunistring" ,libunistring) ("glib:bin" ,glib "bin")) ;the "bin" output of GLib @end lisp This style is now deprecated; it is still supported but support will be removed in a future version. It should not be used for new package definitions. @xref{Invoking guix style}, on how to migrate to the new style. @end quotation @cindex cross compilation, package dependencies The distinction between @code{native-inputs} and @code{inputs} is necessary when considering cross-compilation. When cross-compiling, dependencies listed in @code{inputs} are built for the @emph{target} architecture; conversely, dependencies listed in @code{native-inputs} are built for the architecture of the @emph{build} machine. @code{native-inputs} is typically used to list tools needed at build time, but not at run time, such as Autoconf, Automake, pkg-config, Gettext, or Bison. @command{guix lint} can report likely mistakes in this area (@pxref{Invoking guix lint}). @anchor{package-propagated-inputs} Lastly, @code{propagated-inputs} is similar to @code{inputs}, but the specified packages will be automatically installed to profiles (@pxref{Features, the role of profiles in Guix}) alongside the package they belong to (@pxref{package-cmd-propagated-inputs, @command{guix package}}, for information on how @command{guix package} deals with propagated inputs). For example this is necessary when packaging a C/C++ library that needs headers of another library to compile, or when a pkg-config file refers to another one @i{via} its @code{Requires} field. Another example where @code{propagated-inputs} is useful is for languages that lack a facility to record the run-time search path akin to the @code{RUNPATH} of ELF files; this includes Guile, Python, Perl, and more. When packaging libraries written in those languages, ensure they can find library code they depend on at run time by listing run-time dependencies in @code{propagated-inputs} rather than @code{inputs}. @item @code{outputs} (default: @code{'("out")}) The list of output names of the package. @xref{Packages with Multiple Outputs}, for typical uses of additional outputs. @item @code{native-search-paths} (default: @code{'()}) @itemx @code{search-paths} (default: @code{'()}) A list of @code{search-path-specification} objects describing search-path environment variables honored by the package. @xref{Search Paths}, for more on search path specifications. As for inputs, the distinction between @code{native-search-paths} and @code{search-paths} only matters when cross-compiling. In a cross-compilation context, @code{native-search-paths} applies exclusively to native inputs whereas @code{search-paths} applies only to host inputs. Packages such as cross-compilers care about target inputs---for instance, our (modified) GCC cross-compiler has @env{CROSS_C_INCLUDE_PATH} in @code{search-paths}, which allows it to pick @file{.h} files for the target system and @emph{not} those of native inputs. For the majority of packages though, only @code{native-search-paths} makes sense. @item @code{replacement} (default: @code{#f}) This must be either @code{#f} or a package object that will be used as a @dfn{replacement} for this package. @xref{Security Updates, grafts}, for details. @item @code{synopsis} A one-line description of the package. @item @code{description} A more elaborate description of the package, as a string in Texinfo syntax. @item @code{license} @cindex license, of packages The license of the package; a value from @code{(guix licenses)}, or a list of such values. @item @code{home-page} The URL to the home-page of the package, as a string. @item @code{supported-systems} (default: @code{%supported-systems}) The list of systems supported by the package, as strings of the form @code{architecture-kernel}, for example @code{"x86_64-linux"}. @item @code{location} (default: source location of the @code{package} form) The source location of the package. It is useful to override this when inheriting from another package, in which case this field is not automatically corrected. @end table @end deftp @defmac this-package When used in the @emph{lexical scope} of a package field definition, this identifier resolves to the package being defined. The example below shows how to add a package as a native input of itself when cross-compiling: @lisp (package (name "guile") ;; ... ;; When cross-compiled, Guile, for example, depends on ;; a native version of itself. Add it here. (native-inputs (if (%current-target-system) (list this-package) '()))) @end lisp It is an error to refer to @code{this-package} outside a package definition. @end defmac The following helper procedures are provided to help deal with package inputs. @deffn {Procedure} lookup-package-input package name @deffnx {Procedure} lookup-package-native-input package name @deffnx {Procedure} lookup-package-propagated-input package name @deffnx {Procedure} lookup-package-direct-input package name Look up @var{name} among @var{package}'s inputs (or native, propagated, or direct inputs). Return it if found, @code{#f} otherwise. @var{name} is the name of a package or the file name of an origin depended on. Here's how you might use it: @lisp (use-modules (guix packages) (gnu packages base)) (lookup-package-direct-input coreutils "gmp") @result{} #<package gmp@@6.2.1 @dots{}> @end lisp In this example we obtain the @code{gmp} package that is among the direct inputs of @code{coreutils}. When looking up an origin, use the name that appears in the origin's @code{file-name} field or its default file name---e.g., @code{"foo-1.2.tar.gz"}. @end deffn @cindex development inputs, of a package @cindex implicit inputs, of a package Sometimes you will want to obtain the list of inputs needed to @emph{develop} a package---all the inputs that are visible when the package is compiled. This is what the @code{package-development-inputs} procedure returns. @deffn {Procedure} package-development-inputs package [system] [#:target #f] Return the list of inputs required by @var{package} for development purposes on @var{system}. When @var{target} is true, return the inputs needed to cross-compile @var{package} from @var{system} to @var{target}, where @var{target} is a triplet such as @code{"aarch64-linux-gnu"}. Note that the result includes both explicit inputs and implicit inputs---inputs automatically added by the build system (@pxref{Build Systems}). Let us take the @code{hello} package to illustrate that: @lisp (use-modules (gnu packages base) (guix packages)) hello @result{} #<package hello@@2.10 gnu/packages/base.scm:79 7f585d4f6790> (package-direct-inputs hello) @result{} () (package-development-inputs hello) @result{} (("source" @dots{}) ("tar" #<package tar@@1.32 @dots{}>) @dots{}) @end lisp In this example, @code{package-direct-inputs} returns the empty list, because @code{hello} has zero explicit dependencies. Conversely, @code{package-development-inputs} includes inputs implicitly added by @code{gnu-build-system} that are required to build @code{hello}: tar, gzip, GCC, libc, Bash, and more. To visualize it, @command{guix graph hello} would show you explicit inputs, whereas @command{guix graph -t bag hello} would include implicit inputs (@pxref{Invoking guix graph}). @end deffn Because packages are regular Scheme objects that capture a complete dependency graph and associated build procedures, it is often useful to write procedures that take a package and return a modified version thereof according to some parameters. Below are a few examples. @cindex tool chain, choosing a package's tool chain @deffn {Procedure} package-with-c-toolchain package toolchain Return a variant of @var{package} that uses @var{toolchain} instead of the default GNU C/C++ toolchain. @var{toolchain} must be a list of inputs (label/package tuples) providing equivalent functionality, such as the @code{gcc-toolchain} package. The example below returns a variant of the @code{hello} package built with GCC@tie{}10.x and the rest of the GNU tool chain (Binutils and the GNU C Library) instead of the default tool chain: @lisp (let ((toolchain (specification->package "gcc-toolchain@@10"))) (package-with-c-toolchain hello `(("toolchain" ,toolchain)))) @end lisp The build tool chain is part of the @dfn{implicit inputs} of packages---it's usually not listed as part of the various ``inputs'' fields and is instead pulled in by the build system. Consequently, this procedure works by changing the build system of @var{package} so that it pulls in @var{toolchain} instead of the defaults. @xref{Build Systems}, for more on build systems. @end deffn @node origin Reference @subsection @code{origin} Reference This section documents @dfn{origins}. An @code{origin} declaration specifies data that must be ``produced''---downloaded, usually---and whose content hash is known in advance. Origins are primarily used to represent the source code of packages (@pxref{Defining Packages}). For that reason, the @code{origin} form allows you to declare patches to apply to the original source code as well as code snippets to modify it. @deftp {Data Type} origin This is the data type representing a source code origin. @table @asis @item @code{uri} An object containing the URI of the source. The object type depends on the @code{method} (see below). For example, when using the @var{url-fetch} method of @code{(guix download)}, the valid @code{uri} values are: a URL represented as a string, or a list thereof. @cindex fixed-output derivations, for download @item @code{method} A monadic procedure that handles the given URI@. The procedure must accept at least three arguments: the value of the @code{uri} field and the hash algorithm and hash value specified by the @code{hash} field. It must return a store item or a derivation in the store monad (@pxref{The Store Monad}); most methods return a fixed-output derivation (@pxref{Derivations}). Commonly used methods include @code{url-fetch}, which fetches data from a URL, and @code{git-fetch}, which fetches data from a Git repository (see below). @item @code{sha256} A bytevector containing the SHA-256 hash of the source. This is equivalent to providing a @code{content-hash} SHA256 object in the @code{hash} field described below. @item @code{hash} The @code{content-hash} object of the source---see below for how to use @code{content-hash}. You can obtain this information using @code{guix download} (@pxref{Invoking guix download}) or @code{guix hash} (@pxref{Invoking guix hash}). @item @code{file-name} (default: @code{#f}) The file name under which the source code should be saved. When this is @code{#f}, a sensible default value will be used in most cases. In case the source is fetched from a URL, the file name from the URL will be used. For version control checkouts, it is recommended to provide the file name explicitly because the default is not very descriptive. @item @code{patches} (default: @code{'()}) A list of file names, origins, or file-like objects (@pxref{G-Expressions, file-like objects}) pointing to patches to be applied to the source. This list of patches must be unconditional. In particular, it cannot depend on the value of @code{%current-system} or @code{%current-target-system}. @item @code{snippet} (default: @code{#f}) A G-expression (@pxref{G-Expressions}) or S-expression that will be run in the source directory. This is a convenient way to modify the source, sometimes more convenient than a patch. @item @code{patch-flags} (default: @code{'("-p1")}) A list of command-line flags that should be passed to the @code{patch} command. @item @code{patch-inputs} (default: @code{#f}) Input packages or derivations to the patching process. When this is @code{#f}, the usual set of inputs necessary for patching are provided, such as GNU@tie{}Patch. @item @code{modules} (default: @code{'()}) A list of Guile modules that should be loaded during the patching process and while running the code in the @code{snippet} field. @item @code{patch-guile} (default: @code{#f}) The Guile package that should be used in the patching process. When this is @code{#f}, a sensible default is used. @end table @end deftp @deftp {Data Type} content-hash @var{value} [@var{algorithm}] Construct a content hash object for the given @var{algorithm}, and with @var{value} as its hash value. When @var{algorithm} is omitted, assume it is @code{sha256}. @var{value} can be a literal string, in which case it is base32-decoded, or it can be a bytevector. The following forms are all equivalent: @lisp (content-hash "05zxkyz9bv3j9h0xyid1rhvh3klhsmrpkf3bcs6frvlgyr2gwilj") (content-hash "05zxkyz9bv3j9h0xyid1rhvh3klhsmrpkf3bcs6frvlgyr2gwilj" sha256) (content-hash (base32 "05zxkyz9bv3j9h0xyid1rhvh3klhsmrpkf3bcs6frvlgyr2gwilj")) (content-hash (base64 "kkb+RPaP7uyMZmu4eXPVkM4BN8yhRd8BTHLslb6f/Rc=") sha256) @end lisp Technically, @code{content-hash} is currently implemented as a macro. It performs sanity checks at macro-expansion time, when possible, such as ensuring that @var{value} has the right size for @var{algorithm}. @end deftp As we have seen above, how exactly the data an origin refers to is retrieved is determined by its @code{method} field. The @code{(guix download)} module provides the most common method, @code{url-fetch}, described below. @deffn {Procedure} url-fetch url hash-algo hash [name] [#:executable? #f] Return a fixed-output derivation that fetches data from @var{url} (a string, or a list of strings denoting alternate URLs), which is expected to have hash @var{hash} of type @var{hash-algo} (a symbol). By default, the file name is the base name of URL; optionally, @var{name} can specify a different file name. When @var{executable?} is true, make the downloaded file executable. When one of the URL starts with @code{mirror://}, then its host part is interpreted as the name of a mirror scheme, taken from @file{%mirror-file}. Alternatively, when URL starts with @code{file://}, return the corresponding file name in the store. @end deffn Likewise, the @code{(guix git-download)} module defines the @code{git-fetch} origin method, which fetches data from a Git version control repository, and the @code{git-reference} data type to describe the repository and revision to fetch. @deffn {Procedure} git-fetch ref hash-algo hash [name] Return a fixed-output derivation that fetches @var{ref}, a @code{<git-reference>} object. The output is expected to have recursive hash @var{hash} of type @var{hash-algo} (a symbol). Use @var{name} as the file name, or a generic name if @code{#f}. @end deffn @deffn {Procedure} git-fetch/lfs ref hash-algo hash [name] This is a variant of the @code{git-fetch} procedure that supports the Git @acronym{LFS, Large File Storage} extension. This may be useful to pull some binary test data to run the test suite of a package, for example. @end deffn @deftp {Data Type} git-reference This data type represents a Git reference for @code{git-fetch} to retrieve. @table @asis @item @code{url} The URL of the Git repository to clone. @item @code{commit} This string denotes either the commit to fetch (a hexadecimal string), or the tag to fetch. You can also use a ``short'' commit ID or a @command{git describe} style identifier such as @code{v1.0.1-10-g58d7909c97}. @item @code{recursive?} (default: @code{#f}) This Boolean indicates whether to recursively fetch Git sub-modules. @end table The example below denotes the @code{v2.10} tag of the GNU@tie{}Hello repository: @lisp (git-reference (url "https://git.savannah.gnu.org/git/hello.git") (commit "v2.10")) @end lisp This is equivalent to the reference below, which explicitly names the commit: @lisp (git-reference (url "https://git.savannah.gnu.org/git/hello.git") (commit "dc7dc56a00e48fe6f231a58f6537139fe2908fb9")) @end lisp @end deftp For Mercurial repositories, the module @code{(guix hg-download)} defines the @code{hg-fetch} origin method and @code{hg-reference} data type for support of the Mercurial version control system. @deffn {Procedure} hg-fetch ref hash-algo hash [name] Return a fixed-output derivation that fetches @var{ref}, a @code{<hg-reference>} object. The output is expected to have recursive hash @var{hash} of type @var{hash-algo} (a symbol). Use @var{name} as the file name, or a generic name if @code{#f}. @end deffn @deftp {Data Type} hg-reference This data type represents a Mercurial reference for @code{hg-fetch} to retrieve. @table @asis @item @code{url} The URL of the Mercurial repository to clone. @item @code{changeset} This string denotes the changeset to fetch. @end table @end deftp For Subversion repositories, the module @code{(guix svn-download)} defines the @code{svn-fetch} origin method and @code{svn-reference} data type for support of the Subversion version control system. @deffn {Procedure} svn-fetch ref hash-algo hash [name] Return a fixed-output derivation that fetches @var{ref}, a @code{<svn-reference>} object. The output is expected to have recursive hash @var{hash} of type @var{hash-algo} (a symbol). Use @var{name} as the file name, or a generic name if @code{#f}. @end deffn @deftp {Data Type} svn-reference This data type represents a Subversion reference for @code{svn-fetch} to retrieve. @table @asis @item @code{url} The URL of the Subversion repository to clone. @item @code{revision} This string denotes the revision to fetch specified as a number. @item @code{recursive?} (default: @code{#f}) This Boolean indicates whether to recursively fetch Subversion ``externals''. @item @code{user-name} (default: @code{#f}) The name of an account that has read-access to the repository, if the repository isn't public. @item @code{password} (default: @code{#f}) Password to access the Subversion repository, if required. @end table @end deftp For Bazaar repositories, the module @code{(guix bzr-download)} defines the @code{bzr-fetch} origin method and @code{bzr-reference} data type for support of the Bazaar version control system. @deffn {Procedure} bzr-fetch ref hash-algo hash [name] Return a fixed-output derivation that fetches @var{ref}, a @code{<bzr-reference>} object. The output is expected to have recursive hash @var{hash} of type @var{hash-algo} (a symbol). Use @var{name} as the file name, or a generic name if @code{#f}. @end deffn @deftp {Data Type} bzr-reference This data type represents a Bazaar reference for @code{bzr-fetch} to retrieve. @table @asis @item @code{url} The URL of the Bazaar repository to clone. @item @code{revision} This string denotes revision to fetch specified as a number. @end table @end deftp For CVS repositories, the module @code{(guix cvs-download)} defines the @code{cvs-fetch} origin method and @code{cvs-reference} data type for support of the Concurrent Versions System (CVS). @deffn {Procedure} cvs-fetch ref hash-algo hash [name] Return a fixed-output derivation that fetches @var{ref}, a @code{<cvs-reference>} object. The output is expected to have recursive hash @var{hash} of type @var{hash-algo} (a symbol). Use @var{name} as the file name, or a generic name if @code{#f}. @end deffn @deftp {Data Type} cvs-reference This data type represents a CVS reference for @code{cvs-fetch} to retrieve. @table @asis @item @code{root-directory} The CVS root directory. @item @code{module} Module to fetch. @item @code{revision} Revision to fetch. @end table The example below denotes a version of gnu-standards to fetch: @lisp (cvs-reference (root-directory ":pserver:anonymous@@cvs.savannah.gnu.org:/sources/gnustandards") (module "gnustandards") (revision "2020-11-25")) @end lisp @end deftp @node Defining Package Variants @section Defining Package Variants @cindex customizing packages @cindex variants, of packages One of the nice things with Guix is that, given a package definition, you can easily @emph{derive} variants of that package---for a different upstream version, with different dependencies, different compilation options, and so on. Some of these custom packages can be defined straight from the command line (@pxref{Package Transformation Options}). This section describes how to define package variants in code. This can be useful in ``manifests'' (@pxref{Writing Manifests}) and in your own package collection (@pxref{Creating a Channel}), among others! @cindex inherit, for package definitions As discussed earlier, packages are first-class objects in the Scheme language. The @code{(guix packages)} module provides the @code{package} construct to define new package objects (@pxref{package Reference}). The easiest way to define a package variant is using the @code{inherit} keyword together with @code{package}. This allows you to inherit from a package definition while overriding the fields you want. For example, given the @code{hello} variable, which contains a definition for the current version of GNU@tie{}Hello, here's how you would define a variant for version 2.2 (released in 2006, it's vintage!): @lisp (use-modules (gnu packages base)) ;for 'hello' (define hello-2.2 (package (inherit hello) (version "2.2") (source (origin (method url-fetch) (uri (string-append "mirror://gnu/hello/hello-" version ".tar.gz")) (sha256 (base32 "0lappv4slgb5spyqbh6yl5r013zv72yqg2pcl30mginf3wdqd8k9")))))) @end lisp The example above corresponds to what the @option{--with-version} or @option{--with-source} package transformations option do. Essentially @code{hello-2.2} preserves all the fields of @code{hello}, except @code{version} and @code{source}, which it overrides. Note that the original @code{hello} variable is still there, in the @code{(gnu packages base)} module, unchanged. When you define a custom package like this, you are really @emph{adding} a new package definition; the original one remains available. You can just as well define variants with a different set of dependencies than the original package. For example, the default @code{gdb} package depends on @code{guile}, but since that is an optional dependency, you can define a variant that removes that dependency like so: @lisp (use-modules (gnu packages gdb)) ;for 'gdb' (define gdb-sans-guile (package (inherit gdb) (inputs (modify-inputs (package-inputs gdb) (delete "guile"))))) @end lisp The @code{modify-inputs} form above removes the @code{"guile"} package from the @code{inputs} field of @code{gdb}. The @code{modify-inputs} macro is a helper that can prove useful anytime you want to remove, add, or replace package inputs. @defmac modify-inputs inputs clauses Modify the given package inputs, as returned by @code{package-inputs} & co., according to the given clauses. Each clause must have one of the following forms: @table @code @item (delete @var{name}@dots{}) Delete from the inputs packages with the given @var{name}s (strings). @item (prepend @var{package}@dots{}) Add @var{package}s to the front of the input list. @item (append @var{package}@dots{}) Add @var{package}s to the end of the input list. @item (replace @var{name} @var{replacement}) Replace the package called @var{name} with @var{replacement}. @end table The example below removes the GMP and ACL inputs of Coreutils and adds libcap to the front of the input list: @lisp (modify-inputs (package-inputs coreutils) (delete "gmp" "acl") (prepend libcap)) @end lisp The example below replaces the @code{guile} package from the inputs of @code{guile-redis} with @code{guile-2.2}: @lisp (modify-inputs (package-inputs guile-redis) (replace "guile" guile-2.2)) @end lisp The last type of clause is @code{append}, to add inputs at the back of the list. @end defmac In some cases, you may find it useful to write functions (``procedures'', in Scheme parlance) that return a package based on some parameters. For example, consider the @code{luasocket} library for the Lua programming language. We want to create @code{luasocket} packages for major versions of Lua. One way to do that is to define a procedure that takes a Lua package and returns a @code{luasocket} package that depends on it: @lisp (define (make-lua-socket name lua) ;; Return a luasocket package built with LUA. (package (name name) (version "3.0") ;; several fields omitted (inputs (list lua)) (synopsis "Socket library for Lua"))) (define-public lua5.1-socket (make-lua-socket "lua5.1-socket" lua-5.1)) (define-public lua5.2-socket (make-lua-socket "lua5.2-socket" lua-5.2)) @end lisp Here we have defined packages @code{lua5.1-socket} and @code{lua5.2-socket} by calling @code{make-lua-socket} with different arguments. @xref{Procedures,,, guile, GNU Guile Reference Manual}, for more info on procedures. Having top-level public definitions for these two packages means that they can be referred to from the command line (@pxref{Package Modules}). @cindex package transformations These are pretty simple package variants. As a convenience, the @code{(guix transformations)} module provides a high-level interface that directly maps to the more sophisticated package transformation options (@pxref{Package Transformation Options}): @deffn {Procedure} options->transformation opts Return a procedure that, when passed an object to build (package, derivation, etc.), applies the transformations specified by @var{opts} and returns the resulting objects. @var{opts} must be a list of symbol/string pairs such as: @lisp ((with-branch . "guile-gcrypt=master") (without-tests . "libgcrypt")) @end lisp Each symbol names a transformation and the corresponding string is an argument to that transformation. @end deffn For instance, a manifest equivalent to this command: @example guix build guix \ --with-branch=guile-gcrypt=master \ --with-debug-info=zlib @end example @noindent ... would look like this: @lisp (use-modules (guix transformations)) (define transform ;; The package transformation procedure. (options->transformation '((with-branch . "guile-gcrypt=master") (with-debug-info . "zlib")))) (packages->manifest (list (transform (specification->package "guix")))) @end lisp @cindex input rewriting @cindex dependency graph rewriting The @code{options->transformation} procedure is convenient, but it's perhaps also not as flexible as you may like. How is it implemented? The astute reader probably noticed that most package transformation options go beyond the superficial changes shown in the first examples of this section: they involve @dfn{input rewriting}, whereby the dependency graph of a package is rewritten by replacing specific inputs by others. Dependency graph rewriting, for the purposes of swapping packages in the graph, is what the @code{package-input-rewriting} procedure in @code{(guix packages)} implements. @deffn {Procedure} package-input-rewriting replacements [rewrite-name] @ [#:deep? #t] [#:recursive? #f] Return a procedure that, when passed a package, replaces its direct and indirect dependencies, including implicit inputs when @var{deep?} is true, according to @var{replacements}. @var{replacements} is a list of package pairs; the first element of each pair is the package to replace, and the second one is the replacement. When @var{recursive?} is true, apply replacements to the right-hand sides of @var{replacements} as well, recursively. Optionally, @var{rewrite-name} is a one-argument procedure that takes the name of a package and returns its new name after rewrite. @end deffn @noindent Consider this example: @lisp (define libressl-instead-of-openssl ;; This is a procedure to replace OPENSSL by LIBRESSL, ;; recursively. (package-input-rewriting `((,openssl . ,libressl)))) (define git-with-libressl (libressl-instead-of-openssl git)) @end lisp @noindent Here we first define a rewriting procedure that replaces @var{openssl} with @var{libressl}. Then we use it to define a @dfn{variant} of the @var{git} package that uses @var{libressl} instead of @var{openssl}. This is exactly what the @option{--with-input} command-line option does (@pxref{Package Transformation Options, @option{--with-input}}). The following variant of @code{package-input-rewriting} can match packages to be replaced by name rather than by identity. @deffn {Procedure} package-input-rewriting/spec @var{replacements} @ [#:deep? #t] [#:replace-hidden? #t] Return a procedure that, given a package, applies the given @var{replacements} to all the package graph, including implicit inputs unless @var{deep?} is false. @var{replacements} is a list of spec/procedures pair; each spec is a package specification such as @code{"gcc"} or @code{"guile@@2"}, and each procedure takes a matching package and returns a replacement for that package. Matching packages that have the @code{hidden?} property set are not replaced unless @var{replace-hidden?} is set to true. @end deffn The example above could be rewritten this way: @lisp (define libressl-instead-of-openssl ;; Replace all the packages called "openssl" with LibreSSL. (package-input-rewriting/spec `(("openssl" . ,(const libressl))))) @end lisp The key difference here is that, this time, packages are matched by spec and not by identity. In other words, any package in the graph that is called @code{openssl} will be replaced. A more generic procedure to rewrite a package dependency graph is @code{package-mapping}: it supports arbitrary changes to nodes in the graph. @deffn {Procedure} package-mapping proc [cut?] [#:deep? #f] Return a procedure that, given a package, applies @var{proc} to all the packages depended on and returns the resulting package. The procedure stops recursion when @var{cut?} returns true for a given package. When @var{deep?} is true, @var{proc} is applied to implicit inputs as well. @end deffn @quotation Tips Understanding what a variant really looks like can be difficult as one starts combining the tools shown above. There are several ways to inspect a package before attempting to build it that can prove handy: @itemize @item You can inspect the package interactively at the REPL, for instance to view its inputs, the code of its build phases, or its configure flags (@pxref{Using Guix Interactively}). @item When rewriting dependencies, @command{guix graph} can often help visualize the changes that are made (@pxref{Invoking guix graph}). @end itemize @end quotation @node Writing Manifests @section Writing Manifests @cindex manifest @cindex bill of materials (manifests) @command{guix} commands let you specify package lists on the command line. This is convenient, but as the command line becomes longer and less trivial, it quickly becomes more convenient to have that package list in what we call a @dfn{manifest}. A manifest is some sort of a ``bill of materials'' that defines a package set. You would typically come up with a code snippet that builds the manifest, store it in a file, say @file{manifest.scm}, and then pass that file to the @option{-m} (or @option{--manifest}) option that many @command{guix} commands support. For example, here's what a manifest for a simple package set might look like: @lisp ;; Manifest for three packages. (specifications->manifest '("gcc-toolchain" "make" "git")) @end lisp Once you have that manifest, you can pass it, for example, to @command{guix package} to install just those three packages to your profile (@pxref{profile-manifest, @option{-m} option of @command{guix package}}): @example guix package -m manifest.scm @end example @noindent ... or you can pass it to @command{guix shell} (@pxref{shell-manifest, @command{-m} option of @command{guix shell}}) to spawn an ephemeral environment: @example guix shell -m manifest.scm @end example @noindent ... or you can pass it to @command{guix pack} in pretty much the same way (@pxref{pack-manifest, @option{-m} option of @command{guix pack}}). You can store the manifest under version control, share it with others so they can easily get set up, etc. But how do you write your first manifest? To get started, maybe you'll want to write a manifest that mirrors what you already have in a profile. Rather than start from a blank page, @command{guix package} can generate a manifest for you (@pxref{export-manifest, @command{guix package --export-manifest}}): @example # Write to 'manifest.scm' a manifest corresponding to the # default profile, ~/.guix-profile. guix package --export-manifest > manifest.scm @end example Or maybe you'll want to ``translate'' command-line arguments into a manifest. In that case, @command{guix shell} can help (@pxref{shell-export-manifest, @command{guix shell --export-manifest}}): @example # Write a manifest for the packages specified on the command line. guix shell --export-manifest gcc-toolchain make git > manifest.scm @end example In both cases, the @option{--export-manifest} option tries hard to generate a faithful manifest; in particular, it takes package transformation options into account (@pxref{Package Transformation Options}). @quotation Note Manifests are @emph{symbolic}: they refer to packages of the channels @emph{currently in use} (@pxref{Channels}). In the example above, @code{gcc-toolchain} might refer to version 14 today, but it might refer to version 16 two years from now. If you want to ``pin'' your software environment to specific package versions and variants, you need an additional piece of information: the list of channel revisions in use, as returned by @command{guix describe}. @xref{Replicating Guix}, for more information. @end quotation Once you've obtained your first manifest, perhaps you'll want to customize it. Since your manifest is code, you now have access to all the Guix programming interfaces! Let's assume you want a manifest to deploy a custom variant of GDB, the GNU Debugger, that does not depend on Guile, together with another package. Building on the example seen in the previous section (@pxref{Defining Package Variants}), you can write a manifest along these lines: @lisp (use-modules (guix packages) (gnu packages gdb) ;for 'gdb' (gnu packages version-control)) ;for 'git' ;; Define a variant of GDB without a dependency on Guile. (define gdb-sans-guile (package (inherit gdb) (inputs (modify-inputs (package-inputs gdb) (delete "guile"))))) ;; Return a manifest containing that one package plus Git. (packages->manifest (list gdb-sans-guile git)) @end lisp Note that in this example, the manifest directly refers to the @code{gdb} and @code{git} variables, which are bound to a @code{package} object (@pxref{package Reference}), instead of calling @code{specifications->manifest} to look up packages by name as we did before. The @code{use-modules} form at the top lets us access the core package interface (@pxref{Defining Packages}) and the modules that define @code{gdb} and @code{git} (@pxref{Package Modules}). Seamlessly, we're weaving all this together---the possibilities are endless, unleash your creativity! The data type for manifests as well as supporting procedures are defined in the @code{(guix profiles)} module, which is automatically available to code passed to @option{-m}. The reference follows. @deftp {Data Type} manifest Data type representing a manifest. It currently has one field: @table @code @item entries This must be a list of @code{manifest-entry} records---see below. @end table @end deftp @deftp {Data Type} manifest-entry Data type representing a manifest entry. A manifest entry contains essential metadata: a name and version string, the object (usually a package) for that entry, the desired output (@pxref{Packages with Multiple Outputs}), and a number of optional pieces of information detailed below. Most of the time, you won't build a manifest entry directly; instead, you will pass a package to @code{package->manifest-entry}, described below. In some unusual cases though, you might want to create manifest entries for things that are @emph{not} packages, as in this example: @lisp ;; Manually build a single manifest entry for a non-package object. (let ((hello (program-file "hello" #~(display "Hi!")))) (manifest-entry (name "foo") (version "42") (item (computed-file "hello-directory" #~(let ((bin (string-append #$output "/bin"))) (mkdir #$output) (mkdir bin) (symlink #$hello (string-append bin "/hello"))))))) @end lisp The available fields are the following: @table @asis @item @code{name} @itemx @code{version} Name and version string for this entry. @item @code{item} A package or other file-like object (@pxref{G-Expressions, file-like objects}). @item @code{output} (default: @code{"out"}) Output of @code{item} to use, in case @code{item} has multiple outputs (@pxref{Packages with Multiple Outputs}). @item @code{dependencies} (default: @code{'()}) List of manifest entries this entry depends on. When building a profile, dependencies are added to the profile. Typically, the propagated inputs of a package (@pxref{package Reference, @code{propagated-inputs}}) end up having a corresponding manifest entry in among the dependencies of the package's own manifest entry. @item @code{search-paths} (default: @code{'()}) The list of search path specifications honored by this entry (@pxref{Search Paths}). @item @code{properties} (default: @code{'()}) List of symbol/value pairs. When building a profile, those properties get serialized. This can be used to piggyback additional metadata---e.g., the transformations applied to a package (@pxref{Package Transformation Options}). @item @code{parent} (default: @code{(delay #f)}) A promise pointing to the ``parent'' manifest entry. This is used as a hint to provide context when reporting an error related to a manifest entry coming from a @code{dependencies} field. @end table @end deftp @deffn {Procedure} concatenate-manifests lst Concatenate the manifests listed in @var{lst} and return the resulting manifest. @end deffn @c TODO: <manifest-pattern>, manifest-lookup, manifest-remove, etc. @deffn {Procedure} package->manifest-entry package [output] [#:properties] Return a manifest entry for the @var{output} of package @var{package}, where @var{output} defaults to @code{"out"}, and with the given @var{properties}. By default @var{properties} is the empty list or, if one or more package transformations were applied to @var{package}, it is an association list representing those transformations, suitable as an argument to @code{options->transformation} (@pxref{Defining Package Variants, @code{options->transformation}}). The code snippet below builds a manifest with an entry for the default output and the @code{send-email} output of the @code{git} package: @lisp (use-modules (gnu packages version-control)) (manifest (list (package->manifest-entry git) (package->manifest-entry git "send-email"))) @end lisp @end deffn @deffn {Procedure} packages->manifest packages Return a list of manifest entries, one for each item listed in @var{packages}. Elements of @var{packages} can be either package objects or package/string tuples denoting a specific output of a package. Using this procedure, the manifest above may be rewritten more concisely: @lisp (use-modules (gnu packages version-control)) (packages->manifest (list git `(,git "send-email"))) @end lisp @end deffn @anchor{package-development-manifest} @deffn {Procedure} package->development-manifest package [system] [#:target] Return a manifest for the @dfn{development inputs} of @var{package} for @var{system}, optionally when cross-compiling to @var{target}. Development inputs include both explicit and implicit inputs of @var{package}. Like the @option{-D} option of @command{guix shell} (@pxref{shell-development-option, @command{guix shell -D}}), the resulting manifest describes the environment in which one can develop @var{package}. For example, suppose you're willing to set up a development environment for Inkscape, with the addition of Git for version control; you can describe that ``bill of materials'' with the following manifest: @lisp (use-modules (gnu packages inkscape) ;for 'inkscape' (gnu packages version-control)) ;for 'git' (concatenate-manifests (list (package->development-manifest inkscape) (packages->manifest (list git)))) @end lisp In this example, the development manifest that @code{package->development-manifest} returns includes the compiler (GCC), the many supporting libraries (Boost, GLib, GTK, etc.), and a couple of additional development tools---these are the dependencies @command{guix show inkscape} lists. @end deffn @c TODO: Move (gnu packages) interface to a section of its own. Last, the @code{(gnu packages)} module provides higher-level facilities to build manifests. In particular, it lets you look up packages by name---see below. @deffn {Procedure} specifications->manifest specs Given @var{specs}, a list of specifications such as @code{"emacs@@25.2"} or @code{"guile:debug"}, return a manifest. Specs have the format that command-line tools such as @command{guix install} and @command{guix package} understand (@pxref{Invoking guix package}). As an example, it lets you rewrite the Git manifest that we saw earlier like this: @lisp (specifications->manifest '("git" "git:send-email")) @end lisp Notice that we do not need to worry about @code{use-modules}, importing the right set of modules, and referring to the right variables. Instead, we directly refer to packages in the same way as on the command line, which can often be more convenient. @end deffn @c TODO: specifications->package, etc. @node Build Systems @section Build Systems @cindex build system Each package definition specifies a @dfn{build system} and arguments for that build system (@pxref{Defining Packages}). This @code{build-system} field represents the build procedure of the package, as well as implicit dependencies of that build procedure. Build systems are @code{<build-system>} objects. The interface to create and manipulate them is provided by the @code{(guix build-system)} module, and actual build systems are exported by specific modules. @cindex bag (low-level package representation) Under the hood, build systems first compile package objects to @dfn{bags}. A @dfn{bag} is like a package, but with less ornamentation---in other words, a bag is a lower-level representation of a package, which includes all the inputs of that package, including some that were implicitly added by the build system. This intermediate representation is then compiled to a derivation (@pxref{Derivations}). The @code{package-with-c-toolchain} is an example of a way to change the implicit inputs that a package's build system pulls in (@pxref{package Reference, @code{package-with-c-toolchain}}). Build systems accept an optional list of @dfn{arguments}. In package definitions, these are passed @i{via} the @code{arguments} field (@pxref{Defining Packages}). They are typically keyword arguments (@pxref{Optional Arguments, keyword arguments in Guile,, guile, GNU Guile Reference Manual}). The value of these arguments is usually evaluated in the @dfn{build stratum}---i.e., by a Guile process launched by the daemon (@pxref{Derivations}). The main build system is @code{gnu-build-system}, which implements the standard build procedure for GNU and many other packages. It is provided by the @code{(guix build-system gnu)} module. @defvar gnu-build-system @code{gnu-build-system} represents the GNU Build System, and variants thereof (@pxref{Configuration, configuration and makefile conventions,, standards, GNU Coding Standards}). @cindex build phases In a nutshell, packages using it are configured, built, and installed with the usual @code{./configure && make && make check && make install} command sequence. In practice, a few additional steps are often needed. All these steps are split up in separate @dfn{phases}. @xref{Build Phases}, for more info on build phases and ways to customize them. In addition, this build system ensures that the ``standard'' environment for GNU packages is available. This includes tools such as GCC, libc, Coreutils, Bash, Make, Diffutils, grep, and sed (see the @code{(guix build-system gnu)} module for a complete list). We call these the @dfn{implicit inputs} of a package, because package definitions do not have to mention them. This build system supports a number of keyword arguments, which can be passed @i{via} the @code{arguments} field of a package. Here are some of the main parameters: @table @code @item #:phases This argument specifies build-side code that evaluates to an alist of build phases. @xref{Build Phases}, for more information. @item #:configure-flags This is a list of flags (strings) passed to the @command{configure} script. @xref{Defining Packages}, for an example. @item #:make-flags This list of strings contains flags passed as arguments to @command{make} invocations in the @code{build}, @code{check}, and @code{install} phases. @item #:out-of-source? This Boolean, @code{#f} by default, indicates whether to run builds in a build directory separate from the source tree. When it is true, the @code{configure} phase creates a separate build directory, changes to that directory, and runs the @code{configure} script from there. This is useful for packages that require it, such as @code{glibc}. @item #:tests? This Boolean, @code{#t} by default, indicates whether the @code{check} phase should run the package's test suite. @item #:test-target This string, @code{"check"} by default, gives the name of the makefile target used by the @code{check} phase. @item #:parallel-build? @itemx #:parallel-tests? These Boolean values specify whether to build, respectively run the test suite, in parallel, with the @code{-j} flag of @command{make}. When they are true, @code{make} is passed @code{-j@var{n}}, where @var{n} is the number specified as the @option{--cores} option of @command{guix-daemon} or that of the @command{guix} client command (@pxref{Common Build Options, @option{--cores}}). @cindex RUNPATH, validation @item #:validate-runpath? This Boolean, @code{#t} by default, determines whether to ``validate'' the @code{RUNPATH} of ELF binaries (@code{.so} shared libraries as well as executables) previously installed by the @code{install} phase. @xref{phase-validate-runpath, the @code{validate-runpath} phase}, for details. @item #:substitutable? This Boolean, @code{#t} by default, tells whether the package outputs should be substitutable---i.e., whether users should be able to obtain substitutes for them instead of building locally (@pxref{Substitutes}). @item #:allowed-references @itemx #:disallowed-references When true, these arguments must be a list of dependencies that must not appear among the references of the build results. If, upon build completion, some of these references are retained, the build process fails. This is useful to ensure that a package does not erroneously keep a reference to some of it build-time inputs, in cases where doing so would, for example, unnecessarily increase its size (@pxref{Invoking guix size}). @end table Most other build systems support these keyword arguments. @end defvar Other @code{<build-system>} objects are defined to support other conventions and tools used by free software packages. They inherit most of @code{gnu-build-system}, and differ mainly in the set of inputs implicitly added to the build process, and in the list of phases executed. Some of these build systems are listed below. @defvar agda-build-system This variable is exported by @code{(guix build-system agda)}. It implements a build procedure for Agda libraries. It adds @code{agda} to the set of inputs. A different Agda can be specified with the @code{#:agda} key. The @code{#:plan} key is a list of cons cells @code{(@var{regexp} . @var{parameters})}, where @var{regexp} is a regexp that should match the @code{.agda} files to build, and @var{parameters} is an optional list of parameters that will be passed to @code{agda} when type-checking it. When the library uses Haskell to generate a file containing all imports, the convenience @code{#:gnu-and-haskell?} can be set to @code{#t} to add @code{ghc} and the standard inputs of @code{gnu-build-system} to the input list. You will still need to manually add a phase or tweak the @code{'build} phase, as in the definition of @code{agda-stdlib}. @end defvar @defvar ant-build-system This variable is exported by @code{(guix build-system ant)}. It implements the build procedure for Java packages that can be built with @url{https://ant.apache.org/, Ant build tool}. It adds both @code{ant} and the @dfn{Java Development Kit} (JDK) as provided by the @code{icedtea} package to the set of inputs. Different packages can be specified with the @code{#:ant} and @code{#:jdk} parameters, respectively. When the original package does not provide a suitable Ant build file, the parameter @code{#:jar-name} can be used to generate a minimal Ant build file @file{build.xml} with tasks to build the specified jar archive. In this case the parameter @code{#:source-dir} can be used to specify the source sub-directory, defaulting to ``src''. The @code{#:main-class} parameter can be used with the minimal ant buildfile to specify the main class of the resulting jar. This makes the jar file executable. The @code{#:test-include} parameter can be used to specify the list of junit tests to run. It defaults to @code{(list "**/*Test.java")}. The @code{#:test-exclude} can be used to disable some tests. It defaults to @code{(list "**/Abstract*.java")}, because abstract classes cannot be run as tests. The parameter @code{#:build-target} can be used to specify the Ant task that should be run during the @code{build} phase. By default the ``jar'' task will be run. @end defvar @defvar android-ndk-build-system @cindex Android distribution @cindex Android NDK build system This variable is exported by @code{(guix build-system android-ndk)}. It implements a build procedure for Android NDK (native development kit) packages using a Guix-specific build process. The build system assumes that packages install their public interface (header) files to the subdirectory @file{include} of the @code{out} output and their libraries to the subdirectory @file{lib} the @code{out} output. It's also assumed that the union of all the dependencies of a package has no conflicting files. For the time being, cross-compilation is not supported - so right now the libraries and header files are assumed to be host tools. @end defvar @defvar asdf-build-system/source @defvarx asdf-build-system/sbcl @defvarx asdf-build-system/ecl These variables, exported by @code{(guix build-system asdf)}, implement build procedures for Common Lisp packages using @url{https://common-lisp.net/project/asdf/, ``ASDF''}. ASDF is a system definition facility for Common Lisp programs and libraries. The @code{asdf-build-system/source} system installs the packages in source form, and can be loaded using any common lisp implementation, via ASDF@. The others, such as @code{asdf-build-system/sbcl}, install binary systems in the format which a particular implementation understands. These build systems can also be used to produce executable programs, or lisp images which contain a set of packages pre-loaded. The build system uses naming conventions. For binary packages, the package name should be prefixed with the lisp implementation, such as @code{sbcl-} for @code{asdf-build-system/sbcl}. Additionally, the corresponding source package should be labeled using the same convention as Python packages (@pxref{Python Modules}), using the @code{cl-} prefix. In order to create executable programs and images, the build-side procedures @code{build-program} and @code{build-image} can be used. They should be called in a build phase after the @code{create-asdf-configuration} phase, so that the system which was just built can be used within the resulting image. @code{build-program} requires a list of Common Lisp expressions to be passed as the @code{#:entry-program} argument. By default, all the @file{.asd} files present in the sources are read to find system definitions. The @code{#:asd-files} parameter can be used to specify the list of @file{.asd} files to read. Furthermore, if the package defines a system for its tests in a separate file, it will be loaded before the tests are run if it is specified by the @code{#:test-asd-file} parameter. If it is not set, the files @code{<system>-tests.asd}, @code{<system>-test.asd}, @code{tests.asd}, and @code{test.asd} will be tried if they exist. If for some reason the package must be named in a different way than the naming conventions suggest, or if several systems must be compiled, the @code{#:asd-systems} parameter can be used to specify the list of system names. @end defvar @defvar cargo-build-system @cindex Rust programming language @cindex Cargo (Rust build system) This variable is exported by @code{(guix build-system cargo)}. It supports builds of packages using Cargo, the build tool of the @uref{https://www.rust-lang.org, Rust programming language}. It adds @code{rustc} and @code{cargo} to the set of inputs. A different Rust package can be specified with the @code{#:rust} parameter. Regular cargo dependencies should be added to the package definition similarly to other packages; those needed only at build time to native-inputs, others to inputs. If you need to add source-only crates then you should add them to via the @code{#:cargo-inputs} parameter as a list of name and spec pairs, where the spec can be a package or a source definition. Note that the spec must evaluate to a path to a gzipped tarball which includes a @code{Cargo.toml} file at its root, or it will be ignored. Similarly, cargo dev-dependencies should be added to the package definition via the @code{#:cargo-development-inputs} parameter. In its @code{configure} phase, this build system will make any source inputs specified in the @code{#:cargo-inputs} and @code{#:cargo-development-inputs} parameters available to cargo. It will also remove an included @code{Cargo.lock} file to be recreated by @code{cargo} during the @code{build} phase. The @code{package} phase will run @code{cargo package} to create a source crate for future use. The @code{install} phase installs the binaries defined by the crate. Unless @code{install-source? #f} is defined it will also install a source crate repository of itself and unpacked sources, to ease in future hacking on rust packages. @end defvar @defvar chicken-build-system This variable is exported by @code{(guix build-system chicken)}. It builds @uref{https://call-cc.org/, CHICKEN Scheme} modules, also called ``eggs'' or ``extensions''. CHICKEN generates C source code, which then gets compiled by a C compiler, in this case GCC. This build system adds @code{chicken} to the package inputs, as well as the packages of @code{gnu-build-system}. The build system can't (yet) deduce the egg's name automatically, so just like with @code{go-build-system} and its @code{#:import-path}, you should define @code{#:egg-name} in the package's @code{arguments} field. For example, if you are packaging the @code{srfi-1} egg: @lisp (arguments '(#:egg-name "srfi-1")) @end lisp Egg dependencies must be defined in @code{propagated-inputs}, not @code{inputs} because CHICKEN doesn't embed absolute references in compiled eggs. Test dependencies should go to @code{native-inputs}, as usual. @end defvar @defvar copy-build-system This variable is exported by @code{(guix build-system copy)}. It supports builds of simple packages that don't require much compiling, mostly just moving files around. It adds much of the @code{gnu-build-system} packages to the set of inputs. Because of this, the @code{copy-build-system} does not require all the boilerplate code often needed for the @code{trivial-build-system}. To further simplify the file installation process, an @code{#:install-plan} argument is exposed to let the packager specify which files go where. The install plan is a list of @code{(@var{source} @var{target} [@var{filters}])}. @var{filters} are optional. @itemize @item When @var{source} matches a file or directory without trailing slash, install it to @var{target}. @itemize @item If @var{target} has a trailing slash, install @var{source} basename beneath @var{target}. @item Otherwise install @var{source} as @var{target}. @end itemize @item When @var{source} is a directory with a trailing slash, or when @var{filters} are used, the trailing slash of @var{target} is implied with the same meaning as above. @itemize @item Without @var{filters}, install the full @var{source} @emph{content} to @var{target}. @item With @var{filters} among @code{#:include}, @code{#:include-regexp}, @code{#:exclude}, @code{#:exclude-regexp}, only select files are installed depending on the filters. Each filters is specified by a list of strings. @itemize @item With @code{#:include}, install all the files which the path suffix matches at least one of the elements in the given list. @item With @code{#:include-regexp}, install all the files which the subpaths match at least one of the regular expressions in the given list. @item The @code{#:exclude} and @code{#:exclude-regexp} filters are the complement of their inclusion counterpart. Without @code{#:include} flags, install all files but those matching the exclusion filters. If both inclusions and exclusions are specified, the exclusions are done on top of the inclusions. @end itemize @item When a package has multiple outputs, the @code{#:output} argument can be used to specify which output label the files should be installed to. @end itemize In all cases, the paths relative to @var{source} are preserved within @var{target}. @end itemize Examples: @itemize @item @code{("foo/bar" "share/my-app/")}: Install @file{bar} to @file{share/my-app/bar}. @item @code{("foo/bar" "share/my-app/baz")}: Install @file{bar} to @file{share/my-app/baz}. @item @code{("foo/" "share/my-app")}: Install the content of @file{foo} inside @file{share/my-app}, e.g., install @file{foo/sub/file} to @file{share/my-app/sub/file}. @item @code{("foo/" "share/my-app" #:include ("sub/file"))}: Install only @file{foo/sub/file} to @file{share/my-app/sub/file}. @item @code{("foo/sub" "share/my-app" #:include ("file"))}: Install @file{foo/sub/file} to @file{share/my-app/file}. @item @code{("foo/doc" "share/my-app/doc" #:output "doc")}: Install @file{"foo/doc"} to @file{"share/my-app/doc"} within the @code{"doc"} output. @end itemize @end defvar @defvar vim-build-system This variable is exported by @code{(guix build-system vim)}. It is an extension of the @code{copy-build-system}, installing Vim and Neovim plugins into locations where these two text editors know to find their plugins, using their packpaths. Packages which are prefixed with @code{vim-} will be installed in Vim's packpath, while those prefixed with @code{neovim-} will be installed in Neovim's packpath. If there is a @code{doc} directory with the plugin then helptags will be generated automatically. There are a couple of keywords added with the @code{vim-build-system}: @itemize @item With @code{plugin-name} it is possible to set the name of the plugin. While by default this is set to the name and version of the package, it is often more helpful to set this to name which the upstream author calls their plugin. This is the name used for @command{:packadd} from inside Vim. @item With @code{install-plan} it is possible to augment the built-in install-plan of the @code{vim-build-system}. This is particularly helpful if you have files which should be installed in other locations. For more information about using the @code{install-plan}, see the @code{copy-build-system} (@pxref{Build Systems, @code{copy-build-system}}). @item With @code{#:vim} it is possible to add this package to Vim's packpath, in addition to if it is added automatically because of the @code{vim-} prefix in the package's name. @item With @code{#:neovim} it is possible to add this package to Neovim's packpath, in addition to if it is added automatically because of the @code{neovim-} prefix in the package's name. @item With @code{#:mode} it is possible to adjust the path which the plugin is installed into. By default the plugin is installed into @code{start} and other options are available, including @code{opt}. Adding a plugin into @code{opt} will mean you will need to run, for example, @command{:packadd foo} to load the @code{foo} plugin from inside of Vim. @end itemize @end defvar @cindex Clojure (programming language) @cindex simple Clojure build system @defvar clojure-build-system This variable is exported by @code{(guix build-system clojure)}. It implements a simple build procedure for @uref{https://clojure.org/, Clojure} packages using plain old @code{compile} in Clojure. Cross-compilation is not supported yet. It adds @code{clojure}, @code{icedtea} and @code{zip} to the set of inputs. Different packages can be specified with the @code{#:clojure}, @code{#:jdk} and @code{#:zip} parameters, respectively. A list of source directories, test directories and jar names can be specified with the @code{#:source-dirs}, @code{#:test-dirs} and @code{#:jar-names} parameters, respectively. Compile directory and main class can be specified with the @code{#:compile-dir} and @code{#:main-class} parameters, respectively. Other parameters are documented below. This build system is an extension of @code{ant-build-system}, but with the following phases changed: @table @code @item build This phase calls @code{compile} in Clojure to compile source files and runs @command{jar} to create jars from both source files and compiled files according to the include list and exclude list specified in @code{#:aot-include} and @code{#:aot-exclude}, respectively. The exclude list has priority over the include list. These lists consist of symbols representing Clojure libraries or the special keyword @code{#:all} representing all Clojure libraries found under the source directories. The parameter @code{#:omit-source?} decides if source should be included into the jars. @item check This phase runs tests according to the include list and exclude list specified in @code{#:test-include} and @code{#:test-exclude}, respectively. Their meanings are analogous to that of @code{#:aot-include} and @code{#:aot-exclude}, except that the special keyword @code{#:all} now stands for all Clojure libraries found under the test directories. The parameter @code{#:tests?} decides if tests should be run. @item install This phase installs all jars built previously. @end table Apart from the above, this build system also contains an additional phase: @table @code @item install-doc This phase installs all top-level files with base name matching @code{%doc-regex}. A different regex can be specified with the @code{#:doc-regex} parameter. All files (recursively) inside the documentation directories specified in @code{#:doc-dirs} are installed as well. @end table @end defvar @defvar cmake-build-system This variable is exported by @code{(guix build-system cmake)}. It implements the build procedure for packages using the @url{https://www.cmake.org, CMake build tool}. It automatically adds the @code{cmake} package to the set of inputs. Which package is used can be specified with the @code{#:cmake} parameter. The @code{#:configure-flags} parameter is taken as a list of flags passed to the @command{cmake} command. The @code{#:build-type} parameter specifies in abstract terms the flags passed to the compiler; it defaults to @code{"RelWithDebInfo"} (short for ``release mode with debugging information''), which roughly means that code is compiled with @code{-O2 -g}, as is the case for Autoconf-based packages by default. @end defvar @defvar composer-build-system This variable is exported by @code{(guix build-system composer)}. It implements the build procedure for packages using @url{https://getcomposer.org/, Composer}, the PHP package manager. It automatically adds the @code{php} package to the set of inputs. Which package is used can be specified with the @code{#:php} parameter. The @code{#:test-target} parameter is used to control which script is run for the tests. By default, the @code{test} script is run if it exists. If the script does not exist, the build system will run @code{phpunit} from the source directory, assuming there is a @file{phpunit.xml} file. @end defvar @defvar dune-build-system This variable is exported by @code{(guix build-system dune)}. It supports builds of packages using @uref{https://dune.build/, Dune}, a build tool for the OCaml programming language. It is implemented as an extension of the @code{ocaml-build-system} which is described below. As such, the @code{#:ocaml} and @code{#:findlib} parameters can be passed to this build system. It automatically adds the @code{dune} package to the set of inputs. Which package is used can be specified with the @code{#:dune} parameter. There is no @code{configure} phase because dune packages typically don't need to be configured. The @code{#:build-flags} parameter is taken as a list of flags passed to the @code{dune} command during the build. The @code{#:jbuild?} parameter can be passed to use the @code{jbuild} command instead of the more recent @code{dune} command while building a package. Its default value is @code{#f}. The @code{#:package} parameter can be passed to specify a package name, which is useful when a package contains multiple packages and you want to build only one of them. This is equivalent to passing the @code{-p} argument to @code{dune}. @end defvar @defvar elm-build-system This variable is exported by @code{(guix build-system elm)}. It implements a build procedure for @url{https://elm-lang.org, Elm} packages similar to @samp{elm install}. The build system adds an Elm compiler package to the set of inputs. The default compiler package (currently @code{elm-sans-reactor}) can be overridden using the @code{#:elm} argument. Additionally, Elm packages needed by the build system itself are added as implicit inputs if they are not already present: to suppress this behavior, use the @code{#:implicit-elm-package-inputs?} argument, which is primarily useful for bootstrapping. The @code{"dependencies"} and @code{"test-dependencies"} in an Elm package's @file{elm.json} file correspond to @code{propagated-inputs} and @code{inputs}, respectively. Elm requires a particular structure for package names: @pxref{Elm Packages} for more details, including utilities provided by @code{(guix build-system elm)}. There are currently a few noteworthy limitations to @code{elm-build-system}: @itemize @item The build system is focused on @dfn{packages} in the Elm sense of the word: Elm @dfn{projects} which declare @code{@{ "type": "package" @}} in their @file{elm.json} files. Using @code{elm-build-system} to build Elm @dfn{applications} (which declare @code{@{ "type": "application" @}}) is possible, but requires ad-hoc modifications to the build phases. For examples, see the definitions of the @code{elm-todomvc} example application and the @code{elm} package itself (because the front-end for the @samp{elm reactor} command is an Elm application). @item Elm supports multiple versions of a package coexisting simultaneously under @env{ELM_HOME}, but this does not yet work well with @code{elm-build-system}. This limitation primarily affects Elm applications, because they specify exact versions for their dependencies, whereas Elm packages specify supported version ranges. As a workaround, the example applications mentioned above use the @code{patch-application-dependencies} procedure provided by @code{(guix build elm-build-system)} to rewrite their @file{elm.json} files to refer to the package versions actually present in the build environment. Alternatively, Guix package transformations (@pxref{Defining Package Variants}) could be used to rewrite an application's entire dependency graph. @item We are not yet able to run tests for Elm projects because neither @url{https://github.com/mpizenberg/elm-test-rs, @command{elm-test-rs}} nor the Node.js-based @url{https://github.com/rtfeldman/node-test-runner, @command{elm-test}} runner has been packaged for Guix yet. @end itemize @end defvar @defvar go-build-system This variable is exported by @code{(guix build-system go)}. It implements a build procedure for Go packages using the standard @url{https://golang.org/cmd/go/#hdr-Compile_packages_and_dependencies, Go build mechanisms}. The user is expected to provide a value for the key @code{#:import-path} and, in some cases, @code{#:unpack-path}. The @url{https://golang.org/doc/code.html#ImportPaths, import path} corresponds to the file system path expected by the package's build scripts and any referring packages, and provides a unique way to refer to a Go package. It is typically based on a combination of the package source code's remote URI and file system hierarchy structure. In some cases, you will need to unpack the package's source code to a different directory structure than the one indicated by the import path, and @code{#:unpack-path} should be used in such cases. Packages that provide Go libraries should install their source code into the built output. The key @code{#:install-source?}, which defaults to @code{#t}, controls whether or not the source code is installed. It can be set to @code{#f} for packages that only provide executable files. Packages can be cross-built, and if a specific architecture or operating system is desired then the keywords @code{#:goarch} and @code{#:goos} can be used to force the package to be built for that architecture and operating system. The combinations known to Go can be found @url{https://golang.org/doc/install/source#environment, in their documentation}. The key @code{#:go} can be used to specify the Go compiler package with which to build the package. The phase @code{check} provides a wrapper for @code{go test} which builds a test binary (or multiple binaries), vets the code and then runs the test binary. Build, test and test binary flags can be provided as @code{#:test-flags} parameter, default is @code{'()}. See @code{go help test} and @code{go help testflag} for more details. The key @code{#:embed-files}, default is @code{'()}, provides a list of future embedded files or regexps matching files. They will be copied to build directory after @code{unpack} phase. See @url{https://pkg.go.dev/embed} for more details. @end defvar @defvar glib-or-gtk-build-system This variable is exported by @code{(guix build-system glib-or-gtk)}. It is intended for use with packages making use of GLib or GTK+. This build system adds the following two phases to the ones defined by @code{gnu-build-system}: @table @code @item glib-or-gtk-wrap The phase @code{glib-or-gtk-wrap} ensures that programs in @file{bin/} are able to find GLib ``schemas'' and @uref{https://developer.gnome.org/gtk3/stable/gtk-running.html, GTK+ modules}. This is achieved by wrapping the programs in launch scripts that appropriately set the @env{XDG_DATA_DIRS} and @env{GTK_PATH} environment variables. It is possible to exclude specific package outputs from that wrapping process by listing their names in the @code{#:glib-or-gtk-wrap-excluded-outputs} parameter. This is useful when an output is known not to contain any GLib or GTK+ binaries, and where wrapping would gratuitously add a dependency of that output on GLib and GTK+. @item glib-or-gtk-compile-schemas The phase @code{glib-or-gtk-compile-schemas} makes sure that all @uref{https://developer.gnome.org/gio/stable/glib-compile-schemas.html, GSettings schemas} of GLib are compiled. Compilation is performed by the @command{glib-compile-schemas} program. It is provided by the package @code{glib:bin} which is automatically imported by the build system. The @code{glib} package providing @command{glib-compile-schemas} can be specified with the @code{#:glib} parameter. @end table Both phases are executed after the @code{install} phase. @end defvar @defvar guile-build-system This build system is for Guile packages that consist exclusively of Scheme code and that are so lean that they don't even have a makefile, let alone a @file{configure} script. It compiles Scheme code using @command{guild compile} (@pxref{Compilation,,, guile, GNU Guile Reference Manual}) and installs the @file{.scm} and @file{.go} files in the right place. It also installs documentation. This build system supports cross-compilation by using the @option{--target} option of @samp{guild compile}. Packages built with @code{guile-build-system} must provide a Guile package in their @code{native-inputs} field. @end defvar @defvar julia-build-system This variable is exported by @code{(guix build-system julia)}. It implements the build procedure used by @uref{https://julialang.org/, julia} packages, which essentially is similar to running @samp{julia -e 'using Pkg; Pkg.add(package)'} in an environment where @env{JULIA_LOAD_PATH} contains the paths to all Julia package inputs. Tests are run by calling @code{/test/runtests.jl}. The Julia package name and uuid is read from the file @file{Project.toml}. These values can be overridden by passing the argument @code{#:julia-package-name} (which must be correctly capitalized) or @code{#:julia-package-uuid}. Julia packages usually manage their binary dependencies via @code{JLLWrappers.jl}, a Julia package that creates a module (named after the wrapped library followed by @code{_jll.jl}. To add the binary path @code{_jll.jl} packages, you need to patch the files under @file{src/wrappers/}, replacing the call to the macro @code{JLLWrappers.@@generate_wrapper_header}, adding as a second argument containing the store path the binary. As an example, in the MbedTLS Julia package, we add a build phase (@pxref{Build Phases}) to insert the absolute file name of the wrapped MbedTLS package: @lisp (add-after 'unpack 'override-binary-path (lambda* (#:key inputs #:allow-other-keys) (for-each (lambda (wrapper) (substitute* wrapper (("generate_wrapper_header.*") (string-append "generate_wrapper_header(\"MbedTLS\", \"" (assoc-ref inputs "mbedtls") "\")\n")))) ;; There's a Julia file for each platform, override them all. (find-files "src/wrappers/" "\\.jl$")))) @end lisp Some older packages that aren't using @file{Project.toml} yet, will require this file to be created, too. It is internally done if the arguments @code{#:julia-package-name} and @code{#:julia-package-uuid} are provided. @end defvar @defvar maven-build-system This variable is exported by @code{(guix build-system maven)}. It implements a build procedure for @uref{https://maven.apache.org, Maven} packages. Maven is a dependency and lifecycle management tool for Java. A user of Maven specifies dependencies and plugins in a @file{pom.xml} file that Maven reads. When Maven does not have one of the dependencies or plugins in its repository, it will download them and use them to build the package. The maven build system ensures that maven will not try to download any dependency by running in offline mode. Maven will fail if a dependency is missing. Before running Maven, the @file{pom.xml} (and subprojects) are modified to specify the version of dependencies and plugins that match the versions available in the guix build environment. Dependencies and plugins must be installed in the fake maven repository at @file{lib/m2}, and are symlinked into a proper repository before maven is run. Maven is instructed to use that repository for the build and installs built artifacts there. Changed files are copied to the @file{lib/m2} directory of the package output. You can specify a @file{pom.xml} file with the @code{#:pom-file} argument, or let the build system use the default @file{pom.xml} file in the sources. In case you need to specify a dependency's version manually, you can use the @code{#:local-packages} argument. It takes an association list where the key is the groupId of the package and its value is an association list where the key is the artifactId of the package and its value is the version you want to override in the @file{pom.xml}. Some packages use dependencies or plugins that are not useful at runtime nor at build time in Guix. You can alter the @file{pom.xml} file to remove them using the @code{#:exclude} argument. Its value is an association list where the key is the groupId of the plugin or dependency you want to remove, and the value is a list of artifactId you want to remove. You can override the default @code{jdk} and @code{maven} packages with the corresponding argument, @code{#:jdk} and @code{#:maven}. The @code{#:maven-plugins} argument is a list of maven plugins used during the build, with the same format as the @code{inputs} fields of the package declaration. Its default value is @code{(default-maven-plugins)} which is also exported. @end defvar @defvar minetest-mod-build-system This variable is exported by @code{(guix build-system minetest)}. It implements a build procedure for @uref{https://www.minetest.net, Minetest} mods, which consists of copying Lua code, images and other resources to the location Minetest searches for mods. The build system also minimises PNG images and verifies that Minetest can load the mod without errors. @end defvar @defvar minify-build-system This variable is exported by @code{(guix build-system minify)}. It implements a minification procedure for simple JavaScript packages. It adds @code{uglify-js} to the set of inputs and uses it to compress all JavaScript files in the @file{src} directory. A different minifier package can be specified with the @code{#:uglify-js} parameter, but it is expected that the package writes the minified code to the standard output. When the input JavaScript files are not all located in the @file{src} directory, the parameter @code{#:javascript-files} can be used to specify a list of file names to feed to the minifier. @end defvar @defvar mozilla-build-system This variable is exported by @code{(guix build-system mozilla)}. It sets the @code{--target} and @code{--host} configuration flags to what software developed by Mozilla expects -- due to historical reasons, Mozilla software expects @code{--host} to be the system that is cross-compiled from and @code{--target} to be the system that is cross-compiled to, contrary to the standard Autotools conventions. @end defvar @defvar ocaml-build-system This variable is exported by @code{(guix build-system ocaml)}. It implements a build procedure for @uref{https://ocaml.org, OCaml} packages, which consists of choosing the correct set of commands to run for each package. OCaml packages can expect many different commands to be run. This build system will try some of them. When the package has a @file{setup.ml} file present at the top-level, it will run @code{ocaml setup.ml -configure}, @code{ocaml setup.ml -build} and @code{ocaml setup.ml -install}. The build system will assume that this file was generated by @uref{http://oasis.forge.ocamlcore.org/, OASIS} and will take care of setting the prefix and enabling tests if they are not disabled. You can pass configure and build flags with the @code{#:configure-flags} and @code{#:build-flags}. The @code{#:test-flags} key can be passed to change the set of flags used to enable tests. The @code{#:use-make?} key can be used to bypass this system in the build and install phases. When the package has a @file{configure} file, it is assumed that it is a hand-made configure script that requires a different argument format than in the @code{gnu-build-system}. You can add more flags with the @code{#:configure-flags} key. When the package has a @file{Makefile} file (or @code{#:use-make?} is @code{#t}), it will be used and more flags can be passed to the build and install phases with the @code{#:make-flags} key. Finally, some packages do not have these files and use a somewhat standard location for its build system. In that case, the build system will run @code{ocaml pkg/pkg.ml} or @code{ocaml pkg/build.ml} and take care of providing the path to the required findlib module. Additional flags can be passed via the @code{#:build-flags} key. Install is taken care of by @command{opam-installer}. In this case, the @code{opam} package must be added to the @code{native-inputs} field of the package definition. Note that most OCaml packages assume they will be installed in the same directory as OCaml, which is not what we want in guix. In particular, they will install @file{.so} files in their module's directory, which is usually fine because it is in the OCaml compiler directory. In guix though, these libraries cannot be found and we use @env{CAML_LD_LIBRARY_PATH}. This variable points to @file{lib/ocaml/site-lib/stubslibs} and this is where @file{.so} libraries should be installed. @end defvar @defvar python-build-system This variable is exported by @code{(guix build-system python)}. It implements the more or less standard build procedure used by Python packages, which consists in running @code{python setup.py build} and then @code{python setup.py install --prefix=/gnu/store/@dots{}}. For packages that install stand-alone Python programs under @code{bin/}, it takes care of wrapping these programs so that their @env{GUIX_PYTHONPATH} environment variable points to all the Python libraries they depend on. Which Python package is used to perform the build can be specified with the @code{#:python} parameter. This is a useful way to force a package to be built for a specific version of the Python interpreter, which might be necessary if the package is only compatible with a single interpreter version. By default guix calls @code{setup.py} under control of @code{setuptools}, much like @command{pip} does. Some packages are not compatible with setuptools (and pip), thus you can disable this by setting the @code{#:use-setuptools?} parameter to @code{#f}. If a @code{"python"} output is available, the package is installed into it instead of the default @code{"out"} output. This is useful for packages that include a Python package as only a part of the software, and thus want to combine the phases of @code{python-build-system} with another build system. Python bindings are a common usecase. @end defvar @defvar pyproject-build-system This is a variable exported by @code{guix build-system pyproject}. It is based on @var{python-build-system}, and adds support for @file{pyproject.toml} and @url{https://peps.python.org/pep-0517/, PEP 517}. It also supports a variety of build backends and test frameworks. The API is slightly different from @var{python-build-system}: @itemize @item @code{#:use-setuptools?} and @code{#:test-target} is removed. @item @code{#:configure-flags} is changed. Instead of a list this option must be a JSON object, whose interpretation depends on the build backend. For instance the example from @url{https://peps.python.org/pep-0517/#config-settings,PEP 517} should be written as @code{'(@@ ("CC" "gcc") ("--global-option" ("--some-global-option")) ("--build-option" ("--build-option1" "--build-option2")))} @item @code{#:backend-path} is added. It defaults to @code{#false}, but when set to a list it will be appended to Python’s search path and overrides the definition in @file{pyproject.toml}. @item @code{#:build-backend} is added. It defaults to @code{#false} and will try to guess the appropriate backend based on @file{pyproject.toml}. @item @code{#:test-backend} is added. It defaults to @code{#false} and will guess an appropriate test backend based on what is available in package inputs. @item @code{#:test-flags} is added. The default is @code{'()}. These flags are passed as arguments to the test command. Note that flags for verbose output is always enabled on supported backends. @end itemize It is considered ``experimental'' in that the implementation details are not set in stone yet, however users are encouraged to try it for new Python projects (even those using @file{setup.py}). The API is subject to change, but any breaking changes in the Guix channel will be dealt with. Eventually this build system will be deprecated and merged back into @var{python-build-system}, probably some time in 2024. @end defvar @defvar perl-build-system This variable is exported by @code{(guix build-system perl)}. It implements the standard build procedure for Perl packages, which either consists in running @code{perl Build.PL --prefix=/gnu/store/@dots{}}, followed by @code{Build} and @code{Build install}; or in running @code{perl Makefile.PL PREFIX=/gnu/store/@dots{}}, followed by @code{make} and @code{make install}, depending on which of @code{Build.PL} or @code{Makefile.PL} is present in the package distribution. Preference is given to the former if both @code{Build.PL} and @code{Makefile.PL} exist in the package distribution. This preference can be reversed by specifying @code{#t} for the @code{#:make-maker?} parameter. The initial @code{perl Makefile.PL} or @code{perl Build.PL} invocation passes flags specified by the @code{#:make-maker-flags} or @code{#:module-build-flags} parameter, respectively. Which Perl package is used can be specified with @code{#:perl}. @end defvar @defvar renpy-build-system This variable is exported by @code{(guix build-system renpy)}. It implements the more or less standard build procedure used by Ren'py games, which consists of loading @code{#:game} once, thereby creating bytecode for it. It further creates a wrapper script in @code{bin/} and a desktop entry in @code{share/applications}, both of which can be used to launch the game. Which Ren'py package is used can be specified with @code{#:renpy}. Games can also be installed in outputs other than ``out'' by using @code{#:output}. @end defvar @defvar qt-build-system This variable is exported by @code{(guix build-system qt)}. It is intended for use with applications using Qt or KDE. This build system adds the following two phases to the ones defined by @code{cmake-build-system}: @table @code @item check-setup The phase @code{check-setup} prepares the environment for running the checks as commonly used by Qt test programs. For now this only sets some environment variables: @code{QT_QPA_PLATFORM=offscreen}, @code{DBUS_FATAL_WARNINGS=0} and @code{CTEST_OUTPUT_ON_FAILURE=1}. This phase is added before the @code{check} phase. It's a separate phase to ease adjusting if necessary. @item qt-wrap The phase @code{qt-wrap} searches for Qt5 plugin paths, QML paths and some XDG in the inputs and output. In case some path is found, all programs in the output's @file{bin/}, @file{sbin/}, @file{libexec/} and @file{lib/libexec/} directories are wrapped in scripts defining the necessary environment variables. It is possible to exclude specific package outputs from that wrapping process by listing their names in the @code{#:qt-wrap-excluded-outputs} parameter. This is useful when an output is known not to contain any Qt binaries, and where wrapping would gratuitously add a dependency of that output on Qt, KDE, or such. This phase is added after the @code{install} phase. @end table @end defvar @defvar r-build-system This variable is exported by @code{(guix build-system r)}. It implements the build procedure used by @uref{https://r-project.org, R} packages, which essentially is little more than running @samp{R CMD INSTALL --library=/gnu/store/@dots{}} in an environment where @env{R_LIBS_SITE} contains the paths to all R package inputs. Tests are run after installation using the R function @code{tools::testInstalledPackage}. @end defvar @defvar rakudo-build-system This variable is exported by @code{(guix build-system rakudo)}. It implements the build procedure used by @uref{https://rakudo.org/, Rakudo} for @uref{https://perl6.org/, Perl6} packages. It installs the package to @code{/gnu/store/@dots{}/NAME-VERSION/share/perl6} and installs the binaries, library files and the resources, as well as wrap the files under the @code{bin/} directory. Tests can be skipped by passing @code{#f} to the @code{tests?} parameter. Which rakudo package is used can be specified with @code{rakudo}. Which perl6-tap-harness package used for the tests can be specified with @code{#:prove6} or removed by passing @code{#f} to the @code{with-prove6?} parameter. Which perl6-zef package used for tests and installing can be specified with @code{#:zef} or removed by passing @code{#f} to the @code{with-zef?} parameter. @end defvar @defvar rebar-build-system This variable is exported by @code{(guix build-system rebar)}. It implements a build procedure around @uref{https://rebar3.org,rebar3}, a build system for programs written in the Erlang language. It adds both @code{rebar3} and the @code{erlang} to the set of inputs. Different packages can be specified with the @code{#:rebar} and @code{#:erlang} parameters, respectively. This build system is based on @code{gnu-build-system}, but with the following phases changed: @table @code @item unpack This phase, after unpacking the source like the @code{gnu-build-system} does, checks for a file @code{contents.tar.gz} at the top-level of the source. If this file exists, it will be unpacked, too. This eases handling of package hosted at @uref{https://hex.pm/}, the Erlang and Elixir package repository. @item bootstrap @item configure There are no @code{bootstrap} and @code{configure} phase because erlang packages typically don’t need to be configured. @item build This phase runs @code{rebar3 compile} with the flags listed in @code{#:rebar-flags}. @item check Unless @code{#:tests? #f} is passed, this phase runs @code{rebar3 eunit}, or some other target specified with @code{#:test-target}, with the flags listed in @code{#:rebar-flags}, @item install This installs the files created in the @i{default} profile, or some other profile specified with @code{#:install-profile}. @end table @end defvar @defvar texlive-build-system This variable is exported by @code{(guix build-system texlive)}. It is used to build TeX packages in batch mode with a specified engine. The build system sets the @env{TEXINPUTS} variable to find all TeX source files in the inputs. By default it tries to run @code{luatex} on all @file{.ins} files, and if it fails to find any, on all @file{.dtx} files. A different engine and format can be specified with, respectively, the @code{#:tex-engine} and @code{#:tex-format} arguments. Different build targets can be specified with the @code{#:build-targets} argument, which expects a list of file names. It also generates font metrics (i.e., @file{.tfm} files) out of Metafont files whenever possible. Likewise, it can also create TeX formats (i.e., @file{.fmt} files) listed in the @code{#:create-formats} argument, and generate a symbolic link from @file{bin/} directory to any script located in @file{texmf-dist/scripts/}, provided its file name is listed in @code{#:link-scripts} argument. The build system adds @code{texlive-bin} from @code{(gnu packages tex)} to the native inputs. It can be overridden with the @code{#:texlive-bin} argument. The package @code{texlive-latex-bin}, from the same module, contains most of the tools for building TeX Live packages; for convenience, it is also added by default to the native inputs. However, this can be troublesome when building a dependency of @code{texlive-latex-bin} itself. In this particular situation, the @code{#:texlive-latex-bin?} argument should be set to @code{#f}. @end defvar @defvar ruby-build-system This variable is exported by @code{(guix build-system ruby)}. It implements the RubyGems build procedure used by Ruby packages, which involves running @code{gem build} followed by @code{gem install}. The @code{source} field of a package that uses this build system typically references a gem archive, since this is the format that Ruby developers use when releasing their software. The build system unpacks the gem archive, potentially patches the source, runs the test suite, repackages the gem, and installs it. Additionally, directories and tarballs may be referenced to allow building unreleased gems from Git or a traditional source release tarball. Which Ruby package is used can be specified with the @code{#:ruby} parameter. A list of additional flags to be passed to the @command{gem} command can be specified with the @code{#:gem-flags} parameter. @end defvar @defvar waf-build-system This variable is exported by @code{(guix build-system waf)}. It implements a build procedure around the @code{waf} script. The common phases---@code{configure}, @code{build}, and @code{install}---are implemented by passing their names as arguments to the @code{waf} script. The @code{waf} script is executed by the Python interpreter. Which Python package is used to run the script can be specified with the @code{#:python} parameter. @end defvar @defvar zig-build-system This variable is exported by @code{(guix build-system zig)}. It implements the build procedures for the @uref{https://ziglang.org/, Zig} build system (@command{zig build} command). Selecting this build system adds @code{zig} to the package inputs, in addition to the packages of @code{gnu-build-system}. There is no @code{configure} phase because Zig packages typically do not need to be configured. The @code{#:zig-build-flags} parameter is a list of flags that are passed to the @code{zig} command during the build. The @code{#:zig-test-flags} parameter is a list of flags that are passed to the @code{zig test} command during the @code{check} phase. The default compiler package can be overridden with the @code{#:zig} argument. The optional @code{zig-release-type} parameter declares the type of release. Possible values are: @code{safe}, @code{fast}, or @code{small}. The default value is @code{#f}, which causes the release flag to be omitted from the @code{zig} command. That results in a @code{debug} build. @end defvar @defvar scons-build-system This variable is exported by @code{(guix build-system scons)}. It implements the build procedure used by the SCons software construction tool. This build system runs @code{scons} to build the package, @code{scons test} to run tests, and then @code{scons install} to install the package. Additional flags to be passed to @code{scons} can be specified with the @code{#:scons-flags} parameter. The default build and install targets can be overridden with @code{#:build-targets} and @code{#:install-targets} respectively. The version of Python used to run SCons can be specified by selecting the appropriate SCons package with the @code{#:scons} parameter. @end defvar @defvar haskell-build-system This variable is exported by @code{(guix build-system haskell)}. It implements the Cabal build procedure used by Haskell packages, which involves running @code{runhaskell Setup.hs configure --prefix=/gnu/store/@dots{}} and @code{runhaskell Setup.hs build}. Instead of installing the package by running @code{runhaskell Setup.hs install}, to avoid trying to register libraries in the read-only compiler store directory, the build system uses @code{runhaskell Setup.hs copy}, followed by @code{runhaskell Setup.hs register}. In addition, the build system generates the package documentation by running @code{runhaskell Setup.hs haddock}, unless @code{#:haddock? #f} is passed. Optional Haddock parameters can be passed with the help of the @code{#:haddock-flags} parameter. If the file @code{Setup.hs} is not found, the build system looks for @code{Setup.lhs} instead. Which Haskell compiler is used can be specified with the @code{#:haskell} parameter which defaults to @code{ghc}. @end defvar @defvar dub-build-system This variable is exported by @code{(guix build-system dub)}. It implements the Dub build procedure used by D packages, which involves running @code{dub build} and @code{dub run}. Installation is done by copying the files manually. Which D compiler is used can be specified with the @code{#:ldc} parameter which defaults to @code{ldc}. @end defvar @anchor{emacs-build-system} @defvar emacs-build-system This variable is exported by @code{(guix build-system emacs)}. It implements an installation procedure similar to the packaging system of Emacs itself (@pxref{Packages,,, emacs, The GNU Emacs Manual}). It first creates the @code{@code{package}-autoloads.el} file, then it byte compiles all Emacs Lisp files. Differently from the Emacs packaging system, the Info documentation files are moved to the standard documentation directory and the @file{dir} file is deleted. The Elisp package files are installed directly under @file{share/emacs/site-lisp}. @end defvar @defvar font-build-system This variable is exported by @code{(guix build-system font)}. It implements an installation procedure for font packages where upstream provides pre-compiled TrueType, OpenType, etc.@: font files that merely need to be copied into place. It copies font files to standard locations in the output directory. @end defvar @defvar meson-build-system This variable is exported by @code{(guix build-system meson)}. It implements the build procedure for packages that use @url{https://mesonbuild.com, Meson} as their build system. It adds both Meson and @uref{https://ninja-build.org/, Ninja} to the set of inputs, and they can be changed with the parameters @code{#:meson} and @code{#:ninja} if needed. This build system is an extension of @code{gnu-build-system}, but with the following phases changed to some specific for Meson: @table @code @item configure The phase runs @code{meson} with the flags specified in @code{#:configure-flags}. The flag @option{--buildtype} is always set to @code{debugoptimized} unless something else is specified in @code{#:build-type}. @item build The phase runs @code{ninja} to build the package in parallel by default, but this can be changed with @code{#:parallel-build?}. @item check The phase runs @samp{meson test} with a base set of options that cannot be overridden. This base set of options can be extended via the @code{#:test-options} argument, for example to select or skip a specific test suite. @item install The phase runs @code{ninja install} and can not be changed. @end table Apart from that, the build system also adds the following phases: @table @code @item fix-runpath This phase ensures that all binaries can find the libraries they need. It searches for required libraries in subdirectories of the package being built, and adds those to @code{RUNPATH} where needed. It also removes references to libraries left over from the build phase by @code{meson}, such as test dependencies, that aren't actually required for the program to run. @item glib-or-gtk-wrap This phase is the phase provided by @code{glib-or-gtk-build-system}, and it is not enabled by default. It can be enabled with @code{#:glib-or-gtk?}. @item glib-or-gtk-compile-schemas This phase is the phase provided by @code{glib-or-gtk-build-system}, and it is not enabled by default. It can be enabled with @code{#:glib-or-gtk?}. @end table @end defvar @defvar linux-module-build-system @code{linux-module-build-system} allows building Linux kernel modules. @cindex build phases This build system is an extension of @code{gnu-build-system}, but with the following phases changed: @table @code @item configure This phase configures the environment so that the Linux kernel's Makefile can be used to build the external kernel module. @item build This phase uses the Linux kernel's Makefile in order to build the external kernel module. @item install This phase uses the Linux kernel's Makefile in order to install the external kernel module. @end table It is possible and useful to specify the Linux kernel to use for building the module (in the @code{arguments} form of a package using the @code{linux-module-build-system}, use the key @code{#:linux} to specify it). @end defvar @defvar node-build-system This variable is exported by @code{(guix build-system node)}. It implements the build procedure used by @uref{https://nodejs.org, Node.js}, which implements an approximation of the @code{npm install} command, followed by an @code{npm test} command. Which Node.js package is used to interpret the @code{npm} commands can be specified with the @code{#:node} parameter which defaults to @code{node}. @end defvar @defvar tree-sitter-build-system This variable is exported by @code{(guix build-system tree-sitter)}. It implements procedures to compile grammars for the @url{https://tree-sitter.github.io/tree-sitter/, Tree-sitter} parsing library. It essentially runs @code{tree-sitter generate} to translate @code{grammar.js} grammars to JSON and then to C. Which it then compiles to native code. Tree-sitter packages may support multiple grammars, so this build system supports a @code{#:grammar-directories} keyword to specify a list of locations where a @code{grammar.js} file may be found. Grammars sometimes depend on each other, such as C++ depending on C and TypeScript depending on JavaScript. You may use inputs to declare such dependencies. @end defvar Lastly, for packages that do not need anything as sophisticated, a ``trivial'' build system is provided. It is trivial in the sense that it provides basically no support: it does not pull any implicit inputs, and does not have a notion of build phases. @defvar trivial-build-system This variable is exported by @code{(guix build-system trivial)}. This build system requires a @code{#:builder} argument. This argument must be a Scheme expression that builds the package output(s)---as with @code{build-expression->derivation} (@pxref{Derivations, @code{build-expression->derivation}}). @end defvar @defvar channel-build-system This variable is exported by @code{(guix build-system channel)}. This build system is meant primarily for internal use. A package using this build system must have a channel specification as its @code{source} field (@pxref{Channels}); alternatively, its source can be a directory name, in which case an additional @code{#:commit} argument must be supplied to specify the commit being built (a hexadecimal string). Optionally, a @code{#:channels} argument specifying additional channels can be provided. The resulting package is a Guix instance of the given channel(s), similar to how @command{guix time-machine} would build it. @end defvar @node Build Phases @section Build Phases @cindex build phases, for packages Almost all package build systems implement a notion @dfn{build phases}: a sequence of actions that the build system executes, when you build the package, leading to the installed byproducts in the store. A notable exception is the ``bare-bones'' @code{trivial-build-system} (@pxref{Build Systems}). As discussed in the previous section, those build systems provide a standard list of phases. For @code{gnu-build-system}, the main build phases are the following: @table @code @item set-paths Define search path environment variables for all the input packages, including @env{PATH} (@pxref{Search Paths}). @item unpack Unpack the source tarball, and change the current directory to the extracted source tree. If the source is actually a directory, copy it to the build tree, and enter that directory. @item patch-source-shebangs Patch shebangs encountered in source files so they refer to the right store file names. For instance, this changes @code{#!/bin/sh} to @code{#!/gnu/store/@dots{}-bash-4.3/bin/sh}. @item configure Run the @file{configure} script with a number of default options, such as @option{--prefix=/gnu/store/@dots{}}, as well as the options specified by the @code{#:configure-flags} argument. @item build Run @code{make} with the list of flags specified with @code{#:make-flags}. If the @code{#:parallel-build?} argument is true (the default), build with @code{make -j}. @item check Run @code{make check}, or some other target specified with @code{#:test-target}, unless @code{#:tests? #f} is passed. If the @code{#:parallel-tests?} argument is true (the default), run @code{make check -j}. @item install Run @code{make install} with the flags listed in @code{#:make-flags}. @item patch-shebangs Patch shebangs on the installed executable files. @item strip Strip debugging symbols from ELF files (unless @code{#:strip-binaries?} is false), copying them to the @code{debug} output when available (@pxref{Installing Debugging Files}). @cindex RUNPATH, validation @anchor{phase-validate-runpath} @item validate-runpath Validate the @code{RUNPATH} of ELF binaries, unless @code{#:validate-runpath?} is false (@pxref{Build Systems}). This validation step consists in making sure that all the shared libraries needed by an ELF binary, which are listed as @code{DT_NEEDED} entries in its @code{PT_DYNAMIC} segment, appear in the @code{DT_RUNPATH} entry of that binary. In other words, it ensures that running or using those binaries will not result in a ``file not found'' error at run time. @xref{Options, @option{-rpath},, ld, The GNU Linker}, for more information on @code{RUNPATH}. @end table Other build systems have similar phases, with some variations. For example, @code{cmake-build-system} has same-named phases but its @code{configure} phases runs @code{cmake} instead of @code{./configure}. Others, such as @code{python-build-system}, have a wholly different list of standard phases. All this code runs on the @dfn{build side}: it is evaluated when you actually build the package, in a dedicated build process spawned by the build daemon (@pxref{Invoking guix-daemon}). Build phases are represented as association lists or ``alists'' (@pxref{Association Lists,,, guile, GNU Guile Reference Manual}) where each key is a symbol for the name of the phase and the associated value is a procedure that accepts an arbitrary number of arguments. By convention, those procedures receive information about the build in the form of @dfn{keyword parameters}, which they can use or ignore. @vindex %standard-phases For example, here is how @code{(guix build gnu-build-system)} defines @code{%standard-phases}, the variable holding its alist of build phases@footnote{We present a simplified view of those build phases, but do take a look at @code{(guix build gnu-build-system)} to see all the details!}: @lisp ;; The build phases of 'gnu-build-system'. (define* (unpack #:key source #:allow-other-keys) ;; Extract the source tarball. (invoke "tar" "xvf" source)) (define* (configure #:key outputs #:allow-other-keys) ;; Run the 'configure' script. Install to output "out". (let ((out (assoc-ref outputs "out"))) (invoke "./configure" (string-append "--prefix=" out)))) (define* (build #:allow-other-keys) ;; Compile. (invoke "make")) (define* (check #:key (test-target "check") (tests? #true) #:allow-other-keys) ;; Run the test suite. (if tests? (invoke "make" test-target) (display "test suite not run\n"))) (define* (install #:allow-other-keys) ;; Install files to the prefix 'configure' specified. (invoke "make" "install")) (define %standard-phases ;; The list of standard phases (quite a few are omitted ;; for brevity). Each element is a symbol/procedure pair. (list (cons 'unpack unpack) (cons 'configure configure) (cons 'build build) (cons 'check check) (cons 'install install))) @end lisp This shows how @code{%standard-phases} is defined as a list of symbol/procedure pairs (@pxref{Pairs,,, guile, GNU Guile Reference Manual}). The first pair associates the @code{unpack} procedure with the @code{unpack} symbol---a name; the second pair defines the @code{configure} phase similarly, and so on. When building a package that uses @code{gnu-build-system} with its default list of phases, those phases are executed sequentially. You can see the name of each phase started and completed in the build log of packages that you build. Let's now look at the procedures themselves. Each one is defined with @code{define*}: @code{#:key} lists keyword parameters the procedure accepts, possibly with a default value, and @code{#:allow-other-keys} specifies that other keyword parameters are ignored (@pxref{Optional Arguments,,, guile, GNU Guile Reference Manual}). The @code{unpack} procedure honors the @code{source} parameter, which the build system uses to pass the file name of the source tarball (or version control checkout), and it ignores other parameters. The @code{configure} phase only cares about the @code{outputs} parameter, an alist mapping package output names to their store file name (@pxref{Packages with Multiple Outputs}). It extracts the file name of for @code{out}, the default output, and passes it to @command{./configure} as the installation prefix, meaning that @command{make install} will eventually copy all the files in that directory (@pxref{Configuration, configuration and makefile conventions,, standards, GNU Coding Standards}). @code{build} and @code{install} ignore all their arguments. @code{check} honors the @code{test-target} argument, which specifies the name of the Makefile target to run tests; it prints a message and skips tests when @code{tests?} is false. @cindex build phases, customizing The list of phases used for a particular package can be changed with the @code{#:phases} parameter of the build system. Changing the set of build phases boils down to building a new alist of phases based on the @code{%standard-phases} alist described above. This can be done with standard alist procedures such as @code{alist-delete} (@pxref{SRFI-1 Association Lists,,, guile, GNU Guile Reference Manual}); however, it is more convenient to do so with @code{modify-phases} (@pxref{Build Utilities, @code{modify-phases}}). Here is an example of a package definition that removes the @code{configure} phase of @code{%standard-phases} and inserts a new phase before the @code{build} phase, called @code{set-prefix-in-makefile}: @lisp (define-public example (package (name "example") ;; other fields omitted (build-system gnu-build-system) (arguments (list #:phases #~(modify-phases %standard-phases (delete 'configure) (add-before 'build 'set-prefix-in-makefile (lambda* (#:key inputs #:allow-other-keys) ;; Modify the makefile so that its ;; 'PREFIX' variable points to #$output and ;; 'XMLLINT' points to the correct path. (substitute* "Makefile" (("PREFIX =.*") (string-append "PREFIX = " #$output "\n")) (("XMLLINT =.*") (string-append "XMLLINT = " (search-input-file inputs "/bin/xmllint") "\n")))))))))) @end lisp The new phase that is inserted is written as an anonymous procedure, introduced with @code{lambda*}; it looks for the @file{xmllint} executable under a @file{/bin} directory among the package's inputs (@pxref{package Reference}). It also honors the @code{outputs} parameter we have seen before. @xref{Build Utilities}, for more about the helpers used by this phase, and for more examples of @code{modify-phases}. @quotation Tip You can inspect the code associated with a package's @code{#:phases} argument interactively, at the REPL (@pxref{Using Guix Interactively}). @end quotation @cindex code staging @cindex staging, of code Keep in mind that build phases are code evaluated at the time the package is actually built. This explains why the whole @code{modify-phases} expression above is quoted (it comes after the @code{#~} or hash-tilde): it is @dfn{staged} for later execution. @xref{G-Expressions}, for an explanation of code staging and the @dfn{code strata} involved. @node Build Utilities @section Build Utilities As soon as you start writing non-trivial package definitions (@pxref{Defining Packages}) or other build actions (@pxref{G-Expressions}), you will likely start looking for helpers for ``shell-like'' actions---creating directories, copying and deleting files recursively, manipulating build phases, and so on. The @code{(guix build utils)} module provides such utility procedures. Most build systems load @code{(guix build utils)} (@pxref{Build Systems}). Thus, when writing custom build phases for your package definitions, you can usually assume those procedures are in scope. When writing G-expressions, you can import @code{(guix build utils)} on the ``build side'' using @code{with-imported-modules} and then put it in scope with the @code{use-modules} form (@pxref{Using Guile Modules,,, guile, GNU Guile Reference Manual}): @lisp (with-imported-modules '((guix build utils)) ;import it (computed-file "empty-tree" #~(begin ;; Put it in scope. (use-modules (guix build utils)) ;; Happily use its 'mkdir-p' procedure. (mkdir-p (string-append #$output "/a/b/c"))))) @end lisp The remainder of this section is the reference for most of the utility procedures provided by @code{(guix build utils)}. @c TODO Document what's missing. @subsection Dealing with Store File Names This section documents procedures that deal with store file names. @deffn {Procedure} %store-directory Return the directory name of the store. @end deffn @deffn {Procedure} store-file-name? file Return true if @var{file} is in the store. @end deffn @deffn {Procedure} strip-store-file-name file Strip the @file{/gnu/store} and hash from @var{file}, a store file name. The result is typically a @code{"@var{package}-@var{version}"} string. @end deffn @deffn {Procedure} package-name->name+version name Given @var{name}, a package name like @code{"foo-0.9.1b"}, return two values: @code{"foo"} and @code{"0.9.1b"}. When the version part is unavailable, @var{name} and @code{#f} are returned. The first hyphen followed by a digit is considered to introduce the version part. @end deffn @subsection File Types The procedures below deal with files and file types. @deffn {Procedure} directory-exists? dir Return @code{#t} if @var{dir} exists and is a directory. @end deffn @deffn {Procedure} executable-file? file Return @code{#t} if @var{file} exists and is executable. @end deffn @deffn {Procedure} symbolic-link? file Return @code{#t} if @var{file} is a symbolic link (aka. a ``symlink''). @end deffn @deffn {Procedure} elf-file? file @deffnx {Procedure} ar-file? file @deffnx {Procedure} gzip-file? file Return @code{#t} if @var{file} is, respectively, an ELF file, an @code{ar} archive (such as a @file{.a} static library), or a gzip file. @end deffn @deffn {Procedure} reset-gzip-timestamp file [#:keep-mtime? #t] If @var{file} is a gzip file, reset its embedded timestamp (as with @command{gzip --no-name}) and return true. Otherwise return @code{#f}. When @var{keep-mtime?} is true, preserve @var{file}'s modification time. @end deffn @subsection File Manipulation The following procedures and macros help create, modify, and delete files. They provide functionality comparable to common shell utilities such as @command{mkdir -p}, @command{cp -r}, @command{rm -r}, and @command{sed}. They complement Guile's extensive, but low-level, file system interface (@pxref{POSIX,,, guile, GNU Guile Reference Manual}). @defmac with-directory-excursion directory body @dots{} Run @var{body} with @var{directory} as the process's current directory. Essentially, this macro changes the current directory to @var{directory} before evaluating @var{body}, using @code{chdir} (@pxref{Processes,,, guile, GNU Guile Reference Manual}). It changes back to the initial directory when the dynamic extent of @var{body} is left, be it @i{via} normal procedure return or @i{via} a non-local exit such as an exception. @end defmac @deffn {Procedure} mkdir-p dir Create directory @var{dir} and all its ancestors. @end deffn @deffn {Procedure} install-file file directory Create @var{directory} if it does not exist and copy @var{file} in there under the same name. @end deffn @deffn {Procedure} make-file-writable file Make @var{file} writable for its owner. @end deffn @deffn {Procedure} copy-recursively source destination @ [#:log (current-output-port)] [#:follow-symlinks? #f] @ [#:copy-file copy-file] [#:keep-mtime? #f] [#:keep-permissions? #t] @ [#:select? (const #t)] Copy @var{source} directory to @var{destination}. Follow symlinks if @var{follow-symlinks?} is true; otherwise, just preserve them. Call @var{copy-file} to copy regular files. Call @var{select?}, taking two arguments, @var{file} and @var{stat}, for each entry in @var{source}, where @var{file} is the entry's absolute file name and @var{stat} is the result of @code{lstat} (or @code{stat} if @var{follow-symlinks?} is true); exclude entries for which @var{select?} does not return true. When @var{keep-mtime?} is true, keep the modification time of the files in @var{source} on those of @var{destination}. When @var{keep-permissions?} is true, preserve file permissions. Write verbose output to the @var{log} port. @end deffn @deffn {Procedure} delete-file-recursively dir [#:follow-mounts? #f] Delete @var{dir} recursively, like @command{rm -rf}, without following symlinks. Don't follow mount points either, unless @var{follow-mounts?} is true. Report but ignore errors. @end deffn @defmac substitute* file @ ((regexp match-var@dots{}) body@dots{}) @dots{} Substitute @var{regexp} in @var{file} by the string returned by @var{body}. @var{body} is evaluated with each @var{match-var} bound to the corresponding positional regexp sub-expression. For example: @lisp (substitute* file (("hello") "good morning\n") (("foo([a-z]+)bar(.*)$" all letters end) (string-append "baz" letters end))) @end lisp Here, anytime a line of @var{file} contains @code{hello}, it is replaced by @code{good morning}. Anytime a line of @var{file} matches the second regexp, @code{all} is bound to the complete match, @code{letters} is bound to the first sub-expression, and @code{end} is bound to the last one. When one of the @var{match-var} is @code{_}, no variable is bound to the corresponding match substring. Alternatively, @var{file} may be a list of file names, in which case they are all subject to the substitutions. Be careful about using @code{$} to match the end of a line; by itself it won't match the terminating newline of a line. For example, to match a whole line ending with a backslash, one needs a regex like @code{"(.*)\\\\\n$"}. @end defmac @subsection File Search @cindex file, searching This section documents procedures to search and filter files. @deffn {Procedure} file-name-predicate regexp Return a predicate that returns true when passed a file name whose base name matches @var{regexp}. @end deffn @deffn {Procedure} find-files dir [pred] @ [#:stat lstat] [#:directories? #f] [#:fail-on-error? #f] Return the lexicographically sorted list of files under @var{dir} for which @var{pred} returns true. @var{pred} is passed two arguments: the absolute file name, and its stat buffer; the default predicate always returns true. @var{pred} can also be a regular expression, in which case it is equivalent to @code{(file-name-predicate @var{pred})}. @var{stat} is used to obtain file information; using @code{lstat} means that symlinks are not followed. If @var{directories?} is true, then directories will also be included. If @var{fail-on-error?} is true, raise an exception upon error. @end deffn Here are a few examples where we assume that the current directory is the root of the Guix source tree: @lisp ;; List all the regular files in the current directory. (find-files ".") @result{} ("./.dir-locals.el" "./.gitignore" @dots{}) ;; List all the .scm files under gnu/services. (find-files "gnu/services" "\\.scm$") @result{} ("gnu/services/admin.scm" "gnu/services/audio.scm" @dots{}) ;; List ar files in the current directory. (find-files "." (lambda (file stat) (ar-file? file))) @result{} ("./libformat.a" "./libstore.a" @dots{}) @end lisp @deffn {Procedure} which program Return the complete file name for @var{program} as found in @code{$PATH}, or @code{#f} if @var{program} could not be found. @end deffn @deffn {Procedure} search-input-file inputs name @deffnx {Procedure} search-input-directory inputs name Return the complete file name for @var{name} as found in @var{inputs}; @code{search-input-file} searches for a regular file and @code{search-input-directory} searches for a directory. If @var{name} could not be found, an exception is raised. Here, @var{inputs} must be an association list like @code{inputs} and @code{native-inputs} as available to build phases (@pxref{Build Phases}). @end deffn Here is a (simplified) example of how @code{search-input-file} is used in a build phase of the @code{wireguard-tools} package: @lisp (add-after 'install 'wrap-wg-quick (lambda* (#:key inputs outputs #:allow-other-keys) (let ((coreutils (string-append (assoc-ref inputs "coreutils") "/bin"))) (wrap-program (search-input-file outputs "bin/wg-quick") #:sh (search-input-file inputs "bin/bash") `("PATH" ":" prefix ,(list coreutils)))))) @end lisp @subsection Program Invocation @cindex program invocation, from Scheme @cindex invoking programs, from Scheme You'll find handy procedures to spawn processes in this module, essentially convenient wrappers around Guile's @code{system*} (@pxref{Processes, @code{system*},, guile, GNU Guile Reference Manual}). @deffn {Procedure} invoke program args@dots{} Invoke @var{program} with the given @var{args}. Raise an @code{&invoke-error} exception if the exit code is non-zero; otherwise return @code{#t}. The advantage compared to @code{system*} is that you do not need to check the return value. This reduces boilerplate in shell-script-like snippets for instance in package build phases. @end deffn @deffn {Procedure} invoke-error? c Return true if @var{c} is an @code{&invoke-error} condition. @end deffn @deffn {Procedure} invoke-error-program c @deffnx {Procedure} invoke-error-arguments c @deffnx {Procedure} invoke-error-exit-status c @deffnx {Procedure} invoke-error-term-signal c @deffnx {Procedure} invoke-error-stop-signal c Access specific fields of @var{c}, an @code{&invoke-error} condition. @end deffn @deffn {Procedure} report-invoke-error c [port] Report to @var{port} (by default the current error port) about @var{c}, an @code{&invoke-error} condition, in a human-friendly way. Typical usage would look like this: @lisp (use-modules (srfi srfi-34) ;for 'guard' (guix build utils)) (guard (c ((invoke-error? c) (report-invoke-error c))) (invoke "date" "--imaginary-option")) @print{} command "date" "--imaginary-option" failed with status 1 @end lisp @end deffn @deffn {Procedure} invoke/quiet program args@dots{} Invoke @var{program} with @var{args} and capture @var{program}'s standard output and standard error. If @var{program} succeeds, print nothing and return the unspecified value; otherwise, raise a @code{&message} error condition that includes the status code and the output of @var{program}. Here's an example: @lisp (use-modules (srfi srfi-34) ;for 'guard' (srfi srfi-35) ;for 'message-condition?' (guix build utils)) (guard (c ((message-condition? c) (display (condition-message c)))) (invoke/quiet "date") ;all is fine (invoke/quiet "date" "--imaginary-option")) @print{} 'date --imaginary-option' exited with status 1; output follows: date: unrecognized option '--imaginary-option' Try 'date --help' for more information. @end lisp @end deffn @subsection Build Phases @cindex build phases The @code{(guix build utils)} also contains tools to manipulate build phases as used by build systems (@pxref{Build Systems}). Build phases are represented as association lists or ``alists'' (@pxref{Association Lists,,, guile, GNU Guile Reference Manual}) where each key is a symbol naming the phase and the associated value is a procedure (@pxref{Build Phases}). Guile core and the @code{(srfi srfi-1)} module both provide tools to manipulate alists. The @code{(guix build utils)} module complements those with tools written with build phases in mind. @cindex build phases, modifying @defmac modify-phases phases clause@dots{} Modify @var{phases} sequentially as per each @var{clause}, which may have one of the following forms: @lisp (delete @var{old-phase-name}) (replace @var{old-phase-name} @var{new-phase}) (add-before @var{old-phase-name} @var{new-phase-name} @var{new-phase}) (add-after @var{old-phase-name} @var{new-phase-name} @var{new-phase}) @end lisp Where every @var{phase-name} above is an expression evaluating to a symbol, and @var{new-phase} an expression evaluating to a procedure. @end defmac The example below is taken from the definition of the @code{grep} package. It adds a phase to run after the @code{install} phase, called @code{fix-egrep-and-fgrep}. That phase is a procedure (@code{lambda*} is for anonymous procedures) that takes a @code{#:outputs} keyword argument and ignores extra keyword arguments (@pxref{Optional Arguments,,, guile, GNU Guile Reference Manual}, for more on @code{lambda*} and optional and keyword arguments.) The phase uses @code{substitute*} to modify the installed @file{egrep} and @file{fgrep} scripts so that they refer to @code{grep} by its absolute file name: @lisp (modify-phases %standard-phases (add-after 'install 'fix-egrep-and-fgrep ;; Patch 'egrep' and 'fgrep' to execute 'grep' via its ;; absolute file name instead of searching for it in $PATH. (lambda* (#:key outputs #:allow-other-keys) (let* ((out (assoc-ref outputs "out")) (bin (string-append out "/bin"))) (substitute* (list (string-append bin "/egrep") (string-append bin "/fgrep")) (("^exec grep") (string-append "exec " bin "/grep"))))))) @end lisp In the example below, phases are modified in two ways: the standard @code{configure} phase is deleted, presumably because the package does not have a @file{configure} script or anything similar, and the default @code{install} phase is replaced by one that manually copies the executable files to be installed: @lisp (modify-phases %standard-phases (delete 'configure) ;no 'configure' script (replace 'install (lambda* (#:key outputs #:allow-other-keys) ;; The package's Makefile doesn't provide an "install" ;; rule so do it by ourselves. (let ((bin (string-append (assoc-ref outputs "out") "/bin"))) (install-file "footswitch" bin) (install-file "scythe" bin))))) @end lisp @c TODO: Add more examples. @subsection Wrappers @cindex program wrappers @cindex wrapping programs It is not unusual for a command to require certain environment variables to be set for proper functioning, typically search paths (@pxref{Search Paths}). Failing to do that, the command might fail to find files or other commands it relies on, or it might pick the ``wrong'' ones---depending on the environment in which it runs. Examples include: @itemize @item a shell script that assumes all the commands it uses are in @env{PATH}; @item a Guile program that assumes all its modules are in @env{GUILE_LOAD_PATH} and @env{GUILE_LOAD_COMPILED_PATH}; @item a Qt application that expects to find certain plugins in @env{QT_PLUGIN_PATH}. @end itemize For a package writer, the goal is to make sure commands always work the same rather than depend on some external settings. One way to achieve that is to @dfn{wrap} commands in a thin script that sets those environment variables, thereby ensuring that those run-time dependencies are always found. The wrapper would be used to set @env{PATH}, @env{GUILE_LOAD_PATH}, or @env{QT_PLUGIN_PATH} in the examples above. To ease that task, the @code{(guix build utils)} module provides a couple of helpers to wrap commands. @deffn {Procedure} wrap-program program [#:sh sh] [#:rest variables] Make a wrapper for @var{program}. @var{variables} should look like this: @lisp '(@var{variable} @var{delimiter} @var{position} @var{list-of-directories}) @end lisp where @var{delimiter} is optional. @code{:} will be used if @var{delimiter} is not given. For example, this call: @lisp (wrap-program "foo" '("PATH" ":" = ("/gnu/.../bar/bin")) '("CERT_PATH" suffix ("/gnu/.../baz/certs" "/qux/certs"))) @end lisp will copy @file{foo} to @file{.foo-real} and create the file @file{foo} with the following contents: @example #!location/of/bin/bash export PATH="/gnu/.../bar/bin" export CERT_PATH="$CERT_PATH$@{CERT_PATH:+:@}/gnu/.../baz/certs:/qux/certs" exec -a $0 location/of/.foo-real "$@@" @end example If @var{program} has previously been wrapped by @code{wrap-program}, the wrapper is extended with definitions for @var{variables}. If it is not, @var{sh} will be used as the interpreter. @end deffn @deffn {Procedure} wrap-script program [#:guile guile] [#:rest variables] Wrap the script @var{program} such that @var{variables} are set first. The format of @var{variables} is the same as in the @code{wrap-program} procedure. This procedure differs from @code{wrap-program} in that it does not create a separate shell script. Instead, @var{program} is modified directly by prepending a Guile script, which is interpreted as a comment in the script's language. Special encoding comments as supported by Python are recreated on the second line. Note that this procedure can only be used once per file as Guile scripts are not supported. @end deffn @node Search Paths @section Search Paths @cindex search path Many programs and libraries look for input data in a @dfn{search path}, a list of directories: shells like Bash look for executables in the command search path, a C compiler looks for @file{.h} files in its header search path, the Python interpreter looks for @file{.py} files in its search path, the spell checker has a search path for dictionaries, and so on. Search paths can usually be defined or overridden @i{via} environment variables (@pxref{Environment Variables,,, libc, The GNU C Library Reference Manual}). For example, the search paths mentioned above can be changed by defining the @env{PATH}, @env{C_INCLUDE_PATH}, @env{PYTHONPATH} (or @env{GUIX_PYTHONPATH}), and @env{DICPATH} environment variables---you know, all these something-PATH variables that you need to get right or things ``won't be found''. You may have noticed from the command line that Guix ``knows'' which search path environment variables should be defined, and how. When you install packages in your default profile, the file @file{~/.guix-profile/etc/profile} is created, which you can ``source'' from the shell to set those variables. Likewise, if you ask @command{guix shell} to create an environment containing Python and NumPy, a Python library, and if you pass it the @option{--search-paths} option, it will tell you about @env{PATH} and @env{GUIX_PYTHONPATH} (@pxref{Invoking guix shell}): @example $ guix shell python python-numpy --pure --search-paths export PATH="/gnu/store/@dots{}-profile/bin" export GUIX_PYTHONPATH="/gnu/store/@dots{}-profile/lib/python3.9/site-packages" @end example When you omit @option{--search-paths}, it defines these environment variables right away, such that Python can readily find NumPy: @example $ guix shell python python-numpy -- python3 Python 3.9.6 (default, Jan 1 1970, 00:00:01) [GCC 10.3.0] on linux Type "help", "copyright", "credits" or "license" for more information. >>> import numpy >>> numpy.version.version '1.20.3' @end example For this to work, the definition of the @code{python} package @emph{declares} the search path it cares about and its associated environment variable, @env{GUIX_PYTHONPATH}. It looks like this: @lisp (package (name "python") (version "3.9.9") ;; some fields omitted... (native-search-paths (list (search-path-specification (variable "GUIX_PYTHONPATH") (files (list "lib/python/3.9/site-packages")))))) @end lisp What this @code{native-search-paths} field says is that, when the @code{python} package is used, the @env{GUIX_PYTHONPATH} environment variable must be defined to include all the @file{lib/python/3.9/site-packages} sub-directories encountered in its environment. (The @code{native-} bit means that, if we are in a cross-compilation environment, only native inputs may be added to the search path; @pxref{package Reference, @code{search-paths}}.) In the NumPy example above, the profile where @code{python} appears contains exactly one such sub-directory, and @env{GUIX_PYTHONPATH} is set to that. When there are several @file{lib/python/3.9/site-packages}---this is the case in package build environments---they are all added to @env{GUIX_PYTHONPATH}, separated by colons (@code{:}). @quotation Note Notice that @env{GUIX_PYTHONPATH} is specified as part of the definition of the @code{python} package, and @emph{not} as part of that of @code{python-numpy}. This is because this environment variable ``belongs'' to Python, not NumPy: Python actually reads the value of that variable and honors it. Corollary: if you create a profile that does not contain @code{python}, @code{GUIX_PYTHONPATH} will @emph{not} be defined, even if it contains packages that provide @file{.py} files: @example $ guix shell python-numpy --search-paths --pure export PATH="/gnu/store/@dots{}-profile/bin" @end example This makes a lot of sense if we look at this profile in isolation: no software in this profile would read @env{GUIX_PYTHONPATH}. @end quotation Of course, there are many variations on that theme: some packages honor more than one search path, some use separators other than colon, some accumulate several directories in their search path, and so on. A more complex example is the search path of libxml2: the value of the @env{XML_CATALOG_FILES} environment variable is space-separated, it must contain a list of @file{catalog.xml} files (not directories), which are to be found in @file{xml} sub-directories---nothing less. The search path specification looks like this: @c This is defined at (guix search-paths) as $XML_CATALOG_FILES. @lisp (search-path-specification (variable "XML_CATALOG_FILES") (separator " ") (files '("xml")) (file-pattern "^catalog\\.xml$") (file-type 'regular)) @end lisp Worry not, search path specifications are usually not this tricky. The @code{(guix search-paths)} module defines the data type of search path specifications and a number of helper procedures. Below is the reference of search path specifications. @deftp {Data Type} search-path-specification The data type for search path specifications. @table @asis @item @code{variable} The name of the environment variable for this search path (a string). @item @code{files} The list of sub-directories (strings) that should be added to the search path. @item @code{separator} (default: @code{":"}) The string used to separate search path components. As a special case, a @code{separator} value of @code{#f} specifies a ``single-component search path''---in other words, a search path that cannot contain more than one element. This is useful in some cases, such as the @code{SSL_CERT_DIR} variable (honored by OpenSSL, cURL, and a few other packages) or the @code{ASPELL_DICT_DIR} variable (honored by the GNU Aspell spell checker), both of which must point to a single directory. @item @code{file-type} (default: @code{'directory}) The type of file being matched---@code{'directory} or @code{'regular}, though it can be any symbol returned by @code{stat:type} (@pxref{File System, @code{stat},, guile, GNU Guile Reference Manual}). In the @env{XML_CATALOG_FILES} example above, we would match regular files; in the Python example, we would match directories. @item @code{file-pattern} (default: @code{#f}) This must be either @code{#f} or a regular expression specifying files to be matched @emph{within} the sub-directories specified by the @code{files} field. Again, the @env{XML_CATALOG_FILES} example shows a situation where this is needed. @end table @end deftp Some search paths are not tied by a single package but to many packages. To reduce duplications, some of them are pre-defined in @code{(guix search-paths)}. @defvar $SGML_CATALOG_FILES @defvarx $XML_CATALOG_FILES These two search paths indicate where the @url{https://www.oasis-open.org/specs/a401.htm,TR9401 catalog}@footnote{ Alternatively known as SGML catalog.} or @url{https://www.oasis-open.org/committees/download.php/14809/xml-catalogs.html, XML catalog} files can be found. @end defvar @defvar $SSL_CERT_DIR @defvarx $SSL_CERT_FILE These two search paths indicate where X.509 certificates can be found (@pxref{X.509 Certificates}). @end defvar These pre-defined search paths can be used as in the following example: @lisp (package (name "curl") ;; some fields omitted ... (native-search-paths (list $SSL_CERT_DIR $SSL_CERT_FILE))) @end lisp How do you turn search path specifications on one hand and a bunch of directories on the other hand in a set of environment variable definitions? That's the job of @code{evaluate-search-paths}. @deffn {Procedure} evaluate-search-paths search-paths directories [getenv] Evaluate @var{search-paths}, a list of search-path specifications, for @var{directories}, a list of directory names, and return a list of specification/value pairs. Use @var{getenv} to determine the current settings and report only settings not already effective. @end deffn The @code{(guix profiles)} provides a higher-level helper procedure, @code{load-profile}, that sets the environment variables of a profile. @node The Store @section The Store @cindex store @cindex store items @cindex store paths Conceptually, the @dfn{store} is the place where derivations that have been built successfully are stored---by default, @file{/gnu/store}. Sub-directories in the store are referred to as @dfn{store items} or sometimes @dfn{store paths}. The store has an associated database that contains information such as the store paths referred to by each store path, and the list of @emph{valid} store items---results of successful builds. This database resides in @file{@var{localstatedir}/guix/db}, where @var{localstatedir} is the state directory specified @i{via} @option{--localstatedir} at configure time, usually @file{/var}. The store is @emph{always} accessed by the daemon on behalf of its clients (@pxref{Invoking guix-daemon}). To manipulate the store, clients connect to the daemon over a Unix-domain socket, send requests to it, and read the result---these are remote procedure calls, or RPCs. @quotation Note Users must @emph{never} modify files under @file{/gnu/store} directly. This would lead to inconsistencies and break the immutability assumptions of Guix's functional model (@pxref{Introduction}). @xref{Invoking guix gc, @command{guix gc --verify}}, for information on how to check the integrity of the store and attempt recovery from accidental modifications. @end quotation The @code{(guix store)} module provides procedures to connect to the daemon, and to perform RPCs. These are described below. By default, @code{open-connection}, and thus all the @command{guix} commands, connect to the local daemon or to the URI specified by the @env{GUIX_DAEMON_SOCKET} environment variable. @defvr {Environment Variable} GUIX_DAEMON_SOCKET When set, the value of this variable should be a file name or a URI designating the daemon endpoint. When it is a file name, it denotes a Unix-domain socket to connect to. In addition to file names, the supported URI schemes are: @table @code @item file @itemx unix These are for Unix-domain sockets. @code{file:///var/guix/daemon-socket/socket} is equivalent to @file{/var/guix/daemon-socket/socket}. @item guix @cindex daemon, remote access @cindex remote access to the daemon @cindex daemon, cluster setup @cindex clusters, daemon setup These URIs denote connections over TCP/IP, without encryption nor authentication of the remote host. The URI must specify the host name and optionally a port number (by default port 44146 is used): @example guix://master.guix.example.org:1234 @end example This setup is suitable on local networks, such as clusters, where only trusted nodes may connect to the build daemon at @code{master.guix.example.org}. The @option{--listen} option of @command{guix-daemon} can be used to instruct it to listen for TCP connections (@pxref{Invoking guix-daemon, @option{--listen}}). @item ssh @cindex SSH access to build daemons These URIs allow you to connect to a remote daemon over SSH@. This feature requires Guile-SSH (@pxref{Requirements}) and a working @command{guile} binary in @env{PATH} on the destination machine. It supports public key and GSSAPI authentication. A typical URL might look like this: @example ssh://charlie@@guix.example.org:22 @end example As for @command{guix copy}, the usual OpenSSH client configuration files are honored (@pxref{Invoking guix copy}). @end table Additional URI schemes may be supported in the future. @c XXX: Remove this note when the protocol incurs fewer round trips @c and when (guix derivations) no longer relies on file system access. @quotation Note The ability to connect to remote build daemons is considered experimental as of @value{VERSION}. Please get in touch with us to share any problems or suggestions you may have (@pxref{Contributing}). @end quotation @end defvr @deffn {Procedure} open-connection [uri] [#:reserve-space? #t] Connect to the daemon over the Unix-domain socket at @var{uri} (a string). When @var{reserve-space?} is true, instruct it to reserve a little bit of extra space on the file system so that the garbage collector can still operate should the disk become full. Return a server object. @var{file} defaults to @code{%default-socket-path}, which is the normal location given the options that were passed to @command{configure}. @end deffn @deffn {Procedure} close-connection server Close the connection to @var{server}. @end deffn @defvar current-build-output-port This variable is bound to a SRFI-39 parameter, which refers to the port where build and error logs sent by the daemon should be written. @end defvar Procedures that make RPCs all take a server object as their first argument. @cindex invalid store items @deffn {Procedure} valid-path? server path Return @code{#t} when @var{path} designates a valid store item and @code{#f} otherwise (an invalid item may exist on disk but still be invalid, for instance because it is the result of an aborted or failed build). A @code{&store-protocol-error} condition is raised if @var{path} is not prefixed by the store directory (@file{/gnu/store}). @end deffn @deffn {Procedure} add-text-to-store server name text [references] Add @var{text} under file @var{name} in the store, and return its store path. @var{references} is the list of store paths referred to by the resulting store path. @end deffn @deffn {Procedure} build-derivations store derivations [mode] Build @var{derivations}, a list of @code{<derivation>} objects, @file{.drv} file names, or derivation/output pairs, using the specified @var{mode}---@code{(build-mode normal)} by default. @end deffn Note that the @code{(guix monads)} module provides a monad as well as monadic versions of the above procedures, with the goal of making it more convenient to work with code that accesses the store (@pxref{The Store Monad}). @c FIXME @i{This section is currently incomplete.} @node Derivations @section Derivations @cindex derivations Low-level build actions and the environment in which they are performed are represented by @dfn{derivations}. A derivation contains the following pieces of information: @itemize @item The outputs of the derivation---derivations produce at least one file or directory in the store, but may produce more. @item @cindex build-time dependencies @cindex dependencies, build-time The inputs of the derivation---i.e., its build-time dependencies---which may be other derivations or plain files in the store (patches, build scripts, etc.). @item The system type targeted by the derivation---e.g., @code{x86_64-linux}. @item The file name of a build script in the store, along with the arguments to be passed. @item A list of environment variables to be defined. @end itemize @cindex derivation path Derivations allow clients of the daemon to communicate build actions to the store. They exist in two forms: as an in-memory representation, both on the client- and daemon-side, and as files in the store whose name end in @file{.drv}---these files are referred to as @dfn{derivation paths}. Derivations paths can be passed to the @code{build-derivations} procedure to perform the build actions they prescribe (@pxref{The Store}). @cindex fixed-output derivations Operations such as file downloads and version-control checkouts for which the expected content hash is known in advance are modeled as @dfn{fixed-output derivations}. Unlike regular derivations, the outputs of a fixed-output derivation are independent of its inputs---e.g., a source code download produces the same result regardless of the download method and tools being used. @cindex references @cindex run-time dependencies @cindex dependencies, run-time The outputs of derivations---i.e., the build results---have a set of @dfn{references}, as reported by the @code{references} RPC or the @command{guix gc --references} command (@pxref{Invoking guix gc}). References are the set of run-time dependencies of the build results. References are a subset of the inputs of the derivation; this subset is automatically computed by the build daemon by scanning all the files in the outputs. The @code{(guix derivations)} module provides a representation of derivations as Scheme objects, along with procedures to create and otherwise manipulate derivations. The lowest-level primitive to create a derivation is the @code{derivation} procedure: @deffn {Procedure} derivation store name builder args @ [#:outputs '("out")] [#:hash #f] [#:hash-algo #f] @ [#:recursive? #f] [#:inputs '()] [#:env-vars '()] @ [#:system (%current-system)] [#:references-graphs #f] @ [#:allowed-references #f] [#:disallowed-references #f] @ [#:leaked-env-vars #f] [#:local-build? #f] @ [#:substitutable? #t] [#:properties '()] Build a derivation with the given arguments, and return the resulting @code{<derivation>} object. When @var{hash} and @var{hash-algo} are given, a @dfn{fixed-output derivation} is created---i.e., one whose result is known in advance, such as a file download. If, in addition, @var{recursive?} is true, then that fixed output may be an executable file or a directory and @var{hash} must be the hash of an archive containing this output. When @var{references-graphs} is true, it must be a list of file name/store path pairs. In that case, the reference graph of each store path is exported in the build environment in the corresponding file, in a simple text format. When @var{allowed-references} is true, it must be a list of store items or outputs that the derivation's output may refer to. Likewise, @var{disallowed-references}, if true, must be a list of things the outputs may @emph{not} refer to. When @var{leaked-env-vars} is true, it must be a list of strings denoting environment variables that are allowed to ``leak'' from the daemon's environment to the build environment. This is only applicable to fixed-output derivations---i.e., when @var{hash} is true. The main use is to allow variables such as @code{http_proxy} to be passed to derivations that download files. When @var{local-build?} is true, declare that the derivation is not a good candidate for offloading and should rather be built locally (@pxref{Daemon Offload Setup}). This is the case for small derivations where the costs of data transfers would outweigh the benefits. When @var{substitutable?} is false, declare that substitutes of the derivation's output should not be used (@pxref{Substitutes}). This is useful, for instance, when building packages that capture details of the host CPU instruction set. @var{properties} must be an association list describing ``properties'' of the derivation. It is kept as-is, uninterpreted, in the derivation. @end deffn @noindent Here's an example with a shell script as its builder, assuming @var{store} is an open connection to the daemon, and @var{bash} points to a Bash executable in the store: @lisp (use-modules (guix utils) (guix store) (guix derivations)) (let ((builder ; add the Bash script to the store (add-text-to-store store "my-builder.sh" "echo hello world > $out\n" '()))) (derivation store "foo" bash `("-e" ,builder) #:inputs `((,bash) (,builder)) #:env-vars '(("HOME" . "/homeless")))) @result{} #<derivation /gnu/store/@dots{}-foo.drv => /gnu/store/@dots{}-foo> @end lisp As can be guessed, this primitive is cumbersome to use directly. A better approach is to write build scripts in Scheme, of course! The best course of action for that is to write the build code as a ``G-expression'', and to pass it to @code{gexp->derivation}. For more information, @pxref{G-Expressions}. Once upon a time, @code{gexp->derivation} did not exist and constructing derivations with build code written in Scheme was achieved with @code{build-expression->derivation}, documented below. This procedure is now deprecated in favor of the much nicer @code{gexp->derivation}. @deffn {Procedure} build-expression->derivation store name exp @ [#:system (%current-system)] [#:inputs '()] @ [#:outputs '("out")] [#:hash #f] [#:hash-algo #f] @ [#:recursive? #f] [#:env-vars '()] [#:modules '()] @ [#:references-graphs #f] [#:allowed-references #f] @ [#:disallowed-references #f] @ [#:local-build? #f] [#:substitutable? #t] [#:guile-for-build #f] Return a derivation that executes Scheme expression @var{exp} as a builder for derivation @var{name}. @var{inputs} must be a list of @code{(name drv-path sub-drv)} tuples; when @var{sub-drv} is omitted, @code{"out"} is assumed. @var{modules} is a list of names of Guile modules from the current search path to be copied in the store, compiled, and made available in the load path during the execution of @var{exp}---e.g., @code{((guix build utils) (guix build gnu-build-system))}. @var{exp} is evaluated in an environment where @code{%outputs} is bound to a list of output/path pairs, and where @code{%build-inputs} is bound to a list of string/output-path pairs made from @var{inputs}. Optionally, @var{env-vars} is a list of string pairs specifying the name and value of environment variables visible to the builder. The builder terminates by passing the result of @var{exp} to @code{exit}; thus, when @var{exp} returns @code{#f}, the build is considered to have failed. @var{exp} is built using @var{guile-for-build} (a derivation). When @var{guile-for-build} is omitted or is @code{#f}, the value of the @code{%guile-for-build} fluid is used instead. See the @code{derivation} procedure for the meaning of @var{references-graphs}, @var{allowed-references}, @var{disallowed-references}, @var{local-build?}, and @var{substitutable?}. @end deffn @noindent Here's an example of a single-output derivation that creates a directory containing one file: @lisp (let ((builder '(let ((out (assoc-ref %outputs "out"))) (mkdir out) ; create /gnu/store/@dots{}-goo (call-with-output-file (string-append out "/test") (lambda (p) (display '(hello guix) p)))))) (build-expression->derivation store "goo" builder)) @result{} #<derivation /gnu/store/@dots{}-goo.drv => @dots{}> @end lisp @node The Store Monad @section The Store Monad @cindex monad The procedures that operate on the store described in the previous sections all take an open connection to the build daemon as their first argument. Although the underlying model is functional, they either have side effects or depend on the current state of the store. The former is inconvenient: the connection to the build daemon has to be carried around in all those functions, making it impossible to compose functions that do not take that parameter with functions that do. The latter can be problematic: since store operations have side effects and/or depend on external state, they have to be properly sequenced. @cindex monadic values @cindex monadic functions This is where the @code{(guix monads)} module comes in. This module provides a framework for working with @dfn{monads}, and a particularly useful monad for our uses, the @dfn{store monad}. Monads are a construct that allows two things: associating ``context'' with values (in our case, the context is the store), and building sequences of computations (here computations include accesses to the store). Values in a monad---values that carry this additional context---are called @dfn{monadic values}; procedures that return such values are called @dfn{monadic procedures}. Consider this ``normal'' procedure: @lisp (define (sh-symlink store) ;; Return a derivation that symlinks the 'bash' executable. (let* ((drv (package-derivation store bash)) (out (derivation->output-path drv)) (sh (string-append out "/bin/bash"))) (build-expression->derivation store "sh" `(symlink ,sh %output)))) @end lisp Using @code{(guix monads)} and @code{(guix gexp)}, it may be rewritten as a monadic function: @lisp (define (sh-symlink) ;; Same, but return a monadic value. (mlet %store-monad ((drv (package->derivation bash))) (gexp->derivation "sh" #~(symlink (string-append #$drv "/bin/bash") #$output)))) @end lisp There are several things to note in the second version: the @code{store} parameter is now implicit and is ``threaded'' in the calls to the @code{package->derivation} and @code{gexp->derivation} monadic procedures, and the monadic value returned by @code{package->derivation} is @dfn{bound} using @code{mlet} instead of plain @code{let}. As it turns out, the call to @code{package->derivation} can even be omitted since it will take place implicitly, as we will see later (@pxref{G-Expressions}): @lisp (define (sh-symlink) (gexp->derivation "sh" #~(symlink (string-append #$bash "/bin/bash") #$output))) @end lisp @c See @c <https://syntaxexclamation.wordpress.com/2014/06/26/escaping-continuations/> @c for the funny quote. Calling the monadic @code{sh-symlink} has no effect. As someone once said, ``you exit a monad like you exit a building on fire: by running''. So, to exit the monad and get the desired effect, one must use @code{run-with-store}: @lisp (run-with-store (open-connection) (sh-symlink)) @result{} /gnu/store/...-sh-symlink @end lisp Note that the @code{(guix monad-repl)} module extends the Guile REPL with new ``commands'' to make it easier to deal with monadic procedures: @code{run-in-store}, and @code{enter-store-monad} (@pxref{Using Guix Interactively}). The former is used to ``run'' a single monadic value through the store: @example scheme@@(guile-user)> ,run-in-store (package->derivation hello) $1 = #<derivation /gnu/store/@dots{}-hello-2.9.drv => @dots{}> @end example The latter enters a recursive REPL, where all the return values are automatically run through the store: @example scheme@@(guile-user)> ,enter-store-monad store-monad@@(guile-user) [1]> (package->derivation hello) $2 = #<derivation /gnu/store/@dots{}-hello-2.9.drv => @dots{}> store-monad@@(guile-user) [1]> (text-file "foo" "Hello!") $3 = "/gnu/store/@dots{}-foo" store-monad@@(guile-user) [1]> ,q scheme@@(guile-user)> @end example @noindent Note that non-monadic values cannot be returned in the @code{store-monad} REPL. Other meta-commands are available at the REPL, such as @code{,build} to build a file-like object (@pxref{Using Guix Interactively}). The main syntactic forms to deal with monads in general are provided by the @code{(guix monads)} module and are described below. @defmac with-monad monad body @dots{} Evaluate any @code{>>=} or @code{return} forms in @var{body} as being in @var{monad}. @end defmac @defmac return val Return a monadic value that encapsulates @var{val}. @end defmac @defmac >>= mval mproc @dots{} @dfn{Bind} monadic value @var{mval}, passing its ``contents'' to monadic procedures @var{mproc}@dots{}@footnote{This operation is commonly referred to as ``bind'', but that name denotes an unrelated procedure in Guile. Thus we use this somewhat cryptic symbol inherited from the Haskell language.}. There can be one @var{mproc} or several of them, as in this example: @lisp (run-with-state (with-monad %state-monad (>>= (return 1) (lambda (x) (return (+ 1 x))) (lambda (x) (return (* 2 x))))) 'some-state) @result{} 4 @result{} some-state @end lisp @end defmac @defmac mlet monad ((var mval) @dots{}) body @dots{} @defmacx mlet* monad ((var mval) @dots{}) body @dots{} Bind the variables @var{var} to the monadic values @var{mval} in @var{body}, which is a sequence of expressions. As with the bind operator, this can be thought of as ``unpacking'' the raw, non-monadic value ``contained'' in @var{mval} and making @var{var} refer to that raw, non-monadic value within the scope of the @var{body}. The form (@var{var} -> @var{val}) binds @var{var} to the ``normal'' value @var{val}, as per @code{let}. The binding operations occur in sequence from left to right. The last expression of @var{body} must be a monadic expression, and its result will become the result of the @code{mlet} or @code{mlet*} when run in the @var{monad}. @code{mlet*} is to @code{mlet} what @code{let*} is to @code{let} (@pxref{Local Bindings,,, guile, GNU Guile Reference Manual}). @end defmac @defmac mbegin monad mexp @dots{} Bind @var{mexp} and the following monadic expressions in sequence, returning the result of the last expression. Every expression in the sequence must be a monadic expression. This is akin to @code{mlet}, except that the return values of the monadic expressions are ignored. In that sense, it is analogous to @code{begin}, but applied to monadic expressions. @end defmac @defmac mwhen condition mexp0 mexp* @dots{} When @var{condition} is true, evaluate the sequence of monadic expressions @var{mexp0}..@var{mexp*} as in an @code{mbegin}. When @var{condition} is false, return @code{*unspecified*} in the current monad. Every expression in the sequence must be a monadic expression. @end defmac @defmac munless condition mexp0 mexp* @dots{} When @var{condition} is false, evaluate the sequence of monadic expressions @var{mexp0}..@var{mexp*} as in an @code{mbegin}. When @var{condition} is true, return @code{*unspecified*} in the current monad. Every expression in the sequence must be a monadic expression. @end defmac @cindex state monad The @code{(guix monads)} module provides the @dfn{state monad}, which allows an additional value---the state---to be @emph{threaded} through monadic procedure calls. @defvar %state-monad The state monad. Procedures in the state monad can access and change the state that is threaded. Consider the example below. The @code{square} procedure returns a value in the state monad. It returns the square of its argument, but also increments the current state value: @lisp (define (square x) (mlet %state-monad ((count (current-state))) (mbegin %state-monad (set-current-state (+ 1 count)) (return (* x x))))) (run-with-state (sequence %state-monad (map square (iota 3))) 0) @result{} (0 1 4) @result{} 3 @end lisp When ``run'' through @code{%state-monad}, we obtain that additional state value, which is the number of @code{square} calls. @end defvar @deffn {Monadic Procedure} current-state Return the current state as a monadic value. @end deffn @deffn {Monadic Procedure} set-current-state @var{value} Set the current state to @var{value} and return the previous state as a monadic value. @end deffn @deffn {Monadic Procedure} state-push @var{value} Push @var{value} to the current state, which is assumed to be a list, and return the previous state as a monadic value. @end deffn @deffn {Monadic Procedure} state-pop Pop a value from the current state and return it as a monadic value. The state is assumed to be a list. @end deffn @deffn {Procedure} run-with-state mval [state] Run monadic value @var{mval} starting with @var{state} as the initial state. Return two values: the resulting value, and the resulting state. @end deffn The main interface to the store monad, provided by the @code{(guix store)} module, is as follows. @defvar %store-monad The store monad---an alias for @code{%state-monad}. Values in the store monad encapsulate accesses to the store. When its effect is needed, a value of the store monad must be ``evaluated'' by passing it to the @code{run-with-store} procedure (see below). @end defvar @deffn {Procedure} run-with-store store mval @ [#:guile-for-build] [#:system (%current-system)] Run @var{mval}, a monadic value in the store monad, in @var{store}, an open store connection. @end deffn @deffn {Monadic Procedure} text-file @var{name} @var{text} [@var{references}] Return as a monadic value the absolute file name in the store of the file containing @var{text}, a string. @var{references} is a list of store items that the resulting text file refers to; it defaults to the empty list. @end deffn @deffn {Monadic Procedure} binary-file @var{name} @var{data} [@var{references}] Return as a monadic value the absolute file name in the store of the file containing @var{data}, a bytevector. @var{references} is a list of store items that the resulting binary file refers to; it defaults to the empty list. @end deffn @deffn {Monadic Procedure} interned-file @var{file} [@var{name}] @ [#:recursive? #t] [#:select? (const #t)] Return the name of @var{file} once interned in the store. Use @var{name} as its store name, or the basename of @var{file} if @var{name} is omitted. When @var{recursive?} is true, the contents of @var{file} are added recursively; if @var{file} designates a flat file and @var{recursive?} is true, its contents are added, and its permission bits are kept. When @var{recursive?} is true, call @code{(@var{select?} @var{file} @var{stat})} for each directory entry, where @var{file} is the entry's absolute file name and @var{stat} is the result of @code{lstat}; exclude entries for which @var{select?} does not return true. The example below adds a file to the store, under two different names: @lisp (run-with-store (open-connection) (mlet %store-monad ((a (interned-file "README")) (b (interned-file "README" "LEGU-MIN"))) (return (list a b)))) @result{} ("/gnu/store/rwm@dots{}-README" "/gnu/store/44i@dots{}-LEGU-MIN") @end lisp @end deffn The @code{(guix packages)} module exports the following package-related monadic procedures: @deffn {Monadic Procedure} package-file @var{package} [@var{file}] @ [#:system (%current-system)] [#:target #f] @ [#:output "out"] Return as a monadic value in the absolute file name of @var{file} within the @var{output} directory of @var{package}. When @var{file} is omitted, return the name of the @var{output} directory of @var{package}. When @var{target} is true, use it as a cross-compilation target triplet. Note that this procedure does @emph{not} build @var{package}. Thus, the result might or might not designate an existing file. We recommend not using this procedure unless you know what you are doing. @end deffn @deffn {Monadic Procedure} package->derivation @var{package} [@var{system}] @deffnx {Monadic Procedure} package->cross-derivation @var{package} @ @var{target} [@var{system}] Monadic version of @code{package-derivation} and @code{package-cross-derivation} (@pxref{Defining Packages}). @end deffn @node G-Expressions @section G-Expressions @cindex G-expression @cindex build code quoting So we have ``derivations'', which represent a sequence of build actions to be performed to produce an item in the store (@pxref{Derivations}). These build actions are performed when asking the daemon to actually build the derivations; they are run by the daemon in a container (@pxref{Invoking guix-daemon}). @cindex code staging @cindex staging, of code @cindex strata of code It should come as no surprise that we like to write these build actions in Scheme. When we do that, we end up with two @dfn{strata} of Scheme code@footnote{The term @dfn{stratum} in this context was coined by Manuel Serrano et al.@: in the context of their work on Hop. Oleg Kiselyov, who has written insightful @url{http://okmij.org/ftp/meta-programming/#meta-scheme, essays and code on this topic}, refers to this kind of code generation as @dfn{staging}.}: the ``host code''---code that defines packages, talks to the daemon, etc.---and the ``build code''---code that actually performs build actions, such as making directories, invoking @command{make}, and so on (@pxref{Build Phases}). To describe a derivation and its build actions, one typically needs to embed build code inside host code. It boils down to manipulating build code as data, and the homoiconicity of Scheme---code has a direct representation as data---comes in handy for that. But we need more than the normal @code{quasiquote} mechanism in Scheme to construct build expressions. The @code{(guix gexp)} module implements @dfn{G-expressions}, a form of S-expressions adapted to build expressions. G-expressions, or @dfn{gexps}, consist essentially of three syntactic forms: @code{gexp}, @code{ungexp}, and @code{ungexp-splicing} (or simply: @code{#~}, @code{#$}, and @code{#$@@}), which are comparable to @code{quasiquote}, @code{unquote}, and @code{unquote-splicing}, respectively (@pxref{Expression Syntax, @code{quasiquote},, guile, GNU Guile Reference Manual}). However, there are major differences: @itemize @item Gexps are meant to be written to a file and run or manipulated by other processes. @item When a high-level object such as a package or derivation is unquoted inside a gexp, the result is as if its output file name had been introduced. @item Gexps carry information about the packages or derivations they refer to, and these dependencies are automatically added as inputs to the build processes that use them. @end itemize @cindex lowering, of high-level objects in gexps This mechanism is not limited to package and derivation objects: @dfn{compilers} able to ``lower'' other high-level objects to derivations or files in the store can be defined, such that these objects can also be inserted into gexps. For example, a useful type of high-level objects that can be inserted in a gexp is ``file-like objects'', which make it easy to add files to the store and to refer to them in derivations and such (see @code{local-file} and @code{plain-file} below). To illustrate the idea, here is an example of a gexp: @lisp (define build-exp #~(begin (mkdir #$output) (chdir #$output) (symlink (string-append #$coreutils "/bin/ls") "list-files"))) @end lisp This gexp can be passed to @code{gexp->derivation}; we obtain a derivation that builds a directory containing exactly one symlink to @file{/gnu/store/@dots{}-coreutils-8.22/bin/ls}: @lisp (gexp->derivation "the-thing" build-exp) @end lisp As one would expect, the @code{"/gnu/store/@dots{}-coreutils-8.22"} string is substituted to the reference to the @var{coreutils} package in the actual build code, and @var{coreutils} is automatically made an input to the derivation. Likewise, @code{#$output} (equivalent to @code{(ungexp output)}) is replaced by a string containing the directory name of the output of the derivation. @cindex cross compilation In a cross-compilation context, it is useful to distinguish between references to the @emph{native} build of a package---that can run on the host---versus references to cross builds of a package. To that end, the @code{#+} plays the same role as @code{#$}, but is a reference to a native package build: @lisp (gexp->derivation "vi" #~(begin (mkdir #$output) (mkdir (string-append #$output "/bin")) (system* (string-append #+coreutils "/bin/ln") "-s" (string-append #$emacs "/bin/emacs") (string-append #$output "/bin/vi"))) #:target "aarch64-linux-gnu") @end lisp @noindent In the example above, the native build of @var{coreutils} is used, so that @command{ln} can actually run on the host; but then the cross-compiled build of @var{emacs} is referenced. @cindex imported modules, for gexps @findex with-imported-modules Another gexp feature is @dfn{imported modules}: sometimes you want to be able to use certain Guile modules from the ``host environment'' in the gexp, so those modules should be imported in the ``build environment''. The @code{with-imported-modules} form allows you to express that: @lisp (let ((build (with-imported-modules '((guix build utils)) #~(begin (use-modules (guix build utils)) (mkdir-p (string-append #$output "/bin")))))) (gexp->derivation "empty-dir" #~(begin #$build (display "success!\n") #t))) @end lisp @noindent In this example, the @code{(guix build utils)} module is automatically pulled into the isolated build environment of our gexp, such that @code{(use-modules (guix build utils))} works as expected. @cindex module closure @findex source-module-closure Usually you want the @emph{closure} of the module to be imported---i.e., the module itself and all the modules it depends on---rather than just the module; failing to do that, attempts to use the module will fail because of missing dependent modules. The @code{source-module-closure} procedure computes the closure of a module by looking at its source file headers, which comes in handy in this case: @lisp (use-modules (guix modules)) ;for 'source-module-closure' (with-imported-modules (source-module-closure '((guix build utils) (gnu build image))) (gexp->derivation "something-with-vms" #~(begin (use-modules (guix build utils) (gnu build image)) @dots{}))) @end lisp @cindex extensions, for gexps @findex with-extensions In the same vein, sometimes you want to import not just pure-Scheme modules, but also ``extensions'' such as Guile bindings to C libraries or other ``full-blown'' packages. Say you need the @code{guile-json} package available on the build side, here's how you would do it: @lisp (use-modules (gnu packages guile)) ;for 'guile-json' (with-extensions (list guile-json) (gexp->derivation "something-with-json" #~(begin (use-modules (json)) @dots{}))) @end lisp The syntactic form to construct gexps is summarized below. @defmac #~@var{exp} @defmacx (gexp @var{exp}) Return a G-expression containing @var{exp}. @var{exp} may contain one or more of the following forms: @table @code @item #$@var{obj} @itemx (ungexp @var{obj}) Introduce a reference to @var{obj}. @var{obj} may have one of the supported types, for example a package or a derivation, in which case the @code{ungexp} form is replaced by its output file name---e.g., @code{"/gnu/store/@dots{}-coreutils-8.22}. If @var{obj} is a list, it is traversed and references to supported objects are substituted similarly. If @var{obj} is another gexp, its contents are inserted and its dependencies are added to those of the containing gexp. If @var{obj} is another kind of object, it is inserted as is. @item #$@var{obj}:@var{output} @itemx (ungexp @var{obj} @var{output}) This is like the form above, but referring explicitly to the @var{output} of @var{obj}---this is useful when @var{obj} produces multiple outputs (@pxref{Packages with Multiple Outputs}). Sometimes a gexp unconditionally refers to the @code{"out"} output, but the user of that gexp would still like to insert a reference to another output. The @code{gexp-input} procedure aims to address that. @xref{gexp-input}. @item #+@var{obj} @itemx #+@var{obj}:output @itemx (ungexp-native @var{obj}) @itemx (ungexp-native @var{obj} @var{output}) Same as @code{ungexp}, but produces a reference to the @emph{native} build of @var{obj} when used in a cross compilation context. @item #$output[:@var{output}] @itemx (ungexp output [@var{output}]) Insert a reference to derivation output @var{output}, or to the main output when @var{output} is omitted. This only makes sense for gexps passed to @code{gexp->derivation}. @item #$@@@var{lst} @itemx (ungexp-splicing @var{lst}) Like the above, but splices the contents of @var{lst} inside the containing list. @item #+@@@var{lst} @itemx (ungexp-native-splicing @var{lst}) Like the above, but refers to native builds of the objects listed in @var{lst}. @end table G-expressions created by @code{gexp} or @code{#~} are run-time objects of the @code{gexp?} type (see below). @end defmac @defmac with-imported-modules modules body@dots{} Mark the gexps defined in @var{body}@dots{} as requiring @var{modules} in their execution environment. Each item in @var{modules} can be the name of a module, such as @code{(guix build utils)}, or it can be a module name, followed by an arrow, followed by a file-like object: @lisp `((guix build utils) (guix gcrypt) ((guix config) => ,(scheme-file "config.scm" #~(define-module @dots{})))) @end lisp @noindent In the example above, the first two modules are taken from the search path, and the last one is created from the given file-like object. This form has @emph{lexical} scope: it has an effect on the gexps directly defined in @var{body}@dots{}, but not on those defined, say, in procedures called from @var{body}@dots{}. @end defmac @defmac with-extensions extensions body@dots{} Mark the gexps defined in @var{body}@dots{} as requiring @var{extensions} in their build and execution environment. @var{extensions} is typically a list of package objects such as those defined in the @code{(gnu packages guile)} module. Concretely, the packages listed in @var{extensions} are added to the load path while compiling imported modules in @var{body}@dots{}; they are also added to the load path of the gexp returned by @var{body}@dots{}. @end defmac @deffn {Procedure} gexp? obj Return @code{#t} if @var{obj} is a G-expression. @end deffn G-expressions are meant to be written to disk, either as code building some derivation, or as plain files in the store. The monadic procedures below allow you to do that (@pxref{The Store Monad}, for more information about monads). @deffn {Monadic Procedure} gexp->derivation @var{name} @var{exp} @ [#:system (%current-system)] [#:target #f] [#:graft? #t] @ [#:hash #f] [#:hash-algo #f] @ [#:recursive? #f] [#:env-vars '()] [#:modules '()] @ [#:module-path @code{%load-path}] @ [#:effective-version "2.2"] @ [#:references-graphs #f] [#:allowed-references #f] @ [#:disallowed-references #f] @ [#:leaked-env-vars #f] @ [#:script-name (string-append @var{name} "-builder")] @ [#:deprecation-warnings #f] @ [#:local-build? #f] [#:substitutable? #t] @ [#:properties '()] [#:guile-for-build #f] Return a derivation @var{name} that runs @var{exp} (a gexp) with @var{guile-for-build} (a derivation) on @var{system}; @var{exp} is stored in a file called @var{script-name}. When @var{target} is true, it is used as the cross-compilation target triplet for packages referred to by @var{exp}. @var{modules} is deprecated in favor of @code{with-imported-modules}. Its meaning is to make @var{modules} available in the evaluation context of @var{exp}; @var{modules} is a list of names of Guile modules searched in @var{module-path} to be copied in the store, compiled, and made available in the load path during the execution of @var{exp}---e.g., @code{((guix build utils) (guix build gnu-build-system))}. @var{effective-version} determines the string to use when adding extensions of @var{exp} (see @code{with-extensions}) to the search path---e.g., @code{"2.2"}. @var{graft?} determines whether packages referred to by @var{exp} should be grafted when applicable. When @var{references-graphs} is true, it must be a list of tuples of one of the following forms: @example (@var{file-name} @var{obj}) (@var{file-name} @var{obj} @var{output}) (@var{file-name} @var{gexp-input}) (@var{file-name} @var{store-item}) @end example The right-hand-side of each element of @var{references-graphs} is automatically made an input of the build process of @var{exp}. In the build environment, each @var{file-name} contains the reference graph of the corresponding item, in a simple text format. @var{allowed-references} must be either @code{#f} or a list of output names and packages. In the latter case, the list denotes store items that the result is allowed to refer to. Any reference to another store item will lead to a build error. Similarly for @var{disallowed-references}, which can list items that must not be referenced by the outputs. @var{deprecation-warnings} determines whether to show deprecation warnings while compiling modules. It can be @code{#f}, @code{#t}, or @code{'detailed}. The other arguments are as for @code{derivation} (@pxref{Derivations}). @end deffn @cindex file-like objects The @code{local-file}, @code{plain-file}, @code{computed-file}, @code{program-file}, and @code{scheme-file} procedures below return @dfn{file-like objects}. That is, when unquoted in a G-expression, these objects lead to a file in the store. Consider this G-expression: @lisp #~(system* #$(file-append glibc "/sbin/nscd") "-f" #$(local-file "/tmp/my-nscd.conf")) @end lisp The effect here is to ``intern'' @file{/tmp/my-nscd.conf} by copying it to the store. Once expanded, for instance @i{via} @code{gexp->derivation}, the G-expression refers to that copy under @file{/gnu/store}; thus, modifying or removing the file in @file{/tmp} does not have any effect on what the G-expression does. @code{plain-file} can be used similarly; it differs in that the file content is directly passed as a string. @deffn {Procedure} local-file file [name] [#:recursive? #f] [#:select? (const #t)] Return an object representing local file @var{file} to add to the store; this object can be used in a gexp. If @var{file} is a literal string denoting a relative file name, it is looked up relative to the source file where it appears; if @var{file} is not a literal string, it is looked up relative to the current working directory at run time. @var{file} will be added to the store under @var{name}--by default the base name of @var{file}. When @var{recursive?} is true, the contents of @var{file} are added recursively; if @var{file} designates a flat file and @var{recursive?} is true, its contents are added, and its permission bits are kept. When @var{recursive?} is true, call @code{(@var{select?} @var{file} @var{stat})} for each directory entry, where @var{file} is the entry's absolute file name and @var{stat} is the result of @code{lstat}; exclude entries for which @var{select?} does not return true. @findex assume-valid-file-name @var{file} can be wrapped in the @code{assume-valid-file-name} syntactic keyword. When this is done, there will not be a warning when @code{local-file} is used with a non-literal path. The path is still looked up relative to the current working directory at run time. Wrapping is done like this: @lisp (define alice-key-file-path "alice.pub") ;; ... (local-file (assume-valid-file-name alice-key-file-path)) @end lisp @cindex relative file name, in @code{local-file} @findex assume-source-relative-file-name @var{file} can be wrapped in the @code{assume-source-relative-file-name} syntactic keyword. When this is done, the file name will be looked up relative to the source file where it appears even when it is not a string literal. This is the declarative counterpart of the @code{interned-file} monadic procedure (@pxref{The Store Monad, @code{interned-file}}). @end deffn @deffn {Procedure} plain-file name content Return an object representing a text file called @var{name} with the given @var{content} (a string or a bytevector) to be added to the store. This is the declarative counterpart of @code{text-file}. @end deffn @deffn {Procedure} computed-file name gexp [#:local-build? #t] [#:options '()] Return an object representing the store item @var{name}, a file or directory computed by @var{gexp}. When @var{local-build?} is true (the default), the derivation is built locally. @var{options} is a list of additional arguments to pass to @code{gexp->derivation}. This is the declarative counterpart of @code{gexp->derivation}. @end deffn @deffn {Monadic Procedure} gexp->script @var{name} @var{exp} @ [#:guile (default-guile)] [#:module-path %load-path] @ [#:system (%current-system)] [#:target #f] Return an executable script @var{name} that runs @var{exp} using @var{guile}, with @var{exp}'s imported modules in its search path. Look up @var{exp}'s modules in @var{module-path}. The example below builds a script that simply invokes the @command{ls} command: @lisp (use-modules (guix gexp) (gnu packages base)) (gexp->script "list-files" #~(execl #$(file-append coreutils "/bin/ls") "ls")) @end lisp When ``running'' it through the store (@pxref{The Store Monad, @code{run-with-store}}), we obtain a derivation that produces an executable file @file{/gnu/store/@dots{}-list-files} along these lines: @example #!/gnu/store/@dots{}-guile-2.0.11/bin/guile -ds !# (execl "/gnu/store/@dots{}-coreutils-8.22"/bin/ls" "ls") @end example @end deffn @deffn {Procedure} program-file name exp [#:guile #f] [#:module-path %load-path] Return an object representing the executable store item @var{name} that runs @var{gexp}. @var{guile} is the Guile package used to execute that script. Imported modules of @var{gexp} are looked up in @var{module-path}. This is the declarative counterpart of @code{gexp->script}. @end deffn @deffn {Monadic Procedure} gexp->file @var{name} @var{exp} @ [#:set-load-path? #t] [#:module-path %load-path] @ [#:splice? #f] @ [#:guile (default-guile)] Return a derivation that builds a file @var{name} containing @var{exp}. When @var{splice?} is true, @var{exp} is considered to be a list of expressions that will be spliced in the resulting file. When @var{set-load-path?} is true, emit code in the resulting file to set @code{%load-path} and @code{%load-compiled-path} to honor @var{exp}'s imported modules. Look up @var{exp}'s modules in @var{module-path}. The resulting file holds references to all the dependencies of @var{exp} or a subset thereof. @end deffn @deffn {Procedure} scheme-file name exp [#:splice? #f] @ [#:guile #f] [#:set-load-path? #t] Return an object representing the Scheme file @var{name} that contains @var{exp}. @var{guile} is the Guile package used to produce that file. This is the declarative counterpart of @code{gexp->file}. @end deffn @deffn {Monadic Procedure} text-file* @var{name} @var{text} @dots{} Return as a monadic value a derivation that builds a text file containing all of @var{text}. @var{text} may list, in addition to strings, objects of any type that can be used in a gexp: packages, derivations, local file objects, etc. The resulting store file holds references to all these. This variant should be preferred over @code{text-file} anytime the file to create will reference items from the store. This is typically the case when building a configuration file that embeds store file names, like this: @lisp (define (profile.sh) ;; Return the name of a shell script in the store that ;; initializes the 'PATH' environment variable. (text-file* "profile.sh" "export PATH=" coreutils "/bin:" grep "/bin:" sed "/bin\n")) @end lisp In this example, the resulting @file{/gnu/store/@dots{}-profile.sh} file will reference @var{coreutils}, @var{grep}, and @var{sed}, thereby preventing them from being garbage-collected during its lifetime. @end deffn @deffn {Procedure} mixed-text-file name text @dots{} Return an object representing store file @var{name} containing @var{text}. @var{text} is a sequence of strings and file-like objects, as in: @lisp (mixed-text-file "profile" "export PATH=" coreutils "/bin:" grep "/bin") @end lisp This is the declarative counterpart of @code{text-file*}. @end deffn @deffn {Procedure} file-union name files Return a @code{<computed-file>} that builds a directory containing all of @var{files}. Each item in @var{files} must be a two-element list where the first element is the file name to use in the new directory, and the second element is a gexp denoting the target file. Here's an example: @lisp (file-union "etc" `(("hosts" ,(plain-file "hosts" "127.0.0.1 localhost")) ("bashrc" ,(plain-file "bashrc" "alias ls='ls --color=auto'")))) @end lisp This yields an @code{etc} directory containing these two files. @end deffn @deffn {Procedure} directory-union name things Return a directory that is the union of @var{things}, where @var{things} is a list of file-like objects denoting directories. For example: @lisp (directory-union "guile+emacs" (list guile emacs)) @end lisp yields a directory that is the union of the @code{guile} and @code{emacs} packages. @end deffn @deffn {Procedure} file-append obj suffix @dots{} Return a file-like object that expands to the concatenation of @var{obj} and @var{suffix}, where @var{obj} is a lowerable object and each @var{suffix} is a string. As an example, consider this gexp: @lisp (gexp->script "run-uname" #~(system* #$(file-append coreutils "/bin/uname"))) @end lisp The same effect could be achieved with: @lisp (gexp->script "run-uname" #~(system* (string-append #$coreutils "/bin/uname"))) @end lisp There is one difference though: in the @code{file-append} case, the resulting script contains the absolute file name as a string, whereas in the second case, the resulting script contains a @code{(string-append @dots{})} expression to construct the file name @emph{at run time}. @end deffn @defmac let-system system body@dots{} @defmacx let-system (system target) body@dots{} Bind @var{system} to the currently targeted system---e.g., @code{"x86_64-linux"}---within @var{body}. In the second case, additionally bind @var{target} to the current cross-compilation target---a GNU triplet such as @code{"arm-linux-gnueabihf"}---or @code{#f} if we are not cross-compiling. @code{let-system} is useful in the occasional case where the object spliced into the gexp depends on the target system, as in this example: @lisp #~(system* #+(let-system system (cond ((string-prefix? "armhf-" system) (file-append qemu "/bin/qemu-system-arm")) ((string-prefix? "x86_64-" system) (file-append qemu "/bin/qemu-system-x86_64")) (else (error "dunno!")))) "-net" "user" #$image) @end lisp @end defmac @defmac with-parameters ((parameter value) @dots{}) exp This macro is similar to the @code{parameterize} form for dynamically-bound @dfn{parameters} (@pxref{Parameters,,, guile, GNU Guile Reference Manual}). The key difference is that it takes effect when the file-like object returned by @var{exp} is lowered to a derivation or store item. A typical use of @code{with-parameters} is to force the system in effect for a given object: @lisp (with-parameters ((%current-system "i686-linux")) coreutils) @end lisp The example above returns an object that corresponds to the i686 build of Coreutils, regardless of the current value of @code{%current-system}. @end defmac @anchor{gexp-input} @deffn {Procedure} gexp-input @var{obj} [@var{output}] [#:native? #f] Return a @dfn{gexp input} record for the given @var{output} of file-like object @var{obj}, with @code{#:native?} determining whether this is a native reference (as with @code{ungexp-native}) or not. This procedure is helpful when you want to pass a reference to a specific output of an object to some procedure that may not know about that output. For example, assume you have this procedure, which takes one file-like object: @lisp (define (make-symlink target) (computed-file "the-symlink" #~(symlink #$target #$output))) @end lisp Here @code{make-symlink} can only ever refer to the default output of @var{target}---the @code{"out"} output (@pxref{Packages with Multiple Outputs}). To have it refer to, say, the @code{"lib"} output of the @code{hwloc} package, you can call it like so: @lisp (make-symlink (gexp-input hwloc "lib")) @end lisp You can also compose it like any other file-like object: @lisp (make-symlink (file-append (gexp-input hwloc "lib") "/lib/libhwloc.so")) @end lisp @end deffn Of course, in addition to gexps embedded in ``host'' code, there are also modules containing build tools. To make it clear that they are meant to be used in the build stratum, these modules are kept in the @code{(guix build @dots{})} name space. @cindex lowering, of high-level objects in gexps Internally, high-level objects are @dfn{lowered}, using their compiler, to either derivations or store items. For instance, lowering a package yields a derivation, and lowering a @code{plain-file} yields a store item. This is achieved using the @code{lower-object} monadic procedure. @deffn {Monadic Procedure} lower-object @var{obj} [@var{system}] @ [#:target #f] Return as a value in @code{%store-monad} the derivation or store item corresponding to @var{obj} for @var{system}, cross-compiling for @var{target} if @var{target} is true. @var{obj} must be an object that has an associated gexp compiler, such as a @code{<package>}. @end deffn @deffn {Procedure} gexp->approximate-sexp gexp Sometimes, it may be useful to convert a G-exp into a S-exp. For example, some linters (@pxref{Invoking guix lint}) peek into the build phases of a package to detect potential problems. This conversion can be achieved with this procedure. However, some information can be lost in the process. More specifically, lowerable objects will be silently replaced with some arbitrary object -- currently the list @code{(*approximate*)}, but this may change. @end deffn @node Invoking guix repl @section Invoking @command{guix repl} @cindex @command{guix repl} @cindex REPL, read-eval-print loop, script The @command{guix repl} command makes it easier to program Guix in Guile by launching a Guile @dfn{read-eval-print loop} (REPL) for interactive programming (@pxref{Using Guile Interactively,,, guile, GNU Guile Reference Manual}), or by running Guile scripts (@pxref{Running Guile Scripts,,, guile, GNU Guile Reference Manual}). Compared to just launching the @command{guile} command, @command{guix repl} guarantees that all the Guix modules and all its dependencies are available in the search path. The general syntax is: @example guix repl @var{options} [@var{file} @var{args}] @end example When a @var{file} argument is provided, @var{file} is executed as a Guile scripts: @example guix repl my-script.scm @end example To pass arguments to the script, use @code{--} to prevent them from being interpreted as arguments to @command{guix repl} itself: @example guix repl -- my-script.scm --input=foo.txt @end example To make a script executable directly from the shell, using the guix executable that is on the user's search path, add the following two lines at the top of the script: @example @code{#!/usr/bin/env -S guix repl --} @code{!#} @end example To make a script that launches an interactive REPL directly from the shell, use the @code{--interactive} flag: @example @code{#!/usr/bin/env -S guix repl --interactive} @code{!#} @end example Without a file name argument, a Guile REPL is started, allowing for interactive use (@pxref{Using Guix Interactively}): @example $ guix repl scheme@@(guile-user)> ,use (gnu packages base) scheme@@(guile-user)> coreutils $1 = #<package coreutils@@8.29 gnu/packages/base.scm:327 3e28300> @end example @cindex inferiors In addition, @command{guix repl} implements a simple machine-readable REPL protocol for use by @code{(guix inferior)}, a facility to interact with @dfn{inferiors}, separate processes running a potentially different revision of Guix. The available options are as follows: @table @code @item --list-types Display the @var{TYPE} options for @command{guix repl --type=TYPE} and exit. @item --type=@var{type} @itemx -t @var{type} Start a REPL of the given @var{TYPE}, which can be one of the following: @table @code @item guile This is default, and it spawns a standard full-featured Guile REPL. @item machine Spawn a REPL that uses the machine-readable protocol. This is the protocol that the @code{(guix inferior)} module speaks. @end table @item --listen=@var{endpoint} By default, @command{guix repl} reads from standard input and writes to standard output. When this option is passed, it will instead listen for connections on @var{endpoint}. Here are examples of valid options: @table @code @item --listen=tcp:37146 Accept connections on localhost on port 37146. @item --listen=unix:/tmp/socket Accept connections on the Unix-domain socket @file{/tmp/socket}. @end table @item --interactive @itemx -i Launch the interactive REPL after @var{file} is executed. @item --load-path=@var{directory} @itemx -L @var{directory} Add @var{directory} to the front of the package module search path (@pxref{Package Modules}). This allows users to define their own packages and make them visible to the script or REPL. @item -q Inhibit loading of the @file{~/.guile} file. By default, that configuration file is loaded when spawning a @code{guile} REPL. @end table @node Using Guix Interactively @section Using Guix Interactively @cindex interactive use @cindex REPL, read-eval-print loop The @command{guix repl} command gives you access to a warm and friendly @dfn{read-eval-print loop} (REPL) (@pxref{Invoking guix repl}). If you're getting into Guix programming---defining your own packages, writing manifests, defining services for Guix System or Guix Home, etc.---you will surely find it convenient to toy with ideas at the REPL. If you use Emacs, the most convenient way to do that is with Geiser (@pxref{The Perfect Setup}), but you do not have to use Emacs to enjoy the REPL@. When using @command{guix repl} or @command{guile} in the terminal, we recommend using Readline for completion and Colorized to get colorful output. To do that, you can run: @example guix install guile guile-readline guile-colorized @end example @noindent ... and then create a @file{.guile} file in your home directory containing this: @lisp (use-modules (ice-9 readline) (ice-9 colorized)) (activate-readline) (activate-colorized) @end lisp The REPL lets you evaluate Scheme code; you type a Scheme expression at the prompt, and the REPL prints what it evaluates to: @example $ guix repl scheme@@(guix-user)> (+ 2 3) $1 = 5 scheme@@(guix-user)> (string-append "a" "b") $2 = "ab" @end example It becomes interesting when you start fiddling with Guix at the REPL. The first thing you'll want to do is to ``import'' the @code{(guix)} module, which gives access to the main part of the programming interface, and perhaps a bunch of useful Guix modules. You could type @code{(use-modules (guix))}, which is valid Scheme code to import a module (@pxref{Using Guile Modules,,, guile, GNU Guile Reference Manual}), but the REPL provides the @code{use} @dfn{command} as a shorthand notation (@pxref{REPL Commands,,, guile, GNU Guile Reference Manual}): @example scheme@@(guix-user)> ,use (guix) scheme@@(guix-user)> ,use (gnu packages base) @end example Notice that REPL commands are introduced by a leading comma. A REPL command like @code{use} is not valid Scheme code; it's interpreted specially by the REPL. Guix extends the Guile REPL with additional commands for convenience. Among those, the @code{build} command comes in handy: it ensures that the given file-like object is built, building it if needed, and returns its output file name(s). In the example below, we build the @code{coreutils} and @code{grep} packages, as well as a ``computed file'' (@pxref{G-Expressions, @code{computed-file}}), and we use the @code{scandir} procedure to list the files in Grep's @code{/bin} directory: @example scheme@@(guix-user)> ,build coreutils $1 = "/gnu/store/@dots{}-coreutils-8.32-debug" $2 = "/gnu/store/@dots{}-coreutils-8.32" scheme@@(guix-user)> ,build grep $3 = "/gnu/store/@dots{}-grep-3.6" scheme@@(guix-user)> ,build (computed-file "x" #~(mkdir #$output)) building /gnu/store/@dots{}-x.drv... $4 = "/gnu/store/@dots{}-x" scheme@@(guix-user)> ,use(ice-9 ftw) scheme@@(guix-user)> (scandir (string-append $3 "/bin")) $5 = ("." ".." "egrep" "fgrep" "grep") @end example As a packager, you may be willing to inspect the build phases or flags of a given package; this is particularly useful when relying a lot on inheritance to define package variants (@pxref{Defining Package Variants}) or when package arguments are a result of some computation, both of which can make it harder to foresee what ends up in the package arguments. Additional commands let you inspect those package arguments: @example scheme@@(guix-user)> ,phases grep $1 = (modify-phases %standard-phases (add-after 'install 'fix-egrep-and-fgrep (lambda* (#:key outputs #:allow-other-keys) (let* ((out (assoc-ref outputs "out")) (bin (string-append out "/bin"))) (substitute* (list (string-append bin "/egrep") (string-append bin "/fgrep")) (("^exec grep") (string-append "exec " bin "/grep"))))))) scheme@@(guix-user)> ,configure-flags findutils $2 = (list "--localstatedir=/var") scheme@@(guix-user)> ,make-flags binutils $3 = '("MAKEINFO=true") @end example At a lower-level, a useful command is @code{lower}: it takes a file-like object and ``lowers'' it into a derivation (@pxref{Derivations}) or a store file: @example scheme@@(guix-user)> ,lower grep $6 = #<derivation /gnu/store/@dots{}-grep-3.6.drv => /gnu/store/@dots{}-grep-3.6 7f0e639115f0> scheme@@(guix-user)> ,lower (plain-file "x" "Hello!") $7 = "/gnu/store/@dots{}-x" @end example The full list of REPL commands can be seen by typing @code{,help guix} and is given below for reference. @deffn {REPL command} build @var{object} Lower @var{object} and build it if it's not already built, returning its output file name(s). @end deffn @deffn {REPL command} lower @var{object} Lower @var{object} into a derivation or store file name and return it. @end deffn @deffn {REPL command} verbosity @var{level} Change build verbosity to @var{level}. This is similar to the @option{--verbosity} command-line option (@pxref{Common Build Options}): level 0 means total silence, level 1 shows build events only, and higher levels print build logs. @end deffn @deffn {REPL command} phases @var{package} @deffnx {REPL command} configure-flags @var{package} @deffnx {REPL command} make-flags @var{package} These REPL commands return the value of one element of the @code{arguments} field of @var{package} (@pxref{package Reference}): the first one show the staged code associated with @code{#:phases} (@pxref{Build Phases}), the second shows the code for @code{#:configure-flags}, and @code{,make-flags} returns the code for @code{#:make-flags}. @end deffn @deffn {REPL command} run-in-store @var{exp} Run @var{exp}, a monadic expression, through the store monad. @xref{The Store Monad}, for more information. @end deffn @deffn {REPL command} enter-store-monad Enter a new REPL to evaluate monadic expressions (@pxref{The Store Monad}). You can quit this ``inner'' REPL by typing @code{,q}. @end deffn @c ********************************************************************* @node Utilities @chapter Utilities This section describes Guix command-line utilities. Some of them are primarily targeted at developers and users who write new package definitions, while others are more generally useful. They complement the Scheme programming interface of Guix in a convenient way. @menu * Invoking guix build:: Building packages from the command line. * Invoking guix edit:: Editing package definitions. * Invoking guix download:: Downloading a file and printing its hash. * Invoking guix hash:: Computing the cryptographic hash of a file. * Invoking guix import:: Importing package definitions. * Invoking guix refresh:: Updating package definitions. * Invoking guix style:: Styling package definitions. * Invoking guix lint:: Finding errors in package definitions. * Invoking guix size:: Profiling disk usage. * Invoking guix graph:: Visualizing the graph of packages. * Invoking guix publish:: Sharing substitutes. * Invoking guix challenge:: Challenging substitute servers. * Invoking guix copy:: Copying to and from a remote store. * Invoking guix container:: Process isolation. * Invoking guix weather:: Assessing substitute availability. * Invoking guix processes:: Listing client processes. @end menu @node Invoking guix build @section Invoking @command{guix build} @cindex package building @cindex @command{guix build} The @command{guix build} command builds packages or derivations and their dependencies, and prints the resulting store paths. Note that it does not modify the user's profile---this is the job of the @command{guix package} command (@pxref{Invoking guix package}). Thus, it is mainly useful for distribution developers. The general syntax is: @example guix build @var{options} @var{package-or-derivation}@dots{} @end example As an example, the following command builds the latest versions of Emacs and of Guile, displays their build logs, and finally displays the resulting directories: @example guix build emacs guile @end example Similarly, the following command builds all the available packages: @example guix build --quiet --keep-going \ $(guix package -A | awk '@{ print $1 "@@" $2 @}') @end example @var{package-or-derivation} may be either the name of a package found in the software distribution such as @code{coreutils} or @code{coreutils@@8.20}, or a derivation such as @file{/gnu/store/@dots{}-coreutils-8.19.drv}. In the former case, a package with the corresponding name (and optionally version) is searched for among the GNU distribution modules (@pxref{Package Modules}). Alternatively, the @option{--expression} option may be used to specify a Scheme expression that evaluates to a package; this is useful when disambiguating among several same-named packages or package variants is needed. There may be zero or more @var{options}. The available options are described in the subsections below. @menu * Common Build Options:: Build options for most commands. * Package Transformation Options:: Creating variants of packages. * Additional Build Options:: Options specific to 'guix build'. * Debugging Build Failures:: Real life packaging experience. @end menu @node Common Build Options @subsection Common Build Options A number of options that control the build process are common to @command{guix build} and other commands that can spawn builds, such as @command{guix package} or @command{guix archive}. These are the following: @table @code @item --load-path=@var{directory} @itemx -L @var{directory} Add @var{directory} to the front of the package module search path (@pxref{Package Modules}). This allows users to define their own packages and make them visible to the command-line tools. @item --keep-failed @itemx -K Keep the build tree of failed builds. Thus, if a build fails, its build tree is kept under @file{/tmp}, in a directory whose name is shown at the end of the build log. This is useful when debugging build issues. @xref{Debugging Build Failures}, for tips and tricks on how to debug build issues. This option implies @option{--no-offload}, and it has no effect when connecting to a remote daemon with a @code{guix://} URI (@pxref{The Store, the @env{GUIX_DAEMON_SOCKET} variable}). @item --keep-going @itemx -k Keep going when some of the derivations fail to build; return only once all the builds have either completed or failed. The default behavior is to stop as soon as one of the specified derivations has failed. @item --dry-run @itemx -n Do not build the derivations. @anchor{fallback-option} @item --fallback When substituting a pre-built binary fails, fall back to building packages locally (@pxref{Substitution Failure}). @item --substitute-urls=@var{urls} @anchor{client-substitute-urls} Consider @var{urls} the whitespace-separated list of substitute source URLs, overriding the default list of URLs of @command{guix-daemon} (@pxref{daemon-substitute-urls,, @command{guix-daemon} URLs}). This means that substitutes may be downloaded from @var{urls}, provided they are signed by a key authorized by the system administrator (@pxref{Substitutes}). When @var{urls} is the empty string, substitutes are effectively disabled. @item --no-substitutes Do not use substitutes for build products. That is, always build things locally instead of allowing downloads of pre-built binaries (@pxref{Substitutes}). @item --no-grafts Do not ``graft'' packages. In practice, this means that package updates available as grafts are not applied. @xref{Security Updates}, for more information on grafts. @item --rounds=@var{n} Build each derivation @var{n} times in a row, and raise an error if consecutive build results are not bit-for-bit identical. This is a useful way to detect non-deterministic builds processes. Non-deterministic build processes are a problem because they make it practically impossible for users to @emph{verify} whether third-party binaries are genuine. @xref{Invoking guix challenge}, for more. When used in conjunction with @option{--keep-failed}, the differing output is kept in the store, under @file{/gnu/store/@dots{}-check}. This makes it easy to look for differences between the two results. @item --no-offload Do not use offload builds to other machines (@pxref{Daemon Offload Setup}). That is, always build things locally instead of offloading builds to remote machines. @item --max-silent-time=@var{seconds} When the build or substitution process remains silent for more than @var{seconds}, terminate it and report a build failure. By default, the daemon's setting is honored (@pxref{Invoking guix-daemon, @option{--max-silent-time}}). @item --timeout=@var{seconds} Likewise, when the build or substitution process lasts for more than @var{seconds}, terminate it and report a build failure. By default, the daemon's setting is honored (@pxref{Invoking guix-daemon, @option{--timeout}}). @c Note: This option is actually not part of %standard-build-options but @c most programs honor it. @cindex verbosity, of the command-line tools @cindex build logs, verbosity @item -v @var{level} @itemx --verbosity=@var{level} Use the given verbosity @var{level}, an integer. Choosing 0 means that no output is produced, 1 is for quiet output; 2 is similar to 1 but it additionally displays download URLs; 3 shows all the build log output on standard error. @item --cores=@var{n} @itemx -c @var{n} Allow the use of up to @var{n} CPU cores for the build. The special value @code{0} means to use as many CPU cores as available. @item --max-jobs=@var{n} @itemx -M @var{n} Allow at most @var{n} build jobs in parallel. @xref{Invoking guix-daemon, @option{--max-jobs}}, for details about this option and the equivalent @command{guix-daemon} option. @item --debug=@var{level} Produce debugging output coming from the build daemon. @var{level} must be an integer between 0 and 5; higher means more verbose output. Setting a level of 4 or more may be helpful when debugging setup issues with the build daemon. @end table Behind the scenes, @command{guix build} is essentially an interface to the @code{package-derivation} procedure of the @code{(guix packages)} module, and to the @code{build-derivations} procedure of the @code{(guix derivations)} module. In addition to options explicitly passed on the command line, @command{guix build} and other @command{guix} commands that support building honor the @env{GUIX_BUILD_OPTIONS} environment variable. @defvr {Environment Variable} GUIX_BUILD_OPTIONS Users can define this variable to a list of command line options that will automatically be used by @command{guix build} and other @command{guix} commands that can perform builds, as in the example below: @example $ export GUIX_BUILD_OPTIONS="--no-substitutes -c 2 -L /foo/bar" @end example These options are parsed independently, and the result is appended to the parsed command-line options. @end defvr @node Package Transformation Options @subsection Package Transformation Options @cindex package variants Another set of command-line options supported by @command{guix build} and also @command{guix package} are @dfn{package transformation options}. These are options that make it possible to define @dfn{package variants}---for instance, packages built from different source code. This is a convenient way to create customized packages on the fly without having to type in the definitions of package variants (@pxref{Defining Packages}). Package transformation options are preserved across upgrades: @command{guix upgrade} attempts to apply transformation options initially used when creating the profile to the upgraded packages. The available options are listed below. Most commands support them and also support a @option{--help-transform} option that lists all the available options and a synopsis (these options are not shown in the @option{--help} output for brevity). @table @code @cindex performance, tuning code @cindex optimization, of package code @cindex tuning, of package code @cindex SIMD support @cindex tunable packages @cindex package multi-versioning @item --tune[=@var{cpu}] Use versions of the packages marked as ``tunable'' optimized for @var{cpu}. When @var{cpu} is @code{native}, or when it is omitted, tune for the CPU on which the @command{guix} command is running. Valid @var{cpu} names are those recognized by the underlying compiler, by default the GNU Compiler Collection. On x86_64 processors, this includes CPU names such as @code{nehalem}, @code{haswell}, and @code{skylake} (@pxref{x86 Options, @code{-march},, gcc, Using the GNU Compiler Collection (GCC)}). As new generations of CPUs come out, they augment the standard instruction set architecture (ISA) with additional instructions, in particular instructions for single-instruction/multiple-data (SIMD) parallel processing. For example, while Core2 and Skylake CPUs both implement the x86_64 ISA, only the latter supports AVX2 SIMD instructions. The primary gain one can expect from @option{--tune} is for programs that can make use of those SIMD capabilities @emph{and} that do not already have a mechanism to select the right optimized code at run time. Packages that have the @code{tunable?} property set are considered @dfn{tunable packages} by the @option{--tune} option; a package definition with the property set looks like this: @lisp (package (name "hello-simd") ;; ... ;; This package may benefit from SIMD extensions so ;; mark it as "tunable". (properties '((tunable? . #t)))) @end lisp Other packages are not considered tunable. This allows Guix to use generic binaries in the cases where tuning for a specific CPU is unlikely to provide any gain. Tuned packages are built with @code{-march=@var{CPU}}; under the hood, the @option{-march} option is passed to the actual wrapper by a compiler wrapper. Since the build machine may not be able to run code for the target CPU micro-architecture, the test suite is not run when building a tuned package. To reduce rebuilds to the minimum, tuned packages are @emph{grafted} onto packages that depend on them (@pxref{Security Updates, grafts}). Thus, using @option{--no-grafts} cancels the effect of @option{--tune}. We call this technique @dfn{package multi-versioning}: several variants of tunable packages may be built, one for each CPU variant. It is the coarse-grain counterpart of @dfn{function multi-versioning} as implemented by the GNU tool chain (@pxref{Function Multiversioning,,, gcc, Using the GNU Compiler Collection (GCC)}). @item --with-source=@var{source} @itemx --with-source=@var{package}=@var{source} @itemx --with-source=@var{package}@@@var{version}=@var{source} Use @var{source} as the source of @var{package}, and @var{version} as its version number. @var{source} must be a file name or a URL, as for @command{guix download} (@pxref{Invoking guix download}). When @var{package} is omitted, it is taken to be the package name specified on the command line that matches the base of @var{source}---e.g., if @var{source} is @code{/src/guile-2.0.10.tar.gz}, the corresponding package is @code{guile}. Likewise, when @var{version} is omitted, the version string is inferred from @var{source}; in the previous example, it is @code{2.0.10}. This option allows users to try out versions of packages other than the one provided by the distribution. The example below downloads @file{ed-1.7.tar.gz} from a GNU mirror and uses that as the source for the @code{ed} package: @example guix build ed --with-source=mirror://gnu/ed/ed-1.4.tar.gz @end example As a developer, @option{--with-source} makes it easy to test release candidates, and even to test their impact on packages that depend on them: @example guix build elogind --with-source=@dots{}/shepherd-0.9.0rc1.tar.gz @end example @dots{} or to build from a checkout in a pristine environment: @example $ git clone git://git.sv.gnu.org/guix.git $ guix build guix --with-source=guix@@1.0=./guix @end example @item --with-input=@var{package}=@var{replacement} Replace dependency on @var{package} by a dependency on @var{replacement}. @var{package} must be a package name, and @var{replacement} must be a package specification such as @code{guile} or @code{guile@@1.8}. For instance, the following command builds Guix, but replaces its dependency on the current stable version of Guile with a dependency on the legacy version of Guile, @code{guile@@2.2}: @example guix build --with-input=guile=guile@@2.2 guix @end example This is a recursive, deep replacement. So in this example, both @code{guix} and its dependency @code{guile-json} (which also depends on @code{guile}) get rebuilt against @code{guile@@2.2}. This is implemented using the @code{package-input-rewriting/spec} Scheme procedure (@pxref{Defining Packages, @code{package-input-rewriting/spec}}). @item --with-graft=@var{package}=@var{replacement} This is similar to @option{--with-input} but with an important difference: instead of rebuilding the whole dependency chain, @var{replacement} is built and then @dfn{grafted} onto the binaries that were initially referring to @var{package}. @xref{Security Updates}, for more information on grafts. For example, the command below grafts version 3.5.4 of GnuTLS onto Wget and all its dependencies, replacing references to the version of GnuTLS they currently refer to: @example guix build --with-graft=gnutls=gnutls@@3.5.4 wget @end example This has the advantage of being much faster than rebuilding everything. But there is a caveat: it works if and only if @var{package} and @var{replacement} are strictly compatible---for example, if they provide a library, the application binary interface (ABI) of those libraries must be compatible. If @var{replacement} is somehow incompatible with @var{package}, then the resulting package may be unusable. Use with care! @cindex debugging info, rebuilding @item --with-debug-info=@var{package} Build @var{package} in a way that preserves its debugging info and graft it onto packages that depend on it. This is useful if @var{package} does not already provide debugging info as a @code{debug} output (@pxref{Installing Debugging Files}). For example, suppose you're experiencing a crash in Inkscape and would like to see what's up in GLib, a library deep down in Inkscape's dependency graph. GLib lacks a @code{debug} output, so debugging is tough. Fortunately, you rebuild GLib with debugging info and tack it on Inkscape: @example guix install inkscape --with-debug-info=glib @end example Only GLib needs to be recompiled so this takes a reasonable amount of time. @xref{Installing Debugging Files}, for more info. @quotation Note Under the hood, this option works by passing the @samp{#:strip-binaries? #f} to the build system of the package of interest (@pxref{Build Systems}). Most build systems support that option but some do not. In that case, an error is raised. Likewise, if a C/C++ package is built without @code{-g} (which is rarely the case), debugging info will remain unavailable even when @code{#:strip-binaries?} is false. @end quotation @cindex tool chain, changing the build tool chain of a package @item --with-c-toolchain=@var{package}=@var{toolchain} This option changes the compilation of @var{package} and everything that depends on it so that they get built with @var{toolchain} instead of the default GNU tool chain for C/C++. Consider this example: @example guix build octave-cli \ --with-c-toolchain=fftw=gcc-toolchain@@10 \ --with-c-toolchain=fftwf=gcc-toolchain@@10 @end example The command above builds a variant of the @code{fftw} and @code{fftwf} packages using version 10 of @code{gcc-toolchain} instead of the default tool chain, and then builds a variant of the GNU@tie{}Octave command-line interface using them. GNU@tie{}Octave itself is also built with @code{gcc-toolchain@@10}. This other example builds the Hardware Locality (@code{hwloc}) library and its dependents up to @code{intel-mpi-benchmarks} with the Clang C compiler: @example guix build --with-c-toolchain=hwloc=clang-toolchain \ intel-mpi-benchmarks @end example @quotation Note There can be application binary interface (ABI) incompatibilities among tool chains. This is particularly true of the C++ standard library and run-time support libraries such as that of OpenMP@. By rebuilding all dependents with the same tool chain, @option{--with-c-toolchain} minimizes the risks of incompatibility but cannot entirely eliminate them. Choose @var{package} wisely. @end quotation @item --with-git-url=@var{package}=@var{url} @cindex Git, using the latest commit @cindex latest commit, building Build @var{package} from the latest commit of the @code{master} branch of the Git repository at @var{url}. Git sub-modules of the repository are fetched, recursively. For example, the following command builds the NumPy Python library against the latest commit of the master branch of Python itself: @example guix build python-numpy \ --with-git-url=python=https://github.com/python/cpython @end example This option can also be combined with @option{--with-branch} or @option{--with-commit} (see below). @cindex continuous integration Obviously, since it uses the latest commit of the given branch, the result of such a command varies over time. Nevertheless it is a convenient way to rebuild entire software stacks against the latest commit of one or more packages. This is particularly useful in the context of continuous integration (CI). Checkouts are kept in a cache under @file{~/.cache/guix/checkouts} to speed up consecutive accesses to the same repository. You may want to clean it up once in a while to save disk space. @item --with-branch=@var{package}=@var{branch} Build @var{package} from the latest commit of @var{branch}. If the @code{source} field of @var{package} is an origin with the @code{git-fetch} method (@pxref{origin Reference}) or a @code{git-checkout} object, the repository URL is taken from that @code{source}. Otherwise you have to use @option{--with-git-url} to specify the URL of the Git repository. For instance, the following command builds @code{guile-sqlite3} from the latest commit of its @code{master} branch, and then builds @code{guix} (which depends on it) and @code{cuirass} (which depends on @code{guix}) against this specific @code{guile-sqlite3} build: @example guix build --with-branch=guile-sqlite3=master cuirass @end example @item --with-commit=@var{package}=@var{commit} This is similar to @option{--with-branch}, except that it builds from @var{commit} rather than the tip of a branch. @var{commit} must be a valid Git commit SHA1 identifier, a tag, or a @command{git describe} style identifier such as @code{1.0-3-gabc123}. @item --with-patch=@var{package}=@var{file} Add @var{file} to the list of patches applied to @var{package}, where @var{package} is a spec such as @code{python@@3.8} or @code{glibc}. @var{file} must contain a patch; it is applied with the flags specified in the @code{origin} of @var{package} (@pxref{origin Reference}), which by default includes @code{-p1} (@pxref{patch Directories,,, diffutils, Comparing and Merging Files}). As an example, the command below rebuilds Coreutils with the GNU C Library (glibc) patched with the given patch: @example guix build coreutils --with-patch=glibc=./glibc-frob.patch @end example In this example, glibc itself as well as everything that leads to Coreutils in the dependency graph is rebuilt. @cindex configure flags, changing them @item --with-configure-flag=@var{package}=@var{flag} Append @var{flag} to the configure flags of @var{package}, where @var{package} is a spec such as @code{guile@@3.0} or @code{glibc}. The build system of @var{package} must support the @code{#:configure-flags} argument. For example, the command below builds GNU@tie{}Hello with the configure flag @code{--disable-nls}: @example guix build hello --with-configure-flag=hello=--disable-nls @end example The following command passes an extra flag to @command{cmake} as it builds @code{lapack}: @example guix build lapack \ --with-configure-flag=lapack=-DBUILD_SHARED_LIBS=OFF @end example @quotation Note Under the hood, this option works by passing the @samp{#:configure-flags} argument to the build system of the package of interest (@pxref{Build Systems}). Most build systems support that option but some do not. In that case, an error is raised. @end quotation @cindex upstream, latest version @item --with-latest=@var{package} @itemx --with-version=@var{package}=@var{version} So you like living on the bleeding edge? The @option{--with-latest} option is for you! It replaces occurrences of @var{package} in the dependency graph with its latest upstream version, as reported by @command{guix refresh} (@pxref{Invoking guix refresh}). It does so by determining the latest upstream release of @var{package} (if possible), downloading it, and authenticating it @emph{if} it comes with an OpenPGP signature. As an example, the command below builds Guix against the latest version of Guile-JSON: @example guix build guix --with-latest=guile-json @end example The @option{--with-version} works similarly except that it lets you specify that you want precisely @var{version}, assuming that version exists upstream. For example, to spawn a development environment with SciPy built against version 1.22.4 of NumPy (skipping its test suite because hey, we're not gonna wait this long), you would run: @example guix shell python python-scipy --with-version=python-numpy=1.22.4 @end example @quotation Warning Because they depend on source code published at a given point in time on upstream servers, deployments made with @option{--with-latest} and @option{--with-version} may be non-reproducible: source might disappear or be modified in place on the servers. To deploy old software versions without compromising on reproducibility, @pxref{Invoking guix time-machine, @command{guix time-machine}}. @end quotation There are limitations. First, in cases where the tool cannot or does not know how to authenticate source code, you are at risk of running malicious code; a warning is emitted in this case. Second, this option simply changes the source used in the existing package definitions, which is not always sufficient: there might be additional dependencies that need to be added, patches to apply, and more generally the quality assurance work that Guix developers normally do will be missing. You've been warned! When those limitations are acceptable, it's a snappy way to stay on top. We encourage you to submit patches updating the actual package definitions once you have successfully tested an upgrade with @option{--with-latest} (@pxref{Contributing}). @cindex test suite, skipping @item --without-tests=@var{package} Build @var{package} without running its tests. This can be useful in situations where you want to skip the lengthy test suite of a intermediate package, or if a package's test suite fails in a non-deterministic fashion. It should be used with care because running the test suite is a good way to ensure a package is working as intended. Turning off tests leads to a different store item. Consequently, when using this option, anything that depends on @var{package} must be rebuilt, as in this example: @example guix install --without-tests=python python-notebook @end example The command above installs @code{python-notebook} on top of @code{python} built without running its test suite. To do so, it also rebuilds everything that depends on @code{python}, including @code{python-notebook} itself. Internally, @option{--without-tests} relies on changing the @code{#:tests?} option of a package's @code{check} phase (@pxref{Build Systems}). Note that some packages use a customized @code{check} phase that does not respect a @code{#:tests? #f} setting. Therefore, @option{--without-tests} has no effect on these packages. @end table Wondering how to achieve the same effect using Scheme code, for example in your manifest, or how to write your own package transformation? @xref{Defining Package Variants}, for an overview of the programming interfaces available. @node Additional Build Options @subsection Additional Build Options The command-line options presented below are specific to @command{guix build}. @table @code @item --quiet @itemx -q Build quietly, without displaying the build log; this is equivalent to @option{--verbosity=0}. Upon completion, the build log is kept in @file{/var} (or similar) and can always be retrieved using the @option{--log-file} option. @item --file=@var{file} @itemx -f @var{file} Build the package, derivation, or other file-like object that the code within @var{file} evaluates to (@pxref{G-Expressions, file-like objects}). As an example, @var{file} might contain a package definition like this (@pxref{Defining Packages}): @lisp @include package-hello.scm @end lisp The @var{file} may also contain a JSON representation of one or more package definitions. Running @code{guix build -f} on @file{hello.json} with the following contents would result in building the packages @code{myhello} and @code{greeter}: @example @verbatiminclude package-hello.json @end example @item --manifest=@var{manifest} @itemx -m @var{manifest} Build all packages listed in the given @var{manifest} (@pxref{profile-manifest, @option{--manifest}}). @item --expression=@var{expr} @itemx -e @var{expr} Build the package or derivation @var{expr} evaluates to. For example, @var{expr} may be @code{(@@ (gnu packages guile) guile-1.8)}, which unambiguously designates this specific variant of version 1.8 of Guile. Alternatively, @var{expr} may be a G-expression, in which case it is used as a build program passed to @code{gexp->derivation} (@pxref{G-Expressions}). Lastly, @var{expr} may refer to a zero-argument monadic procedure (@pxref{The Store Monad}). The procedure must return a derivation as a monadic value, which is then passed through @code{run-with-store}. @item --development @itemx -D Build the ``development environment'' (build dependencies) of the following package. For example, the following command builds the inputs of @code{hello}, but @emph{not} @code{hello} itself, and also builds @code{guile}: @example guix build -D hello guile @end example Notice that @option{-D} (or @option{--development}) only applies to the immediately following package on the command line. Under the hood, it uses @code{package->development-manifest} (@pxref{package-development-manifest, @code{package->development-manifest}}). @quotation Note The effect of combining @option{--development} with @option{--target} (for cross-compilation) may not be what you expect: it will cross-compile all the dependencies of the given package when it is built natively. @end quotation @cindex dependents of a package, building them @cindex building the dependents of a package @anchor{build-dependents} @item --dependents[=@var{depth}] @itemx -P [@var{depth}] Build the dependents of the following package. By default, build all the direct and indirect dependents; when @var{depth} is provided, limit to dependents at that distance: 1 for direct dependents, 2 for dependents of dependents, and so on. For example, the command below builds @emph{all} the dependents of libgit2: @example guix build --dependents libgit2 @end example To build all the packages that directly depend on NumPy, run: @example guix build -P1 python-numpy @end example The list of dependents is computed in the same way as with @command{guix refresh --list-dependent} (@pxref{Invoking guix refresh}). @item --source @itemx -S Build the source derivations of the packages, rather than the packages themselves. For instance, @code{guix build -S gcc} returns something like @file{/gnu/store/@dots{}-gcc-4.7.2.tar.bz2}, which is the GCC source tarball. The returned source tarball is the result of applying any patches and code snippets specified in the package @code{origin} (@pxref{Defining Packages}). @cindex source, verification As with other derivations, the result of building a source derivation can be verified using the @option{--check} option (@pxref{build-check}). This is useful to validate that a (potentially already built or substituted, thus cached) package source matches against its declared hash. Note that @command{guix build -S} compiles the sources only of the specified packages. They do not include the sources of statically linked dependencies and by themselves are insufficient for reproducing the packages. @item --sources Fetch and return the source of @var{package-or-derivation} and all their dependencies, recursively. This is a handy way to obtain a local copy of all the source code needed to build @var{packages}, allowing you to eventually build them even without network access. It is an extension of the @option{--source} option and can accept one of the following optional argument values: @table @code @item package This value causes the @option{--sources} option to behave in the same way as the @option{--source} option. @item all Build the source derivations of all packages, including any source that might be listed as @code{inputs}. This is the default value. @example $ guix build --sources tzdata The following derivations will be built: /gnu/store/@dots{}-tzdata2015b.tar.gz.drv /gnu/store/@dots{}-tzcode2015b.tar.gz.drv @end example @item transitive Build the source derivations of all packages, as well of all transitive inputs to the packages. This can be used e.g.@: to prefetch package source for later offline building. @example $ guix build --sources=transitive tzdata The following derivations will be built: /gnu/store/@dots{}-tzcode2015b.tar.gz.drv /gnu/store/@dots{}-findutils-4.4.2.tar.xz.drv /gnu/store/@dots{}-grep-2.21.tar.xz.drv /gnu/store/@dots{}-coreutils-8.23.tar.xz.drv /gnu/store/@dots{}-make-4.1.tar.xz.drv /gnu/store/@dots{}-bash-4.3.tar.xz.drv @dots{} @end example @end table @item --system=@var{system} @itemx -s @var{system} Attempt to build for @var{system}---e.g., @code{i686-linux}---instead of the system type of the build host. The @command{guix build} command allows you to repeat this option several times, in which case it builds for all the specified systems; other commands ignore extraneous @option{-s} options. @quotation Note The @option{--system} flag is for @emph{native} compilation and must not be confused with cross-compilation. See @option{--target} below for information on cross-compilation. @end quotation An example use of this is on Linux-based systems, which can emulate different personalities. For instance, passing @option{--system=i686-linux} on an @code{x86_64-linux} system or @option{--system=armhf-linux} on an @code{aarch64-linux} system allows you to build packages in a complete 32-bit environment. @quotation Note Building for an @code{armhf-linux} system is unconditionally enabled on @code{aarch64-linux} machines, although certain aarch64 chipsets do not allow for this functionality, notably the ThunderX. @end quotation Similarly, when transparent emulation with QEMU and @code{binfmt_misc} is enabled (@pxref{Virtualization Services, @code{qemu-binfmt-service-type}}), you can build for any system for which a QEMU @code{binfmt_misc} handler is installed. Builds for a system other than that of the machine you are using can also be offloaded to a remote machine of the right architecture. @xref{Daemon Offload Setup}, for more information on offloading. @item --target=@var{triplet} @cindex cross-compilation Cross-build for @var{triplet}, which must be a valid GNU triplet, such as @code{"aarch64-linux-gnu"} (@pxref{Specifying Target Triplets, GNU configuration triplets,, autoconf, Autoconf}). @item --list-systems List all the supported systems, that can be passed as an argument to @option{--system}. @item --list-targets List all the supported targets, that can be passed as an argument to @option{--target}. @anchor{build-check} @item --check @cindex determinism, checking @cindex reproducibility, checking Rebuild @var{package-or-derivation}, which are already available in the store, and raise an error if the build results are not bit-for-bit identical. This mechanism allows you to check whether previously installed substitutes are genuine (@pxref{Substitutes}), or whether the build result of a package is deterministic. @xref{Invoking guix challenge}, for more background information and tools. When used in conjunction with @option{--keep-failed}, the differing output is kept in the store, under @file{/gnu/store/@dots{}-check}. This makes it easy to look for differences between the two results. @item --repair @cindex repairing store items @cindex corruption, recovering from Attempt to repair the specified store items, if they are corrupt, by re-downloading or rebuilding them. This operation is not atomic and thus restricted to @code{root}. @item --derivations @itemx -d Return the derivation paths, not the output paths, of the given packages. @item --root=@var{file} @itemx -r @var{file} @cindex GC roots, adding @cindex garbage collector roots, adding Make @var{file} a symlink to the result, and register it as a garbage collector root. Consequently, the results of this @command{guix build} invocation are protected from garbage collection until @var{file} is removed. When that option is omitted, build results are eligible for garbage collection as soon as the build completes. @xref{Invoking guix gc}, for more on GC roots. @item --log-file @cindex build logs, access Return the build log file names or URLs for the given @var{package-or-derivation}, or raise an error if build logs are missing. This works regardless of how packages or derivations are specified. For instance, the following invocations are equivalent: @example guix build --log-file $(guix build -d guile) guix build --log-file $(guix build guile) guix build --log-file guile guix build --log-file -e '(@@ (gnu packages guile) guile-2.0)' @end example If a log is unavailable locally, and unless @option{--no-substitutes} is passed, the command looks for a corresponding log on one of the substitute servers. So for instance, imagine you want to see the build log of GDB on @code{aarch64}, but you are actually on an @code{x86_64} machine: @example $ guix build --log-file gdb -s aarch64-linux https://@value{SUBSTITUTE-SERVER-1}/log/@dots{}-gdb-7.10 @end example You can freely access a huge library of build logs! @end table @node Debugging Build Failures @subsection Debugging Build Failures @cindex build failures, debugging When defining a new package (@pxref{Defining Packages}), you will probably find yourself spending some time debugging and tweaking the build until it succeeds. To do that, you need to operate the build commands yourself in an environment as close as possible to the one the build daemon uses. To that end, the first thing to do is to use the @option{--keep-failed} or @option{-K} option of @command{guix build}, which will keep the failed build tree in @file{/tmp} or whatever directory you specified as @env{TMPDIR} (@pxref{Common Build Options, @option{--keep-failed}}). From there on, you can @command{cd} to the failed build tree and source the @file{environment-variables} file, which contains all the environment variable definitions that were in place when the build failed. So let's say you're debugging a build failure in package @code{foo}; a typical session would look like this: @example $ guix build foo -K @dots{} @i{build fails} $ cd /tmp/guix-build-foo.drv-0 $ source ./environment-variables $ cd foo-1.2 @end example Now, you can invoke commands as if you were the daemon (almost) and troubleshoot your build process. Sometimes it happens that, for example, a package's tests pass when you run them manually but they fail when the daemon runs them. This can happen because the daemon runs builds in containers where, unlike in our environment above, network access is missing, @file{/bin/sh} does not exist, etc. (@pxref{Build Environment Setup}). In such cases, you may need to inspect the build process from within a container similar to the one the build daemon creates: @example $ guix build -K foo @dots{} $ cd /tmp/guix-build-foo.drv-0 $ guix shell --no-grafts -C -D foo strace gdb [env]# source ./environment-variables [env]# cd foo-1.2 @end example Here, @command{guix shell -C} creates a container and spawns a new shell in it (@pxref{Invoking guix shell}). The @command{strace gdb} part adds the @command{strace} and @command{gdb} commands to the container, which you may find handy while debugging. The @option{--no-grafts} option makes sure we get the exact same environment, with ungrafted packages (@pxref{Security Updates}, for more info on grafts). To get closer to a container like that used by the build daemon, we can remove @file{/bin/sh}: @example [env]# rm /bin/sh @end example (Don't worry, this is harmless: this is all happening in the throw-away container created by @command{guix shell}.) The @command{strace} command is probably not in the search path, but we can run: @example [env]# $GUIX_ENVIRONMENT/bin/strace -f -o log make check @end example In this way, not only you will have reproduced the environment variables the daemon uses, you will also be running the build process in a container similar to the one the daemon uses. @node Invoking guix edit @section Invoking @command{guix edit} @cindex @command{guix edit} @cindex package definition, editing So many packages, so many source files! The @command{guix edit} command facilitates the life of users and packagers by pointing their editor at the source file containing the definition of the specified packages. For instance: @example guix edit gcc@@4.9 vim @end example @noindent launches the program specified in the @env{VISUAL} or in the @env{EDITOR} environment variable to view the recipe of GCC@tie{}4.9.3 and that of Vim. If you are using a Guix Git checkout (@pxref{Building from Git}), or have created your own packages on @env{GUIX_PACKAGE_PATH} (@pxref{Package Modules}), you will be able to edit the package recipes. In other cases, you will be able to examine the read-only recipes for packages currently in the store. Instead of @env{GUIX_PACKAGE_PATH}, the command-line option @option{--load-path=@var{directory}} (or in short @option{-L @var{directory}}) allows you to add @var{directory} to the front of the package module search path and so make your own packages visible. @node Invoking guix download @section Invoking @command{guix download} @cindex @command{guix download} @cindex downloading package sources When writing a package definition, developers typically need to download a source tarball, compute its SHA256 hash, and write that hash in the package definition (@pxref{Defining Packages}). The @command{guix download} tool helps with this task: it downloads a file from the given URI, adds it to the store, and prints both its file name in the store and its SHA256 hash. The fact that the downloaded file is added to the store saves bandwidth: when the developer eventually tries to build the newly defined package with @command{guix build}, the source tarball will not have to be downloaded again because it is already in the store. It is also a convenient way to temporarily stash files, which may be deleted eventually (@pxref{Invoking guix gc}). The @command{guix download} command supports the same URIs as used in package definitions. In particular, it supports @code{mirror://} URIs. @code{https} URIs (HTTP over TLS) are supported @emph{provided} the Guile bindings for GnuTLS are available in the user's environment; when they are not available, an error is raised. @xref{Guile Preparations, how to install the GnuTLS bindings for Guile,, gnutls-guile, GnuTLS-Guile}, for more information. @command{guix download} verifies HTTPS server certificates by loading the certificates of X.509 authorities from the directory pointed to by the @env{SSL_CERT_DIR} environment variable (@pxref{X.509 Certificates}), unless @option{--no-check-certificate} is used. Alternatively, @command{guix download} can also retrieve a Git repository, possibly a specific commit, tag, or branch. The following options are available: @table @code @item --hash=@var{algorithm} @itemx -H @var{algorithm} Compute a hash using the specified @var{algorithm}. @xref{Invoking guix hash}, for more information. @item --format=@var{fmt} @itemx -f @var{fmt} Write the hash in the format specified by @var{fmt}. For more information on the valid values for @var{fmt}, @pxref{Invoking guix hash}. @item --no-check-certificate Do not validate the X.509 certificates of HTTPS servers. When using this option, you have @emph{absolutely no guarantee} that you are communicating with the authentic server responsible for the given URL, which makes you vulnerable to ``man-in-the-middle'' attacks. @item --output=@var{file} @itemx -o @var{file} Save the downloaded file to @var{file} instead of adding it to the store. @item --git @itemx -g Checkout the Git repository at the latest commit on the default branch. @item --commit=@var{commit-or-tag} Checkout the Git repository at @var{commit-or-tag}. @var{commit-or-tag} can be either a tag or a commit defined in the Git repository. @item --branch=@var{branch} Checkout the Git repository at @var{branch}. The repository will be checked out at the latest commit of @var{branch}, which must be a valid branch of the Git repository. @item --recursive @itemx -r Recursively clone the Git repository. @end table @node Invoking guix hash @section Invoking @command{guix hash} @cindex @command{guix hash} The @command{guix hash} command computes the hash of a file. It is primarily a convenience tool for anyone contributing to the distribution: it computes the cryptographic hash of one or more files, which can be used in the definition of a package (@pxref{Defining Packages}). The general syntax is: @example guix hash @var{option} @var{file} ... @end example When @var{file} is @code{-} (a hyphen), @command{guix hash} computes the hash of data read from standard input. @command{guix hash} has the following options: @table @code @item --hash=@var{algorithm} @itemx -H @var{algorithm} Compute a hash using the specified @var{algorithm}, @code{sha256} by default. @var{algorithm} must be the name of a cryptographic hash algorithm supported by Libgcrypt @i{via} Guile-Gcrypt---e.g., @code{sha512} or @code{sha3-256} (@pxref{Hash Functions,,, guile-gcrypt, Guile-Gcrypt Reference Manual}). @item --format=@var{fmt} @itemx -f @var{fmt} Write the hash in the format specified by @var{fmt}. Supported formats: @code{base64}, @code{nix-base32}, @code{base32}, @code{base16} (@code{hex} and @code{hexadecimal} can be used as well). If the @option{--format} option is not specified, @command{guix hash} will output the hash in @code{nix-base32}. This representation is used in the definitions of packages. @item --recursive @itemx -r The @option{--recursive} option is deprecated in favor of @option{--serializer=nar} (see below); @option{-r} remains accepted as a convenient shorthand. @item --serializer=@var{type} @itemx -S @var{type} Compute the hash on @var{file} using @var{type} serialization. @var{type} may be one of the following: @table @code @item none This is the default: it computes the hash of a file's contents. @item nar Compute the hash of a ``normalized archive'' (or ``nar'') containing @var{file}, including its children if it is a directory. Some of the metadata of @var{file} is part of the archive; for instance, when @var{file} is a regular file, the hash is different depending on whether @var{file} is executable or not. Metadata such as time stamps have no impact on the hash (@pxref{Invoking guix archive}, for more info on the nar format). @c FIXME: Replace xref above with xref to an ``Archive'' section when @c it exists. @item git Compute the hash of the file or directory as a Git ``tree'', following the same method as the Git version control system. @end table @item --exclude-vcs @itemx -x When combined with @option{--recursive}, exclude version control system directories (@file{.bzr}, @file{.git}, @file{.hg}, etc.). @vindex git-fetch As an example, here is how you would compute the hash of a Git checkout, which is useful when using the @code{git-fetch} method (@pxref{origin Reference}): @example $ git clone http://example.org/foo.git $ cd foo $ guix hash -x --serializer=nar . @end example @end table @node Invoking guix import @section Invoking @command{guix import} @cindex importing packages @cindex package import @cindex package conversion @cindex Invoking @command{guix import} The @command{guix import} command is useful for people who would like to add a package to the distribution with as little work as possible---a legitimate demand. The command knows of a few repositories from which it can ``import'' package metadata. The result is a package definition, or a template thereof, in the format we know (@pxref{Defining Packages}). The general syntax is: @example guix import [@var{global-options}@dots{}] @var{importer} @var{package} [@var{options}@dots{}] @end example @var{importer} specifies the source from which to import package metadata, and @var{options} specifies a package identifier and other options specific to @var{importer}. @command{guix import} itself has the following @var{global-options}: @table @code @item --insert=@var{file} @itemx -i @var{file} Insert the package definition(s) that the @var{importer} generated into the specified @var{file}, either in alphabetical order among existing package definitions, or at the end of the file otherwise. @end table Some of the importers rely on the ability to run the @command{gpgv} command. For these, GnuPG must be installed and in @code{$PATH}; run @code{guix install gnupg} if needed. Currently, the available ``importers'' are: @table @code @item gnu Import metadata for the given GNU package. This provides a template for the latest version of that GNU package, including the hash of its source tarball, and its canonical synopsis and description. Additional information such as the package dependencies and its license needs to be figured out manually. For example, the following command returns a package definition for GNU@tie{}Hello: @example guix import gnu hello @end example Specific command-line options are: @table @code @item --key-download=@var{policy} As for @command{guix refresh}, specify the policy to handle missing OpenPGP keys when verifying the package signature. @xref{Invoking guix refresh, @option{--key-download}}. @end table @item pypi @cindex pypi Import metadata from the @uref{https://pypi.python.org/, Python Package Index}. Information is taken from the JSON-formatted description available at @code{pypi.python.org} and usually includes all the relevant information, including package dependencies. For maximum efficiency, it is recommended to install the @command{unzip} utility, so that the importer can unzip Python wheels and gather data from them. The command below imports metadata for the latest version of the @code{itsdangerous} Python package: @example guix import pypi itsdangerous @end example You can also ask for a specific version: @example guix import pypi itsdangerous@@1.1.0 @end example @table @code @item --recursive @itemx -r Traverse the dependency graph of the given upstream package recursively and generate package expressions for all those packages that are not yet in Guix. @end table @item gem @cindex gem Import metadata from @uref{https://rubygems.org/, RubyGems}. Information is taken from the JSON-formatted description available at @code{rubygems.org} and includes most relevant information, including runtime dependencies. There are some caveats, however. The metadata doesn't distinguish between synopses and descriptions, so the same string is used for both fields. Additionally, the details of non-Ruby dependencies required to build native extensions is unavailable and left as an exercise to the packager. The command below imports metadata for the @code{rails} Ruby package: @example guix import gem rails @end example You can also ask for a specific version: @example guix import gem rails@@7.0.4 @end example @table @code @item --recursive @itemx -r Traverse the dependency graph of the given upstream package recursively and generate package expressions for all those packages that are not yet in Guix. @end table @item minetest @cindex minetest @cindex ContentDB Import metadata from @uref{https://content.minetest.net, ContentDB}. Information is taken from the JSON-formatted metadata provided through @uref{https://content.minetest.net/help/api/, ContentDB's API} and includes most relevant information, including dependencies. There are some caveats, however. The license information is often incomplete. The commit hash is sometimes missing. The descriptions are in the Markdown format, but Guix uses Texinfo instead. Texture packs and subgames are unsupported. The command below imports metadata for the Mesecons mod by Jeija: @example guix import minetest Jeija/mesecons @end example The author name can also be left out: @example guix import minetest mesecons @end example @table @code @item --recursive @itemx -r Traverse the dependency graph of the given upstream package recursively and generate package expressions for all those packages that are not yet in Guix. @end table @item cpan @cindex CPAN Import metadata from @uref{https://www.metacpan.org/, MetaCPAN}. Information is taken from the JSON-formatted metadata provided through @uref{https://fastapi.metacpan.org/, MetaCPAN's API} and includes most relevant information, such as module dependencies. License information should be checked closely. If Perl is available in the store, then the @code{corelist} utility will be used to filter core modules out of the list of dependencies. The command below imports metadata for the Acme::Boolean Perl module: @example guix import cpan Acme::Boolean @end example Like many other importers, the @code{cpan} importer supports recursive imports: @table @code @item --recursive @itemx -r Traverse the dependency graph of the given upstream package recursively and generate package expressions for all those packages that are not yet in Guix. @end table @item cran @cindex CRAN @cindex Bioconductor Import metadata from @uref{https://cran.r-project.org/, CRAN}, the central repository for the @uref{https://r-project.org, GNU@tie{}R statistical and graphical environment}. Information is extracted from the @file{DESCRIPTION} file of the package. The command below imports metadata for the Cairo R package: @example guix import cran Cairo @end example You can also ask for a specific version: @example guix import cran rasterVis@@0.50.3 @end example When @option{--recursive} is added, the importer will traverse the dependency graph of the given upstream package recursively and generate package expressions for all those packages that are not yet in Guix. When @option{--style=specification} is added, the importer will generate package definitions whose inputs are package specifications instead of references to package variables. This is useful when generated package definitions are to be appended to existing user modules, as the list of used package modules need not be changed. The default is @option{--style=variable}. When @option{--prefix=license:} is added, the importer will prefix license atoms with @code{license:}, allowing a prefixed import of @code{(guix licenses)}. When @option{--archive=bioconductor} is added, metadata is imported from @uref{https://www.bioconductor.org/, Bioconductor}, a repository of R packages for the analysis and comprehension of high-throughput genomic data in bioinformatics. Information is extracted from the @file{DESCRIPTION} file contained in the package archive. The command below imports metadata for the GenomicRanges R package: @example guix import cran --archive=bioconductor GenomicRanges @end example Finally, you can also import R packages that have not yet been published on CRAN or Bioconductor as long as they are in a git repository. Use @option{--archive=git} followed by the URL of the git repository: @example guix import cran --archive=git https://github.com/immunogenomics/harmony @end example @item texlive @cindex TeX Live @cindex CTAN Import TeX package information from the TeX Live package database for TeX packages that are part of the @uref{https://www.tug.org/texlive/, TeX Live distribution}. Information about the package is obtained from the TeX Live package database, a plain text file that is included in the @code{texlive-scripts} package. The source code is downloaded from possibly multiple locations in the SVN repository of the Tex Live project. Note that therefore SVN must be installed and in @code{$PATH}; run @code{guix install subversion} if needed. The command below imports metadata for the @code{fontspec} TeX package: @example guix import texlive fontspec @end example Additional options include: @table @code @item --recursive @itemx -r Traverse the dependency graph of the given upstream package recursively and generate package expressions for all those packages that are not yet in Guix. @end table @item json @cindex JSON, import Import package metadata from a local JSON file. Consider the following example package definition in JSON format: @example @{ "name": "hello", "version": "2.10", "source": "mirror://gnu/hello/hello-2.10.tar.gz", "build-system": "gnu", "home-page": "https://www.gnu.org/software/hello/", "synopsis": "Hello, GNU world: An example GNU package", "description": "GNU Hello prints a greeting.", "license": "GPL-3.0+", "native-inputs": ["gettext"] @} @end example The field names are the same as for the @code{<package>} record (@xref{Defining Packages}). References to other packages are provided as JSON lists of quoted package specification strings such as @code{guile} or @code{guile@@2.0}. The importer also supports a more explicit source definition using the common fields for @code{<origin>} records: @example @{ @dots{} "source": @{ "method": "url-fetch", "uri": "mirror://gnu/hello/hello-2.10.tar.gz", "sha256": @{ "base32": "0ssi1wpaf7plaswqqjwigppsg5fyh99vdlb9kzl7c9lng89ndq1i" @} @} @dots{} @} @end example The command below reads metadata from the JSON file @code{hello.json} and outputs a package expression: @example guix import json hello.json @end example @item hackage @cindex hackage Import metadata from the Haskell community's central package archive @uref{https://hackage.haskell.org/, Hackage}. Information is taken from Cabal files and includes all the relevant information, including package dependencies. Specific command-line options are: @table @code @item --stdin @itemx -s Read a Cabal file from standard input. @item --no-test-dependencies @itemx -t Do not include dependencies required only by the test suites. @item --cabal-environment=@var{alist} @itemx -e @var{alist} @var{alist} is a Scheme alist defining the environment in which the Cabal conditionals are evaluated. The accepted keys are: @code{os}, @code{arch}, @code{impl} and a string representing the name of a flag. The value associated with a flag has to be either the symbol @code{true} or @code{false}. The value associated with other keys has to conform to the Cabal file format definition. The default value associated with the keys @code{os}, @code{arch} and @code{impl} is @samp{linux}, @samp{x86_64} and @samp{ghc}, respectively. @item --recursive @itemx -r Traverse the dependency graph of the given upstream package recursively and generate package expressions for all those packages that are not yet in Guix. @end table The command below imports metadata for the latest version of the HTTP Haskell package without including test dependencies and specifying the value of the flag @samp{network-uri} as @code{false}: @example guix import hackage -t -e "'((\"network-uri\" . false))" HTTP @end example A specific package version may optionally be specified by following the package name by an at-sign and a version number as in the following example: @example guix import hackage mtl@@2.1.3.1 @end example @item stackage @cindex stackage The @code{stackage} importer is a wrapper around the @code{hackage} one. It takes a package name, looks up the package version included in a long-term support (LTS) @uref{https://www.stackage.org, Stackage} release and uses the @code{hackage} importer to retrieve its metadata. Note that it is up to you to select an LTS release compatible with the GHC compiler used by Guix. Specific command-line options are: @table @code @item --no-test-dependencies @itemx -t Do not include dependencies required only by the test suites. @item --lts-version=@var{version} @itemx -l @var{version} @var{version} is the desired LTS release version. If omitted the latest release is used. @item --recursive @itemx -r Traverse the dependency graph of the given upstream package recursively and generate package expressions for all those packages that are not yet in Guix. @end table The command below imports metadata for the HTTP Haskell package included in the LTS Stackage release version 7.18: @example guix import stackage --lts-version=7.18 HTTP @end example @item elpa @cindex elpa Import metadata from an Emacs Lisp Package Archive (ELPA) package repository (@pxref{Packages,,, emacs, The GNU Emacs Manual}). Specific command-line options are: @table @code @item --archive=@var{repo} @itemx -a @var{repo} @var{repo} identifies the archive repository from which to retrieve the information. Currently the supported repositories and their identifiers are: @itemize - @item @uref{https://elpa.gnu.org/packages, GNU}, selected by the @code{gnu} identifier. This is the default. Packages from @code{elpa.gnu.org} are signed with one of the keys contained in the GnuPG keyring at @file{share/emacs/25.1/etc/package-keyring.gpg} (or similar) in the @code{emacs} package (@pxref{Package Installation, ELPA package signatures,, emacs, The GNU Emacs Manual}). @item @uref{https://elpa.nongnu.org/nongnu/, NonGNU}, selected by the @code{nongnu} identifier. @item @uref{https://stable.melpa.org/packages, MELPA-Stable}, selected by the @code{melpa-stable} identifier. @item @uref{https://melpa.org/packages, MELPA}, selected by the @code{melpa} identifier. @end itemize @item --recursive @itemx -r Traverse the dependency graph of the given upstream package recursively and generate package expressions for all those packages that are not yet in Guix. @end table @item crate @cindex crate Import metadata from the crates.io Rust package repository @uref{https://crates.io, crates.io}, as in this example: @example guix import crate blake2-rfc @end example The crate importer also allows you to specify a version string: @example guix import crate constant-time-eq@@0.1.0 @end example Additional options include: @table @code @item --recursive @itemx -r Traverse the dependency graph of the given upstream package recursively and generate package expressions for all those packages that are not yet in Guix. @item --recursive-dev-dependencies If @option{--recursive-dev-dependencies} is specified, also the recursively imported packages contain their development dependencies, which are recursively imported as well. @item --allow-yanked If no non-yanked version of a crate is available, use the latest yanked version instead instead of aborting. @end table @item elm @cindex elm Import metadata from the Elm package repository @uref{https://package.elm-lang.org, package.elm-lang.org}, as in this example: @example guix import elm elm-explorations/webgl @end example The Elm importer also allows you to specify a version string: @example guix import elm elm-explorations/webgl@@1.1.3 @end example Additional options include: @table @code @item --recursive @itemx -r Traverse the dependency graph of the given upstream package recursively and generate package expressions for all those packages that are not yet in Guix. @end table @item npm-binary @cindex npm @cindex Node.js Import metadata from the @uref{https://registry.npmjs.org, npm Registry}, as in this example: @example guix import npm-binary buffer-crc32 @end example The npm-binary importer also allows you to specify a version string: @example guix import npm-binary buffer-crc32@@1.0.0 @end example @quotation Note Generated package expressions skip the build step of the @code{node-build-system}. As such, generated package expressions often refer to transpiled or generated files, instead of being built from source. @end quotation Additional options include: @table @code @item --recursive @itemx -r Traverse the dependency graph of the given upstream package recursively and generate package expressions for all those packages that are not yet in Guix. @end table @item opam @cindex OPAM @cindex OCaml Import metadata from the @uref{https://opam.ocaml.org/, OPAM} package repository used by the OCaml community. Additional options include: @table @code @item --recursive @itemx -r Traverse the dependency graph of the given upstream package recursively and generate package expressions for all those packages that are not yet in Guix. @end table @item composer @cindex Composer @cindex PHP Import metadata from the @uref{https://getcomposer.org/, Composer} package archive used by the PHP community, as in this example: @example guix import composer phpunit/phpunit @end example Additional options include: @table @code @item --recursive @itemx -r Traverse the dependency graph of the given upstream package recursively and generate package expressions for all those packages that are not yet in Guix. @item --repo By default, packages are searched in the official OPAM repository. This option, which can be used more than once, lets you add other repositories which will be searched for packages. It accepts as valid arguments: @itemize @item the name of a known repository - can be one of @code{opam}, @code{coq} (equivalent to @code{coq-released}), @code{coq-core-dev}, @code{coq-extra-dev} or @code{grew}. @item the URL of a repository as expected by the @code{opam repository add} command (for instance, the URL equivalent of the above @code{opam} name would be @uref{https://opam.ocaml.org}). @item the path to a local copy of a repository (a directory containing a @file{packages/} sub-directory). @end itemize Repositories are assumed to be passed to this option by order of preference. The additional repositories will not replace the default @code{opam} repository, which is always kept as a fallback. Also, please note that versions are not compared across repositories. The first repository (from left to right) that has at least one version of a given package will prevail over any others, and the version imported will be the latest one found @emph{in this repository only}. @end table @item go @cindex go Import metadata for a Go module using @uref{https://proxy.golang.org, proxy.golang.org}. @example guix import go gopkg.in/yaml.v2 @end example It is possible to use a package specification with a @code{@@VERSION} suffix to import a specific version. Additional options include: @table @code @item --recursive @itemx -r Traverse the dependency graph of the given upstream package recursively and generate package expressions for all those packages that are not yet in Guix. @item --pin-versions When using this option, the importer preserves the exact versions of the Go modules dependencies instead of using their latest available versions. This can be useful when attempting to import packages that recursively depend on former versions of themselves to build. When using this mode, the symbol of the package is made by appending the version to its name, so that multiple versions of the same package can coexist. @end table @item egg @cindex egg Import metadata for @uref{https://wiki.call-cc.org/eggs, CHICKEN eggs}. The information is taken from @file{PACKAGE.egg} files found in the @uref{git://code.call-cc.org/eggs-5-all, eggs-5-all} Git repository. However, it does not provide all the information that we need, there is no ``description'' field, and the licenses used are not always precise (BSD is often used instead of BSD-N). @example guix import egg sourcehut @end example You can also ask for a specific version: @example guix import egg arrays@@1.0 @end example Additional options include: @table @code @item --recursive @itemx -r Traverse the dependency graph of the given upstream package recursively and generate package expressions for all those packages that are not yet in Guix. @end table @item hexpm @cindex hexpm Import metadata from the hex.pm Erlang and Elixir package repository @uref{https://hex.pm, hex.pm}, as in this example: @example guix import hexpm stun @end example The importer tries to determine the build system used by the package. The hexpm importer also allows you to specify a version string: @example guix import hexpm cf@@0.3.0 @end example Additional options include: @table @code @item --recursive @itemx -r Traverse the dependency graph of the given upstream package recursively and generate package expressions for all those packages that are not yet in Guix. @end table @end table The structure of the @command{guix import} code is modular. It would be useful to have more importers for other package formats, and your help is welcome here (@pxref{Contributing}). @node Invoking guix refresh @section Invoking @command{guix refresh} @cindex @command {guix refresh} The primary audience of the @command{guix refresh} command is packagers. As a user, you may be interested in the @option{--with-latest} option, which can bring you package update superpowers built upon @command{guix refresh} (@pxref{Package Transformation Options, @option{--with-latest}}). By default, @command{guix refresh} reports any packages provided by the distribution that are outdated compared to the latest upstream version, like this: @example $ guix refresh gnu/packages/gettext.scm:29:13: gettext would be upgraded from 0.18.1.1 to 0.18.2.1 gnu/packages/glib.scm:77:12: glib would be upgraded from 2.34.3 to 2.37.0 @end example Alternatively, one can specify packages to consider, in which case a warning is emitted for packages that lack an updater: @example $ guix refresh coreutils guile guile-ssh gnu/packages/ssh.scm:205:2: warning: no updater for guile-ssh gnu/packages/guile.scm:136:12: guile would be upgraded from 2.0.12 to 2.0.13 @end example @command{guix refresh} browses the upstream repository of each package and determines the highest version number of the releases therein. The command knows how to update specific types of packages: GNU packages, ELPA packages, etc.---see the documentation for @option{--type} below. There are many packages, though, for which it lacks a method to determine whether a new upstream release is available. However, the mechanism is extensible, so feel free to get in touch with us to add a new method! @table @code @item --recursive Consider the packages specified, and all the packages upon which they depend. @example $ guix refresh --recursive coreutils gnu/packages/acl.scm:40:13: acl would be upgraded from 2.2.53 to 2.3.1 gnu/packages/m4.scm:30:12: 1.4.18 is already the latest version of m4 gnu/packages/xml.scm:68:2: warning: no updater for expat gnu/packages/multiprecision.scm:40:12: 6.1.2 is already the latest version of gmp @dots{} @end example @end table If for some reason you don't want to update to the latest version, you can update to a specific version by appending an equal sign and the desired version number to the package specification. Note that not all updaters support this; an error is reported when an updater cannot refresh to the specified version. @example $ guix refresh trytond-party gnu/packages/guile.scm:392:2: guile would be upgraded from 3.0.3 to 3.0.5 $ guix refresh -u guile=3.0.4 @dots{} gnu/packages/guile.scm:392:2: guile: updating from version 3.0.3 to version 3.0.4... @dots{} $ guix refresh -u guile@@2.0=2.0.12 @dots{} gnu/packages/guile.scm:147:2: guile: updating from version 2.0.10 to version 2.0.12... @dots{} @end example In some specific cases, you may have many packages specified via a manifest or a module selection which should all be updated together; for these cases, the @option{--target-version} option can be provided to have them all refreshed to the same version, as shown in the examples below: @example $ guix refresh qtbase qtdeclarative --target-version=6.5.2 gnu/packages/qt.scm:1248:13: qtdeclarative would be upgraded from 6.3.2 to 6.5.2 gnu/packages/qt.scm:584:2: qtbase would be upgraded from 6.3.2 to 6.5.2 @end example @example $ guix refresh --manifest=qt5-manifest.scm --target-version=5.15.10 gnu/packages/qt.scm:1173:13: qtxmlpatterns would be upgraded from 5.15.8 to 5.15.10 gnu/packages/qt.scm:1202:13: qtdeclarative would be upgraded from 5.15.8 to 5.15.10 gnu/packages/qt.scm:1762:13: qtserialbus would be upgraded from 5.15.8 to 5.15.10 gnu/packages/qt.scm:2070:13: qtquickcontrols2 would be upgraded from 5.15.8 to 5.15.10 @dots{} @end example Sometimes the upstream name differs from the package name used in Guix, and @command{guix refresh} needs a little help. Most updaters honor the @code{upstream-name} property in package definitions, which can be used to that effect: @lisp (define-public network-manager (package (name "network-manager") ;; @dots{} (properties '((upstream-name . "NetworkManager"))))) @end lisp When passed @option{--update}, it modifies distribution source files to update the version numbers and source code hashes of those package definitions, as well as possibly their inputs (@pxref{Defining Packages}). This is achieved by downloading each package's latest source tarball and its associated OpenPGP signature, authenticating the downloaded tarball against its signature using @command{gpgv}, and finally computing its hash---note that GnuPG must be installed and in @code{$PATH}; run @code{guix install gnupg} if needed. When the public key used to sign the tarball is missing from the user's keyring, an attempt is made to automatically retrieve it from a public key server; when this is successful, the key is added to the user's keyring; otherwise, @command{guix refresh} reports an error. The following options are supported: @table @code @item --expression=@var{expr} @itemx -e @var{expr} Consider the package @var{expr} evaluates to. This is useful to precisely refer to a package, as in this example: @example guix refresh -l -e '(@@@@ (gnu packages commencement) glibc-final)' @end example This command lists the dependents of the ``final'' libc (essentially all the packages). @item --update @itemx -u Update distribution source files (package definitions) in place. This is usually run from a checkout of the Guix source tree (@pxref{Running Guix Before It Is Installed}): @example ./pre-inst-env guix refresh -s non-core -u @end example @xref{Defining Packages}, for more information on package definitions. You can also run it on packages from a third-party channel: @example guix refresh -L /path/to/channel -u @var{package} @end example @xref{Creating a Channel}, on how to create a channel. This command updates the version and source code hash of the package. Depending on the updater being used, it can also update the various @samp{inputs} fields of the package. In some cases, the updater might get inputs wrong---it might not know about an extra input that's necessary, or it might add an input that should be avoided. @cindex @code{updater-extra-inputs}, package property @cindex @code{updater-ignored-inputs}, package property To address that, packagers can add properties stating inputs that should be added to those found by the updater or inputs that should be ignored: the @code{updater-extra-inputs} and @code{updater-ignored-inputs} properties pertain to ``regular'' inputs, and there are equivalent properties for @samp{native} and @samp{propagated} inputs. In the example below, we tell the updater that we need @samp{openmpi} as an additional input: @lisp (define-public python-mpi4py (package (name "python-mpi4py") ;; @dots{} (inputs (list openmpi)) (properties '((updater-extra-inputs . ("openmpi")))))) @end lisp That way, @command{guix refresh -u python-mpi4py} will leave the @samp{openmpi} input, even if it is not among the inputs it would normally add. @item --select=[@var{subset}] @itemx -s @var{subset} Select all the packages in @var{subset}, one of @code{core}, @code{non-core} or @code{module:@var{name}}. The @code{core} subset refers to all the packages at the core of the distribution---i.e., packages that are used to build ``everything else''. This includes GCC, libc, Binutils, Bash, etc. Usually, changing one of these packages in the distribution entails a rebuild of all the others. Thus, such updates are an inconvenience to users in terms of build time or bandwidth used to achieve the upgrade. The @code{non-core} subset refers to the remaining packages. It is typically useful in cases where an update of the core packages would be inconvenient. The @code{module:@var{name}} subset refers to all the packages in a specified guile module. The module can be specified as @code{module:guile} or @code{module:(gnu packages guile)}, the former is a shorthand for the later. @item --manifest=@var{file} @itemx -m @var{file} Select all the packages from the manifest in @var{file}. This is useful to check if any packages of the user manifest can be updated. @item --type=@var{updater} @itemx -t @var{updater} Select only packages handled by @var{updater} (may be a comma-separated list of updaters). Currently, @var{updater} may be one of: @table @code @item gnu the updater for GNU packages; @item savannah the updater for packages hosted at @uref{https://savannah.gnu.org, Savannah}; @item sourceforge the updater for packages hosted at @uref{https://sourceforge.net, SourceForge}; @item gnome the updater for GNOME packages; @item kde the updater for KDE packages; @item xorg the updater for X.org packages; @item kernel.org the updater for packages hosted on kernel.org; @item egg the updater for @uref{https://wiki.call-cc.org/eggs/, Egg} packages; @item elpa the updater for @uref{https://elpa.gnu.org/, ELPA} packages; @item cran the updater for @uref{https://cran.r-project.org/, CRAN} packages; @item bioconductor the updater for @uref{https://www.bioconductor.org/, Bioconductor} R packages; @item cpan the updater for @uref{https://www.cpan.org/, CPAN} packages; @item pypi the updater for @uref{https://pypi.python.org, PyPI} packages. @item gem the updater for @uref{https://rubygems.org, RubyGems} packages. @item github the updater for @uref{https://github.com, GitHub} packages. @item hackage the updater for @uref{https://hackage.haskell.org, Hackage} packages. @item stackage the updater for @uref{https://www.stackage.org, Stackage} packages. @item crate the updater for @uref{https://crates.io, Crates} packages. @item launchpad the updater for @uref{https://launchpad.net, Launchpad} packages. @item generic-html a generic updater that crawls the HTML page where the source tarball of the package is hosted, when applicable, or the HTML page specified by the @code{release-monitoring-url} property of the package. @item generic-git a generic updater for packages hosted on Git repositories. It tries to be smart about parsing Git tag names, but if it is not able to parse the tag name and compare tags correctly, users can define the following properties for a package. @itemize @item @code{release-tag-prefix}: a regular expression for matching a prefix of the tag name. @item @code{release-tag-suffix}: a regular expression for matching a suffix of the tag name. @item @code{release-tag-version-delimiter}: a string used as the delimiter in the tag name for separating the numbers of the version. @item @code{accept-pre-releases}: by default, the updater will ignore pre-releases; to make it also look for pre-releases, set the this property to @code{#t}. @end itemize @lisp (package (name "foo") ;; ... (properties '((release-tag-prefix . "^release0-") (release-tag-suffix . "[a-z]?$") (release-tag-version-delimiter . ":")))) @end lisp @end table For instance, the following command only checks for updates of Emacs packages hosted at @code{elpa.gnu.org} and for updates of CRAN packages: @example $ guix refresh --type=elpa,cran gnu/packages/statistics.scm:819:13: r-testthat would be upgraded from 0.10.0 to 0.11.0 gnu/packages/emacs.scm:856:13: emacs-auctex would be upgraded from 11.88.6 to 11.88.9 @end example @item --list-updaters List available updaters and exit (see @option{--type} above). For each updater, display the fraction of packages it covers; at the end, display the fraction of packages covered by all these updaters. @end table In addition, @command{guix refresh} can be passed one or more package names, as in this example: @example $ ./pre-inst-env guix refresh -u emacs idutils gcc@@4.8 @end example @noindent The command above specifically updates the @code{emacs} and @code{idutils} packages. The @option{--select} option would have no effect in this case. You might also want to update definitions that correspond to the packages installed in your profile: @example $ ./pre-inst-env guix refresh -u \ $(guix package --list-installed | cut -f1) @end example When considering whether to upgrade a package, it is sometimes convenient to know which packages would be affected by the upgrade and should be checked for compatibility. For this the following option may be used when passing @command{guix refresh} one or more package names: @table @code @item --list-dependent @itemx -l List top-level dependent packages that would need to be rebuilt as a result of upgrading one or more packages. @xref{Invoking guix graph, the @code{reverse-package} type of @command{guix graph}}, for information on how to visualize the list of dependents of a package. @xref{build-dependents, @command{guix build --dependents}}, for a convenient way to build all the dependents of a package. @end table Be aware that the @option{--list-dependent} option only @emph{approximates} the rebuilds that would be required as a result of an upgrade. More rebuilds might be required under some circumstances. @example $ guix refresh --list-dependent flex Building the following 120 packages would ensure 213 dependent packages are rebuilt: hop@@2.4.0 emacs-geiser@@0.13 notmuch@@0.18 mu@@0.9.9.5 cflow@@1.4 idutils@@4.6 @dots{} @end example The command above lists a set of packages that could be built to check for compatibility with an upgraded @code{flex} package. @table @code @item --list-transitive @itemx -T List all the packages which one or more packages depend upon. @example $ guix refresh --list-transitive flex flex@@2.6.4 depends on the following 25 packages: perl@@5.28.0 help2man@@1.47.6 bison@@3.0.5 indent@@2.2.10 tar@@1.30 gzip@@1.9 bzip2@@1.0.6 xz@@5.2.4 file@@5.33 @dots{} @end example @end table The command above lists a set of packages which, when changed, would cause @code{flex} to be rebuilt. The following options can be used to customize GnuPG operation: @table @code @item --gpg=@var{command} Use @var{command} as the GnuPG 2.x command. @var{command} is searched for in @code{$PATH}. @item --keyring=@var{file} Use @var{file} as the keyring for upstream keys. @var{file} must be in the @dfn{keybox format}. Keybox files usually have a name ending in @file{.kbx} and the GNU@tie{}Privacy Guard (GPG) can manipulate these files (@pxref{kbxutil, @command{kbxutil},, gnupg, Using the GNU Privacy Guard}, for information on a tool to manipulate keybox files). When this option is omitted, @command{guix refresh} uses @file{~/.config/guix/upstream/trustedkeys.kbx} as the keyring for upstream signing keys. OpenPGP signatures are checked against keys from this keyring; missing keys are downloaded to this keyring as well (see @option{--key-download} below). You can export keys from your default GPG keyring into a keybox file using commands like this one: @example gpg --export rms@@gnu.org | kbxutil --import-openpgp >> mykeyring.kbx @end example Likewise, you can fetch keys to a specific keybox file like this: @example gpg --no-default-keyring --keyring mykeyring.kbx \ --recv-keys @value{OPENPGP-SIGNING-KEY-ID} @end example @xref{GPG Configuration Options, @option{--keyring},, gnupg, Using the GNU Privacy Guard}, for more information on GPG's @option{--keyring} option. @item --key-download=@var{policy} Handle missing OpenPGP keys according to @var{policy}, which may be one of: @table @code @item always Always download missing OpenPGP keys from the key server, and add them to the user's GnuPG keyring. @item never Never try to download missing OpenPGP keys. Instead just bail out. @item interactive When a package signed with an unknown OpenPGP key is encountered, ask the user whether to download it or not. This is the default behavior. @end table @item --key-server=@var{host} Use @var{host} as the OpenPGP key server when importing a public key. @item --load-path=@var{directory} @itemx -L @var{directory} Add @var{directory} to the front of the package module search path (@pxref{Package Modules}). This allows users to define their own packages and make them visible to the command-line tools. @end table The @code{github} updater uses the @uref{https://developer.github.com/v3/, GitHub API} to query for new releases. When used repeatedly e.g.@: when refreshing all packages, GitHub will eventually refuse to answer any further API requests. By default 60 API requests per hour are allowed, and a full refresh on all GitHub packages in Guix requires more than this. Authentication with GitHub through the use of an API token alleviates these limits. To use an API token, set the environment variable @env{GUIX_GITHUB_TOKEN} to a token procured from @uref{https://github.com/settings/tokens} or otherwise. @node Invoking guix style @section Invoking @command{guix style} @cindex @command{guix style} @cindex styling rules @cindex lint, code style @cindex format, code style @cindex format conventions The @command{guix style} command helps users and packagers alike style their package definitions and configuration files according to the latest fashionable trends. It can either reformat whole files, with the @option{--whole-file} option, or apply specific @dfn{styling rules} to individual package definitions. The command currently provides the following styling rules: @itemize @item formatting package definitions according to the project's conventions (@pxref{Formatting Code}); @item rewriting package inputs to the ``new style'', as explained below. @end itemize The way package inputs are written is going through a transition (@pxref{package Reference}, for more on package inputs). Until version 1.3.0, package inputs were written using the ``old style'', where each input was given an explicit label, most of the time the package name: @lisp (package ;; @dots{} ;; The "old style" (deprecated). (inputs `(("libunistring" ,libunistring) ("libffi" ,libffi)))) @end lisp Today, the old style is deprecated and the preferred style looks like this: @lisp (package ;; @dots{} ;; The "new style". (inputs (list libunistring libffi))) @end lisp Likewise, uses of @code{alist-delete} and friends to manipulate inputs is now deprecated in favor of @code{modify-inputs} (@pxref{Defining Package Variants}, for more info on @code{modify-inputs}). In the vast majority of cases, this is a purely mechanical change on the surface syntax that does not even incur a package rebuild. Running @command{guix style -S inputs} can do that for you, whether you're working on packages in Guix proper or in an external channel. The general syntax is: @example guix style [@var{options}] @var{package}@dots{} @end example This causes @command{guix style} to analyze and rewrite the definition of @var{package}@dots{} or, when @var{package} is omitted, of @emph{all} the packages. The @option{--styling} or @option{-S} option allows you to select the style rule, the default rule being @code{format}---see below. To reformat entire source files, the syntax is: @example guix style --whole-file @var{file}@dots{} @end example The available options are listed below. @table @code @item --dry-run @itemx -n Show source file locations that would be edited but do not modify them. @item --whole-file @itemx -f Reformat the given files in their entirety. In that case, subsequent arguments are interpreted as file names (rather than package names), and the @option{--styling} option has no effect. As an example, here is how you might reformat your operating system configuration (you need write permissions for the file): @example guix style -f /etc/config.scm @end example @item --alphabetical-sort @itemx -A Place the top-level package definitions in the given files in alphabetical order. Package definitions with matching names are placed with versions in descending order. This option only has an effect in combination with @option{--whole-file}. @item --styling=@var{rule} @itemx -S @var{rule} Apply @var{rule}, one of the following styling rules: @table @code @item format Format the given package definition(s)---this is the default styling rule. For example, a packager running Guix on a checkout (@pxref{Running Guix Before It Is Installed}) might want to reformat the definition of the Coreutils package like so: @example ./pre-inst-env guix style coreutils @end example @item inputs Rewrite package inputs to the ``new style'', as described above. This is how you would rewrite inputs of package @code{whatnot} in your own channel: @example guix style -L ~/my/channel -S inputs whatnot @end example Rewriting is done in a conservative way: preserving comments and bailing out if it cannot make sense of the code that appears in an inputs field. The @option{--input-simplification} option described below provides fine-grain control over when inputs should be simplified. @item arguments Rewrite package arguments to use G-expressions (@pxref{G-Expressions}). For example, consider this package definition: @lisp (define-public my-package (package ;; @dots{} (arguments ;old-style quoted arguments '(#:make-flags '("V=1") #:phases (modify-phases %standard-phases (delete 'build)))))) @end lisp @noindent Running @command{guix style -S arguments} on this package would rewrite its @code{arguments} field like to: @lisp (define-public my-package (package ;; @dots{} (arguments (list #:make-flags #~'("V=1") #:phases #~(modify-phases %standard-phases (delete 'build)))))) @end lisp Note that changes made by the @code{arguments} rule do not entail a rebuild of the affected packages. Furthermore, if a package definition happens to be using G-expressions already, @command{guix style} leaves it unchanged. @end table @item --list-stylings @itemx -l List and describe the available styling rules and exit. @item --load-path=@var{directory} @itemx -L @var{directory} Add @var{directory} to the front of the package module search path (@pxref{Package Modules}). @item --expression=@var{expr} @itemx -e @var{expr} Style the package @var{expr} evaluates to. For example, running: @example guix style -e '(@@ (gnu packages gcc) gcc-5)' @end example styles the @code{gcc-5} package definition. @item --input-simplification=@var{policy} When using the @code{inputs} styling rule, with @samp{-S inputs}, this option specifies the package input simplification policy for cases where an input label does not match the corresponding package name. @var{policy} may be one of the following: @table @code @item silent Simplify inputs only when the change is ``silent'', meaning that the package does not need to be rebuilt (its derivation is unchanged). @item safe Simplify inputs only when that is ``safe'' to do: the package might need to be rebuilt, but the change is known to have no observable effect. @item always Simplify inputs even when input labels do not match package names, and even if that might have an observable effect. @end table The default is @code{silent}, meaning that input simplifications do not trigger any package rebuild. @end table @node Invoking guix lint @section Invoking @command{guix lint} @cindex @command{guix lint} @cindex package, checking for errors The @command{guix lint} command is meant to help package developers avoid common errors and use a consistent style. It runs a number of checks on a given set of packages in order to find common mistakes in their definitions. Available @dfn{checkers} include (see @option{--list-checkers} for a complete list): @table @code @item synopsis @itemx description Validate certain typographical and stylistic rules about package descriptions and synopses. @item inputs-should-be-native Identify inputs that should most likely be native inputs. @item source @itemx home-page @itemx mirror-url @itemx github-url @itemx source-file-name Probe @code{home-page} and @code{source} URLs and report those that are invalid. Suggest a @code{mirror://} URL when applicable. If the @code{source} URL redirects to a GitHub URL, recommend usage of the GitHub URL@. Check that the source file name is meaningful, e.g.@: is not just a version number or ``git-checkout'', without a declared @code{file-name} (@pxref{origin Reference}). @item source-unstable-tarball Parse the @code{source} URL to determine if a tarball from GitHub is autogenerated or if it is a release tarball. Unfortunately GitHub's autogenerated tarballs are sometimes regenerated. @item derivation Check that the derivation of the given packages can be successfully computed for all the supported systems (@pxref{Derivations}). @item profile-collisions Check whether installing the given packages in a profile would lead to collisions. Collisions occur when several packages with the same name but a different version or a different store file name are propagated. @xref{package Reference, @code{propagated-inputs}}, for more information on propagated inputs. @item archival @cindex Software Heritage, source code archive @cindex archival of source code, Software Heritage Checks whether the package's source code is archived at @uref{https://www.softwareheritage.org, Software Heritage}. When the source code that is not archived comes from a version-control system (VCS)---e.g., it's obtained with @code{git-fetch}, send Software Heritage a ``save'' request so that it eventually archives it. This ensures that the source will remain available in the long term, and that Guix can fall back to Software Heritage should the source code disappear from its original host. The status of recent ``save'' requests can be @uref{https://archive.softwareheritage.org/save/#requests, viewed on-line}. When source code is a tarball obtained with @code{url-fetch}, simply print a message when it is not archived. As of this writing, Software Heritage does not allow requests to save arbitrary tarballs; we are working on ways to ensure that non-VCS source code is also archived. Software Heritage @uref{https://archive.softwareheritage.org/api/#rate-limiting, limits the request rate per IP address}. When the limit is reached, @command{guix lint} prints a message and the @code{archival} checker stops doing anything until that limit has been reset. @item cve @cindex security vulnerabilities @cindex CVE, Common Vulnerabilities and Exposures Report known vulnerabilities found in the Common Vulnerabilities and Exposures (CVE) databases of the current and past year @uref{https://nvd.nist.gov/vuln/data-feeds, published by the US NIST}. To view information about a particular vulnerability, visit pages such as: @itemize @item @indicateurl{https://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-YYYY-ABCD} @item @indicateurl{https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-YYYY-ABCD} @end itemize @noindent where @code{CVE-YYYY-ABCD} is the CVE identifier---e.g., @code{CVE-2015-7554}. Package developers can specify in package recipes the @uref{https://nvd.nist.gov/products/cpe,Common Platform Enumeration (CPE)} name and version of the package when they differ from the name or version that Guix uses, as in this example: @lisp (package (name "grub") ;; @dots{} ;; CPE calls this package "grub2". (properties '((cpe-name . "grub2") (cpe-version . "2.3")))) @end lisp @c See <https://www.openwall.com/lists/oss-security/2017/03/15/3>. Some entries in the CVE database do not specify which version of a package they apply to, and would thus ``stick around'' forever. Package developers who found CVE alerts and verified they can be ignored can declare them as in this example: @lisp (package (name "t1lib") ;; @dots{} ;; These CVEs no longer apply and can be safely ignored. (properties `((lint-hidden-cve . ("CVE-2011-0433" "CVE-2011-1553" "CVE-2011-1554" "CVE-2011-5244"))))) @end lisp @item formatting Warn about obvious source code formatting issues: trailing white space, use of tabulations, etc. @item input-labels Report old-style input labels that do not match the name of the corresponding package. This aims to help migrate from the ``old input style''. @xref{package Reference}, for more information on package inputs and input styles. @xref{Invoking guix style}, on how to migrate to the new style. @end table The general syntax is: @example guix lint @var{options} @var{package}@dots{} @end example If no package is given on the command line, then all packages are checked. The @var{options} may be zero or more of the following: @table @code @item --list-checkers @itemx -l List and describe all the available checkers that will be run on packages and exit. @item --checkers @itemx -c Only enable the checkers specified in a comma-separated list using the names returned by @option{--list-checkers}. @item --exclude @itemx -x Only disable the checkers specified in a comma-separated list using the names returned by @option{--list-checkers}. @item --expression=@var{expr} @itemx -e @var{expr} Consider the package @var{expr} evaluates to. This is useful to unambiguously designate packages, as in this example: @example guix lint -c archival -e '(@@ (gnu packages guile) guile-3.0)' @end example @item --no-network @itemx -n Only enable the checkers that do not depend on Internet access. @item --load-path=@var{directory} @itemx -L @var{directory} Add @var{directory} to the front of the package module search path (@pxref{Package Modules}). This allows users to define their own packages and make them visible to the command-line tools. @end table @node Invoking guix size @section Invoking @command{guix size} @cindex size @cindex package size @cindex closure @cindex @command{guix size} The @command{guix size} command helps package developers profile the disk usage of packages. It is easy to overlook the impact of an additional dependency added to a package, or the impact of using a single output for a package that could easily be split (@pxref{Packages with Multiple Outputs}). Such are the typical issues that @command{guix size} can highlight. The command can be passed one or more package specifications such as @code{gcc@@4.8} or @code{guile:debug}, or a file name in the store. Consider this example: @example $ guix size coreutils store item total self /gnu/store/@dots{}-gcc-5.5.0-lib 60.4 30.1 38.1% /gnu/store/@dots{}-glibc-2.27 30.3 28.8 36.6% /gnu/store/@dots{}-coreutils-8.28 78.9 15.0 19.0% /gnu/store/@dots{}-gmp-6.1.2 63.1 2.7 3.4% /gnu/store/@dots{}-bash-static-4.4.12 1.5 1.5 1.9% /gnu/store/@dots{}-acl-2.2.52 61.1 0.4 0.5% /gnu/store/@dots{}-attr-2.4.47 60.6 0.2 0.3% /gnu/store/@dots{}-libcap-2.25 60.5 0.2 0.2% total: 78.9 MiB @end example @cindex closure The store items listed here constitute the @dfn{transitive closure} of Coreutils---i.e., Coreutils and all its dependencies, recursively---as would be returned by: @example $ guix gc -R /gnu/store/@dots{}-coreutils-8.23 @end example Here the output shows three columns next to store items. The first column, labeled ``total'', shows the size in mebibytes (MiB) of the closure of the store item---that is, its own size plus the size of all its dependencies. The next column, labeled ``self'', shows the size of the item itself. The last column shows the ratio of the size of the item itself to the space occupied by all the items listed here. In this example, we see that the closure of Coreutils weighs in at 79@tie{}MiB, most of which is taken by libc and GCC's run-time support libraries. (That libc and GCC's libraries represent a large fraction of the closure is not a problem @i{per se} because they are always available on the system anyway.) Since the command also accepts store file names, assessing the size of a build result is straightforward: @example guix size $(guix system build config.scm) @end example When the package(s) passed to @command{guix size} are available in the store@footnote{More precisely, @command{guix size} looks for the @emph{ungrafted} variant of the given package(s), as returned by @code{guix build @var{package} --no-grafts}. @xref{Security Updates}, for information on grafts.}, @command{guix size} queries the daemon to determine its dependencies, and measures its size in the store, similar to @command{du -ms --apparent-size} (@pxref{du invocation,,, coreutils, GNU Coreutils}). When the given packages are @emph{not} in the store, @command{guix size} reports information based on the available substitutes (@pxref{Substitutes}). This makes it possible to profile the disk usage of store items that are not even on disk, only available remotely. You can also specify several package names: @example $ guix size coreutils grep sed bash store item total self /gnu/store/@dots{}-coreutils-8.24 77.8 13.8 13.4% /gnu/store/@dots{}-grep-2.22 73.1 0.8 0.8% /gnu/store/@dots{}-bash-4.3.42 72.3 4.7 4.6% /gnu/store/@dots{}-readline-6.3 67.6 1.2 1.2% @dots{} total: 102.3 MiB @end example @noindent In this example we see that the combination of the four packages takes 102.3@tie{}MiB in total, which is much less than the sum of each closure since they have a lot of dependencies in common. When looking at the profile returned by @command{guix size}, you may find yourself wondering why a given package shows up in the profile at all. To understand it, you can use @command{guix graph --path -t references} to display the shortest path between the two packages (@pxref{Invoking guix graph}). The available options are: @table @option @item --substitute-urls=@var{urls} Use substitute information from @var{urls}. @xref{client-substitute-urls, the same option for @code{guix build}}. @item --sort=@var{key} Sort lines according to @var{key}, one of the following options: @table @code @item self the size of each item (the default); @item closure the total size of the item's closure. @end table @item --map-file=@var{file} Write a graphical map of disk usage in PNG format to @var{file}. For the example above, the map looks like this: @image{images/coreutils-size-map,5in,, map of Coreutils disk usage produced by @command{guix size}} This option requires that @uref{https://wingolog.org/software/guile-charting/, Guile-Charting} be installed and visible in Guile's module search path. When that is not the case, @command{guix size} fails as it tries to load it. @item --system=@var{system} @itemx -s @var{system} Consider packages for @var{system}---e.g., @code{x86_64-linux}. @item --load-path=@var{directory} @itemx -L @var{directory} Add @var{directory} to the front of the package module search path (@pxref{Package Modules}). This allows users to define their own packages and make them visible to the command-line tools. @end table @node Invoking guix graph @section Invoking @command{guix graph} @cindex DAG @cindex @command{guix graph} @cindex package dependencies Packages and their dependencies form a @dfn{graph}, specifically a directed acyclic graph (DAG). It can quickly become difficult to have a mental model of the package DAG, so the @command{guix graph} command provides a visual representation of the DAG@. By default, @command{guix graph} emits a DAG representation in the input format of @uref{https://www.graphviz.org/, Graphviz}, so its output can be passed directly to the @command{dot} command of Graphviz. It can also emit an HTML page with embedded JavaScript code to display a ``chord diagram'' in a Web browser, using the @uref{https://d3js.org/, d3.js} library, or emit Cypher queries to construct a graph in a graph database supporting the @uref{https://www.opencypher.org/, openCypher} query language. With @option{--path}, it simply displays the shortest path between two packages. The general syntax is: @example guix graph @var{options} @var{package}@dots{} @end example For example, the following command generates a PDF file representing the package DAG for the GNU@tie{}Core Utilities, showing its build-time dependencies: @example guix graph coreutils | dot -Tpdf > dag.pdf @end example The output looks like this: @image{images/coreutils-graph,2in,,Dependency graph of the GNU Coreutils} Nice little graph, no? You may find it more pleasant to navigate the graph interactively with @command{xdot} (from the @code{xdot} package): @example guix graph coreutils | xdot - @end example But there is more than one graph! The one above is concise: it is the graph of package objects, omitting implicit inputs such as GCC, libc, grep, etc. It is often useful to have such a concise graph, but sometimes one may want to see more details. @command{guix graph} supports several types of graphs, allowing you to choose the level of detail: @table @code @item package This is the default type used in the example above. It shows the DAG of package objects, excluding implicit dependencies. It is concise, but filters out many details. @item reverse-package This shows the @emph{reverse} DAG of packages. For example: @example guix graph --type=reverse-package ocaml @end example ...@: yields the graph of packages that @emph{explicitly} depend on OCaml (if you are also interested in cases where OCaml is an implicit dependency, see @code{reverse-bag} below). Note that for core packages this can yield huge graphs. If all you want is to know the number of packages that depend on a given package, use @command{guix refresh --list-dependent} (@pxref{Invoking guix refresh, @option{--list-dependent}}). @item bag-emerged This is the package DAG, @emph{including} implicit inputs. For instance, the following command: @example guix graph --type=bag-emerged coreutils @end example ...@: yields this bigger graph: @image{images/coreutils-bag-graph,,5in,Detailed dependency graph of the GNU Coreutils} At the bottom of the graph, we see all the implicit inputs of @var{gnu-build-system} (@pxref{Build Systems, @code{gnu-build-system}}). Now, note that the dependencies of these implicit inputs---that is, the @dfn{bootstrap dependencies} (@pxref{Bootstrapping})---are not shown here, for conciseness. @item bag Similar to @code{bag-emerged}, but this time including all the bootstrap dependencies. @item bag-with-origins Similar to @code{bag}, but also showing origins and their dependencies. @item reverse-bag This shows the @emph{reverse} DAG of packages. Unlike @code{reverse-package}, it also takes implicit dependencies into account. For example: @example guix graph -t reverse-bag dune @end example @noindent ...@: yields the graph of all packages that depend on Dune, directly or indirectly. Since Dune is an @emph{implicit} dependency of many packages @i{via} @code{dune-build-system}, this shows a large number of packages, whereas @code{reverse-package} would show very few if any. @item derivation This is the most detailed representation: It shows the DAG of derivations (@pxref{Derivations}) and plain store items. Compared to the above representation, many additional nodes are visible, including build scripts, patches, Guile modules, etc. For this type of graph, it is also possible to pass a @file{.drv} file name instead of a package name, as in: @example guix graph -t derivation $(guix system build -d my-config.scm) @end example @item module This is the graph of @dfn{package modules} (@pxref{Package Modules}). For example, the following command shows the graph for the package module that defines the @code{guile} package: @example guix graph -t module guile | xdot - @end example @end table All the types above correspond to @emph{build-time dependencies}. The following graph type represents the @emph{run-time dependencies}: @table @code @item references This is the graph of @dfn{references} of a package output, as returned by @command{guix gc --references} (@pxref{Invoking guix gc}). If the given package output is not available in the store, @command{guix graph} attempts to obtain dependency information from substitutes. Here you can also pass a store file name instead of a package name. For example, the command below produces the reference graph of your profile (which can be big!): @example guix graph -t references $(readlink -f ~/.guix-profile) @end example @item referrers This is the graph of the @dfn{referrers} of a store item, as returned by @command{guix gc --referrers} (@pxref{Invoking guix gc}). This relies exclusively on local information from your store. For instance, let us suppose that the current Inkscape is available in 10 profiles on your machine; @command{guix graph -t referrers inkscape} will show a graph rooted at Inkscape and with those 10 profiles linked to it. It can help determine what is preventing a store item from being garbage collected. @end table @cindex shortest path, between packages Often, the graph of the package you are interested in does not fit on your screen, and anyway all you want to know is @emph{why} that package actually depends on some seemingly unrelated package. The @option{--path} option instructs @command{guix graph} to display the shortest path between two packages (or derivations, or store items, etc.): @example $ guix graph --path emacs libunistring emacs@@26.3 mailutils@@3.9 libunistring@@0.9.10 $ guix graph --path -t derivation emacs libunistring /gnu/store/@dots{}-emacs-26.3.drv /gnu/store/@dots{}-mailutils-3.9.drv /gnu/store/@dots{}-libunistring-0.9.10.drv $ guix graph --path -t references emacs libunistring /gnu/store/@dots{}-emacs-26.3 /gnu/store/@dots{}-libidn2-2.2.0 /gnu/store/@dots{}-libunistring-0.9.10 @end example Sometimes you still want to visualize the graph but would like to trim it so it can actually be displayed. One way to do it is via the @option{--max-depth} (or @option{-M}) option, which lets you specify the maximum depth of the graph. In the example below, we visualize only @code{libreoffice} and the nodes whose distance to @code{libreoffice} is at most 2: @example guix graph -M 2 libreoffice | xdot -f fdp - @end example Mind you, that's still a big ball of spaghetti, but at least @command{dot} can render it quickly and it can be browsed somewhat. The available options are the following: @table @option @item --type=@var{type} @itemx -t @var{type} Produce a graph output of @var{type}, where @var{type} must be one of the values listed above. @item --list-types List the supported graph types. @item --backend=@var{backend} @itemx -b @var{backend} Produce a graph using the selected @var{backend}. @item --list-backends List the supported graph backends. Currently, the available backends are Graphviz and d3.js. @item --path Display the shortest path between two nodes of the type specified by @option{--type}. The example below shows the shortest path between @code{libreoffice} and @code{llvm} according to the references of @code{libreoffice}: @example $ guix graph --path -t references libreoffice llvm /gnu/store/@dots{}-libreoffice-6.4.2.2 /gnu/store/@dots{}-libepoxy-1.5.4 /gnu/store/@dots{}-mesa-19.3.4 /gnu/store/@dots{}-llvm-9.0.1 @end example @item --expression=@var{expr} @itemx -e @var{expr} Consider the package @var{expr} evaluates to. This is useful to precisely refer to a package, as in this example: @example guix graph -e '(@@@@ (gnu packages commencement) gnu-make-final)' @end example @item --system=@var{system} @itemx -s @var{system} Display the graph for @var{system}---e.g., @code{i686-linux}. The package dependency graph is largely architecture-independent, but there are some architecture-dependent bits that this option allows you to visualize. @item --load-path=@var{directory} @itemx -L @var{directory} Add @var{directory} to the front of the package module search path (@pxref{Package Modules}). This allows users to define their own packages and make them visible to the command-line tools. @end table On top of that, @command{guix graph} supports all the usual package transformation options (@pxref{Package Transformation Options}). This makes it easy to view the effect of a graph-rewriting transformation such as @option{--with-input}. For example, the command below outputs the graph of @code{git} once @code{openssl} has been replaced by @code{libressl} everywhere in the graph: @example guix graph git --with-input=openssl=libressl @end example So many possibilities, so much fun! @node Invoking guix publish @section Invoking @command{guix publish} @cindex @command{guix publish} The purpose of @command{guix publish} is to enable users to easily share their store with others, who can then use it as a substitute server (@pxref{Substitutes}). When @command{guix publish} runs, it spawns an HTTP server which allows anyone with network access to obtain substitutes from it. This means that any machine running Guix can also act as if it were a build farm, since the HTTP interface is compatible with Cuirass, the software behind the @code{@value{SUBSTITUTE-SERVER-1}} build farm. For security, each substitute is signed, allowing recipients to check their authenticity and integrity (@pxref{Substitutes}). Because @command{guix publish} uses the signing key of the system, which is only readable by the system administrator, it must be started as root; the @option{--user} option makes it drop root privileges early on. The signing key pair must be generated before @command{guix publish} is launched, using @command{guix archive --generate-key} (@pxref{Invoking guix archive}). When the @option{--advertise} option is passed, the server advertises its availability on the local network using multicast DNS (mDNS) and DNS service discovery (DNS-SD), currently @i{via} Guile-Avahi (@pxref{Top,,, guile-avahi, Using Avahi in Guile Scheme Programs}). The general syntax is: @example guix publish @var{options}@dots{} @end example Running @command{guix publish} without any additional arguments will spawn an HTTP server on port 8080: @example guix publish @end example @cindex socket activation, for @command{guix publish} @command{guix publish} can also be started following the systemd ``socket activation'' protocol (@pxref{Service De- and Constructors, @code{make-systemd-constructor},, shepherd, The GNU Shepherd Manual}). Once a publishing server has been authorized, the daemon may download substitutes from it. @xref{Getting Substitutes from Other Servers}. By default, @command{guix publish} compresses archives on the fly as it serves them. This ``on-the-fly'' mode is convenient in that it requires no setup and is immediately available. However, when serving lots of clients, we recommend using the @option{--cache} option, which enables caching of the archives before they are sent to clients---see below for details. The @command{guix weather} command provides a handy way to check what a server provides (@pxref{Invoking guix weather}). As a bonus, @command{guix publish} also serves as a content-addressed mirror for source files referenced in @code{origin} records (@pxref{origin Reference}). For instance, assuming @command{guix publish} is running on @code{example.org}, the following URL returns the raw @file{hello-2.10.tar.gz} file with the given SHA256 hash (represented in @code{nix-base32} format, @pxref{Invoking guix hash}): @example http://example.org/file/hello-2.10.tar.gz/sha256/0ssi1@dots{}ndq1i @end example Obviously, these URLs only work for files that are in the store; in other cases, they return 404 (``Not Found''). @cindex build logs, publication Build logs are available from @code{/log} URLs like: @example http://example.org/log/gwspk@dots{}-guile-2.2.3 @end example @noindent When @command{guix-daemon} is configured to save compressed build logs, as is the case by default (@pxref{Invoking guix-daemon}), @code{/log} URLs return the compressed log as-is, with an appropriate @code{Content-Type} and/or @code{Content-Encoding} header. We recommend running @command{guix-daemon} with @option{--log-compression=gzip} since Web browsers can automatically decompress it, which is not the case with Bzip2 compression. The following options are available: @table @code @item --port=@var{port} @itemx -p @var{port} Listen for HTTP requests on @var{port}. @item --listen=@var{host} Listen on the network interface for @var{host}. The default is to accept connections from any interface. @item --user=@var{user} @itemx -u @var{user} Change privileges to @var{user} as soon as possible---i.e., once the server socket is open and the signing key has been read. @item --compression[=@var{method}[:@var{level}]] @itemx -C [@var{method}[:@var{level}]] Compress data using the given @var{method} and @var{level}. @var{method} is one of @code{lzip}, @code{zstd}, and @code{gzip}; when @var{method} is omitted, @code{gzip} is used. When @var{level} is zero, disable compression. The range 1 to 9 corresponds to different compression levels: 1 is the fastest, and 9 is the best (CPU-intensive). The default is 3. Usually, @code{lzip} compresses noticeably better than @code{gzip} for a small increase in CPU usage; see @uref{https://nongnu.org/lzip/lzip_benchmark.html,benchmarks on the lzip Web page}. However, @code{lzip} achieves low decompression throughput (on the order of 50@tie{}MiB/s on modern hardware), which can be a bottleneck for someone who downloads over a fast network connection. The compression ratio of @code{zstd} is between that of @code{lzip} and that of @code{gzip}; its main advantage is a @uref{https://facebook.github.io/zstd/,high decompression speed}. Unless @option{--cache} is used, compression occurs on the fly and the compressed streams are not cached. Thus, to reduce load on the machine that runs @command{guix publish}, it may be a good idea to choose a low compression level, to run @command{guix publish} behind a caching proxy, or to use @option{--cache}. Using @option{--cache} has the advantage that it allows @command{guix publish} to add @code{Content-Length} HTTP header to its responses. This option can be repeated, in which case every substitute gets compressed using all the selected methods, and all of them are advertised. This is useful when users may not support all the compression methods: they can select the one they support. @item --cache=@var{directory} @itemx -c @var{directory} Cache archives and meta-data (@code{.narinfo} URLs) to @var{directory} and only serve archives that are in cache. When this option is omitted, archives and meta-data are created on-the-fly. This can reduce the available bandwidth, especially when compression is enabled, since this may become CPU-bound. Another drawback of the default mode is that the length of archives is not known in advance, so @command{guix publish} does not add a @code{Content-Length} HTTP header to its responses, which in turn prevents clients from knowing the amount of data being downloaded. Conversely, when @option{--cache} is used, the first request for a store item (@i{via} a @code{.narinfo} URL) triggers a background process to @dfn{bake} the archive---computing its @code{.narinfo} and compressing the archive, if needed. Once the archive is cached in @var{directory}, subsequent requests succeed and are served directly from the cache, which guarantees that clients get the best possible bandwidth. That first @code{.narinfo} request nonetheless returns 200, provided the requested store item is ``small enough'', below the cache bypass threshold---see @option{--cache-bypass-threshold} below. That way, clients do not have to wait until the archive is baked. For larger store items, the first @code{.narinfo} request returns 404, meaning that clients have to wait until the archive is baked. The ``baking'' process is performed by worker threads. By default, one thread per CPU core is created, but this can be customized. See @option{--workers} below. When @option{--ttl} is used, cached entries are automatically deleted when they have expired. @item --workers=@var{N} When @option{--cache} is used, request the allocation of @var{N} worker threads to ``bake'' archives. @item --ttl=@var{ttl} Produce @code{Cache-Control} HTTP headers that advertise a time-to-live (TTL) of @var{ttl}. @var{ttl} must denote a duration: @code{5d} means 5 days, @code{1m} means 1 month, and so on. This allows the user's Guix to keep substitute information in cache for @var{ttl}. However, note that @code{guix publish} does not itself guarantee that the store items it provides will indeed remain available for as long as @var{ttl}. Additionally, when @option{--cache} is used, cached entries that have not been accessed for @var{ttl} and that no longer have a corresponding item in the store, may be deleted. @item --negative-ttl=@var{ttl} Similarly produce @code{Cache-Control} HTTP headers to advertise the time-to-live (TTL) of @emph{negative} lookups---missing store items, for which the HTTP 404 code is returned. By default, no negative TTL is advertised. This parameter can help adjust server load and substitute latency by instructing cooperating clients to be more or less patient when a store item is missing. @item --cache-bypass-threshold=@var{size} When used in conjunction with @option{--cache}, store items smaller than @var{size} are immediately available, even when they are not yet in cache. @var{size} is a size in bytes, or it can be suffixed by @code{M} for megabytes and so on. The default is @code{10M}. ``Cache bypass'' allows you to reduce the publication delay for clients at the expense of possibly additional I/O and CPU use on the server side: depending on the client access patterns, those store items can end up being baked several times until a copy is available in cache. Increasing the threshold may be useful for sites that have few users, or to guarantee that users get substitutes even for store items that are not popular. @item --nar-path=@var{path} Use @var{path} as the prefix for the URLs of ``nar'' files (@pxref{Invoking guix archive, normalized archives}). By default, nars are served at a URL such as @code{/nar/gzip/@dots{}-coreutils-8.25}. This option allows you to change the @code{/nar} part to @var{path}. @item --public-key=@var{file} @itemx --private-key=@var{file} Use the specific @var{file}s as the public/private key pair used to sign the store items being published. The files must correspond to the same key pair (the private key is used for signing and the public key is merely advertised in the signature metadata). They must contain keys in the canonical s-expression format as produced by @command{guix archive --generate-key} (@pxref{Invoking guix archive}). By default, @file{/etc/guix/signing-key.pub} and @file{/etc/guix/signing-key.sec} are used. @item --repl[=@var{port}] @itemx -r [@var{port}] Spawn a Guile REPL server (@pxref{REPL Servers,,, guile, GNU Guile Reference Manual}) on @var{port} (37146 by default). This is used primarily for debugging a running @command{guix publish} server. @end table Enabling @command{guix publish} on Guix System is a one-liner: just instantiate a @code{guix-publish-service-type} service in the @code{services} field of the @code{operating-system} declaration (@pxref{guix-publish-service-type, @code{guix-publish-service-type}}). If you are instead running Guix on a ``foreign distro'', follow these instructions: @itemize @item If your host distro uses the systemd init system: @example # ln -s ~root/.guix-profile/lib/systemd/system/guix-publish.service \ /etc/systemd/system/ # systemctl start guix-publish && systemctl enable guix-publish @end example @item If your host distro uses the Upstart init system: @example # ln -s ~root/.guix-profile/lib/upstart/system/guix-publish.conf /etc/init/ # start guix-publish @end example @item Otherwise, proceed similarly with your distro's init system. @end itemize @node Invoking guix challenge @section Invoking @command{guix challenge} @cindex reproducible builds @cindex verifiable builds @cindex @command{guix challenge} @cindex challenge Do the binaries provided by this server really correspond to the source code it claims to build? Is a package build process deterministic? These are the questions the @command{guix challenge} command attempts to answer. The former is obviously an important question: Before using a substitute server (@pxref{Substitutes}), one had better @emph{verify} that it provides the right binaries, and thus @emph{challenge} it. The latter is what enables the former: If package builds are deterministic, then independent builds of the package should yield the exact same result, bit for bit; if a server provides a binary different from the one obtained locally, it may be either corrupt or malicious. We know that the hash that shows up in @file{/gnu/store} file names is the hash of all the inputs of the process that built the file or directory---compilers, libraries, build scripts, etc. (@pxref{Introduction}). Assuming deterministic build processes, one store file name should map to exactly one build output. @command{guix challenge} checks whether there is, indeed, a single mapping by comparing the build outputs of several independent builds of any given store item. The command output looks like this: @smallexample $ guix challenge \ --substitute-urls="https://@value{SUBSTITUTE-SERVER-1} https://guix.example.org" \ openssl git pius coreutils grep updating substitutes from 'https://@value{SUBSTITUTE-SERVER-1}'... 100.0% updating substitutes from 'https://guix.example.org'... 100.0% /gnu/store/@dots{}-openssl-1.0.2d contents differ: local hash: 0725l22r5jnzazaacncwsvp9kgf42266ayyp814v7djxs7nk963q https://@value{SUBSTITUTE-SERVER-1}/nar/@dots{}-openssl-1.0.2d: 0725l22r5jnzazaacncwsvp9kgf42266ayyp814v7djxs7nk963q https://guix.example.org/nar/@dots{}-openssl-1.0.2d: 1zy4fmaaqcnjrzzajkdn3f5gmjk754b43qkq47llbyak9z0qjyim differing files: /lib/libcrypto.so.1.1 /lib/libssl.so.1.1 /gnu/store/@dots{}-git-2.5.0 contents differ: local hash: 00p3bmryhjxrhpn2gxs2fy0a15lnip05l97205pgbk5ra395hyha https://@value{SUBSTITUTE-SERVER-1}/nar/@dots{}-git-2.5.0: 069nb85bv4d4a6slrwjdy8v1cn4cwspm3kdbmyb81d6zckj3nq9f https://guix.example.org/nar/@dots{}-git-2.5.0: 0mdqa9w1p6cmli6976v4wi0sw9r4p5prkj7lzfd1877wk11c9c73 differing file: /libexec/git-core/git-fsck /gnu/store/@dots{}-pius-2.1.1 contents differ: local hash: 0k4v3m9z1zp8xzzizb7d8kjj72f9172xv078sq4wl73vnq9ig3ax https://@value{SUBSTITUTE-SERVER-1}/nar/@dots{}-pius-2.1.1: 0k4v3m9z1zp8xzzizb7d8kjj72f9172xv078sq4wl73vnq9ig3ax https://guix.example.org/nar/@dots{}-pius-2.1.1: 1cy25x1a4fzq5rk0pmvc8xhwyffnqz95h2bpvqsz2mpvlbccy0gs differing file: /share/man/man1/pius.1.gz @dots{} 5 store items were analyzed: - 2 (40.0%) were identical - 3 (60.0%) differed - 0 (0.0%) were inconclusive @end smallexample @noindent In this example, @command{guix challenge} queries all the substitute servers for each of the fives packages specified on the command line. It then reports those store items for which the servers obtained a result different from the local build (if it exists) and/or different from one another; here, the @samp{local hash} lines indicate that a local build result was available for each of these packages and shows its hash. @cindex non-determinism, in package builds As an example, @code{guix.example.org} always gets a different answer. Conversely, @code{@value{SUBSTITUTE-SERVER-1}} agrees with local builds, except in the case of Git. This might indicate that the build process of Git is non-deterministic, meaning that its output varies as a function of various things that Guix does not fully control, in spite of building packages in isolated environments (@pxref{Features}). Most common sources of non-determinism include the addition of timestamps in build results, the inclusion of random numbers, and directory listings sorted by inode number. See @uref{https://reproducible-builds.org/docs/}, for more information. To find out what is wrong with this Git binary, the easiest approach is to run: @example guix challenge git \ --diff=diffoscope \ --substitute-urls="https://@value{SUBSTITUTE-SERVER-1} https://guix.example.org" @end example This automatically invokes @command{diffoscope}, which displays detailed information about files that differ. Alternatively, we can do something along these lines (@pxref{Invoking guix archive}): @example $ wget -q -O - https://@value{SUBSTITUTE-SERVER-1}/nar/lzip/@dots{}-git-2.5.0 \ | lzip -d | guix archive -x /tmp/git $ diff -ur --no-dereference /gnu/store/@dots{}-git.2.5.0 /tmp/git @end example This command shows the difference between the files resulting from the local build, and the files resulting from the build on @code{@value{SUBSTITUTE-SERVER-1}} (@pxref{Overview, Comparing and Merging Files,, diffutils, Comparing and Merging Files}). The @command{diff} command works great for text files. When binary files differ, a better option is @uref{https://diffoscope.org/, Diffoscope}, a tool that helps visualize differences for all kinds of files. Once you have done that work, you can tell whether the differences are due to a non-deterministic build process or to a malicious server. We try hard to remove sources of non-determinism in packages to make it easier to verify substitutes, but of course, this is a process that involves not just Guix, but a large part of the free software community. In the meantime, @command{guix challenge} is one tool to help address the problem. If you are writing packages for Guix, you are encouraged to check whether @code{@value{SUBSTITUTE-SERVER-1}} and other substitute servers obtain the same build result as you did with: @example guix challenge @var{package} @end example The general syntax is: @example guix challenge @var{options} @var{argument}@dots{} @end example @noindent where @var{argument} is a package specification such as @code{guile@@2.0} or @code{glibc:debug} or, alternatively, a store file name as returned, for example, by @command{guix build} or @command{guix gc --list-live}. When a difference is found between the hash of a locally-built item and that of a server-provided substitute, or among substitutes provided by different servers, the command displays it as in the example above and its exit code is 2 (other non-zero exit codes denote other kinds of errors). The one option that matters is: @table @code @item --substitute-urls=@var{urls} Consider @var{urls} the whitespace-separated list of substitute source URLs to compare to. @item --diff=@var{mode} Upon mismatches, show differences according to @var{mode}, one of: @table @asis @item @code{simple} (the default) Show the list of files that differ. @item @code{diffoscope} @itemx @var{command} Invoke @uref{https://diffoscope.org/, Diffoscope}, passing it two directories whose contents do not match. When @var{command} is an absolute file name, run @var{command} instead of Diffoscope. @item @code{none} Do not show further details about the differences. @end table Thus, unless @option{--diff=none} is passed, @command{guix challenge} downloads the store items from the given substitute servers so that it can compare them. @item --verbose @itemx -v Show details about matches (identical contents) in addition to information about mismatches. @end table @node Invoking guix copy @section Invoking @command{guix copy} @cindex @command{guix copy} @cindex copy, of store items, over SSH @cindex SSH, copy of store items @cindex sharing store items across machines @cindex transferring store items across machines The @command{guix copy} command copies items from the store of one machine to that of another machine over a secure shell (SSH) connection@footnote{This command is available only when Guile-SSH was found. @xref{Requirements}, for details.}. For example, the following command copies the @code{coreutils} package, the user's profile, and all their dependencies over to @var{host}, logged in as @var{user}: @example guix copy --to=@var{user}@@@var{host} \ coreutils $(readlink -f ~/.guix-profile) @end example If some of the items to be copied are already present on @var{host}, they are not actually sent. The command below retrieves @code{libreoffice} and @code{gimp} from @var{host}, assuming they are available there: @example guix copy --from=@var{host} libreoffice gimp @end example The SSH connection is established using the Guile-SSH client, which is compatible with OpenSSH: it honors @file{~/.ssh/known_hosts} and @file{~/.ssh/config}, and uses the SSH agent for authentication. The key used to sign items that are sent must be accepted by the remote machine. Likewise, the key used by the remote machine to sign items you are retrieving must be in @file{/etc/guix/acl} so it is accepted by your own daemon. @xref{Invoking guix archive}, for more information about store item authentication. The general syntax is: @example guix copy [--to=@var{spec}|--from=@var{spec}] @var{items}@dots{} @end example You must always specify one of the following options: @table @code @item --to=@var{spec} @itemx --from=@var{spec} Specify the host to send to or receive from. @var{spec} must be an SSH spec such as @code{example.org}, @code{charlie@@example.org}, or @code{charlie@@example.org:2222}. @end table The @var{items} can be either package names, such as @code{gimp}, or store items, such as @file{/gnu/store/@dots{}-idutils-4.6}. When specifying the name of a package to send, it is first built if needed, unless @option{--dry-run} was specified. Common build options are supported (@pxref{Common Build Options}). @node Invoking guix container @section Invoking @command{guix container} @cindex container @cindex @command{guix container} @quotation Note As of version @value{VERSION}, this tool is experimental. The interface is subject to radical change in the future. @end quotation The purpose of @command{guix container} is to manipulate processes running within an isolated environment, commonly known as a ``container'', typically created by the @command{guix shell} (@pxref{Invoking guix shell}) and @command{guix system container} (@pxref{Invoking guix system}) commands. The general syntax is: @example guix container @var{action} @var{options}@dots{} @end example @var{action} specifies the operation to perform with a container, and @var{options} specifies the context-specific arguments for the action. The following actions are available: @table @code @item exec Execute a command within the context of a running container. The syntax is: @example guix container exec @var{pid} @var{program} @var{arguments}@dots{} @end example @var{pid} specifies the process ID of the running container. @var{program} specifies an executable file name within the root file system of the container. @var{arguments} are the additional options that will be passed to @var{program}. The following command launches an interactive login shell inside a Guix system container, started by @command{guix system container}, and whose process ID is 9001: @example guix container exec 9001 /run/current-system/profile/bin/bash --login @end example Note that the @var{pid} cannot be the parent process of a container. It must be PID 1 of the container or one of its child processes. @end table @node Invoking guix weather @section Invoking @command{guix weather} @cindex @command{guix weather} Occasionally you're grumpy because substitutes are lacking and you end up building packages by yourself (@pxref{Substitutes}). The @command{guix weather} command reports on substitute availability on the specified servers so you can have an idea of whether you'll be grumpy today. It can sometimes be useful info as a user, but it is primarily useful to people running @command{guix publish} (@pxref{Invoking guix publish}). Sometimes substitutes @emph{are} available but they are not authorized on your system; @command{guix weather} reports it so you can authorize them if you want (@pxref{Getting Substitutes from Other Servers}). @cindex statistics, for substitutes @cindex availability of substitutes @cindex substitute availability @cindex weather, substitute availability Here's a sample run: @example $ guix weather --substitute-urls=https://guix.example.org computing 5,872 package derivations for x86_64-linux... looking for 6,128 store items on https://guix.example.org.. updating substitutes from 'https://guix.example.org'... 100.0% https://guix.example.org 43.4% substitutes available (2,658 out of 6,128) 7,032.5 MiB of nars (compressed) 19,824.2 MiB on disk (uncompressed) 0.030 seconds per request (182.9 seconds in total) 33.5 requests per second 9.8% (342 out of 3,470) of the missing items are queued 867 queued builds x86_64-linux: 518 (59.7%) i686-linux: 221 (25.5%) aarch64-linux: 128 (14.8%) build rate: 23.41 builds per hour x86_64-linux: 11.16 builds per hour i686-linux: 6.03 builds per hour aarch64-linux: 6.41 builds per hour @end example @cindex continuous integration, statistics As you can see, it reports the fraction of all the packages for which substitutes are available on the server---regardless of whether substitutes are enabled, and regardless of whether this server's signing key is authorized. It also reports the size of the compressed archives (``nars'') provided by the server, the size the corresponding store items occupy in the store (assuming deduplication is turned off), and the server's throughput. The second part gives continuous integration (CI) statistics, if the server supports it. In addition, using the @option{--coverage} option, @command{guix weather} can list ``important'' package substitutes missing on the server (see below). To achieve that, @command{guix weather} queries over HTTP(S) meta-data (@dfn{narinfos}) for all the relevant store items. Like @command{guix challenge}, it ignores signatures on those substitutes, which is innocuous since the command only gathers statistics and cannot install those substitutes. The general syntax is: @example guix weather @var{options}@dots{} [@var{packages}@dots{}] @end example When @var{packages} is omitted, @command{guix weather} checks the availability of substitutes for @emph{all} the packages, or for those specified with @option{--manifest}; otherwise it only considers the specified packages. It is also possible to query specific system types with @option{--system}. @command{guix weather} exits with a non-zero code when the fraction of available substitutes is below 100%. The available options are listed below. @table @code @item --substitute-urls=@var{urls} @var{urls} is the space-separated list of substitute server URLs to query. When this option is omitted, the URLs specified with the @option{--substitute-urls} option of @command{guix-daemon} are used or, as a last resort, the default set of substitute URLs. @item --system=@var{system} @itemx -s @var{system} Query substitutes for @var{system}---e.g., @code{aarch64-linux}. This option can be repeated, in which case @command{guix weather} will query substitutes for several system types. @item --manifest=@var{file} Instead of querying substitutes for all the packages, only ask for those specified in @var{file}. @var{file} must contain a @dfn{manifest}, as with the @code{-m} option of @command{guix package} (@pxref{Invoking guix package}). This option can be repeated several times, in which case the manifests are concatenated. @item --expression=@var{expr} @itemx -e @var{expr} Consider the package @var{expr} evaluates to. A typical use case for this option is specifying a package that is hidden and thus cannot be referred to in the usual way, as in this example: @example guix weather -e '(@@@@ (gnu packages rust) rust-bootstrap)' @end example This option can be repeated. @item --coverage[=@var{count}] @itemx -c [@var{count}] Report on substitute coverage for packages: list packages with at least @var{count} dependents (zero by default) for which substitutes are unavailable. Dependent packages themselves are not listed: if @var{b} depends on @var{a} and @var{a} has no substitutes, only @var{a} is listed, even though @var{b} usually lacks substitutes as well. The result looks like this: @example $ guix weather --substitute-urls=@value{SUBSTITUTE-URLS} -c 10 computing 8,983 package derivations for x86_64-linux... looking for 9,343 store items on @value{SUBSTITUTE-URLS}... updating substitutes from '@value{SUBSTITUTE-URLS}'... 100.0% @value{SUBSTITUTE-URLS} 64.7% substitutes available (6,047 out of 9,343) @dots{} 2502 packages are missing from '@value{SUBSTITUTE-URLS}' for 'x86_64-linux', among which: 58 kcoreaddons@@5.49.0 /gnu/store/@dots{}-kcoreaddons-5.49.0 46 qgpgme@@1.11.1 /gnu/store/@dots{}-qgpgme-1.11.1 37 perl-http-cookiejar@@0.008 /gnu/store/@dots{}-perl-http-cookiejar-0.008 @dots{} @end example What this example shows is that @code{kcoreaddons} and presumably the 58 packages that depend on it have no substitutes at @code{@value{SUBSTITUTE-SERVER-1}}; likewise for @code{qgpgme} and the 46 packages that depend on it. If you are a Guix developer, or if you are taking care of this build farm, you'll probably want to have a closer look at these packages: they may simply fail to build. @item --display-missing Display the list of store items for which substitutes are missing. @end table @node Invoking guix processes @section Invoking @command{guix processes} @cindex @command{guix processes} The @command{guix processes} command can be useful to developers and system administrators, especially on multi-user machines and on build farms: it lists the current sessions (connections to the daemon), as well as information about the processes involved@footnote{Remote sessions, when @command{guix-daemon} is started with @option{--listen} specifying a TCP endpoint, are @emph{not} listed.}. Here's an example of the information it returns: @example $ sudo guix processes SessionPID: 19002 ClientPID: 19090 ClientCommand: guix shell python SessionPID: 19402 ClientPID: 19367 ClientCommand: guix publish -u guix-publish -p 3000 -C 9 @dots{} SessionPID: 19444 ClientPID: 19419 ClientCommand: cuirass --cache-directory /var/cache/cuirass @dots{} LockHeld: /gnu/store/@dots{}-perl-ipc-cmd-0.96.lock LockHeld: /gnu/store/@dots{}-python-six-bootstrap-1.11.0.lock LockHeld: /gnu/store/@dots{}-libjpeg-turbo-2.0.0.lock ChildPID: 20495 ChildCommand: guix offload x86_64-linux 7200 1 28800 ChildPID: 27733 ChildCommand: guix offload x86_64-linux 7200 1 28800 ChildPID: 27793 ChildCommand: guix offload x86_64-linux 7200 1 28800 @end example In this example we see that @command{guix-daemon} has three clients: @command{guix shell}, @command{guix publish}, and the Cuirass continuous integration tool; their process identifier (PID) is given by the @code{ClientPID} field. The @code{SessionPID} field gives the PID of the @command{guix-daemon} sub-process of this particular session. The @code{LockHeld} fields show which store items are currently locked by this session, which corresponds to store items being built or substituted (the @code{LockHeld} field is not displayed when @command{guix processes} is not running as root). Last, by looking at the @code{ChildPID} and @code{ChildCommand} fields, we understand that these three builds are being offloaded (@pxref{Daemon Offload Setup}). The output is in Recutils format so we can use the handy @command{recsel} command to select sessions of interest (@pxref{Selection Expressions,,, recutils, GNU recutils manual}). As an example, the command shows the command line and PID of the client that triggered the build of a Perl package: @example $ sudo guix processes | \ recsel -p ClientPID,ClientCommand -e 'LockHeld ~ "perl"' ClientPID: 19419 ClientCommand: cuirass --cache-directory /var/cache/cuirass @dots{} @end example Additional options are listed below. @table @code @item --format=@var{format} @itemx -f @var{format} Produce output in the specified @var{format}, one of: @table @code @item recutils The default option. It outputs a set of Session recutils records that include each @code{ChildProcess} as a field. @item normalized Normalize the output records into record sets (@pxref{Record Sets,,, recutils, GNU recutils manual}). Normalizing into record sets allows joins across record types. The example below lists the PID of each @code{ChildProcess} and the associated PID for @code{Session} that spawned the @code{ChildProcess} where the @code{Session} was started using @command{guix build}. @example $ guix processes --format=normalized | \ recsel \ -j Session \ -t ChildProcess \ -p Session.PID,PID \ -e 'Session.ClientCommand ~ "guix build"' PID: 4435 Session_PID: 4278 PID: 4554 Session_PID: 4278 PID: 4646 Session_PID: 4278 @end example @end table @end table @node Foreign Architectures @chapter Foreign Architectures You can target computers of different CPU architectures when producing packages (@pxref{Invoking guix package}), packs (@pxref{Invoking guix pack}) or full systems (@pxref{Invoking guix system}). GNU Guix supports two distinct mechanisms to target foreign architectures: @enumerate @item The traditional @uref{https://en.wikipedia.org/wiki/Cross_compiler,cross-compilation} mechanism. @item The native building mechanism which consists in building using the CPU instruction set of the foreign system you are targeting. It often requires emulation, using the QEMU program for instance. @end enumerate @menu * Cross-Compilation:: Cross-compiling for another architecture. * Native Builds:: Targeting another architecture through native builds. @end menu @node Cross-Compilation @section Cross-Compilation @cindex foreign architectures The commands supporting cross-compilation are proposing the @option{--list-targets} and @option{--target} options. The @option{--list-targets} option lists all the supported targets that can be passed as an argument to @option{--target}. @example $ guix build --list-targets The available targets are: - aarch64-linux-gnu - arm-linux-gnueabihf - avr - i586-pc-gnu - i686-linux-gnu - i686-w64-mingw32 - mips64el-linux-gnu - or1k-elf - powerpc-linux-gnu - powerpc64le-linux-gnu - riscv64-linux-gnu - x86_64-linux-gnu - x86_64-linux-gnux32 - x86_64-w64-mingw32 - xtensa-ath9k-elf @end example Targets are specified as GNU triplets (@pxref{Specifying Target Triplets, GNU configuration triplets,, autoconf, Autoconf}). Those triplets are passed to GCC and the other underlying compilers possibly involved when building a package, a system image or any other GNU Guix output. @example $ guix build --target=aarch64-linux-gnu hello /gnu/store/9926by9qrxa91ijkhw9ndgwp4bn24g9h-hello-2.12 $ file /gnu/store/9926by9qrxa91ijkhw9ndgwp4bn24g9h-hello-2.12/bin/hello /gnu/store/9926by9qrxa91ijkhw9ndgwp4bn24g9h-hello-2.12/bin/hello: ELF 64-bit LSB executable, ARM aarch64 @dots{} @end example The major benefit of cross-compilation is that there are no performance penalty compared to emulation using QEMU. There are however higher risks that some packages fail to cross-compile because fewer users are using this mechanism extensively. @node Native Builds @section Native Builds The commands that support impersonating a specific system have the @option{--list-systems} and @option{--system} options. The @option{--list-systems} option lists all the supported systems that can be passed as an argument to @option{--system}. @example $ guix build --list-systems The available systems are: - x86_64-linux [current] - aarch64-linux - armhf-linux - i586-gnu - i686-linux - mips64el-linux - powerpc-linux - powerpc64le-linux - riscv64-linux $ guix build --system=i686-linux hello /gnu/store/cc0km35s8x2z4pmwkrqqjx46i8b1i3gm-hello-2.12 $ file /gnu/store/cc0km35s8x2z4pmwkrqqjx46i8b1i3gm-hello-2.12/bin/hello /gnu/store/cc0km35s8x2z4pmwkrqqjx46i8b1i3gm-hello-2.12/bin/hello: ELF 32-bit LSB executable, Intel 80386 @dots{} @end example In the above example, the current system is @var{x86_64-linux}. The @var{hello} package is however built for the @var{i686-linux} system. This is possible because the @var{i686} CPU instruction set is a subset of the @var{x86_64}, hence @var{i686} targeting binaries can be run on @var{x86_64}. Still in the context of the previous example, if picking the @var{aarch64-linux} system and the @command{guix build --system=aarch64-linux hello} has to build some derivations, an extra step might be needed. The @var{aarch64-linux} targeting binaries cannot directly be run on a @var{x86_64-linux} system. An emulation layer is requested. The GNU Guix daemon can take advantage of the Linux kernel @uref{https://en.wikipedia.org/wiki/Binfmt_misc,binfmt_misc} mechanism for that. In short, the Linux kernel can defer the execution of a binary targeting a foreign platform, here @var{aarch64-linux}, to a userspace program, usually an emulator. There is a service that registers QEMU as a backend for the @code{binfmt_misc} mechanism (@pxref{Virtualization Services, @code{qemu-binfmt-service-type}}). On Debian based foreign distributions, the alternative would be the @code{qemu-user-static} package. If the @code{binfmt_misc} mechanism is not setup correctly, the building will fail this way: @example $ guix build --system=armhf-linux hello --check @dots{} @ unsupported-platform /gnu/store/jjn969pijv7hff62025yxpfmc8zy0aq0-hello-2.12.drv aarch64-linux while setting up the build environment: a `aarch64-linux' is required to build `/gnu/store/jjn969pijv7hff62025yxpfmc8zy0aq0-hello-2.12.drv', but I am a `x86_64-linux'@dots{} @end example whereas, with the @code{binfmt_misc} mechanism correctly linked with QEMU, one can expect to see: @example $ guix build --system=armhf-linux hello --check /gnu/store/13xz4nghg39wpymivlwghy08yzj97hlj-hello-2.12 @end example The main advantage of native building compared to cross-compiling, is that more packages are likely to build correctly. However it comes at a price: compilation backed by QEMU is @emph{way slower} than cross-compilation, because every instruction needs to be emulated. The availability of substitutes for the architecture targeted by the @code{--system} option can mitigate this problem. An other way to work around it is to install GNU Guix on a machine whose CPU supports the targeted instruction set, and set it up as an offload machine (@pxref{Daemon Offload Setup}). @node System Configuration @chapter System Configuration @cindex system configuration Guix System supports a consistent whole-system configuration mechanism. By that we mean that all aspects of the global system configuration---such as the available system services, timezone and locale settings, user accounts---are declared in a single place. Such a @dfn{system configuration} can be @dfn{instantiated}---i.e., effected. One of the advantages of putting all the system configuration under the control of Guix is that it supports transactional system upgrades, and makes it possible to roll back to a previous system instantiation, should something go wrong with the new one (@pxref{Features}). Another advantage is that it makes it easy to replicate the exact same configuration across different machines, or at different points in time, without having to resort to additional administration tools layered on top of the own tools of the system. @c Yes, we're talking of Puppet, Chef, & co. here. ↑ This section describes this mechanism. First we focus on the system administrator's viewpoint---explaining how the system is configured and instantiated. Then we show how this mechanism can be extended, for instance to support new system services. @menu * Getting Started with the System:: Your first steps. * Using the Configuration System:: Customizing your GNU system. * operating-system Reference:: Detail of operating-system declarations. * File Systems:: Configuring file system mounts. * Mapped Devices:: Block device extra processing. * Swap Space:: Backing RAM with disk space. * User Accounts:: Specifying user accounts. * Keyboard Layout:: How the system interprets key strokes. * Locales:: Language and cultural convention settings. * Services:: Specifying system services. * Privileged Programs:: Programs running with elevated privileges. * X.509 Certificates:: Authenticating HTTPS servers. * Name Service Switch:: Configuring libc's name service switch. * Initial RAM Disk:: Linux-Libre bootstrapping. * Bootloader Configuration:: Configuring the boot loader. * Invoking guix system:: Instantiating a system configuration. * Invoking guix deploy:: Deploying a system configuration to a remote host. * Running Guix in a VM:: How to run Guix System in a virtual machine. * Defining Services:: Adding new service definitions. @end menu @node Getting Started with the System @section Getting Started @cindex system configuration file @cindex configuration file, of the system You're reading this section probably because you have just installed Guix System (@pxref{System Installation}) and would like to know where to go from here. If you're already familiar with GNU/Linux system administration, the way Guix System is configured is very different from what you're used to: you won't install a system service by running @command{guix install}, you won't configure services by modifying files under @file{/etc}, and you won't create user accounts by invoking @command{useradd}; instead, all these aspects are spelled out in a @dfn{system configuration file}. The first step with Guix System is thus to write the @dfn{system configuration file}; luckily, system installation already generated one for you and stored it under @file{/etc/config.scm}. @quotation Note You can store your system configuration file anywhere you like---it doesn't have to be at @file{/etc/config.scm}. It's a good idea to keep it under version control, for instance in a @uref{https://git-scm.com/book/en/, Git repository}. @end quotation The @emph{entire} configuration of the system---user accounts, system services, timezone, locale settings---is declared in this file, which follows this template: @lisp (use-modules (gnu)) (use-package-modules @dots{}) (use-service-modules @dots{}) (operating-system (host-name @dots{}) (timezone @dots{}) (locale @dots{}) (bootloader @dots{}) (file-systems @dots{}) (users @dots{}) (packages @dots{}) (services @dots{})) @end lisp This configuration file is in fact a Scheme program; the first lines pull in modules providing variables you might need in the rest of the file---e.g., packages, services, etc. The @code{operating-system} form declares the system configuration as a @dfn{record} with a number of @dfn{fields}. @xref{Using the Configuration System}, to view complete examples and learn what to put in there. The second step, once you have this configuration file, is to test it. Of course, you can skip this step if you're feeling lucky---you choose! To do that, pass your configuration file to @command{guix system vm} (no need to be root, you can do that as a regular user): @example guix system vm /etc/config.scm @end example @noindent This command returns the name of a shell script that starts a virtual machine (VM) running the system @emph{as described in the configuration file}: @example /gnu/store/@dots{}-run-vm.sh @end example @noindent In this VM, you can log in as @code{root} with no password. That's a good way to check that your configuration file is correct and that it gives the expected result, without touching your system. @xref{Invoking guix system}, for more information. @quotation Note When using @command{guix system vm}, aspects tied to your hardware such as file systems and mapped devices are overridden because they cannot be meaningfully tested in the VM@. Other aspects such as static network configuration (@pxref{Networking Setup, @code{static-networking-service-type}}) are @emph{not} overridden but they may not work inside the VM@. @end quotation @cindex system instantiation @cindex reconfiguring the system The third step, once you're happy with your configuration, is to @dfn{instantiate} it---make this configuration effective on your system. To do that, run: @example sudo guix system reconfigure /etc/config.scm @end example @cindex upgrading system services @cindex system services, upgrading @noindent This operation is @dfn{transactional}: either it succeeds and you end up with an upgraded system, or it fails and nothing has changed. Note that it does @emph{not} restart system services that were already running. Thus, to upgrade those services, you have to reboot or to explicitly restart them; for example, to restart the secure shell (SSH) daemon, you would run: @example sudo herd restart sshd @end example @quotation Note System services are managed by the Shepherd (@pxref{Jump Start,,, shepherd, The GNU Shepherd Manual}). The @code{herd} command lets you inspect, start, and stop services. To view the status of services, run: @example sudo herd status @end example To view detailed information about a given service, add its name to the command: @example sudo herd status sshd @end example @xref{Services}, for more information. @end quotation @cindex provenance, of the system The system records its @dfn{provenance}---the configuration file and channels that were used to deploy it. You can view it like so: @example guix system describe @end example Additionally, @command{guix system reconfigure} preserves previous system generations, which you can list: @example guix system list-generations @end example @noindent @cindex roll back, for the system Crucially, that means that you can always @emph{roll back} to an earlier generation should something go wrong! When you eventually reboot, you'll notice a sub-menu in the bootloader that reads ``Old system generations'': it's what allows you to boot @emph{an older generation of your system}, should the latest generation be ``broken'' or otherwise unsatisfying. You can also ``permanently'' roll back, like so: @example sudo guix system roll-back @end example @noindent Alternatively, you can use @command{guix system switch-generation} to switch to a specific generation. Once in a while, you'll want to delete old generations that you do not need anymore to allow @dfn{garbage collection} to free space (@pxref{Invoking guix gc}). For example, to remove generations older than 4 months, run: @example sudo guix system delete-generations 4m @end example From there on, anytime you want to change something in the system configuration, be it adding a user account or changing parameters of a service, you will first update your configuration file and then run @command{guix system reconfigure} as shown above. @cindex upgrade, of the system Likewise, to @emph{upgrade} system software, you first fetch an up-to-date Guix and then reconfigure your system with that new Guix: @example guix pull sudo guix system reconfigure /etc/config.scm @end example @noindent We recommend doing that regularly so that your system includes the latest security updates (@pxref{Security Updates}). @c See <https://lists.gnu.org/archive/html/guix-devel/2019-01/msg00268.html>. @quotation Note @cindex sudo vs. @command{guix pull} @command{sudo guix} runs your user's @command{guix} command and @emph{not} root's, because @command{sudo} leaves @env{PATH} unchanged. The difference matters here, because @command{guix pull} updates the @command{guix} command and package definitions only for the user it is run as. This means that if you choose to use @command{guix system reconfigure} in root's login shell, you'll need to @command{guix pull} separately. @end quotation That's it! If you're getting started with Guix entirely, @pxref{Getting Started}. The next sections dive in more detail into the crux of the matter: system configuration. @node Using the Configuration System @section Using the Configuration System The previous section showed the overall workflow you would follow when administering a Guix System machine (@pxref{Getting Started with the System}). Let's now see in more detail what goes into the system configuration file. The operating system is configured by providing an @code{operating-system} declaration in a file that can then be passed to the @command{guix system} command (@pxref{Invoking guix system}), as we've seen before. A simple setup, with the default Linux-Libre kernel, initial RAM disk, and a couple of system services added to those provided by default looks like this: @findex operating-system @lisp @include os-config-bare-bones.texi @end lisp The configuration is declarative. It is code in the Scheme programming language; the whole @code{(operating-system @dots{})} expression produces a @dfn{record} with a number of @dfn{fields}. Some of the fields defined above, such as @code{host-name} and @code{bootloader}, are mandatory. Others, such as @code{packages} and @code{services}, can be omitted, in which case they get a default value. @xref{operating-system Reference}, for details about all the available fields. Below we discuss the meaning of some of the most important fields. @quotation Troubleshooting The configuration file is a Scheme program and you might get the syntax or semantics wrong as you get started. Syntactic issues such as misplaced parentheses can often be identified by reformatting your file: @example guix style -f config.scm @end example The Cookbook has a short section to get started with the Scheme programming language that explains the fundamentals, which you will find helpful when hacking your configuration. @xref{A Scheme Crash Course,,, guix-cookbook, GNU Guix Cookbook}. @end quotation @unnumberedsubsec Bootloader @cindex legacy boot, on Intel machines @cindex BIOS boot, on Intel machines @cindex UEFI boot @cindex EFI boot The @code{bootloader} field describes the method that will be used to boot your system. Machines based on Intel processors can boot in ``legacy'' BIOS mode, as in the example above. However, more recent machines rely instead on the @dfn{Unified Extensible Firmware Interface} (UEFI) to boot. In that case, the @code{bootloader} field should contain something along these lines: @lisp (bootloader-configuration (bootloader grub-efi-bootloader) (targets '("/boot/efi"))) @end lisp @xref{Bootloader Configuration}, for more information on the available configuration options. @unnumberedsubsec Globally-Visible Packages @vindex %base-packages The @code{packages} field lists packages that will be globally visible on the system, for all user accounts---i.e., in every user's @env{PATH} environment variable---in addition to the per-user profiles (@pxref{Invoking guix package}). The @code{%base-packages} variable provides all the tools one would expect for basic user and administrator tasks---including the GNU Core Utilities, the GNU Networking Utilities, the @command{mg} lightweight text editor, @command{find}, @command{grep}, etc. The example above adds GNU@tie{}Screen to those, taken from the @code{(gnu packages screen)} module (@pxref{Package Modules}). The @code{(list package output)} syntax can be used to add a specific output of a package: @lisp (use-modules (gnu packages)) (use-modules (gnu packages dns)) (operating-system ;; ... (packages (cons (list isc-bind "utils") %base-packages))) @end lisp @findex specification->package Referring to packages by variable name, like @code{isc-bind} above, has the advantage of being unambiguous; it also allows typos and such to be diagnosed right away as ``unbound variables''. The downside is that one needs to know which module defines which package, and to augment the @code{use-package-modules} line accordingly. To avoid that, one can use the @code{specification->package} procedure of the @code{(gnu packages)} module, which returns the best package for a given name or name and version: @lisp (use-modules (gnu packages)) (operating-system ;; ... (packages (append (map specification->package '("tcpdump" "htop" "gnupg@@2.0")) %base-packages))) @end lisp @findex specifications->packages When a package has more than one output it can be a challenge to refer to a specific output instead of just to the standard @code{out} output. For these situations one can use the @code{specifications->packages} procedure from the @code{(gnu packages)} module. For example: @lisp (use-modules (gnu packages)) (operating-system ;; ... (packages (append (specifications->packages '("git" "git:send-email")) %base-packages))) @end lisp @unnumberedsubsec System Services @cindex services @vindex %base-services The @code{services} field lists @dfn{system services} to be made available when the system starts (@pxref{Services}). The @code{operating-system} declaration above specifies that, in addition to the basic services, we want the OpenSSH secure shell daemon listening on port 2222 (@pxref{Networking Services, @code{openssh-service-type}}). Under the hood, @code{openssh-service-type} arranges so that @command{sshd} is started with the right command-line options, possibly with supporting configuration files generated as needed (@pxref{Defining Services}). @cindex customization, of services @findex modify-services Occasionally, instead of using the base services as is, you will want to customize them. To do this, use @code{modify-services} (@pxref{Service Reference, @code{modify-services}}) to modify the list. @anchor{auto-login to TTY} For example, suppose you want to modify @code{guix-daemon} and Mingetty (the console log-in) in the @code{%base-services} list (@pxref{Base Services, @code{%base-services}}). To do that, you can write the following in your operating system declaration: @lisp (define %my-services ;; My very own list of services. (modify-services %base-services (guix-service-type config => (guix-configuration (inherit config) ;; Fetch substitutes from example.org. (substitute-urls (list "https://example.org/guix" "https://ci.guix.gnu.org")))) (mingetty-service-type config => (mingetty-configuration (inherit config) ;; Automatically log in as "guest". (auto-login "guest"))))) (operating-system ;; @dots{} (services %my-services)) @end lisp This changes the configuration---i.e., the service parameters---of the @code{guix-service-type} instance, and that of all the @code{mingetty-service-type} instances in the @code{%base-services} list (@pxref{Auto-Login to a Specific TTY, see the cookbook for how to auto-login one user to a specific TTY,, guix-cookbook, GNU Guix Cookbook})). Observe how this is accomplished: first, we arrange for the original configuration to be bound to the identifier @code{config} in the @var{body}, and then we write the @var{body} so that it evaluates to the desired configuration. In particular, notice how we use @code{inherit} to create a new configuration which has the same values as the old configuration, but with a few modifications. @cindex encrypted disk The configuration for a typical ``desktop'' usage, with an encrypted root partition, a swap file on the root partition, the X11 display server, GNOME and Xfce (users can choose which of these desktop environments to use at the log-in screen by pressing @kbd{F1}), network management, power management, and more, would look like this: @lisp @include os-config-desktop.texi @end lisp A graphical system with a choice of lightweight window managers instead of full-blown desktop environments would look like this: @lisp @include os-config-lightweight-desktop.texi @end lisp This example refers to the @file{/boot/efi} file system by its UUID, @code{1234-ABCD}. Replace this UUID with the right UUID on your system, as returned by the @command{blkid} command. @xref{Desktop Services}, for the exact list of services provided by @code{%desktop-services}. Again, @code{%desktop-services} is just a list of service objects. If you want to remove services from there, you can do so using the procedures for list filtering (@pxref{SRFI-1 Filtering and Partitioning,,, guile, GNU Guile Reference Manual}). For instance, the following expression returns a list that contains all the services in @code{%desktop-services} minus the Avahi service: @lisp (remove (lambda (service) (eq? (service-kind service) avahi-service-type)) %desktop-services) @end lisp Alternatively, the @code{modify-services} macro can be used: @lisp (modify-services %desktop-services (delete avahi-service-type)) @end lisp @unnumberedsubsec Inspecting Services @cindex troubleshooting, for system services @cindex inspecting system services @cindex system services, inspecting As you work on your system configuration, you might wonder why some system service doesn't show up or why the system is not as you expected. There are several ways to inspect and troubleshoot problems. @cindex dependency graph, of Shepherd services First, you can inspect the dependency graph of Shepherd services like so: @example guix system shepherd-graph /etc/config.scm | \ guix shell xdot -- xdot - @end example This lets you visualize the Shepherd services as defined in @file{/etc/config.scm}. Each box is a service as would be shown by @command{sudo herd status} on the running system, and each arrow denotes a dependency (in the sense that if service @var{A} depends on @var{B}, then @var{B} must be started before @var{A}). @cindex extension graph, of services Not all ``services'' are Shepherd services though, since Guix System uses a broader definition of the term (@pxref{Services}). To visualize system services and their relations at a higher level, run: @example guix system extension-graph /etc/config.scm | \ guix shell xdot -- xdot - @end example This lets you view the @dfn{service extension graph}: how services ``extend'' each other, for instance by contributing to their configuration. @xref{Service Composition}, to understand the meaning of this graph. Last, you may also find it useful to inspect your system configuration at the REPL (@pxref{Using Guix Interactively}). Here is an example session: @example $ guix repl scheme@@(guix-user)> ,use (gnu) scheme@@(guix-user)> (define os (load "config.scm")) scheme@@(guix-user)> ,pp (map service-kind (operating-system-services os)) $1 = (#<service-type localed cabba93> @dots{}) @end example @xref{Service Reference}, to learn about the Scheme interface to manipulate and inspect services. @unnumberedsubsec Instantiating the System @cindex system instantiation @cindex reconfiguring the system Assuming the @code{operating-system} declaration is stored in the @file{config.scm} file, the @command{sudo guix system reconfigure config.scm} command instantiates that configuration, and makes it the default boot entry. @xref{Getting Started with the System}, for an overview. The normal way to change the system configuration is by updating this file and re-running @command{guix system reconfigure}. One should never have to touch files in @file{/etc} or to run commands that modify the system state such as @command{useradd} or @command{grub-install}. In fact, you must avoid that since that would not only void your warranty but also prevent you from rolling back to previous versions of your system, should you ever need to. @unnumberedsubsec The Programming Interface At the Scheme level, the bulk of an @code{operating-system} declaration is instantiated with the following monadic procedure (@pxref{The Store Monad}): @deffn {Monadic Procedure} operating-system-derivation os Return a derivation that builds @var{os}, an @code{operating-system} object (@pxref{Derivations}). The output of the derivation is a single directory that refers to all the packages, configuration files, and other supporting files needed to instantiate @var{os}. @end deffn This procedure is provided by the @code{(gnu system)} module. Along with @code{(gnu services)} (@pxref{Services}), this module contains the guts of Guix System. Make sure to visit it! @node operating-system Reference @section @code{operating-system} Reference This section summarizes all the options available in @code{operating-system} declarations (@pxref{Using the Configuration System}). @deftp {Data Type} operating-system This is the data type representing an operating system configuration. By that, we mean all the global system configuration, not per-user configuration (@pxref{Using the Configuration System}). @table @asis @item @code{kernel} (default: @code{linux-libre}) @c footnote duplicated in @pxref{Installation} The package object of the operating system kernel to use@footnote{Currently only the Linux-libre kernel is fully supported. Using GNU@tie{}mach with the GNU@tie{}Hurd is experimental and only available when building a virtual machine disk image.}. @cindex hurd @item @code{hurd} (default: @code{#f}) The package object of the Hurd to be started by the kernel. When this field is set, produce a GNU/Hurd operating system. In that case, @code{kernel} must also be set to the @code{gnumach} package---the microkernel the Hurd runs on. @quotation Warning This feature is experimental and only supported for disk images. @end quotation @item @code{kernel-loadable-modules} (default: '()) A list of objects (usually packages) to collect loadable kernel modules from--e.g. @code{(list ddcci-driver-linux)}. @item @code{kernel-arguments} (default: @code{%default-kernel-arguments}) List of strings or gexps representing additional arguments to pass on the command-line of the kernel---e.g., @code{("console=ttyS0")}. @item @code{bootloader} The system bootloader configuration object. @xref{Bootloader Configuration}. @item @code{label} This is the label (a string) as it appears in the bootloader's menu entry. The default label includes the kernel name and version. @item @code{keyboard-layout} (default: @code{#f}) This field specifies the keyboard layout to use in the console. It can be either @code{#f}, in which case the default keyboard layout is used (usually US English), or a @code{<keyboard-layout>} record. @xref{Keyboard Layout}, for more information. This keyboard layout is in effect as soon as the kernel has booted. For instance, it is the keyboard layout in effect when you type a passphrase if your root file system is on a @code{luks-device-mapping} mapped device (@pxref{Mapped Devices}). @quotation Note This does @emph{not} specify the keyboard layout used by the bootloader, nor that used by the graphical display server. @xref{Bootloader Configuration}, for information on how to specify the bootloader's keyboard layout. @xref{X Window}, for information on how to specify the keyboard layout used by the X Window System. @end quotation @item @code{initrd-modules} (default: @code{%base-initrd-modules}) @cindex initrd @cindex initial RAM disk The list of Linux kernel modules that need to be available in the initial RAM disk. @xref{Initial RAM Disk}. @item @code{initrd} (default: @code{base-initrd}) A procedure that returns an initial RAM disk for the Linux kernel. This field is provided to support low-level customization and should rarely be needed for casual use. @xref{Initial RAM Disk}. @item @code{firmware} (default: @code{%base-firmware}) @cindex firmware List of firmware packages loadable by the operating system kernel. The default includes firmware needed for Atheros- and Broadcom-based WiFi devices (Linux-libre modules @code{ath9k} and @code{b43-open}, respectively). @xref{Hardware Considerations}, for more info on supported hardware. @item @code{host-name} The host name. @item @code{mapped-devices} (default: @code{'()}) A list of mapped devices. @xref{Mapped Devices}. @item @code{file-systems} A list of file systems. @xref{File Systems}. @item @code{swap-devices} (default: @code{'()}) @cindex swap devices A list of swap spaces. @xref{Swap Space}. @item @code{users} (default: @code{%base-user-accounts}) @itemx @code{groups} (default: @code{%base-groups}) List of user accounts and groups. @xref{User Accounts}. If the @code{users} list lacks a user account with UID@tie{}0, a ``root'' account with UID@tie{}0 is automatically added. @item @code{skeletons} (default: @code{(default-skeletons)}) A list of target file name/file-like object tuples (@pxref{G-Expressions, file-like objects}). These are the skeleton files that will be added to the home directory of newly-created user accounts. For instance, a valid value may look like this: @lisp `((".bashrc" ,(plain-file "bashrc" "echo Hello\n")) (".guile" ,(plain-file "guile" "(use-modules (ice-9 readline)) (activate-readline)"))) @end lisp @item @code{issue} (default: @code{%default-issue}) A string denoting the contents of the @file{/etc/issue} file, which is displayed when users log in on a text console. @item @code{packages} (default: @code{%base-packages}) A list of packages to be installed in the global profile, which is accessible at @file{/run/current-system/profile}. Each element is either a package variable or a package/output tuple. Here's a simple example of both: @lisp (cons* git ; the default "out" output (list git "send-email") ; another output of git %base-packages) ; the default set @end lisp The default set includes core utilities and it is good practice to install non-core utilities in user profiles (@pxref{Invoking guix package}). @item @code{timezone} (default: @code{"Etc/UTC"}) A timezone identifying string---e.g., @code{"Europe/Paris"}. You can run the @command{tzselect} command to find out which timezone string corresponds to your region. Choosing an invalid timezone name causes @command{guix system} to fail. @item @code{locale} (default: @code{"en_US.utf8"}) The name of the default locale (@pxref{Locale Names,,, libc, The GNU C Library Reference Manual}). @xref{Locales}, for more information. @item @code{locale-definitions} (default: @code{%default-locale-definitions}) The list of locale definitions to be compiled and that may be used at run time. @xref{Locales}. @item @code{locale-libcs} (default: @code{(list @var{glibc})}) The list of GNU@tie{}libc packages whose locale data and tools are used to build the locale definitions. @xref{Locales}, for compatibility considerations that justify this option. @item @code{name-service-switch} (default: @code{%default-nss}) Configuration of the libc name service switch (NSS)---a @code{<name-service-switch>} object. @xref{Name Service Switch}, for details. @item @code{services} (default: @code{%base-services}) A list of service objects denoting system services. @xref{Services}. @anchor{operating-system-essential-services} @cindex essential services @item @code{essential-services} (default: ...) The list of ``essential services''---i.e., things like instances of @code{system-service-type} (@pxref{Service Reference}) and @code{host-name-service-type}, which are derived from the operating system definition itself. As a user you should @emph{never} need to touch this field. @item @code{pam-services} (default: @code{(base-pam-services)}) @cindex PAM @cindex pluggable authentication modules Linux @dfn{pluggable authentication module} (PAM) services. @c FIXME: Add xref to PAM services section. @item @code{privileged-programs} (default: @code{%default-privileged-programs}) List of @code{<privileged-program>}. @xref{Privileged Programs}, for more information. @item @code{sudoers-file} (default: @code{%sudoers-specification}) @cindex sudoers file The contents of the @file{/etc/sudoers} file as a file-like object (@pxref{G-Expressions, @code{local-file} and @code{plain-file}}). This file specifies which users can use the @command{sudo} command, what they are allowed to do, and what privileges they may gain. The default is that only @code{root} and members of the @code{wheel} group may use @code{sudo}. @end table @defmac this-operating-system When used in the @emph{lexical scope} of an operating system field definition, this identifier resolves to the operating system being defined. The example below shows how to refer to the operating system being defined in the definition of the @code{label} field: @lisp (use-modules (gnu) (guix)) (operating-system ;; ... (label (package-full-name (operating-system-kernel this-operating-system)))) @end lisp It is an error to refer to @code{this-operating-system} outside an operating system definition. @end defmac @end deftp @node File Systems @section File Systems The list of file systems to be mounted is specified in the @code{file-systems} field of the operating system declaration (@pxref{Using the Configuration System}). Each file system is declared using the @code{file-system} form, like this: @lisp (file-system (mount-point "/home") (device "/dev/sda3") (type "ext4")) @end lisp As usual, some of the fields are mandatory---those shown in the example above---while others can be omitted. These are described below. @deftp {Data Type} file-system Objects of this type represent file systems to be mounted. They contain the following members: @table @asis @item @code{type} This is a string specifying the type of the file system---e.g., @code{"ext4"}. @item @code{mount-point} This designates the place where the file system is to be mounted. @item @code{device} This names the ``source'' of the file system. It can be one of three things: a file system label, a file system UUID, or the name of a @file{/dev} node. Labels and UUIDs offer a way to refer to file systems without having to hard-code their actual device name@footnote{Note that, while it is tempting to use @file{/dev/disk/by-uuid} and similar device names to achieve the same result, this is not recommended: These special device nodes are created by the udev daemon and may be unavailable at the time the device is mounted.}. @findex file-system-label File system labels are created using the @code{file-system-label} procedure, UUIDs are created using @code{uuid}, and @file{/dev} nodes are plain strings. Here's an example of a file system referred to by its label, as shown by the @command{e2label} command: @lisp (file-system (mount-point "/home") (type "ext4") (device (file-system-label "my-home"))) @end lisp @findex uuid UUIDs are converted from their string representation (as shown by the @command{tune2fs -l} command) using the @code{uuid} form@footnote{The @code{uuid} form expects 16-byte UUIDs as defined in @uref{https://tools.ietf.org/html/rfc4122, RFC@tie{}4122}. This is the form of UUID used by the ext2 family of file systems and others, but it is different from ``UUIDs'' found in FAT file systems, for instance.}, like this: @lisp (file-system (mount-point "/home") (type "ext4") (device (uuid "4dab5feb-d176-45de-b287-9b0a6e4c01cb"))) @end lisp When the source of a file system is a mapped device (@pxref{Mapped Devices}), its @code{device} field @emph{must} refer to the mapped device name---e.g., @file{"/dev/mapper/root-partition"}. This is required so that the system knows that mounting the file system depends on having the corresponding device mapping established. @item @code{flags} (default: @code{'()}) This is a list of symbols denoting mount flags. Recognized flags include @code{read-only}, @code{bind-mount}, @code{no-dev} (disallow access to special files), @code{no-suid} (ignore setuid and setgid bits), @code{no-atime} (do not update file access times), @code{no-diratime} (likewise for directories only), @code{strict-atime} (update file access time), @code{lazy-time} (only update time on the in-memory version of the file inode), @code{no-exec} (disallow program execution), and @code{shared} (make the mount shared). @xref{Mount-Unmount-Remount,,, libc, The GNU C Library Reference Manual}, for more information on these flags. @item @code{options} (default: @code{#f}) This is either @code{#f}, or a string denoting mount options passed to the file system driver. @xref{Mount-Unmount-Remount,,, libc, The GNU C Library Reference Manual}, for details. Run @command{man 8 mount} for options for various file systems, but beware that what it lists as file-system-independent ``mount options'' are in fact flags, and belong in the @code{flags} field described above. The @code{file-system-options->alist} and @code{alist->file-system-options} procedures from @code{(gnu system file-systems)} can be used to convert file system options given as an association list to the string representation, and vice-versa. @item @code{mount?} (default: @code{#t}) This value indicates whether to automatically mount the file system when the system is brought up. When set to @code{#f}, the file system gets an entry in @file{/etc/fstab} (read by the @command{mount} command) but is not automatically mounted. @item @code{needed-for-boot?} (default: @code{#f}) This Boolean value indicates whether the file system is needed when booting. If that is true, then the file system is mounted when the initial RAM disk (initrd) is loaded. This is always the case, for instance, for the root file system. @item @code{check?} (default: @code{#t}) This Boolean indicates whether the file system should be checked for errors before being mounted. How and when this happens can be further adjusted with the following options. @item @code{skip-check-if-clean?} (default: @code{#t}) When true, this Boolean indicates that a file system check triggered by @code{check?} may exit early if the file system is marked as ``clean'', meaning that it was previously correctly unmounted and should not contain errors. Setting this to false will always force a full consistency check when @code{check?} is true. This may take a very long time and is not recommended on healthy systems---in fact, it may reduce reliability! Conversely, some primitive file systems like @code{fat} do not keep track of clean shutdowns and will perform a full scan regardless of the value of this option. @item @code{repair} (default: @code{'preen}) When @code{check?} finds errors, it can (try to) repair them and continue booting. This option controls when and how to do so. If false, try not to modify the file system at all. Checking certain file systems like @code{jfs} may still write to the device to replay the journal. No repairs will be attempted. If @code{#t}, try to repair any errors found and assume ``yes'' to all questions. This will fix the most errors, but may be risky. If @code{'preen}, repair only errors that are safe to fix without human interaction. What that means is left up to the developers of each file system and may be equivalent to ``none'' or ``all''. @item @code{create-mount-point?} (default: @code{#f}) When true, the mount point is created if it does not exist yet. @item @code{mount-may-fail?} (default: @code{#f}) When true, this indicates that mounting this file system can fail but that should not be considered an error. This is useful in unusual cases; an example of this is @code{efivarfs}, a file system that can only be mounted on EFI/UEFI systems. @item @code{dependencies} (default: @code{'()}) This is a list of @code{<file-system>} or @code{<mapped-device>} objects representing file systems that must be mounted or mapped devices that must be opened before (and unmounted or closed after) this one. As an example, consider a hierarchy of mounts: @file{/sys/fs/cgroup} is a dependency of @file{/sys/fs/cgroup/cpu} and @file{/sys/fs/cgroup/memory}. Another example is a file system that depends on a mapped device, for example for an encrypted partition (@pxref{Mapped Devices}). @item @code{shepherd-requirements} (default: @code{'()}) This is a list of symbols denoting Shepherd requirements that must be met before mounting the file system. As an example, an NFS file system would typically have a requirement for @code{networking}. Typically, file systems are mounted before most other Shepherd services are started. However, file systems with a non-empty shepherd-requirements field are mounted after Shepherd services have begun. Any Shepherd service that depends on a file system with a non-empty shepherd-requirements field must depend on it directly and not on the generic symbol @code{file-systems}. @end table @end deftp @deffn {Procedure} file-system-label str This procedure returns an opaque file system label from @var{str}, a string: @lisp (file-system-label "home") @result{} #<file-system-label "home"> @end lisp File system labels are used to refer to file systems by label rather than by device name. See above for examples. @end deffn The @code{(gnu system file-systems)} exports the following useful variables. @defvar %base-file-systems These are essential file systems that are required on normal systems, such as @code{%pseudo-terminal-file-system} and @code{%immutable-store} (see below). Operating system declarations should always contain at least these. @end defvar @defvar %pseudo-terminal-file-system This is the file system to be mounted as @file{/dev/pts}. It supports @dfn{pseudo-terminals} created @i{via} @code{openpty} and similar functions (@pxref{Pseudo-Terminals,,, libc, The GNU C Library Reference Manual}). Pseudo-terminals are used by terminal emulators such as @command{xterm}. @end defvar @defvar %shared-memory-file-system This file system is mounted as @file{/dev/shm} and is used to support memory sharing across processes (@pxref{Memory-mapped I/O, @code{shm_open},, libc, The GNU C Library Reference Manual}). @end defvar @defvar %immutable-store This file system performs a read-only ``bind mount'' of @file{/gnu/store}, making it read-only for all the users including @code{root}. This prevents against accidental modification by software running as @code{root} or by system administrators. The daemon itself is still able to write to the store: it remounts it read-write in its own ``name space.'' @end defvar @defvar %binary-format-file-system The @code{binfmt_misc} file system, which allows handling of arbitrary executable file types to be delegated to user space. This requires the @code{binfmt.ko} kernel module to be loaded. @end defvar @defvar %fuse-control-file-system The @code{fusectl} file system, which allows unprivileged users to mount and unmount user-space FUSE file systems. This requires the @code{fuse.ko} kernel module to be loaded. @end defvar The @code{(gnu system uuid)} module provides tools to deal with file system ``unique identifiers'' (UUIDs). @deffn {Procedure} uuid str [type] Return an opaque UUID (unique identifier) object of the given @var{type} (a symbol) by parsing @var{str} (a string): @lisp (uuid "4dab5feb-d176-45de-b287-9b0a6e4c01cb") @result{} #<<uuid> type: dce bv: @dots{}> (uuid "1234-ABCD" 'fat) @result{} #<<uuid> type: fat bv: @dots{}> @end lisp @var{type} may be one of @code{dce}, @code{iso9660}, @code{fat}, @code{ntfs}, or one of the commonly found synonyms for these. UUIDs are another way to unambiguously refer to file systems in operating system configuration. See the examples above. @end deffn @menu * Btrfs file system:: @end menu @node Btrfs file system @subsection Btrfs file system The Btrfs has special features, such as subvolumes, that merit being explained in more details. The following section attempts to cover basic as well as complex uses of a Btrfs file system with the Guix System. In its simplest usage, a Btrfs file system can be described, for example, by: @lisp (file-system (mount-point "/home") (type "btrfs") (device (file-system-label "my-home"))) @end lisp The example below is more complex, as it makes use of a Btrfs subvolume, named @code{rootfs}. The parent Btrfs file system is labeled @code{my-btrfs-pool}, and is located on an encrypted device (hence the dependency on @code{mapped-devices}): @lisp (file-system (device (file-system-label "my-btrfs-pool")) (mount-point "/") (type "btrfs") (options "subvol=rootfs") (dependencies mapped-devices)) @end lisp Some bootloaders, for example GRUB, only mount a Btrfs partition at its top level during the early boot, and rely on their configuration to refer to the correct subvolume path within that top level. The bootloaders operating in this way typically produce their configuration on a running system where the Btrfs partitions are already mounted and where the subvolume information is readily available. As an example, @command{grub-mkconfig}, the configuration generator command shipped with GRUB, reads @file{/proc/self/mountinfo} to determine the top-level path of a subvolume. The Guix System produces a bootloader configuration using the operating system configuration as its sole input; it is therefore necessary to extract the subvolume name on which @file{/gnu/store} lives (if any) from that operating system configuration. To better illustrate, consider a subvolume named 'rootfs' which contains the root file system data. In such situation, the GRUB bootloader would only see the top level of the root Btrfs partition, e.g.: @example / (top level) ├── rootfs (subvolume directory) ├── gnu (normal directory) ├── store (normal directory) [...] @end example Thus, the subvolume name must be prepended to the @file{/gnu/store} path of the kernel, initrd binaries and any other files referred to in the GRUB configuration that must be found during the early boot. The next example shows a nested hierarchy of subvolumes and directories: @example / (top level) ├── rootfs (subvolume) ├── gnu (normal directory) ├── store (subvolume) [...] @end example This scenario would work without mounting the 'store' subvolume. Mounting 'rootfs' is sufficient, since the subvolume name matches its intended mount point in the file system hierarchy. Alternatively, the 'store' subvolume could be referred to by setting the @code{subvol} option to either @code{/rootfs/gnu/store} or @code{rootfs/gnu/store}. Finally, a more contrived example of nested subvolumes: @example / (top level) ├── root-snapshots (subvolume) ├── root-current (subvolume) ├── guix-store (subvolume) [...] @end example Here, the 'guix-store' subvolume doesn't match its intended mount point, so it is necessary to mount it. The subvolume must be fully specified, by passing its file name to the @code{subvol} option. To illustrate, the 'guix-store' subvolume could be mounted on @file{/gnu/store} by using a file system declaration such as: @lisp (file-system (device (file-system-label "btrfs-pool-1")) (mount-point "/gnu/store") (type "btrfs") (options "subvol=root-snapshots/root-current/guix-store,\ compress-force=zstd,space_cache=v2")) @end lisp @node Mapped Devices @section Mapped Devices @cindex device mapping @cindex mapped devices The Linux kernel has a notion of @dfn{device mapping}: a block device, such as a hard disk partition, can be @dfn{mapped} into another device, usually in @code{/dev/mapper/}, with additional processing over the data that flows through it@footnote{Note that the GNU@tie{}Hurd makes no difference between the concept of a ``mapped device'' and that of a file system: both boil down to @emph{translating} input/output operations made on a file to operations on its backing store. Thus, the Hurd implements mapped devices, like file systems, using the generic @dfn{translator} mechanism (@pxref{Translators,,, hurd, The GNU Hurd Reference Manual}).}. A typical example is encryption device mapping: all writes to the mapped device are encrypted, and all reads are deciphered, transparently. Guix extends this notion by considering any device or set of devices that are @dfn{transformed} in some way to create a new device; for instance, RAID devices are obtained by @dfn{assembling} several other devices, such as hard disks or partitions, into a new one that behaves as one partition. Mapped devices are declared using the @code{mapped-device} form, defined as follows; for examples, see below. @deftp {Data Type} mapped-device Objects of this type represent device mappings that will be made when the system boots up. @table @code @item source This is either a string specifying the name of the block device to be mapped, such as @code{"/dev/sda3"}, or a list of such strings when several devices need to be assembled for creating a new one. In case of LVM this is a string specifying name of the volume group to be mapped. @item target This string specifies the name of the resulting mapped device. For kernel mappers such as encrypted devices of type @code{luks-device-mapping}, specifying @code{"my-partition"} leads to the creation of the @code{"/dev/mapper/my-partition"} device. For RAID devices of type @code{raid-device-mapping}, the full device name such as @code{"/dev/md0"} needs to be given. LVM logical volumes of type @code{lvm-device-mapping} need to be specified as @code{"VGNAME-LVNAME"}. @item targets This list of strings specifies names of the resulting mapped devices in case there are several. The format is identical to @var{target}. @item type This must be a @code{mapped-device-kind} object, which specifies how @var{source} is mapped to @var{target}. @end table @end deftp @defvar luks-device-mapping This defines LUKS block device encryption using the @command{cryptsetup} command from the package with the same name. It relies on the @code{dm-crypt} Linux kernel module. @end defvar @deffn {Procedure} luks-device-mapping-with-options [#:key-file] Return a @code{luks-device-mapping} object, which defines LUKS block device encryption using the @command{cryptsetup} command from the package with the same name. It relies on the @code{dm-crypt} Linux kernel module. If @code{key-file} is provided, unlocking is first attempted using that key file. This has an advantage of not requiring a password entry, so it can be used (for example) to unlock RAID arrays automatically on boot. If key file unlock fails, password unlock is attempted as well. Key file is not stored in the store and needs to be available at the given location at the time of the unlock attempt. @lisp ;; Following definition would be equivalent to running: ;; cryptsetup open --key-file /crypto.key /dev/sdb1 data (mapped-device (source "/dev/sdb1) (target "data) (type (luks-device-mapping-with-options #:key-file "/crypto.key"))) @end lisp @end deffn @defvar raid-device-mapping This defines a RAID device, which is assembled using the @code{mdadm} command from the package with the same name. It requires a Linux kernel module for the appropriate RAID level to be loaded, such as @code{raid456} for RAID-4, RAID-5 or RAID-6, or @code{raid10} for RAID-10. @end defvar @cindex LVM, logical volume manager @defvar lvm-device-mapping This defines one or more logical volumes for the Linux @uref{https://www.sourceware.org/lvm2/, Logical Volume Manager (LVM)}. The volume group is activated by the @command{vgchange} command from the @code{lvm2} package. @end defvar @cindex disk encryption @cindex LUKS The following example specifies a mapping from @file{/dev/sda3} to @file{/dev/mapper/home} using LUKS---the @url{https://gitlab.com/cryptsetup/cryptsetup,Linux Unified Key Setup}, a standard mechanism for disk encryption. The @file{/dev/mapper/home} device can then be used as the @code{device} of a @code{file-system} declaration (@pxref{File Systems}). @lisp (mapped-device (source "/dev/sda3") (target "home") (type luks-device-mapping)) @end lisp Alternatively, to become independent of device numbering, one may obtain the LUKS UUID (@dfn{unique identifier}) of the source device by a command like: @example cryptsetup luksUUID /dev/sda3 @end example and use it as follows: @lisp (mapped-device (source (uuid "cb67fc72-0d54-4c88-9d4b-b225f30b0f44")) (target "home") (type luks-device-mapping)) @end lisp @cindex swap encryption It is also desirable to encrypt swap space, since swap space may contain sensitive data. One way to accomplish that is to use a swap file in a file system on a device mapped via LUKS encryption. In this way, the swap file is encrypted because the entire device is encrypted. @xref{Swap Space}, or @xref{Preparing for Installation,,Disk Partitioning}, for an example. A RAID device formed of the partitions @file{/dev/sda1} and @file{/dev/sdb1} may be declared as follows: @lisp (mapped-device (source (list "/dev/sda1" "/dev/sdb1")) (target "/dev/md0") (type raid-device-mapping)) @end lisp The @file{/dev/md0} device can then be used as the @code{device} of a @code{file-system} declaration (@pxref{File Systems}). Note that the RAID level need not be given; it is chosen during the initial creation and formatting of the RAID device and is determined automatically later. LVM logical volumes ``alpha'' and ``beta'' from volume group ``vg0'' can be declared as follows: @lisp (mapped-device (source "vg0") (targets (list "vg0-alpha" "vg0-beta")) (type lvm-device-mapping)) @end lisp Devices @file{/dev/mapper/vg0-alpha} and @file{/dev/mapper/vg0-beta} can then be used as the @code{device} of a @code{file-system} declaration (@pxref{File Systems}). @node Swap Space @section Swap Space @cindex swap space Swap space, as it is commonly called, is a disk area specifically designated for paging: the process in charge of memory management (the Linux kernel or Hurd's default pager) can decide that some memory pages stored in RAM which belong to a running program but are unused should be stored on disk instead. It unloads those from the RAM, freeing up precious fast memory, and writes them to the swap space. If the program tries to access that very page, the memory management process loads it back into memory for the program to use. A common misconception about swap is that it is only useful when small amounts of RAM are available to the system. However, it should be noted that kernels often use all available RAM for disk access caching to make I/O faster, and thus paging out unused portions of program memory will expand the RAM available for such caching. For a more detailed description of how memory is managed from the viewpoint of a monolithic kernel, @pxref{Memory Concepts,,, libc, The GNU C Library Reference Manual}. The Linux kernel has support for swap partitions and swap files: the former uses a whole disk partition for paging, whereas the second uses a file on a file system for that (the file system driver needs to support it). On a comparable setup, both have the same performance, so one should consider ease of use when deciding between them. Partitions are ``simpler'' and do not need file system support, but need to be allocated at disk formatting time (logical volumes notwithstanding), whereas files can be allocated and deallocated at any time. @cindex hibernation @cindex suspend to disk Swap space is also required to put the system into @dfn{hibernation} (also called @dfn{suspend to disk}), whereby memory is dumped to swap before shutdown so it can be restored when the machine is eventually restarted. Hibernation uses at most half the size of the RAM in the configured swap space. The Linux kernel needs to know about the swap space to be used to resume from hibernation on boot (@i{via} a kernel argument). When using a swap file, its offset in the device holding it also needs to be given to the kernel; that value has to be updated if the file is initialized again as swap---e.g., because its size was changed. Note that swap space is not zeroed on shutdown, so sensitive data (such as passwords) may linger on it if it was paged out. As such, you should consider having your swap reside on an encrypted device (@pxref{Mapped Devices}). @deftp {Data Type} swap-space Objects of this type represent swap spaces. They contain the following members: @table @asis @item @code{target} The device or file to use, either a UUID, a @code{file-system-label} or a string, as in the definition of a @code{file-system} (@pxref{File Systems}). @item @code{dependencies} (default: @code{'()}) A list of @code{file-system} or @code{mapped-device} objects, upon which the availability of the space depends. Note that just like for @code{file-system} objects, dependencies which are needed for boot and mounted in early userspace are not managed by the Shepherd, and so automatically filtered out for you. @item @code{priority} (default: @code{#f}) Only supported by the Linux kernel. Either @code{#f} to disable swap priority, or an integer between 0 and 32767. The kernel will first use swap spaces of higher priority when paging, and use same priority spaces on a round-robin basis. The kernel will use swap spaces without a set priority after prioritized spaces, and in the order that they appeared in (not round-robin). @item @code{discard?} (default: @code{#f}) Only supported by the Linux kernel. When true, the kernel will notify the disk controller of discarded pages, for example with the TRIM operation on Solid State Drives. @end table @end deftp Here are some examples: @lisp (swap-space (target (uuid "4dab5feb-d176-45de-b287-9b0a6e4c01cb"))) @end lisp Use the swap partition with the given UUID@. You can learn the UUID of a Linux swap partition by running @command{swaplabel @var{device}}, where @var{device} is the @file{/dev} file name of that partition. @lisp (swap-space (target (file-system-label "swap")) (dependencies mapped-devices)) @end lisp Use the partition with label @code{swap}, which can be found after all the @var{mapped-devices} mapped devices have been opened. Again, the @command{swaplabel} command allows you to view and change the label of a Linux swap partition. Here's a more involved example with the corresponding @code{file-systems} part of an @code{operating-system} declaration. @lisp (file-systems (list (file-system (device (file-system-label "root")) (mount-point "/") (type "ext4")) (file-system (device (file-system-label "btrfs")) (mount-point "/btrfs") (type "btrfs")))) (swap-devices (list (swap-space (target "/btrfs/swapfile") (dependencies (filter (file-system-mount-point-predicate "/btrfs") file-systems))))) @end lisp Use the file @file{/btrfs/swapfile} as swap space, which depends on the file system mounted at @file{/btrfs}. Note how we use Guile's filter to select the file system in an elegant fashion! @lisp (swap-devices (list (swap-space (target "/dev/mapper/my-swap") (dependencies mapped-devices)))) (kernel-arguments (cons* "resume=/dev/mapper/my-swap" %default-kernel-arguments)) @end lisp The above snippet of an @code{operating-system} declaration enables the mapped device @file{/dev/mapper/my-swap} (which may be part of an encrypted device) as swap space, and tells the kernel to use it for hibernation via the @code{resume} kernel argument (@pxref{operating-system Reference}, @code{kernel-arguments}). @lisp (swap-devices (list (swap-space (target "/swapfile") (dependencies (filter (file-system-mount-point-predicate "/") file-systems))))) (kernel-arguments (cons* "resume=/dev/sda3" ;device that holds /swapfile "resume_offset=92514304" ;offset of /swapfile on device %default-kernel-arguments)) @end lisp This other snippet of @code{operating-system} enables the swap file @file{/swapfile} for hibernation by telling the kernel about the partition containing it (@code{resume} argument) and its offset on that partition (@code{resume_offset} argument). The latter value can be found in the output of the command @command{filefrag -e} as the first number right under the @code{physical_offset} column header (the second command extracts its value directly): @smallexample $ sudo filefrag -e /swapfile Filesystem type is: ef53 File size of /swapfile is 2463842304 (601524 blocks of 4096 bytes) ext: logical_offset: physical_offset: length: expected: flags: 0: 0.. 2047: 92514304.. 92516351: 2048: @dots{} $ sudo filefrag -e /swapfile | grep '^ *0:' | cut -d: -f3 | cut -d. -f1 92514304 @end smallexample @node User Accounts @section User Accounts @cindex users @cindex accounts @cindex user accounts User accounts and groups are entirely managed through the @code{operating-system} declaration. They are specified with the @code{user-account} and @code{user-group} forms: @lisp (user-account (name "alice") (group "users") (supplementary-groups '("wheel" ;allow use of sudo, etc. "audio" ;sound card "video" ;video devices such as webcams "cdrom")) ;the good ol' CD-ROM (comment "Bob's sister")) @end lisp Here's a user account that uses a different shell and a custom home directory (the default would be @file{"/home/bob"}): @lisp (user-account (name "bob") (group "users") (comment "Alice's bro") (shell (file-append zsh "/bin/zsh")) (home-directory "/home/robert")) @end lisp When booting or upon completion of @command{guix system reconfigure}, the system ensures that only the user accounts and groups specified in the @code{operating-system} declaration exist, and with the specified properties. Thus, account or group creations or modifications made by directly invoking commands such as @command{useradd} are lost upon reconfiguration or reboot. This ensures that the system remains exactly as declared. @deftp {Data Type} user-account Objects of this type represent user accounts. The following members may be specified: @table @asis @item @code{name} The name of the user account. @item @code{group} @cindex groups This is the name (a string) or identifier (a number) of the user group this account belongs to. @item @code{supplementary-groups} (default: @code{'()}) Optionally, this can be defined as a list of group names that this account belongs to. @item @code{uid} (default: @code{#f}) This is the user ID for this account (a number), or @code{#f}. In the latter case, a number is automatically chosen by the system when the account is created. @item @code{comment} (default: @code{""}) A comment about the account, such as the account owner's full name. Note that, for non-system accounts, users are free to change their real name as it appears in @file{/etc/passwd} using the @command{chfn} command. When they do, their choice prevails over the system administrator's choice; reconfiguring does @emph{not} change their name. @item @code{home-directory} This is the name of the home directory for the account. @item @code{create-home-directory?} (default: @code{#t}) Indicates whether the home directory of this account should be created if it does not exist yet. @item @code{shell} (default: Bash) This is a G-expression denoting the file name of a program to be used as the shell (@pxref{G-Expressions}). For example, you would refer to the Bash executable like this: @lisp (file-append bash "/bin/bash") @end lisp @noindent ... and to the Zsh executable like that: @lisp (file-append zsh "/bin/zsh") @end lisp @item @code{system?} (default: @code{#f}) This Boolean value indicates whether the account is a ``system'' account. System accounts are sometimes treated specially; for instance, graphical login managers do not list them. @anchor{user-account-password} @cindex password, for user accounts @item @code{password} (default: @code{#f}) You would normally leave this field to @code{#f}, initialize user passwords as @code{root} with the @command{passwd} command, and then let users change it with @command{passwd}. Passwords set with @command{passwd} are of course preserved across reboot and reconfiguration. If you @emph{do} want to set an initial password for an account, then this field must contain the encrypted password, as a string. You can use the @code{crypt} procedure for this purpose: @lisp (user-account (name "charlie") (group "users") ;; Specify a SHA-512-hashed initial password. (password (crypt "InitialPassword!" "$6$abc"))) @end lisp @quotation Note The hash of this initial password will be available in a file in @file{/gnu/store}, readable by all the users, so this method must be used with care. @end quotation @xref{Passphrase Storage,,, libc, The GNU C Library Reference Manual}, for more information on password encryption, and @ref{Encryption,,, guile, GNU Guile Reference Manual}, for information on Guile's @code{crypt} procedure. @end table @end deftp @cindex groups User group declarations are even simpler: @lisp (user-group (name "students")) @end lisp @deftp {Data Type} user-group This type is for, well, user groups. There are just a few fields: @table @asis @item @code{name} The name of the group. @item @code{id} (default: @code{#f}) The group identifier (a number). If @code{#f}, a new number is automatically allocated when the group is created. @item @code{system?} (default: @code{#f}) This Boolean value indicates whether the group is a ``system'' group. System groups have low numerical IDs. @item @code{password} (default: @code{#f}) What, user groups can have a password? Well, apparently yes. Unless @code{#f}, this field specifies the password of the group. @end table @end deftp For convenience, a variable lists all the basic user groups one may expect: @defvar %base-groups This is the list of basic user groups that users and/or packages expect to be present on the system. This includes groups such as ``root'', ``wheel'', and ``users'', as well as groups used to control access to specific devices such as ``audio'', ``disk'', and ``cdrom''. @end defvar @defvar %base-user-accounts This is the list of basic system accounts that programs may expect to find on a GNU/Linux system, such as the ``nobody'' account. Note that the ``root'' account is not included here. It is a special-case and is automatically added whether or not it is specified. @end defvar @cindex containers, subordinate IDs The Linux kernel also implements @dfn{subordinate user and group IDs}, or ``subids'', which are used to map the ID of a user and group to several IDs inside separate name spaces---inside ``containers''. @xref{subordinate-user-group-ids, the subordinate user and group ID service}, for information on how to configure it. @node Keyboard Layout @section Keyboard Layout @cindex keyboard layout @cindex keymap To specify what each key of your keyboard does, you need to tell the operating system what @dfn{keyboard layout} you want to use. The default, when nothing is specified, is the US English QWERTY layout for 105-key PC keyboards. However, German speakers will usually prefer the German QWERTZ layout, French speakers will want the AZERTY layout, and so on; hackers might prefer Dvorak or bépo, and they might even want to further customize the effect of some of the keys. This section explains how to get that done. @cindex keyboard layout, definition There are three components that will want to know about your keyboard layout: @itemize @item The @emph{bootloader} may want to know what keyboard layout you want to use (@pxref{Bootloader Configuration, @code{keyboard-layout}}). This is useful if you want, for instance, to make sure that you can type the passphrase of your encrypted root partition using the right layout. @item The @emph{operating system kernel}, Linux, will need that so that the console is properly configured (@pxref{operating-system Reference, @code{keyboard-layout}}). @item The @emph{graphical display server}, usually Xorg, also has its own idea of the keyboard layout (@pxref{X Window, @code{keyboard-layout}}). @end itemize Guix allows you to configure all three separately but, fortunately, it allows you to share the same keyboard layout for all three components. @cindex XKB, keyboard layouts Keyboard layouts are represented by records created by the @code{keyboard-layout} procedure of @code{(gnu system keyboard)}. Following the X Keyboard extension (XKB), each layout has four attributes: a name (often a language code such as ``fi'' for Finnish or ``jp'' for Japanese), an optional variant name, an optional keyboard model name, and a possibly empty list of additional options. In most cases the layout name is all you care about. @deffn {Procedure} keyboard-layout name [variant] [#:model] [#:options '()] Return a new keyboard layout with the given @var{name} and @var{variant}. @var{name} must be a string such as @code{"fr"}; @var{variant} must be a string such as @code{"bepo"} or @code{"nodeadkeys"}. See the @code{xkeyboard-config} package for valid options. @end deffn Here are a few examples: @lisp ;; The German QWERTZ layout. Here we assume a standard ;; "pc105" keyboard model. (keyboard-layout "de") ;; The bépo variant of the French layout. (keyboard-layout "fr" "bepo") ;; The Catalan layout. (keyboard-layout "es" "cat") ;; Arabic layout with "Alt-Shift" to switch to US layout. (keyboard-layout "ar,us" #:options '("grp:alt_shift_toggle")) ;; The Latin American Spanish layout. In addition, the ;; "Caps Lock" key is used as an additional "Ctrl" key, ;; and the "Menu" key is used as a "Compose" key to enter ;; accented letters. (keyboard-layout "latam" #:options '("ctrl:nocaps" "compose:menu")) ;; The Russian layout for a ThinkPad keyboard. (keyboard-layout "ru" #:model "thinkpad") ;; The "US international" layout, which is the US layout plus ;; dead keys to enter accented characters. This is for an ;; Apple MacBook keyboard. (keyboard-layout "us" "intl" #:model "macbook78") @end lisp See the @file{share/X11/xkb} directory of the @code{xkeyboard-config} package for a complete list of supported layouts, variants, and models. @cindex keyboard layout, configuration Let's say you want your system to use the Turkish keyboard layout throughout your system---bootloader, console, and Xorg. Here's what your system configuration would look like: @findex set-xorg-configuration @lisp ;; Using the Turkish layout for the bootloader, the console, ;; and for Xorg. (operating-system ;; ... (keyboard-layout (keyboard-layout "tr")) ;for the console (bootloader (bootloader-configuration (bootloader grub-efi-bootloader) (targets '("/boot/efi")) (keyboard-layout keyboard-layout))) ;for GRUB (services (cons (set-xorg-configuration (xorg-configuration ;for Xorg (keyboard-layout keyboard-layout))) %desktop-services))) @end lisp In the example above, for GRUB and for Xorg, we just refer to the @code{keyboard-layout} field defined above, but we could just as well refer to a different layout. The @code{set-xorg-configuration} procedure communicates the desired Xorg configuration to the graphical log-in manager, by default GDM. We've discussed how to specify the @emph{default} keyboard layout of your system when it starts, but you can also adjust it at run time: @itemize @item If you're using GNOME, its settings panel has a ``Region & Language'' entry where you can select one or more keyboard layouts. @item Under Xorg, the @command{setxkbmap} command (from the same-named package) allows you to change the current layout. For example, this is how you would change the layout to US Dvorak: @example setxkbmap us dvorak @end example @item The @code{loadkeys} command changes the keyboard layout in effect in the Linux console. However, note that @code{loadkeys} does @emph{not} use the XKB keyboard layout categorization described above. The command below loads the French bépo layout: @example loadkeys fr-bepo @end example @end itemize @node Locales @section Locales @cindex locale A @dfn{locale} defines cultural conventions for a particular language and region of the world (@pxref{Locales,,, libc, The GNU C Library Reference Manual}). Each locale has a name that typically has the form @code{@var{language}_@var{territory}.@var{codeset}}---e.g., @code{fr_LU.utf8} designates the locale for the French language, with cultural conventions from Luxembourg, and using the UTF-8 encoding. @cindex locale definition Usually, you will want to specify the default locale for the machine using the @code{locale} field of the @code{operating-system} declaration (@pxref{operating-system Reference, @code{locale}}). The selected locale is automatically added to the @dfn{locale definitions} known to the system if needed, with its codeset inferred from its name---e.g., @code{bo_CN.utf8} will be assumed to use the @code{UTF-8} codeset. Additional locale definitions can be specified in the @code{locale-definitions} slot of @code{operating-system}---this is useful, for instance, if the codeset could not be inferred from the locale name. The default set of locale definitions includes some widely used locales, but not all the available locales, in order to save space. For instance, to add the North Frisian locale for Germany, the value of that field may be: @lisp (cons (locale-definition (name "fy_DE.utf8") (source "fy_DE")) %default-locale-definitions) @end lisp Likewise, to save space, one might want @code{locale-definitions} to list only the locales that are actually used, as in: @lisp (list (locale-definition (name "ja_JP.eucjp") (source "ja_JP") (charset "EUC-JP"))) @end lisp @vindex LOCPATH The compiled locale definitions are available at @file{/run/current-system/locale/X.Y}, where @code{X.Y} is the libc version, which is the default location where the GNU@tie{}libc provided by Guix looks for locale data. This can be overridden using the @env{LOCPATH} environment variable (@pxref{locales-and-locpath, @env{LOCPATH} and locale packages}). The @code{locale-definition} form is provided by the @code{(gnu system locale)} module. Details are given below. @deftp {Data Type} locale-definition This is the data type of a locale definition. @table @asis @item @code{name} The name of the locale. @xref{Locale Names,,, libc, The GNU C Library Reference Manual}, for more information on locale names. @item @code{source} The name of the source for that locale. This is typically the @code{@var{language}_@var{territory}} part of the locale name. @item @code{charset} (default: @code{"UTF-8"}) The ``character set'' or ``code set'' for that locale, @uref{https://www.iana.org/assignments/character-sets, as defined by IANA}. @end table @end deftp @defvar %default-locale-definitions A list of commonly used UTF-8 locales, used as the default value of the @code{locale-definitions} field of @code{operating-system} declarations. @cindex locale name @cindex normalized codeset in locale names These locale definitions use the @dfn{normalized codeset} for the part that follows the dot in the name (@pxref{Using gettextized software, normalized codeset,, libc, The GNU C Library Reference Manual}). So for instance it has @code{uk_UA.utf8} but @emph{not}, say, @code{uk_UA.UTF-8}. @end defvar @subsection Locale Data Compatibility Considerations @cindex incompatibility, of locale data @code{operating-system} declarations provide a @code{locale-libcs} field to specify the GNU@tie{}libc packages that are used to compile locale declarations (@pxref{operating-system Reference}). ``Why would I care?'', you may ask. Well, it turns out that the binary format of locale data is occasionally incompatible from one libc version to another. @c See <https://sourceware.org/ml/libc-alpha/2015-09/msg00575.html> @c and <https://lists.gnu.org/archive/html/guix-devel/2015-08/msg00737.html>. For instance, a program linked against libc version 2.21 is unable to read locale data produced with libc 2.22; worse, that program @emph{aborts} instead of simply ignoring the incompatible locale data@footnote{Versions 2.23 and later of GNU@tie{}libc will simply skip the incompatible locale data, which is already an improvement.}. Similarly, a program linked against libc 2.22 can read most, but not all, of the locale data from libc 2.21 (specifically, @env{LC_COLLATE} data is incompatible); thus calls to @code{setlocale} may fail, but programs will not abort. The ``problem'' with Guix is that users have a lot of freedom: They can choose whether and when to upgrade software in their profiles, and might be using a libc version different from the one the system administrator used to build the system-wide locale data. Fortunately, unprivileged users can also install their own locale data and define @env{GUIX_LOCPATH} accordingly (@pxref{locales-and-locpath, @env{GUIX_LOCPATH} and locale packages}). Still, it is best if the system-wide locale data at @file{/run/current-system/locale} is built for all the libc versions actually in use on the system, so that all the programs can access it---this is especially crucial on a multi-user system. To do that, the administrator can specify several libc packages in the @code{locale-libcs} field of @code{operating-system}: @lisp (use-package-modules base) (operating-system ;; @dots{} (locale-libcs (list glibc-2.21 (canonical-package glibc)))) @end lisp This example would lead to a system containing locale definitions for both libc 2.21 and the current version of libc in @file{/run/current-system/locale}. @node Services @section Services @cindex system services An important part of preparing an @code{operating-system} declaration is listing @dfn{system services} and their configuration (@pxref{Using the Configuration System}). System services are typically daemons launched when the system boots, or other actions needed at that time---e.g., configuring network access. Guix has a broad definition of ``service'' (@pxref{Service Composition}), but many services are managed by the GNU@tie{}Shepherd (@pxref{Shepherd Services}). On a running system, the @command{herd} command allows you to list the available services, show their status, start and stop them, or do other specific operations (@pxref{Jump Start,,, shepherd, The GNU Shepherd Manual}). For example: @example # herd status @end example The above command, run as @code{root}, lists the currently defined services. The @command{herd doc} command shows a synopsis of the given service and its associated actions: @example # herd doc nscd Run libc's name service cache daemon (nscd). # herd doc nscd action invalidate invalidate: Invalidate the given cache--e.g., 'hosts' for host name lookups. @end example The @command{start}, @command{stop}, and @command{restart} sub-commands have the effect you would expect. For instance, the commands below stop the nscd service and restart the Xorg display server: @example # herd stop nscd Service nscd has been stopped. # herd restart xorg-server Service xorg-server has been stopped. Service xorg-server has been started. @end example @cindex configuration, action for shepherd services @cindex configuration file, of a shepherd service For some services, @command{herd configuration} returns the name of the service's configuration file, which can be handy to inspect its configuration: @example # herd configuration sshd /gnu/store/@dots{}-sshd_config @end example The following sections document the available services, starting with the core services, that may be used in an @code{operating-system} declaration. @menu * Base Services:: Essential system services. * Scheduled Job Execution:: The mcron service. * Log Rotation:: The rottlog service. * Networking Setup:: Setting up network interfaces. * Networking Services:: Firewall, SSH daemon, etc. * Unattended Upgrades:: Automated system upgrades. * X Window:: Graphical display. * Printing Services:: Local and remote printer support. * Desktop Services:: D-Bus and desktop services. * Sound Services:: ALSA and Pulseaudio services. * File Search Services:: Tools to search for files. * Database Services:: SQL databases, key-value stores, etc. * Mail Services:: IMAP, POP3, SMTP, and all that. * Messaging Services:: Messaging services. * Telephony Services:: Telephony services. * File-Sharing Services:: File-sharing services. * Monitoring Services:: Monitoring services. * Kerberos Services:: Kerberos services. * LDAP Services:: LDAP services. * Web Services:: Web servers. * Certificate Services:: TLS certificates via Let's Encrypt. * DNS Services:: DNS daemons. * VNC Services:: VNC daemons. * VPN Services:: VPN daemons. * Network File System:: NFS related services. * Samba Services:: Samba services. * Continuous Integration:: Cuirass and Laminar services. * Power Management Services:: Extending battery life. * Audio Services:: The MPD. * Virtualization Services:: Virtualization services. * Version Control Services:: Providing remote access to Git repositories. * Game Services:: Game servers. * PAM Mount Service:: Service to mount volumes when logging in. * Guix Services:: Services relating specifically to Guix. * Linux Services:: Services tied to the Linux kernel. * Hurd Services:: Services specific for a Hurd System. * Miscellaneous Services:: Other services. @end menu @node Base Services @subsection Base Services The @code{(gnu services base)} module provides definitions for the basic services that one expects from the system. The services exported by this module are listed below. @defvar %base-services This variable contains a list of basic services (@pxref{Service Types and Services}, for more information on service objects) one would expect from the system: a login service (mingetty) on each tty, syslogd, the libc name service cache daemon (nscd), the udev device manager, and more. This is the default value of the @code{services} field of @code{operating-system} declarations. Usually, when customizing a system, you will want to append services to @code{%base-services}, like this: @lisp (append (list (service avahi-service-type) (service openssh-service-type)) %base-services) @end lisp @end defvar @defvar special-files-service-type This is the service that sets up ``special files'' such as @file{/bin/sh}; an instance of it is part of @code{%base-services}. The value associated with @code{special-files-service-type} services must be a list of two-element lists where the first element is the ``special file'' and the second element is its target. By default it is: @cindex @file{/bin/sh} @cindex @file{sh}, in @file{/bin} @lisp `(("/bin/sh" ,(file-append bash "/bin/sh")) ("/usr/bin/env" ,(file-append coreutils "/bin/env"))) @end lisp @cindex @file{/usr/bin/env} @cindex @file{env}, in @file{/usr/bin} If you want to add, say, @code{/bin/bash} to your system, you can change it to: @lisp `(("/bin/sh" ,(file-append bash "/bin/sh")) ("/usr/bin/env" ,(file-append coreutils "/bin/env")) ("/bin/bash" ,(file-append bash "/bin/bash"))) @end lisp Since this is part of @code{%base-services}, you can use @code{modify-services} to customize the set of special files (@pxref{Service Reference, @code{modify-services}}). But the simple way to add a special file is @i{via} the @code{extra-special-file} procedure (see below). @end defvar @deffn {Procedure} extra-special-file file target Use @var{target} as the ``special file'' @var{file}. For example, adding the following lines to the @code{services} field of your operating system declaration leads to a @file{/usr/bin/env} symlink: @lisp (extra-special-file "/usr/bin/env" (file-append coreutils "/bin/env")) @end lisp This procedure is meant for @code{/bin/sh}, @code{/usr/bin/env} and similar targets. In particular, use for targets under @code{/etc} might not work as expected if the target is managed by Guix in other ways. @end deffn @defvar host-name-service-type Type of the service that sets the system host name, whose value is a string. This service is included in @code{operating-system} by default (@pxref{operating-system-essential-services,@code{essential-services}}). @end defvar @defvar console-font-service-type Install the given fonts on the specified ttys (fonts are per virtual console on the kernel Linux). The value of this service is a list of tty/font pairs. The font can be the name of a font provided by the @code{kbd} package or any valid argument to @command{setfont}, as in this example: @lisp `(("tty1" . "LatGrkCyr-8x16") ("tty2" . ,(file-append font-tamzen "/share/kbd/consolefonts/TamzenForPowerline10x20.psf")) ("tty3" . ,(file-append font-terminus "/share/consolefonts/ter-132n"))) ; for HDPI @end lisp @end defvar @defvar hosts-service-type Type of the service that populates the entries for (@file{/etc/hosts}). This service type can be @emph{extended} by passing it a list of @code{host} records. The example below shows how to add two entries to @file{/etc/hosts}: @c TRANSLATORS: The domain names below SHOULD NOT be translated. @c They're domains reserved for use in documentation. (RFC6761 Section 6.5) @c The addresses used are explained in RFC3849 and RFC5737. @lisp (simple-service 'add-extra-hosts hosts-service-type (list (host "192.0.2.1" "example.com" '("example.net" "example.org")) (host "2001:db8::1" "example.com" '("example.net" "example.org")))) @end lisp @quotation Note @cindex @file{/etc/hosts} default entries By default @file{/etc/hosts} comes with the following entries: @example 127.0.0.1 localhost @var{host-name} ::1 localhost @var{host-name} @end example For most setups this is what you want though if you find yourself in the situation where you want to change the default entries, you can do so in @code{operating-system} via @code{modify-services} (@pxref{Service Reference,@code{modify-services}}). The following example shows how to unset @var{host-name} from being an alias of @code{localhost}. @lisp (operating-system ;; @dots{} (essential-services (modify-services (operating-system-default-essential-services this-operating-system) (hosts-service-type config => (list (host "127.0.0.1" "localhost") (host "::1" "localhost")))))) @end lisp @end quotation @end defvar @deffn {Procedure} host @var{address} @var{canonical-name} [@var{aliases}] Return a new record for the host at @var{address} with the given @var{canonical-name} and possibly @var{aliases}. @var{address} must be a string denoting a valid IPv4 or IPv6 address, and @var{canonical-name} and the strings listed in @var{aliases} must be valid host names. @end deffn @defvar login-service-type Type of the service that provides a console login service, whose value is a @code{<login-configuration>} object. @end defvar @deftp {Data Type} login-configuration Data type representing the configuration of login, which specifies the @acronym{MOTD, message of the day}, among other things. @table @asis @item @code{motd} @cindex message of the day A file-like object containing the ``message of the day''. @item @code{allow-empty-passwords?} (default: @code{#t}) Allow empty passwords by default so that first-time users can log in when the 'root' account has just been created. @end table @end deftp @defvar mingetty-service-type Type of the service that runs Mingetty, an implementation of the virtual console log-in. The value for this service is a @code{<mingetty-configuration>} object. @end defvar @deftp {Data Type} mingetty-configuration Data type representing the configuration of Mingetty, which specifies the tty to run, among other things. @table @asis @item @code{tty} The name of the console this Mingetty runs on---e.g., @code{"tty1"}. @item @code{auto-login} (default: @code{#f}) When true, this field must be a string denoting the user name under which the system automatically logs in. When it is @code{#f}, a user name and password must be entered to log in. @item @code{login-program} (default: @code{#f}) This must be either @code{#f}, in which case the default log-in program is used (@command{login} from the Shadow tool suite), or a gexp denoting the name of the log-in program. @item @code{login-pause?} (default: @code{#f}) When set to @code{#t} in conjunction with @var{auto-login}, the user will have to press a key before the log-in shell is launched. @item @code{clear-on-logout?} (default: @code{#t}) When set to @code{#t}, the screen will be cleared before showing the login prompt. The field name is bit unfortunate, since it controls clearing also before the initial login, not just after a logout. @item @code{delay} (default: @code{#f}) When set to a number, sleep that many seconds after startup. @item @code{print-issue} (default: @code{#t}) When set to @code{#t}, write out a new line and the content of @file{/etc/issue}. Value of @code{'no-nl} can be used to suppress the new line. @item @code{print-hostname} (default: @code{#t}) When set to @code{#t}, print the host name before the login prompt. The host name is printed up to the first dot. Can be set to @code{'long} to print the full host name. @item @code{nice} (default: @code{#f}) When set to a number, change the process priority using @code{nice}. @item @code{working-directory} (default: @code{#f}) When set to a string, change into that directory before calling the login program. @item @code{root-directory} (default: @code{#f}) When set to a string, use this directory at the process's root directory. @item @code{shepherd-requirement} List of shepherd requirements. Unless you know what you are doing, it is recommended to extend the default list instead of overriding it. As an example, when using auto-login on a system with elogind, it is necessary to wait on the @code{'dbus-system} service: @lisp (modify-services %base-services (mingetty-service-type config => (mingetty-configuration (inherit config) ;; Automatically log in as "guest". (auto-login "guest") (shepherd-requirement (cons 'dbus-system (mingetty-configuration-shepherd-requirement config)))))) @end lisp @item @code{mingetty} (default: @var{mingetty}) The Mingetty package to use. @end table @end deftp @defvar agetty-service-type Type of the service that runs agetty, which implements virtual and serial console log-in. The value for this service is a @code{<agetty-configuration>} object. @end defvar @deftp {Data Type} agetty-configuration Data type representing the configuration of agetty, which specifies the tty to run, among other things@footnote{See the @code{agetty(8)} man page for more information.}. @table @asis @item @code{tty} The name of the console this agetty runs on, as a string---e.g., @code{"ttyS0"}. This argument is optional, it will default to a reasonable default serial port used by the kernel Linux. For this, if there is a value for an option @code{agetty.tty} in the kernel command line, agetty will extract the device name of the serial port from it and use that. If not and if there is a value for an option @code{console} with a tty in the Linux command line, agetty will extract the device name of the serial port from it and use that. In both cases, agetty will leave the other serial device settings (baud rate etc.)@: alone---in the hope that Linux pinned them to the correct values. @item @code{baud-rate} (default: @code{#f}) A string containing a comma-separated list of one or more baud rates, in descending order. @item @code{term} (default: @code{#f}) A string containing the value used for the @env{TERM} environment variable. @item @code{eight-bits?} (default: @code{#f}) When @code{#t}, the tty is assumed to be 8-bit clean, and parity detection is disabled. @item @code{auto-login} (default: @code{#f}) When passed a login name, as a string, the specified user will be logged in automatically without prompting for their login name or password. @item @code{no-reset?} (default: @code{#f}) When @code{#t}, don't reset terminal cflags (control modes). @item @code{host} (default: @code{#f}) This accepts a string containing the ``login_host'', which will be written into the @file{/var/run/utmpx} file. @item @code{remote?} (default: @code{#f}) When set to @code{#t} in conjunction with @var{host}, this will add an @code{-r} fakehost option to the command line of the login program specified in @var{login-program}. @item @code{flow-control?} (default: @code{#f}) When set to @code{#t}, enable hardware (RTS/CTS) flow control. @item @code{no-issue?} (default: @code{#f}) When set to @code{#t}, the contents of the @file{/etc/issue} file will not be displayed before presenting the login prompt. @item @code{init-string} (default: @code{#f}) This accepts a string that will be sent to the tty or modem before sending anything else. It can be used to initialize a modem. @item @code{no-clear?} (default: @code{#f}) When set to @code{#t}, agetty will not clear the screen before showing the login prompt. @item @code{login-program} (default: (file-append shadow "/bin/login")) This must be either a gexp denoting the name of a log-in program, or unset, in which case the default value is the @command{login} from the Shadow tool suite. @item @code{local-line} (default: @code{#f}) Control the CLOCAL line flag. This accepts one of three symbols as arguments, @code{'auto}, @code{'always}, or @code{'never}. If @code{#f}, the default value chosen by agetty is @code{'auto}. @item @code{extract-baud?} (default: @code{#f}) When set to @code{#t}, instruct agetty to try to extract the baud rate from the status messages produced by certain types of modems. @item @code{skip-login?} (default: @code{#f}) When set to @code{#t}, do not prompt the user for a login name. This can be used with @var{login-program} field to use non-standard login systems. @item @code{no-newline?} (default: @code{#f}) When set to @code{#t}, do not print a newline before printing the @file{/etc/issue} file. @c Is this dangerous only when used with login-program, or always? @item @code{login-options} (default: @code{#f}) This option accepts a string containing options that are passed to the login program. When used with the @var{login-program}, be aware that a malicious user could try to enter a login name containing embedded options that could be parsed by the login program. @item @code{login-pause} (default: @code{#f}) When set to @code{#t}, wait for any key before showing the login prompt. This can be used in conjunction with @var{auto-login} to save memory by lazily spawning shells. @item @code{chroot} (default: @code{#f}) Change root to the specified directory. This option accepts a directory path as a string. @item @code{hangup?} (default: @code{#f}) Use the Linux system call @code{vhangup} to do a virtual hangup of the specified terminal. @item @code{keep-baud?} (default: @code{#f}) When set to @code{#t}, try to keep the existing baud rate. The baud rates from @var{baud-rate} are used when agetty receives a @key{BREAK} character. @item @code{timeout} (default: @code{#f}) When set to an integer value, terminate if no user name could be read within @var{timeout} seconds. @item @code{detect-case?} (default: @code{#f}) When set to @code{#t}, turn on support for detecting an uppercase-only terminal. This setting will detect a login name containing only uppercase letters as indicating an uppercase-only terminal and turn on some upper-to-lower case conversions. Note that this will not support Unicode characters. @item @code{wait-cr?} (default: @code{#f}) When set to @code{#t}, wait for the user or modem to send a carriage-return or linefeed character before displaying @file{/etc/issue} or login prompt. This is typically used with the @var{init-string} option. @item @code{no-hints?} (default: @code{#f}) When set to @code{#t}, do not print hints about Num, Caps, and Scroll locks. @item @code{no-hostname?} (default: @code{#f}) By default, the hostname is printed. When this option is set to @code{#t}, no hostname will be shown at all. @item @code{long-hostname?} (default: @code{#f}) By default, the hostname is only printed until the first dot. When this option is set to @code{#t}, the fully qualified hostname by @code{gethostname} or @code{getaddrinfo} is shown. @item @code{erase-characters} (default: @code{#f}) This option accepts a string of additional characters that should be interpreted as backspace when the user types their login name. @item @code{kill-characters} (default: @code{#f}) This option accepts a string that should be interpreted to mean ``ignore all previous characters'' (also called a ``kill'' character) when the user types their login name. @item @code{chdir} (default: @code{#f}) This option accepts, as a string, a directory path that will be changed to before login. @item @code{delay} (default: @code{#f}) This options accepts, as an integer, the number of seconds to sleep before opening the tty and displaying the login prompt. @item @code{nice} (default: @code{#f}) This option accepts, as an integer, the nice value with which to run the @command{login} program. @item @code{extra-options} (default: @code{'()}) This option provides an ``escape hatch'' for the user to provide arbitrary command-line arguments to @command{agetty} as a list of strings. @item @code{shepherd-requirement} (default: @code{'()}) The option can be used to provides extra shepherd requirements (for example @code{'syslogd}) to the respective @code{'term-}* shepherd service. @end table @end deftp @defvar kmscon-service-type Type of the service that runs @uref{https://www.freedesktop.org/wiki/Software/kmscon,kmscon}, which implements virtual console log-in. The value for this service is a @code{<kmscon-configuration>} object. @end defvar @deftp {Data Type} kmscon-configuration Data type representing the configuration of Kmscon, which specifies the tty to run, among other things. @table @asis @item @code{virtual-terminal} The name of the console this Kmscon runs on---e.g., @code{"tty1"}. @item @code{login-program} (default: @code{#~(string-append #$shadow "/bin/login")}) A gexp denoting the name of the log-in program. The default log-in program is @command{login} from the Shadow tool suite. @item @code{login-arguments} (default: @code{'("-p")}) A list of arguments to pass to @command{login}. @item @code{auto-login} (default: @code{#f}) When passed a login name, as a string, the specified user will be logged in automatically without prompting for their login name or password. @item @code{hardware-acceleration?} (default: #f) Whether to use hardware acceleration. @item @code{font-engine} (default: @code{"pango"}) Font engine used in Kmscon. @item @code{font-size} (default: @code{12}) Font size used in Kmscon. @item @code{keyboard-layout} (default: @code{#f}) If this is @code{#f}, Kmscon uses the default keyboard layout---usually US English (``qwerty'') for a 105-key PC keyboard. Otherwise this must be a @code{keyboard-layout} object specifying the keyboard layout. @xref{Keyboard Layout}, for more information on how to specify the keyboard layout. @item @code{kmscon} (default: @var{kmscon}) The Kmscon package to use. @end table @end deftp @cindex @abbr{nscd, name service cache daemon} @defvar nscd-service-type Type of the service that runs the libc @abbr{nscd, name service cache daemon}, whose value is an @code{<nscd-configuration>} object. For convenience, the Shepherd service for nscd provides the following actions: @table @code @item invalidate @cindex nscd, cache invalidation @cindex cache invalidation, nscd This invalidate the given cache. For instance, running: @example herd invalidate nscd hosts @end example @noindent invalidates the host name lookup cache of nscd. @item statistics Running @command{herd statistics nscd} displays information about nscd usage and caches. @end table @end defvar @deftp {Data Type} nscd-configuration Data type representing the @abbr{nscd, name service cache daemon} configuration. @table @asis @item @code{name-services} (default: @code{'()}) List of packages denoting @dfn{name services} that must be visible to the nscd---e.g., @code{(list @var{nss-mdns})}. @item @code{glibc} (default: @var{glibc}) Package object denoting the GNU C Library providing the @command{nscd} command. @item @code{log-file} (default: @code{#f}) Name of the nscd log file. Debugging output goes to that file when @code{debug-level} is strictly positive, or to standard error if it is @code{#f}. Regular messages are written to syslog when @code{debug-level} is zero, regardless of the value of @code{log-file}. @item @code{debug-level} (default: @code{0}) Integer denoting the debugging levels. Higher numbers mean that more debugging output is logged. @item @code{caches} (default: @code{%nscd-default-caches}) List of @code{<nscd-cache>} objects denoting things to be cached; see below. @end table @end deftp @deftp {Data Type} nscd-cache Data type representing a cache database of nscd and its parameters. @table @asis @item @code{database} This is a symbol representing the name of the database to be cached. Valid values are @code{passwd}, @code{group}, @code{hosts}, and @code{services}, which designate the corresponding NSS database (@pxref{NSS Basics,,, libc, The GNU C Library Reference Manual}). @item @code{positive-time-to-live} @itemx @code{negative-time-to-live} (default: @code{20}) A number representing the number of seconds during which a positive or negative lookup result remains in cache. @item @code{check-files?} (default: @code{#t}) Whether to check for updates of the files corresponding to @var{database}. For instance, when @var{database} is @code{hosts}, setting this flag instructs nscd to check for updates in @file{/etc/hosts} and to take them into account. @item @code{persistent?} (default: @code{#t}) Whether the cache should be stored persistently on disk. @item @code{shared?} (default: @code{#t}) Whether the cache should be shared among users. @item @code{max-database-size} (default: 32@tie{}MiB) Maximum size in bytes of the database cache. @c XXX: 'suggested-size' and 'auto-propagate?' seem to be expert @c settings, so leave them out. @end table @end deftp @defvar %nscd-default-caches List of @code{<nscd-cache>} objects used by default by @code{nscd-configuration} (see above). It enables persistent and aggressive caching of service and host name lookups. The latter provides better host name lookup performance, resilience in the face of unreliable name servers, and also better privacy---often the result of host name lookups is in local cache, so external name servers do not even need to be queried. @end defvar @cindex syslog @cindex logging @defvar syslog-service-type Type of the service that runs the syslog daemon, whose value is a @code{<syslog-configuration>} object. @end defvar To have a modified @code{syslog-configuration} come into effect after reconfiguring your system, the @samp{reload} action should be preferred to restarting the service, as many services such as the login manager depend on it and would be restarted as well: @example # herd reload syslog @end example which will cause the running @command{syslogd} process to reload its configuration. @deftp {Data Type} syslog-configuration Data type representing the configuration of the syslog daemon. @table @asis @item @code{syslogd} (default: @code{#~(string-append #$inetutils "/libexec/syslogd")}) The syslog daemon to use. @item @code{config-file} (default: @code{%default-syslog.conf}) The syslog configuration file to use. @xref{syslogd invocation,,, inetutils, GNU Inetutils}, for more information on the configuration file syntax. @item @code{extra-options} (default: @code{'()}) List of extra command-line options for @command{syslog}. @end table @end deftp @defvar guix-service-type This is the type of the service that runs the build daemon, @command{guix-daemon} (@pxref{Invoking guix-daemon}). Its value must be a @code{guix-configuration} record as described below. @end defvar @anchor{guix-configuration-type} @deftp {Data Type} guix-configuration This data type represents the configuration of the Guix build daemon. @xref{Invoking guix-daemon}, for more information. @table @asis @item @code{guix} (default: @var{guix}) The Guix package to use. @xref{Customizing the System-Wide Guix} to learn how to provide a package with a pre-configured set of channels. @item @code{build-group} (default: @code{"guixbuild"}) Name of the group for build user accounts. @item @code{build-accounts} (default: @code{10}) Number of build user accounts to create. @item @code{authorize-key?} (default: @code{#t}) @cindex substitutes, authorization thereof Whether to authorize the substitute keys listed in @code{authorized-keys}---by default that of @code{@value{SUBSTITUTE-SERVER-1}} and @code{@value{SUBSTITUTE-SERVER-2}} (@pxref{Substitutes}). When @code{authorize-key?} is true, @file{/etc/guix/acl} cannot be changed by invoking @command{guix archive --authorize}. You must instead adjust @code{guix-configuration} as you wish and reconfigure the system. This ensures that your operating system configuration file is self-contained. @quotation Note When booting or reconfiguring to a system where @code{authorize-key?} is true, the existing @file{/etc/guix/acl} file is backed up as @file{/etc/guix/acl.bak} if it was determined to be a manually modified file. This is to facilitate migration from earlier versions, which allowed for in-place modifications to @file{/etc/guix/acl}. @end quotation @vindex %default-authorized-guix-keys @item @code{authorized-keys} (default: @code{%default-authorized-guix-keys}) The list of authorized key files for archive imports, as a list of string-valued gexps (@pxref{Invoking guix archive}). By default, it contains that of @code{@value{SUBSTITUTE-SERVER-1}} and @code{@value{SUBSTITUTE-SERVER-2}} (@pxref{Substitutes}). See @code{substitute-urls} below for an example on how to change it. @item @code{use-substitutes?} (default: @code{#t}) Whether to use substitutes. @item @code{substitute-urls} (default: @code{%default-substitute-urls}) The list of URLs where to look for substitutes by default. Suppose you would like to fetch substitutes from @code{guix.example.org} in addition to @code{@value{SUBSTITUTE-SERVER-1}}. You will need to do two things: (1) add @code{guix.example.org} to @code{substitute-urls}, and (2) authorize its signing key, having done appropriate checks (@pxref{Substitute Server Authorization}). The configuration below does exactly that: @lisp (guix-configuration (substitute-urls (append (list "https://guix.example.org") %default-substitute-urls)) (authorized-keys (append (list (local-file "./guix.example.org-key.pub")) %default-authorized-guix-keys))) @end lisp This example assumes that the file @file{./guix.example.org-key.pub} contains the public key that @code{guix.example.org} uses to sign substitutes. @item @code{generate-substitute-key?} (default: @code{#t}) Whether to generate a @dfn{substitute key pair} under @file{/etc/guix/signing-key.pub} and @file{/etc/guix/signing-key.sec} if there is not already one. This key pair is used when exporting store items, for instance with @command{guix publish} (@pxref{Invoking guix publish}) or @command{guix archive} (@pxref{Invoking guix archive}). Generating a key pair takes a few seconds when enough entropy is available and is only done once; you might want to turn it off for instance in a virtual machine that does not need it and where the extra boot time is a problem. @anchor{guix-configuration-channels} @item @code{channels} (default: @code{#f}) List of channels to be specified in @file{/etc/guix/channels.scm}, which is what @command{guix pull} uses by default (@pxref{Invoking guix pull}). @quotation Note When reconfiguring a system, the existing @file{/etc/guix/channels.scm} file is backed up as @file{/etc/guix/channels.scm.bak} if it was determined to be a manually modified file. This is to facilitate migration from earlier versions, which allowed for in-place modifications to @file{/etc/guix/channels.scm}. @end quotation @item @code{max-silent-time} (default: @code{3600}) @itemx @code{timeout} (default: @code{(* 3600 24)}) The number of seconds of silence and the number of seconds of activity, respectively, after which a build process times out. A value of zero disables the timeout. @item @code{log-compression} (default: @code{'gzip}) The type of compression used for build logs---one of @code{gzip}, @code{bzip2}, or @code{none}. @item @code{discover?} (default: @code{#f}) Whether to discover substitute servers on the local network using mDNS and DNS-SD. @anchor{guix-configuration-build-machines} @item @code{build-machines} (default: @code{#f}) This field must be either @code{#f} or a list of gexps evaluating to a @code{build-machine} record or to a list of @code{build-machine} records (@pxref{Daemon Offload Setup}). When it is @code{#f}, the @file{/etc/guix/machines.scm} file is left untouched. Otherwise, the list of of gexps is written to @file{/etc/guix/machines.scm}; if a previously-existing file is found, it is backed up as @file{/etc/guix/machines.scm.bak}. This allows you to declare build machines for offloading directly in the operating system declaration, like so: @lisp (guix-configuration (build-machines (list #~(build-machine (name "foo.example.org") @dots{}) #~(build-machine (name "bar.example.org") @dots{})))) @end lisp Additional build machines may be added @i{via} the @code{guix-extension} mechanism (see below). @item @code{extra-options} (default: @code{'()}) List of extra command-line options for @command{guix-daemon}. @item @code{log-file} (default: @code{"/var/log/guix-daemon.log"}) File where @command{guix-daemon}'s standard output and standard error are written. @cindex HTTP proxy, for @code{guix-daemon} @cindex proxy, for @code{guix-daemon} HTTP access @item @code{http-proxy} (default: @code{#f}) The URL of the HTTP and HTTPS proxy used for downloading fixed-output derivations and substitutes. It is also possible to change the daemon's proxy at run time through the @code{set-http-proxy} action, which restarts it: @example herd set-http-proxy guix-daemon http://localhost:8118 @end example To clear the proxy settings, run: @example herd set-http-proxy guix-daemon @end example @item @code{tmpdir} (default: @code{#f}) A directory path where the @command{guix-daemon} will perform builds. @item @code{environment} (default: @code{'()}) Environment variables to be set before starting the daemon, as a list of @code{key=value} strings. @item @code{socket-directory-permissions} (default: @code{#o755}) Permissions to set for the directory @file{/var/guix/daemon-socket}. This, together with @code{socket-directory-group} and @code{socket-directory-user}, determines who can connect to the build daemon via its Unix socket. TCP socket operation is unaffected by these. @item @code{socket-directory-user} (default: @code{#f}) @itemx @code{socket-directory-group} (default: @code{#f}) User and group owning the @file{/var/guix/daemon-socket} directory or @code{#f} to keep the user or group as root. @end table @end deftp @deftp {Data Type} guix-extension This data type represents the parameters of the Guix build daemon that are extendable. This is the type of the object that must be used within a guix service extension. @xref{Service Composition}, for more information. @table @asis @item @code{authorized-keys} (default: @code{'()}) A list of file-like objects where each element contains a public key. @item @code{substitute-urls} (default: @code{'()}) A list of strings where each element is a substitute URL. @item @code{build-machines} (default: @code{'()}) A list of gexps that evaluate to @code{build-machine} records or to a list of @code{build-machine} records. (@pxref{Daemon Offload Setup}). Using this field, a service may add new build machines to receive builds offloaded by the daemon. This is useful for a service such as @code{hurd-vm-service-type}, which can make a GNU/Hurd virtual machine directly usable for offloading (@pxref{hurd-vm, @code{hurd-vm-service-type}}). @item @code{chroot-directories} (default: @code{'()}) A list of file-like objects or strings pointing to additional directories the build daemon can use. @end table @end deftp @defvar udev-service-type Type of the service that runs udev, a service which populates the @file{/dev} directory dynamically, whose value is a @code{<udev-configuration>} object. Since the file names for udev rules and hardware description files matter, the configuration items for rules and hardware cannot simply be plain file-like objects with the rules content, because the name would be ignored. Instead, they are directory file-like objects that contain optional rules in @file{lib/udev/rules.d} and optional hardware files in @file{lib/udev/hwdb.d}. This way, the service can be configured with whole packages from which to take rules and hwdb files. The @code{udev-service-type} can be @emph{extended} with file-like directories that respect this hierarchy. For convenience, the @code{udev-rule} and @code{file->udev-rule} can be used to construct udev rules, while @code{udev-hardware} and @code{file->udev-hardware} can be used to construct hardware description files. In an @code{operating-system} declaration, this service type can be @emph{extended} using procedures @code{udev-rules-service} and @code{udev-hardware-service}. @end defvar @deftp {Data Type} udev-configuration Data type representing the configuration of udev. @table @asis @item @code{udev} (default: @code{eudev}) (type: file-like) Package object of the udev service. This package is used at run-time, when compiled for the target system. In order to generate the @file{hwdb.bin} hardware index, it is also used when generating the system definition, compiled for the current system. @item @code{rules} (default: @var{'()}) (type: list-of-file-like) List of file-like objects denoting udev rule files under a sub-directory. @item @code{hardware} (default: @var{'()}) (type: list-of-file-like) List of file-like objects denoting udev hardware description files under a sub-directory. @end table @end deftp @deffn {Procedure} udev-rule @var{file-name} @var{contents} Return a udev-rule file named @var{file-name} containing the rules defined by the @var{contents} literal. In the following example, a rule for a USB device is defined to be stored in the file @file{90-usb-thing.rules}. The rule runs a script upon detecting a USB device with a given product identifier. @lisp (define %example-udev-rule (udev-rule "90-usb-thing.rules" (string-append "ACTION==\"add\", SUBSYSTEM==\"usb\", " "ATTR@{product@}==\"Example\", " "RUN+=\"/path/to/script\""))) @end lisp @end deffn @deffn {Procedure} udev-hardware @var{file-name} @var{contents} Return a udev hardware description file named @var{file-name} containing the hardware information @var{contents}. @end deffn @deffn {Procedure} udev-rules-service @var{name} @var{rules} [#:groups '()] Return a service that extends @code{udev-service-type} with @var{rules} and @code{account-service-type} with @var{groups} as system groups. This works by creating a singleton service type @code{@var{name}-udev-rules}, of which the returned service is an instance. Here we show how it can be used to extend @code{udev-service-type} with the previously defined rule @code{%example-udev-rule}. @lisp (operating-system ;; @dots{} (services (cons (udev-rules-service 'usb-thing %example-udev-rule) %desktop-services))) @end lisp @end deffn @deffn {Procedure} udev-hardware-service @var{name} @var{hardware} Return a service that extends @code{udev-service-type} with @var{hardware}. The service name is @code{@var{name}-udev-hardware}. @end deffn @deffn {Procedure} file->udev-rule @var{file-name} @var{file} Return a udev-rule file named @var{file-name} containing the rules defined within @var{file}, a file-like object. The following example showcases how we can use an existing rule file. @lisp (use-modules (guix download) ;for url-fetch (guix packages) ;for origin @dots{}) (define %android-udev-rules (file->udev-rule "51-android-udev.rules" (let ((version "20170910")) (origin (method url-fetch) (uri (string-append "https://raw.githubusercontent.com/M0Rf30/" "android-udev-rules/" version "/51-android.rules")) (sha256 (base32 "0lmmagpyb6xsq6zcr2w1cyx9qmjqmajkvrdbhjx32gqf1d9is003")))))) @end lisp @end deffn Since guix package definitions can be included in @var{rules} in order to use all their rules under the @file{lib/udev/rules.d} sub-directory, then in lieu of the previous @var{file->udev-rule} example, we could have used the @var{android-udev-rules} package which exists in Guix in the @code{(gnu packages android)} module. @deffn {Procedure} file->udev-hardware @var{file-name} @var{file} Return a udev hardware description file named @var{file-name} containing the rules defined within @var{file}, a file-like object. @end deffn The following example shows how to use the @var{android-udev-rules} package so that the Android tool @command{adb} can detect devices without root privileges. It also details how to create the @code{adbusers} group, which is required for the proper functioning of the rules defined within the @code{android-udev-rules} package. To create such a group, we must define it both as part of the @code{supplementary-groups} of our @code{user-account} declaration, as well as in the @var{groups} of the @code{udev-rules-service} procedure. @lisp (use-modules (gnu packages android) ;for android-udev-rules (gnu system shadow) ;for user-group @dots{}) (operating-system ;; @dots{} (users (cons (user-account ;; @dots{} (supplementary-groups '("adbusers" ;for adb "wheel" "netdev" "audio" "video"))))) ;; @dots{} (services (cons (udev-rules-service 'android android-udev-rules #:groups '("adbusers")) %desktop-services))) @end lisp @defvar urandom-seed-service-type Save some entropy in @code{%random-seed-file} to seed @file{/dev/urandom} when rebooting. It also tries to seed @file{/dev/urandom} from @file{/dev/hwrng} while booting, if @file{/dev/hwrng} exists and is readable. @end defvar @defvar %random-seed-file This is the name of the file where some random bytes are saved by @var{urandom-seed-service} to seed @file{/dev/urandom} when rebooting. It defaults to @file{/var/lib/random-seed}. @end defvar @cindex mouse @cindex gpm @defvar gpm-service-type This is the type of the service that runs GPM, the @dfn{general-purpose mouse daemon}, which provides mouse support to the Linux console. GPM allows users to use the mouse in the console, notably to select, copy, and paste text. The value for services of this type must be a @code{gpm-configuration} (see below). This service is not part of @code{%base-services}. @end defvar @deftp {Data Type} gpm-configuration Data type representing the configuration of GPM. @table @asis @item @code{options} (default: @code{%default-gpm-options}) Command-line options passed to @command{gpm}. The default set of options instruct @command{gpm} to listen to mouse events on @file{/dev/input/mice}. @xref{Command Line,,, gpm, gpm manual}, for more information. @item @code{gpm} (default: @code{gpm}) The GPM package to use. @end table @end deftp @anchor{guix-publish-service-type} @defvar guix-publish-service-type This is the service type for @command{guix publish} (@pxref{Invoking guix publish}). Its value must be a @code{guix-publish-configuration} object, as described below. This assumes that @file{/etc/guix} already contains a signing key pair as created by @command{guix archive --generate-key} (@pxref{Invoking guix archive}). If that is not the case, the service will fail to start. @end defvar @deftp {Data Type} guix-publish-configuration Data type representing the configuration of the @code{guix publish} service. @table @asis @item @code{guix} (default: @code{guix}) The Guix package to use. @item @code{port} (default: @code{80}) The TCP port to listen for connections. @item @code{host} (default: @code{"localhost"}) The host (and thus, network interface) to listen to. Use @code{"0.0.0.0"} to listen on all the network interfaces. @item @code{advertise?} (default: @code{#f}) When true, advertise the service on the local network @i{via} the DNS-SD protocol, using Avahi. This allows neighboring Guix devices with discovery on (see @code{guix-configuration} above) to discover this @command{guix publish} instance and to automatically download substitutes from it. @item @code{compression} (default: @code{'(("gzip" 3) ("zstd" 3))}) This is a list of compression method/level tuple used when compressing substitutes. For example, to compress all substitutes with @emph{both} lzip at level 7 and gzip at level 9, write: @lisp '(("lzip" 7) ("gzip" 9)) @end lisp Level 9 achieves the best compression ratio at the expense of increased CPU usage, whereas level 1 achieves fast compression. @xref{Invoking guix publish}, for more information on the available compression methods and the tradeoffs involved. An empty list disables compression altogether. @item @code{nar-path} (default: @code{"nar"}) The URL path at which ``nars'' can be fetched. @xref{Invoking guix publish, @option{--nar-path}}, for details. @item @code{cache} (default: @code{#f}) When it is @code{#f}, disable caching and instead generate archives on demand. Otherwise, this should be the name of a directory---e.g., @code{"/var/cache/guix/publish"}---where @command{guix publish} caches archives and meta-data ready to be sent. @xref{Invoking guix publish, @option{--cache}}, for more information on the tradeoffs involved. @item @code{workers} (default: @code{#f}) When it is an integer, this is the number of worker threads used for caching; when @code{#f}, the number of processors is used. @xref{Invoking guix publish, @option{--workers}}, for more information. @item @code{cache-bypass-threshold} (default: 10 MiB) When @code{cache} is true, this is the maximum size in bytes of a store item for which @command{guix publish} may bypass its cache in case of a cache miss. @xref{Invoking guix publish, @option{--cache-bypass-threshold}}, for more information. @item @code{ttl} (default: @code{#f}) When it is an integer, this denotes the @dfn{time-to-live} in seconds of the published archives. @xref{Invoking guix publish, @option{--ttl}}, for more information. @item @code{negative-ttl} (default: @code{#f}) When it is an integer, this denotes the @dfn{time-to-live} in seconds for the negative lookups. @xref{Invoking guix publish, @option{--negative-ttl}}, for more information. @end table @end deftp @defvar rngd-service-type Type of the service that runs rng-tools rngd, whose value is an @code{<rngd-configuration>} object. @end defvar @deftp {Data Type} rngd-configuration Data type representing the configuration of rngd. @table @asis @item @code{rng-tools} (default: @code{rng-tools}) (type: file-like) Package object of the rng-tools rngd. @item @code{device} (default: @var{"/dev/hwrng"}) (type: string) Path of the device to add to the kernel's entropy pool. The service will fail if @var{device} does not exist. @end table @end deftp @cindex session limits @cindex ulimit @cindex priority @cindex realtime @cindex jackd @cindex nofile @cindex open file descriptors @anchor{pam-limits-service-type} @defvar pam-limits-service-type Type of the service that installs a configuration file for the @uref{http://linux-pam.org/Linux-PAM-html/sag-pam_limits.html, @code{pam_limits} module}. The value for this service type is a list of @code{pam-limits-entry} values, which can be used to specify @code{ulimit} limits and @code{nice} priority limits to user sessions. By default, the value is the empty list. The following limits definition sets two hard and soft limits for all login sessions of users in the @code{realtime} group: @lisp (service pam-limits-service-type (list (pam-limits-entry "@@realtime" 'both 'rtprio 99) (pam-limits-entry "@@realtime" 'both 'memlock 'unlimited))) @end lisp The first entry increases the maximum realtime priority for non-privileged processes; the second entry lifts any restriction of the maximum address space that can be locked in memory. These settings are commonly used for real-time audio systems. Another useful example is raising the maximum number of open file descriptors that can be used: @lisp (service pam-limits-service-type (list (pam-limits-entry "*" 'both 'nofile 100000))) @end lisp In the above example, the asterisk means the limit should apply to any user. It is important to ensure the chosen value doesn't exceed the maximum system value visible in the @file{/proc/sys/fs/file-max} file, else the users would be prevented from login in. For more information about the Pluggable Authentication Module (PAM) limits, refer to the @samp{pam_limits} man page from the @code{linux-pam} package. @end defvar @defvar greetd-service-type @uref{https://git.sr.ht/~kennylevinsen/greetd, @code{greetd}} is a minimal and flexible login manager daemon, that makes no assumptions about what you want to launch. If you can run it from your shell in a TTY, greetd can start it. If it can be taught to speak a simple JSON-based IPC protocol, then it can be a geeter. @code{greetd-service-type} provides necessary infrastructure for logging in users, including: @itemize @bullet @item @code{greetd} PAM service @item Special variation of @code{pam-mount} to mount @code{XDG_RUNTIME_DIR} @end itemize Here is an example of switching from @code{mingetty-service-type} to @code{greetd-service-type}, and how different terminals could be: @lisp (append (modify-services %base-services ;; greetd-service-type provides "greetd" PAM service (delete login-service-type) ;; and can be used in place of mingetty-service-type (delete mingetty-service-type)) (list (service greetd-service-type (greetd-configuration (terminals (list ;; we can make any terminal active by default (greetd-terminal-configuration (terminal-vt "1") (terminal-switch #t)) ;; we can make environment without XDG_RUNTIME_DIR set ;; even provide our own environment variables (greetd-terminal-configuration (terminal-vt "2") (default-session-command (greetd-agreety-session (extra-env '(("MY_VAR" . "1"))) (xdg-env? #f)))) ;; we can use different shell instead of default bash (greetd-terminal-configuration (terminal-vt "3") (default-session-command (greetd-agreety-session (command (file-append zsh "/bin/zsh"))))) ;; we can use any other executable command as greeter (greetd-terminal-configuration (terminal-vt "4") (default-session-command (program-file "my-noop-greeter" #~(exit)))) (greetd-terminal-configuration (terminal-vt "5")) (greetd-terminal-configuration (terminal-vt "6")))))) ;; mingetty-service-type can be used in parallel ;; if needed to do so, do not (delete login-service-type) ;; as illustrated above #| (service mingetty-service-type (mingetty-configuration (tty "tty8"))) |#)) @end lisp @end defvar @deftp {Data Type} greetd-configuration Configuration record for the @code{greetd-service-type}. @table @asis @item @code{motd} A file-like object containing the ``message of the day''. @item @code{allow-empty-passwords?} (default: @code{#t}) Allow empty passwords by default so that first-time users can log in when the 'root' account has just been created. @item @code{terminals} (default: @code{'()}) List of @code{greetd-terminal-configuration} per terminal for which @code{greetd} should be started. @item @code{greeter-supplementary-groups} (default: @code{'()}) List of groups which should be added to @code{greeter} user. For instance: @lisp (greeter-supplementary-groups '("seat" "video")) @end lisp Note that this example will fail if @code{seat} group does not exist. @end table @end deftp @deftp {Data Type} greetd-terminal-configuration Configuration record for per terminal greetd daemon service. @table @asis @item @code{greetd} (default: @code{greetd}) The greetd package to use. @item @code{config-file-name} Configuration file name to use for greetd daemon. Generally, autogenerated derivation based on @code{terminal-vt} value. @item @code{log-file-name} Log file name to use for greetd daemon. Generally, autogenerated name based on @code{terminal-vt} value. @item @code{terminal-vt} (default: @samp{"7"}) The VT to run on. Use of a specific VT with appropriate conflict avoidance is recommended. @item @code{terminal-switch} (default: @code{#f}) Make this terminal active on start of @code{greetd}. @item @code{source-profile?} (default: @code{#t}) Whether to source @file{/etc/profile} and @file{~/.profile}, when they exist. @item @code{default-session-user} (default: @samp{"greeter"}) The user to use for running the greeter. @item @code{default-session-command} (default: @code{(greetd-agreety-session)}) Can be either instance of @code{greetd-agreety-session} configuration or @code{gexp->script} like object to use as greeter. @end table @end deftp @deftp {Data Type} greetd-agreety-session Configuration record for the agreety greetd greeter. @table @asis @item @code{agreety} (default: @code{greetd}) The package with @command{/bin/agreety} command. @item @code{command} (default: @code{(file-append bash "/bin/bash")}) Command to be started by @command{/bin/agreety} on successful login. @item @code{command-args} (default: @code{'("-l")}) Command arguments to pass to command. @item @code{extra-env} (default: @code{'()}) Extra environment variables to set on login. @item @code{xdg-env?} (default: @code{#t}) If true @code{XDG_RUNTIME_DIR} and @code{XDG_SESSION_TYPE} will be set before starting command. One should note that, @code{extra-env} variables are set right after mentioned variables, so that they can be overridden. @end table @end deftp @deftp {Data Type} greetd-wlgreet-session Generic configuration record for the wlgreet greetd greeter. @table @asis @item @code{wlgreet} (default: @code{wlgreet}) The package with the @command{/bin/wlgreet} command. @item @code{command} (default: @code{(file-append sway "/bin/sway")}) Command to be started by @command{/bin/wlgreet} on successful login. @item @code{command-args} (default: @code{'()}) Command arguments to pass to command. @item @code{output-mode} (default: @code{"all"}) Option to use for @code{outputMode} in the TOML configuration file. @item @code{scale} (default: @code{1}) Option to use for @code{scale} in the TOML configuration file. @item @code{background} (default: @code{'(0 0 0 0.9)}) RGBA list to use as the background colour of the login prompt. @item @code{headline} (default: @code{'(1 1 1 1)}) RGBA list to use as the headline colour of the UI popup. @item @code{prompt} (default: @code{'(1 1 1 1)}) RGBA list to use as the prompt colour of the UI popup. @item @code{prompt-error} (default: @code{'(1 1 1 1)}) RGBA list to use as the error colour of the UI popup. @item @code{border} (default: @code{'(1 1 1 1)}) RGBA list to use as the border colour of the UI popup. @item @code{extra-env} (default: @code{'()}) Extra environment variables to set on login. @end table @end deftp @deftp {Data Type} greetd-wlgreet-sway-session Sway-specific configuration record for the wlgreet greetd greeter. @table @asis @item @code{wlgreet-session} (default: @code{(greetd-wlgreet-session)}) A @code{greetd-wlgreet-session} record for generic wlgreet configuration, on top of the Sway-specific @code{greetd-wlgreet-sway-session}. @item @code{sway} (default: @code{sway}) The package providing the @command{/bin/sway} command. @item @code{sway-configuration} (default: #f) File-like object providing an additional Sway configuration file to be prepended to the mandatory part of the configuration. @end table Here is an example of a greetd configuration that uses wlgreet and Sway: @lisp (greetd-configuration ;; We need to give the greeter user these permissions, otherwise ;; Sway will crash on launch. (greeter-supplementary-groups (list "video" "input" "seat")) (terminals (list (greetd-terminal-configuration (terminal-vt "1") (terminal-switch #t) (default-session-command (greetd-wlgreet-sway-session (sway-configuration (local-file "sway-greetd.conf")))))))) @end lisp @end deftp @node Scheduled Job Execution @subsection Scheduled Job Execution @cindex cron @cindex mcron @cindex scheduling jobs The @code{(gnu services mcron)} module provides an interface to GNU@tie{}mcron, a daemon to run jobs at scheduled times (@pxref{Top,,, mcron, GNU@tie{}mcron}). GNU@tie{}mcron is similar to the traditional Unix @command{cron} daemon; the main difference is that it is implemented in Guile Scheme, which provides a lot of flexibility when specifying the scheduling of jobs and their actions. The example below defines an operating system that runs the @command{updatedb} (@pxref{Invoking updatedb,,, find, Finding Files}) and the @command{guix gc} commands (@pxref{Invoking guix gc}) daily, as well as the @command{mkid} command on behalf of an unprivileged user (@pxref{mkid invocation,,, idutils, ID Database Utilities}). It uses gexps to introduce job definitions that are passed to mcron (@pxref{G-Expressions}). @lisp (use-modules (guix) (gnu) (gnu services mcron)) (use-package-modules base idutils) (define updatedb-job ;; Run 'updatedb' at 3AM every day. Here we write the ;; job's action as a Scheme procedure. #~(job '(next-hour '(3)) (lambda () (system* (string-append #$findutils "/bin/updatedb") "--prunepaths=/tmp /var/tmp /gnu/store")) "updatedb")) (define garbage-collector-job ;; Collect garbage 5 minutes after midnight every day. ;; The job's action is a shell command. #~(job "5 0 * * *" ;Vixie cron syntax "guix gc -F 1G")) (define idutils-job ;; Update the index database as user "charlie" at 12:15PM ;; and 19:15PM. This runs from the user's home directory. #~(job '(next-minute-from (next-hour '(12 19)) '(15)) (string-append #$idutils "/bin/mkid src") #:user "charlie")) (operating-system ;; @dots{} ;; %BASE-SERVICES already includes an instance of ;; 'mcron-service-type', which we extend with additional ;; jobs using 'simple-service'. (services (cons (simple-service 'my-cron-jobs mcron-service-type (list garbage-collector-job updatedb-job idutils-job)) %base-services))) @end lisp @quotation Tip When providing the action of a job specification as a procedure, you should provide an explicit name for the job via the optional 3rd argument as done in the @code{updatedb-job} example above. Otherwise, the job would appear as ``Lambda function'' in the output of @command{herd schedule mcron}, which is not nearly descriptive enough! @end quotation @quotation Tip Avoid calling the Guile procedures @code{execl}, @code{execle} or @code{execlp} inside a job specification, else mcron won't be able to output the completion status of the job. @end quotation For more complex jobs defined in Scheme where you need control over the top level, for instance to introduce a @code{use-modules} form, you can move your code to a separate program using the @code{program-file} procedure of the @code{(guix gexp)} module (@pxref{G-Expressions}). The example below illustrates that. @lisp (define %battery-alert-job ;; Beep when the battery percentage falls below %MIN-LEVEL. #~(job '(next-minute (range 0 60 1)) #$(program-file "battery-alert.scm" (with-imported-modules (source-module-closure '((guix build utils))) #~(begin (use-modules (guix build utils) (ice-9 popen) (ice-9 regex) (ice-9 textual-ports) (srfi srfi-2)) (define %min-level 20) (setenv "LC_ALL" "C") ;ensure English output (and-let* ((input-pipe (open-pipe* OPEN_READ #$(file-append acpi "/bin/acpi"))) (output (get-string-all input-pipe)) (m (string-match "Discharging, ([0-9]+)%" output)) (level (string->number (match:substring m 1))) ((< level %min-level))) (format #t "warning: Battery level is low (~a%)~%" level) (invoke #$(file-append beep "/bin/beep") "-r5"))))))) @end lisp @xref{Guile Syntax, mcron job specifications,, mcron, GNU@tie{}mcron}, for more information on mcron job specifications. Below is the reference of the mcron service. On a running system, you can use the @code{schedule} action of the service to visualize the mcron jobs that will be executed next: @example # herd schedule mcron @end example @noindent The example above lists the next five tasks that will be executed, but you can also specify the number of tasks to display: @example # herd schedule mcron 10 @end example @defvar mcron-service-type This is the type of the @code{mcron} service, whose value is an @code{mcron-configuration} object. This service type can be the target of a service extension that provides additional job specifications (@pxref{Service Composition}). In other words, it is possible to define services that provide additional mcron jobs to run. @end defvar @c Generated via (generate-documentation) at the bottom of (gnu services @c mcron). @c %start of fragment @deftp {Data Type} mcron-configuration Available @code{mcron-configuration} fields are: @table @asis @item @code{mcron} (default: @code{mcron}) (type: file-like) The mcron package to use. @item @code{jobs} (default: @code{'()}) (type: list-of-gexps) This is a list of gexps (@pxref{G-Expressions}), where each gexp corresponds to an mcron job specification (@pxref{Syntax, mcron job specifications,, mcron,GNU@tie{}mcron}). @item @code{log?} (default: @code{#t}) (type: boolean) Log messages to standard output. @item @code{log-file} (default: @code{"/var/log/mcron.log"}) (type: string) Log file location. @item @code{log-format} (default: @code{"~1@@*~a ~a: ~a~%"}) (type: string) @code{(ice-9 format)} format string for log messages. The default value produces messages like @samp{@var{pid} @var{name}: @var{message}} (@pxref{Invoking mcron, Invoking,, mcron,GNU@tie{}mcron}). Each message is also prefixed by a timestamp by GNU Shepherd. @item @code{date-format} (type: maybe-string) @code{(srfi srfi-19)} format string for date. @end table @end deftp @c %end of fragment @node Log Rotation @subsection Log Rotation @cindex rottlog @cindex log rotation @cindex logging Log files such as those found in @file{/var/log} tend to grow endlessly, so it's a good idea to @dfn{rotate} them once in a while---i.e., archive their contents in separate files, possibly compressed. The @code{(gnu services admin)} module provides an interface to GNU@tie{}Rot[t]log, a log rotation tool (@pxref{Top,,, rottlog, GNU Rot[t]log Manual}). This service is part of @code{%base-services}, and thus enabled by default, with the default settings, for commonly encountered log files. The example below shows how to extend it with an additional @dfn{rotation}, should you need to do that (usually, services that produce log files already take care of that): @lisp (use-modules (guix) (gnu)) (use-service-modules admin) (define my-log-files ;; Log files that I want to rotate. '("/var/log/something.log" "/var/log/another.log")) (operating-system ;; @dots{} (services (cons (simple-service 'rotate-my-stuff rottlog-service-type (list (log-rotation (frequency 'daily) (files my-log-files)))) %base-services))) @end lisp @defvar rottlog-service-type This is the type of the Rottlog service, whose value is a @code{rottlog-configuration} object. Other services can extend this one with new @code{log-rotation} objects (see below), thereby augmenting the set of files to be rotated. This service type can define mcron jobs (@pxref{Scheduled Job Execution}) to run the rottlog service. @end defvar @deftp {Data Type} rottlog-configuration Data type representing the configuration of rottlog. @table @asis @item @code{rottlog} (default: @code{rottlog}) The Rottlog package to use. @item @code{rc-file} (default: @code{(file-append rottlog "/etc/rc")}) The Rottlog configuration file to use (@pxref{Mandatory RC Variables,,, rottlog, GNU Rot[t]log Manual}). @item @code{rotations} (default: @code{%default-rotations}) A list of @code{log-rotation} objects as defined below. @item @code{jobs} This is a list of gexps where each gexp corresponds to an mcron job specification (@pxref{Scheduled Job Execution}). @end table @end deftp @deftp {Data Type} log-rotation Data type representing the rotation of a group of log files. Taking an example from the Rottlog manual (@pxref{Period Related File Examples,,, rottlog, GNU Rot[t]log Manual}), a log rotation might be defined like this: @lisp (log-rotation (frequency 'daily) (files '("/var/log/apache/*")) (options '("storedir apache-archives" "rotate 6" "notifempty" "nocompress"))) @end lisp The list of fields is as follows: @table @asis @item @code{frequency} (default: @code{'weekly}) The log rotation frequency, a symbol. @item @code{files} The list of files or file glob patterns to rotate. @vindex %default-log-rotation-options @item @code{options} (default: @code{%default-log-rotation-options}) The list of rottlog options for this rotation (@pxref{Configuration parameters,,, rottlog, GNU Rot[t]log Manual}). @item @code{post-rotate} (default: @code{#f}) Either @code{#f} or a gexp to execute once the rotation has completed. @end table @end deftp @defvar %default-rotations Specifies weekly rotation of @code{%rotated-files} and of @file{/var/log/guix-daemon.log}. @end defvar @defvar %rotated-files The list of syslog-controlled files to be rotated. By default it is: @code{'("/var/log/messages" "/var/log/secure" "/var/log/debug" \ "/var/log/maillog")}. @end defvar Some log files just need to be deleted periodically once they are old, without any other criterion and without any archival step. This is the case of build logs stored by @command{guix-daemon} under @file{/var/log/guix/drvs} (@pxref{Invoking guix-daemon}). The @code{log-cleanup} service addresses this use case. For example, @code{%base-services} (@pxref{Base Services}) includes the following: @lisp ;; Periodically delete old build logs. (service log-cleanup-service-type (log-cleanup-configuration (directory "/var/log/guix/drvs"))) @end lisp That ensures build logs do not accumulate endlessly. @defvar log-cleanup-service-type This is the type of the service to delete old logs. Its value must be a @code{log-cleanup-configuration} record as described below. @end defvar @deftp {Data Type} log-cleanup-configuration Data type representing the log cleanup configuration @table @asis @item @code{directory} Name of the directory containing log files. @item @code{expiry} (default: @code{(* 6 30 24 3600)}) Age in seconds after which a file is subject to deletion (six months by default). @item @code{schedule} (default: @code{"30 12 01,08,15,22 * *"}) String or gexp denoting the corresponding mcron job schedule (@pxref{Scheduled Job Execution}). @end table @end deftp @cindex logging, anonymization @subheading Anonip Service Anonip is a privacy filter that removes IP address from web server logs. This service creates a FIFO and filters any written lines with anonip before writing the filtered log to a target file. The following example sets up the FIFO @file{/var/run/anonip/https.access.log} and writes the filtered log file @file{/var/log/anonip/https.access.log}. @lisp (service anonip-service-type (anonip-configuration (input "/var/run/anonip/https.access.log") (output "/var/log/anonip/https.access.log"))) @end lisp Configure your web server to write its logs to the FIFO at @file{/var/run/anonip/https.access.log} and collect the anonymized log file at @file{/var/web-logs/https.access.log}. @deftp {Data Type} anonip-configuration This data type represents the configuration of anonip. It has the following parameters: @table @asis @item @code{anonip} (default: @code{anonip}) The anonip package to use. @item @code{input} The file name of the input log file to process. The service creates a FIFO of this name. The web server should write its logs to this FIFO. @item @code{output} The file name of the processed log file. @end table The following optional settings may be provided: @table @code @item debug? Print debug messages when @code{#true}. @item skip-private? When @code{#true} do not mask addresses in private ranges. @item column A 1-based indexed column number. Assume IP address is in the specified column (default is 1). @item replacement Replacement string in case address parsing fails, e.g. @code{"0.0.0.0"}. @item ipv4mask Number of bits to mask in IPv4 addresses. @item ipv6mask Number of bits to mask in IPv6 addresses. @item increment Increment the IP address by the given number. By default this is zero. @item delimiter Log delimiter string. @item regex Regular expression for detecting IP addresses. Use this instead of @code{column}. @end table @end deftp @node Networking Setup @subsection Networking Setup The @code{(gnu services networking)} module provides services to configure network interfaces and set up networking on your machine. Those services provide different ways for you to set up your machine: by declaring a static network configuration, by running a Dynamic Host Configuration Protocol (DHCP) client, or by running daemons such as NetworkManager and Connman that automate the whole process, automatically adapt to connectivity changes, and provide a high-level user interface. On a laptop, NetworkManager and Connman are by far the most convenient options, which is why the default desktop services include NetworkManager (@pxref{Desktop Services, @code{%desktop-services}}). For a server, or for a virtual machine or a container, static network configuration or a simple DHCP client are often more appropriate. This section describes the various network setup services available, starting with static network configuration. @defvar static-networking-service-type This is the type for statically-configured network interfaces. Its value must be a list of @code{static-networking} records. Each of them declares a set of @dfn{addresses}, @dfn{routes}, and @dfn{links}, as shown below. @cindex network interface controller (NIC) @cindex NIC, networking interface controller Here is the simplest configuration, with only one network interface controller (NIC) and only IPv4 connectivity: @lisp ;; Static networking for one NIC, IPv4-only. (service static-networking-service-type (list (static-networking (addresses (list (network-address (device "eno1") (value "10.0.2.15/24")))) (routes (list (network-route (destination "default") (gateway "10.0.2.2")))) (name-servers '("10.0.2.3"))))) @end lisp The snippet above can be added to the @code{services} field of your operating system configuration (@pxref{Using the Configuration System}). It will configure your machine to have 10.0.2.15 as its IP address, with a 24-bit netmask for the local network---meaning that any 10.0.2.@var{x} address is on the local area network (LAN). Traffic to addresses outside the local network is routed @i{via} 10.0.2.2. Host names are resolved by sending domain name system (DNS) queries to 10.0.2.3. @end defvar @deftp {Data Type} static-networking This is the data type representing a static network configuration. As an example, here is how you would declare the configuration of a machine with a single network interface controller (NIC) available as @code{eno1}, and with one IPv4 and one IPv6 address: @lisp ;; Network configuration for one NIC, IPv4 + IPv6. (static-networking (addresses (list (network-address (device "eno1") (value "10.0.2.15/24")) (network-address (device "eno1") (value "2001:123:4567:101::1/64")))) (routes (list (network-route (destination "default") (gateway "10.0.2.2")) (network-route (destination "default") (gateway "2020:321:4567:42::1")))) (name-servers '("10.0.2.3"))) @end lisp If you are familiar with the @command{ip} command of the @uref{https://wiki.linuxfoundation.org/networking/iproute2, @code{iproute2} package} found on Linux-based systems, the declaration above is equivalent to typing: @example ip address add 10.0.2.15/24 dev eno1 ip address add 2001:123:4567:101::1/64 dev eno1 ip route add default via inet 10.0.2.2 ip route add default via inet6 2020:321:4567:42::1 @end example Run @command{man 8 ip} for more info. Venerable GNU/Linux users will certainly know how to do it with @command{ifconfig} and @command{route}, but we'll spare you that. The available fields of this data type are as follows: @table @asis @item @code{addresses} @itemx @code{links} (default: @code{'()}) @itemx @code{routes} (default: @code{'()}) The list of @code{network-address}, @code{network-link}, and @code{network-route} records for this network (see below). @item @code{name-servers} (default: @code{'()}) The list of IP addresses (strings) of domain name servers. These IP addresses go to @file{/etc/resolv.conf}. @item @code{provision} (default: @code{'(networking)}) If true, this should be a list of symbols for the Shepherd service corresponding to this network configuration. @item @code{requirement} (default @code{'()}) The list of Shepherd services depended on. @end table @end deftp @deftp {Data Type} network-address This is the data type representing the IP address of a network interface. @table @code @item device The name of the network interface for this address---e.g., @code{"eno1"}. @item value The actual IP address and network mask, in @uref{https://en.wikipedia.org/wiki/CIDR#CIDR_notation, @acronym{CIDR, Classless Inter-Domain Routing} notation}, as a string. For example, @code{"10.0.2.15/24"} denotes IPv4 address 10.0.2.15 on a 24-bit sub-network---all 10.0.2.@var{x} addresses are on the same local network. @item ipv6? Whether @code{value} denotes an IPv6 address. By default this is automatically determined. @end table @end deftp @deftp {Data Type} network-route This is the data type representing a network route. @table @asis @item @code{destination} The route destination (a string), either an IP address and network mask or @code{"default"} to denote the default route. @item @code{source} (default: @code{#f}) The route source. @item @code{device} (default: @code{#f}) The device used for this route---e.g., @code{"eno2"}. @item @code{ipv6?} (default: auto) Whether this is an IPv6 route. By default this is automatically determined based on @code{destination} or @code{gateway}. @item @code{gateway} (default: @code{#f}) IP address (a string) through which traffic is routed. @end table @end deftp @deftp {Data Type} network-link Data type for a network link (@pxref{Link,,, guile-netlink, Guile-Netlink Manual}). During startup, network links are employed to construct or modify existing or virtual ethernet links. These ethernet links can be identified by their @var{name} or @var{mac-address}. If there is a need to create virtual interface, @var{name} and @var{type} fields are required. @table @code @item name The name of the link---e.g., @code{"v0p0"} (default: @code{#f}). @item type A symbol denoting the type of the link---e.g., @code{'veth} (default: @code{#f}). @item mac-address The mac-address of the link---e.g., @code{"98:11:22:33:44:55"} (default: @code{#f}). @item arguments List of arguments for this type of link. @end table @end deftp Consider a scenario where a server equipped with a network interface which has multiple ports. These ports are connected to a switch, which supports @uref{https://en.wikipedia.org/wiki/Link_aggregation, link aggregation} (also known as bonding or NIC teaming). The switch uses port channels to consolidate multiple physical interfaces into one logical interface to provide higher bandwidth, load balancing, and link redundancy. When a port is added to a LAG (or link aggregation group), it inherits the properties of the port-channel. Some of these properties are VLAN membership, trunk status, and so on. @uref{https://en.wikipedia.org/wiki/Virtual_LAN, VLAN} (or virtual local area network) is a logical network that is isolated from other VLANs on the same physical network. This can be used to segregate traffic, improve security, and simplify network management. With all that in mind let's configure our static network for the server. We will bond two existing interfaces together using 802.3ad schema and on top of it, build a VLAN interface with id 1055. We assign a static ip to our new VLAN interface. @lisp (static-networking (links (list (network-link (name "bond0") (type 'bond) (arguments '((mode . "802.3ad") (miimon . 100) (lacp-active . "on") (lacp-rate . "fast")))) (network-link (mac-address "98:11:22:33:44:55") (arguments '((master . "bond0")))) (network-link (mac-address "98:11:22:33:44:56") (arguments '((master . "bond0")))) (network-link (name "bond0.1055") (type 'vlan) (arguments '((id . 1055) (link . "bond0")))))) (addresses (list (network-address (value "192.168.1.4/24") (device "bond0.1055"))))) @end lisp @cindex loopback device @defvar %loopback-static-networking This is the @code{static-networking} record representing the ``loopback device'', @code{lo}, for IP addresses 127.0.0.1 and ::1, and providing the @code{loopback} Shepherd service. @end defvar @cindex networking, with QEMU @cindex QEMU, networking @defvar %qemu-static-networking This is the @code{static-networking} record representing network setup when using QEMU's user-mode network stack on @code{eth0} (@pxref{Using the user mode network stack,,, qemu, QEMU Documentation}). @end defvar @cindex DHCP, networking service @defvar dhcp-client-service-type This is the type of services that run @var{dhclient}, the ISC Dynamic Host Configuration Protocol (DHCP) client. @end defvar @deftp {Data Type} dhcp-client-configuration Data type representing the configuration of the ISC DHCP client service. @table @asis @item @code{package} (default: @code{isc-dhcp}) The ISC DHCP client package to use. @item @code{interfaces} (default: @code{'all}) Either @code{'all} or the list of interface names that the ISC DHCP client should listen on---e.g., @code{'("eno1")}. When set to @code{'all}, the ISC DHCP client listens on all the available non-loopback interfaces that can be activated. Otherwise the ISC DHCP client listens only on the specified interfaces. @item @code{config-file} (default: @code{#f}) The configuration file for the ISC DHCP client. @item @code{version} (default: @code{"4"}) The DHCP protocol version to use, as a string. Accepted values are @code{"4"} or @code{"6"} for DHCPv4 or DHCPv6, respectively, as well as @code{"4o6"}, for DHCPv4 over DHCPv6 (as specified by RFC 7341). @item @code{shepherd-requirement} (default: @code{'()}) @itemx @code{shepherd-provision} (default: @code{'(networking)}) This option can be used to provide a list of symbols naming Shepherd services that this service will depend on, such as @code{'wpa-supplicant} or @code{'iwd} if you require authenticated access for encrypted WiFi or Ethernet networks. Likewise, @code{shepherd-provision} is a list of Shepherd service names (symbols) provided by this service. You might want to change the default value if you intend to run several ISC DHCP clients, only one of which provides the @code{networking} Shepherd service. @end table @end deftp @cindex NetworkManager @defvar network-manager-service-type This is the service type for the @uref{https://wiki.gnome.org/Projects/NetworkManager, NetworkManager} service. The value for this service type is a @code{network-manager-configuration} record. This service is part of @code{%desktop-services} (@pxref{Desktop Services}). @end defvar @deftp {Data Type} network-manager-configuration Data type representing the configuration of NetworkManager. @table @asis @item @code{network-manager} (default: @code{network-manager}) The NetworkManager package to use. @item @code{shepherd-requirement} (default: @code{'(wpa-supplicant)}) This option can be used to provide a list of symbols naming Shepherd services that this service will depend on, such as @code{'wpa-supplicant} or @code{'iwd} if you require authenticated access for encrypted WiFi or Ethernet networks. @item @code{dns} (default: @code{"default"}) Processing mode for DNS, which affects how NetworkManager uses the @code{resolv.conf} configuration file. @table @samp @item default NetworkManager will update @code{resolv.conf} to reflect the nameservers provided by currently active connections. @item dnsmasq NetworkManager will run @code{dnsmasq} as a local caching nameserver, using a @dfn{conditional forwarding} configuration if you are connected to a VPN, and then update @code{resolv.conf} to point to the local nameserver. With this setting, you can share your network connection. For example when you want to share your network connection to another laptop @i{via} an Ethernet cable, you can open @command{nm-connection-editor} and configure the Wired connection's method for IPv4 and IPv6 to be ``Shared to other computers'' and reestablish the connection (or reboot). You can also set up a @dfn{host-to-guest connection} to QEMU VMs (@pxref{Installing Guix in a VM}). With a host-to-guest connection, you can e.g.@: access a Web server running on the VM (@pxref{Web Services}) from a Web browser on your host system, or connect to the VM @i{via} SSH (@pxref{Networking Services, @code{openssh-service-type}}). To set up a host-to-guest connection, run this command once: @example nmcli connection add type tun \ connection.interface-name tap0 \ tun.mode tap tun.owner $(id -u) \ ipv4.method shared \ ipv4.addresses 172.28.112.1/24 @end example Then each time you launch your QEMU VM (@pxref{Running Guix in a VM}), pass @option{-nic tap,ifname=tap0,script=no,downscript=no} to @command{qemu-system-...}. @item none NetworkManager will not modify @code{resolv.conf}. @end table @item @code{vpn-plugins} (default: @code{'()}) This is the list of available plugins for virtual private networks (VPNs). An example of this is the @code{network-manager-openvpn} package, which allows NetworkManager to manage VPNs @i{via} OpenVPN. @end table @end deftp @cindex Connman @defvar connman-service-type This is the service type to run @url{https://01.org/connman,Connman}, a network connection manager. Its value must be a @code{connman-configuration} record as in this example: @lisp (service connman-service-type (connman-configuration (disable-vpn? #t))) @end lisp See below for details about @code{connman-configuration}. @end defvar @deftp {Data Type} connman-configuration Data Type representing the configuration of connman. @table @asis @item @code{connman} (default: @var{connman}) The connman package to use. @item @code{shepherd-requirement} (default: @code{'()}) This option can be used to provide a list of symbols naming Shepherd services that this service will depend on, such as @code{'wpa-supplicant} or @code{'iwd} if you require authenticated access for encrypted WiFi or Ethernet networks. @item @code{disable-vpn?} (default: @code{#f}) When true, disable connman's vpn plugin. @item @code{general-configuration} (default: @code{(connman-general-configuration)}) Configuration serialized to @file{main.conf} and passed as @option{--config} to @command{connmand}. @end table @end deftp @c %start of fragment @deftp {Data Type} connman-general-configuration Available @code{connman-general-configuration} fields are: @table @asis @item @code{input-request-timeout} (type: maybe-number) Set input request timeout. Default is 120 seconds. The request for inputs like passphrase will timeout after certain amount of time. Use this setting to increase the value in case of different user interface designs. @item @code{browser-launch-timeout} (type: maybe-number) Set browser launch timeout. Default is 300 seconds. The request for launching a browser for portal pages will timeout after certain amount of time. Use this setting to increase the value in case of different user interface designs. @item @code{background-scanning?} (type: maybe-boolean) Enable background scanning. Default is true. If wifi is disconnected, the background scanning will follow a simple back off mechanism from 3s up to 5 minutes. Then, it will stay in 5 minutes unless user specifically asks for scanning through a D-Bus call. If so, the mechanism will start again from 3s. This feature activates also the background scanning while being connected, which is required for roaming on wifi. When @code{background-scanning?} is false, ConnMan will not perform any scan regardless of wifi is connected or not, unless it is requested by the user through a D-Bus call. @item @code{use-gateways-as-timeservers?} (type: maybe-boolean) Assume that service gateways also function as timeservers. Default is false. @item @code{fallback-timeservers} (type: maybe-list) List of Fallback timeservers. These timeservers are used for NTP sync when there are no timeservers set by the user or by the service, and when @code{use-gateways-as-timeservers?} is @code{#f}. These can contain a mixed combination of fully qualified domain names, IPv4 and IPv6 addresses. @item @code{fallback-nameservers} (type: maybe-list) List of fallback nameservers appended to the list of nameservers given by the service. The nameserver entries must be in numeric format, host names are ignored. @item @code{default-auto-connect-technologies} (type: maybe-list) List of technologies that are marked autoconnectable by default. The default value for this entry when empty is @code{"ethernet"}, @code{"wifi"}, @code{"cellular"}. Services that are automatically connected must have been set up and saved to storage beforehand. @item @code{default-favourite-technologies} (type: maybe-list) List of technologies that are marked favorite by default. The default value for this entry when empty is @code{"ethernet"}. Connects to services from this technology even if not setup and saved to storage. @item @code{always-connected-technologies} (type: maybe-list) List of technologies which are always connected regardless of preferred-technologies setting (@code{auto-connect?} @code{#t}). The default value is empty and this feature is disabled unless explicitly enabled. @item @code{preferred-technologies} (type: maybe-list) List of preferred technologies from the most preferred one to the least preferred one. Services of the listed technology type will be tried one by one in the order given, until one of them gets connected or they are all tried. A service of a preferred technology type in state 'ready' will get the default route when compared to another preferred type further down the list with state 'ready' or with a non-preferred type; a service of a preferred technology type in state 'online' will get the default route when compared to either a non-preferred type or a preferred type further down in the list. @item @code{network-interface-blacklist} (type: maybe-list) List of blacklisted network interfaces. Found interfaces will be compared to the list and will not be handled by ConnMan, if their first characters match any of the list entries. Default value is @code{"vmnet"}, @code{"vboxnet"}, @code{"virbr"}, @code{"ifb"}. @item @code{allow-hostname-updates?} (type: maybe-boolean) Allow ConnMan to change the system hostname. This can happen for example if we receive DHCP hostname option. Default value is @code{#t}. @item @code{allow-domainname-updates?} (type: maybe-boolean) Allow connman to change the system domainname. This can happen for example if we receive DHCP domainname option. Default value is @code{#t}. @item @code{single-connected-technology?} (type: maybe-boolean) Keep only a single connected technology at any time. When a new service is connected by the user or a better one is found according to preferred-technologies, the new service is kept connected and all the other previously connected services are disconnected. With this setting it does not matter whether the previously connected services are in 'online' or 'ready' states, the newly connected service is the only one that will be kept connected. A service connected by the user will be used until going out of network coverage. With this setting enabled applications will notice more network breaks than normal. Note this options can't be used with VPNs. Default value is @code{#f}. @item @code{tethering-technologies} (type: maybe-list) List of technologies that are allowed to enable tethering. The default value is @code{"wifi"}, @code{"bluetooth"}, @code{"gadget"}. Only those technologies listed here are used for tethering. If one wants to tether ethernet, then add @code{"ethernet"} in the list. Note that if ethernet tethering is enabled, then a DHCP server is started on all ethernet interfaces. Tethered ethernet should never be connected to corporate or home network as it will disrupt normal operation of these networks. Due to this ethernet is not tethered by default. Do not activate ethernet tethering unless you really know what you are doing. @item @code{persistent-tethering-mode?} (type: maybe-boolean) Restore earlier tethering status when returning from offline mode, re-enabling a technology, and after restarts and reboots. Default value is @code{#f}. @item @code{enable-6to4?} (type: maybe-boolean) Automatically enable anycast 6to4 if possible. This is not recommended, as the use of 6to4 will generally lead to a severe degradation of connection quality. See RFC6343. Default value is @code{#f} (as recommended by RFC6343 section 4.1). @item @code{vendor-class-id} (type: maybe-string) Set DHCP option 60 (Vendor Class ID) to the given string. This option can be used by DHCP servers to identify specific clients without having to rely on MAC address ranges, etc. @item @code{enable-online-check?} (type: maybe-boolean) Enable or disable use of HTTP GET as an online status check. When a service is in a READY state, and is selected as default, ConnMan will issue an HTTP GET request to verify that end-to-end connectivity is successful. Only then the service will be transitioned to ONLINE state. If this setting is false, the default service will remain in READY state. Default value is @code{#t}. @item @code{online-check-ipv4-url} (type: maybe-string) IPv4 URL used during the online status check. Please refer to the README for more detailed information. Default value is @uref{http://ipv4.connman.net/online/status.html}. @item @code{online-check-ipv6-url} (type: maybe-string) IPv6 URL used during the online status check. Please refer to the README for more detailed information. Default value is @uref{http://ipv6.connman.net/online/status.html}. @item @code{online-check-initial-interval} (type: maybe-number) Range of intervals between two online check requests. Please refer to the README for more detailed information. Default value is @samp{1}. @item @code{online-check-max-interval} (type: maybe-number) Range of intervals between two online check requests. Please refer to the README for more detailed information. Default value is @samp{1}. @item @code{enable-online-to-ready-transition?} (type: maybe-boolean) WARNING: This is an experimental feature. In addition to @code{enable-online-check} setting, enable or disable use of HTTP GET to detect the loss of end-to-end connectivity. If this setting is @code{#f}, when the default service transitions to ONLINE state, the HTTP GET request is no more called until next cycle, initiated by a transition of the default service to DISCONNECT state. If this setting is @code{#t}, the HTTP GET request keeps being called to guarantee that end-to-end connectivity is still successful. If not, the default service will transition to READY state, enabling another service to become the default one, in replacement. Default value is @code{#f}. @item @code{auto-connect-roaming-services?} (type: maybe-boolean) Automatically connect roaming services. This is not recommended unless you know you won't have any billing problem. Default value is @code{#f}. @item @code{address-conflict-detection?} (type: maybe-boolean) Enable or disable the implementation of IPv4 address conflict detection according to RFC5227. ConnMan will send probe ARP packets to see if an IPv4 address is already in use before assigning the address to an interface. If an address conflict occurs for a statically configured address, an IPv4LL address will be chosen instead (according to RFC3927). If an address conflict occurs for an address offered via DHCP, ConnMan sends a DHCP DECLINE once and for the second conflict resorts to finding an IPv4LL address. Default value is @code{#f}. @item @code{localtime} (type: maybe-string) Path to localtime file. Defaults to @file{/etc/localtime}. @item @code{regulatory-domain-follows-timezone?} (type: maybe-boolean) Enable regulatory domain to be changed along timezone changes. With this option set to true each time the timezone changes the first present ISO3166 country code is read from @file{/usr/share/zoneinfo/zone1970.tab} and set as regulatory domain value. Default value is @code{#f}. @item @code{resolv-conf} (type: maybe-string) Path to resolv.conf file. If the file does not exist, but intermediate directories exist, it will be created. If this option is not set, it tries to write into @file{/var/run/connman/resolv.conf} if it fails (@file{/var/run/connman} does not exist or is not writeable). If you do not want to update resolv.conf, you can set @file{/dev/null}. @end table @end deftp @cindex WPA Supplicant @defvar wpa-supplicant-service-type This is the service type to run @url{https://w1.fi/wpa_supplicant/,WPA supplicant}, an authentication daemon required to authenticate against encrypted WiFi or ethernet networks. @end defvar @deftp {Data Type} wpa-supplicant-configuration Data type representing the configuration of WPA Supplicant. It takes the following parameters: @table @asis @item @code{wpa-supplicant} (default: @code{wpa-supplicant}) The WPA Supplicant package to use. @item @code{requirement} (default: @code{'(user-processes loopback syslogd)} List of services that should be started before WPA Supplicant starts. @item @code{dbus?} (default: @code{#t}) Whether to listen for requests on D-Bus. @item @code{pid-file} (default: @code{"/var/run/wpa_supplicant.pid"}) Where to store the PID file. @item @code{interface} (default: @code{#f}) If this is set, it must specify the name of a network interface that WPA supplicant will control. @item @code{config-file} (default: @code{#f}) Optional configuration file to use. @item @code{extra-options} (default: @code{'()}) List of additional command-line arguments to pass to the daemon. @end table @end deftp @cindex ModemManager Some networking devices such as modems require special care, and this is what the services below focus on. @defvar modem-manager-service-type This is the service type for the @uref{https://wiki.gnome.org/Projects/ModemManager, ModemManager} service. The value for this service type is a @code{modem-manager-configuration} record. This service is part of @code{%desktop-services} (@pxref{Desktop Services}). @end defvar @deftp {Data Type} modem-manager-configuration Data type representing the configuration of ModemManager. @table @asis @item @code{modem-manager} (default: @code{modem-manager}) The ModemManager package to use. @end table @end deftp @cindex USB_ModeSwitch @cindex Modeswitching @defvar usb-modeswitch-service-type This is the service type for the @uref{https://www.draisberghof.de/usb_modeswitch/, USB_ModeSwitch} service. The value for this service type is a @code{usb-modeswitch-configuration} record. When plugged in, some USB modems (and other USB devices) initially present themselves as a read-only storage medium and not as a modem. They need to be @dfn{modeswitched} before they are usable. The USB_ModeSwitch service type installs udev rules to automatically modeswitch these devices when they are plugged in. This service is part of @code{%desktop-services} (@pxref{Desktop Services}). @end defvar @deftp {Data Type} usb-modeswitch-configuration Data type representing the configuration of USB_ModeSwitch. @table @asis @item @code{usb-modeswitch} (default: @code{usb-modeswitch}) The USB_ModeSwitch package providing the binaries for modeswitching. @item @code{usb-modeswitch-data} (default: @code{usb-modeswitch-data}) The package providing the device data and udev rules file used by USB_ModeSwitch. @item @code{config-file} (default: @code{#~(string-append #$usb-modeswitch:dispatcher "/etc/usb_modeswitch.conf")}) Which config file to use for the USB_ModeSwitch dispatcher. By default the config file shipped with USB_ModeSwitch is used which disables logging to @file{/var/log} among other default settings. If set to @code{#f}, no config file is used. @end table @end deftp @node Networking Services @subsection Networking Services The @code{(gnu services networking)} module discussed in the previous section provides services for more advanced setups: providing a DHCP service for others to use, filtering packets with iptables or nftables, running a WiFi access point with @command{hostapd}, running the @command{inetd} ``superdaemon'', and more. This section describes those. @defvar dhcpd-service-type This type defines a service that runs a DHCP daemon. To create a service of this type, you must supply a @code{<dhcpd-configuration>}. For example: @lisp (service dhcpd-service-type (dhcpd-configuration (config-file (local-file "my-dhcpd.conf")) (interfaces '("enp0s25")))) @end lisp @end defvar @deftp {Data Type} dhcpd-configuration @table @asis @item @code{package} (default: @code{isc-dhcp}) The package that provides the DHCP daemon. This package is expected to provide the daemon at @file{sbin/dhcpd} relative to its output directory. The default package is the @uref{https://www.isc.org/dhcp/, ISC's DHCP server}. @item @code{config-file} (default: @code{#f}) The configuration file to use. This is required. It will be passed to @code{dhcpd} via its @code{-cf} option. This may be any ``file-like'' object (@pxref{G-Expressions, file-like objects}). See @code{man dhcpd.conf} for details on the configuration file syntax. @item @code{version} (default: @code{"4"}) The DHCP version to use. The ISC DHCP server supports the values ``4'', ``6'', and ``4o6''. These correspond to the @code{dhcpd} program options @code{-4}, @code{-6}, and @code{-4o6}. See @code{man dhcpd} for details. @item @code{run-directory} (default: @code{"/run/dhcpd"}) The run directory to use. At service activation time, this directory will be created if it does not exist. @item @code{pid-file} (default: @code{"/run/dhcpd/dhcpd.pid"}) The PID file to use. This corresponds to the @code{-pf} option of @code{dhcpd}. See @code{man dhcpd} for details. @item @code{interfaces} (default: @code{'()}) The names of the network interfaces on which dhcpd should listen for broadcasts. If this list is not empty, then its elements (which must be strings) will be appended to the @code{dhcpd} invocation when starting the daemon. It may not be necessary to explicitly specify any interfaces here; see @code{man dhcpd} for details. @end table @end deftp @cindex hostapd service, for Wi-Fi access points @cindex Wi-Fi access points, hostapd service @defvar hostapd-service-type This is the service type to run the @uref{https://w1.fi/hostapd/, hostapd} daemon to set up WiFi (IEEE 802.11) access points and authentication servers. Its associated value must be a @code{hostapd-configuration} as shown below: @lisp ;; Use wlan1 to run the access point for "My Network". (service hostapd-service-type (hostapd-configuration (interface "wlan1") (ssid "My Network") (channel 12))) @end lisp @end defvar @deftp {Data Type} hostapd-configuration This data type represents the configuration of the hostapd service, with the following fields: @table @asis @item @code{package} (default: @code{hostapd}) The hostapd package to use. @item @code{interface} (default: @code{"wlan0"}) The network interface to run the WiFi access point. @item @code{ssid} The SSID (@dfn{service set identifier}), a string that identifies this network. @item @code{broadcast-ssid?} (default: @code{#t}) Whether to broadcast this SSID. @item @code{channel} (default: @code{1}) The WiFi channel to use. @item @code{driver} (default: @code{"nl80211"}) The driver interface type. @code{"nl80211"} is used with all Linux mac80211 drivers. Use @code{"none"} if building hostapd as a standalone RADIUS server that does not control any wireless/wired driver. @item @code{extra-settings} (default: @code{""}) Extra settings to append as-is to the hostapd configuration file. See @uref{https://w1.fi/cgit/hostap/plain/hostapd/hostapd.conf} for the configuration file reference. @end table @end deftp @defvar simulated-wifi-service-type This is the type of a service to simulate WiFi networking, which can be useful in virtual machines for testing purposes. The service loads the Linux kernel @uref{https://www.kernel.org/doc/html/latest/networking/mac80211_hwsim/mac80211_hwsim.html, @code{mac80211_hwsim} module} and starts hostapd to create a pseudo WiFi network that can be seen on @code{wlan0}, by default. The service's value is a @code{hostapd-configuration} record. @end defvar @cindex iptables @defvar iptables-service-type This is the service type to set up an iptables configuration. iptables is a packet filtering framework supported by the Linux kernel. This service supports configuring iptables for both IPv4 and IPv6. A simple example configuration rejecting all incoming connections except those to the ssh port 22 is shown below. @lisp (service iptables-service-type (iptables-configuration (ipv4-rules (plain-file "iptables.rules" "*filter :INPUT ACCEPT :FORWARD ACCEPT :OUTPUT ACCEPT -A INPUT -m conntrack --ctstate ESTABLISHED,RELATED -j ACCEPT -A INPUT -p tcp --dport 22 -j ACCEPT -A INPUT -j REJECT --reject-with icmp-port-unreachable COMMIT ")) (ipv6-rules (plain-file "ip6tables.rules" "*filter :INPUT ACCEPT :FORWARD ACCEPT :OUTPUT ACCEPT -A INPUT -m conntrack --ctstate ESTABLISHED,RELATED -j ACCEPT -A INPUT -p tcp --dport 22 -j ACCEPT -A INPUT -j REJECT --reject-with icmp6-port-unreachable COMMIT ")))) @end lisp @end defvar @deftp {Data Type} iptables-configuration The data type representing the configuration of iptables. @table @asis @item @code{iptables} (default: @code{iptables}) The iptables package that provides @code{iptables-restore} and @code{ip6tables-restore}. @item @code{ipv4-rules} (default: @code{%iptables-accept-all-rules}) The iptables rules to use. It will be passed to @code{iptables-restore}. This may be any ``file-like'' object (@pxref{G-Expressions, file-like objects}). @item @code{ipv6-rules} (default: @code{%iptables-accept-all-rules}) The ip6tables rules to use. It will be passed to @code{ip6tables-restore}. This may be any ``file-like'' object (@pxref{G-Expressions, file-like objects}). @end table @end deftp @cindex nftables @defvar nftables-service-type This is the service type to set up a nftables configuration. nftables is a netfilter project that aims to replace the existing iptables, ip6tables, arptables and ebtables framework. It provides a new packet filtering framework, a new user-space utility @command{nft}, and a compatibility layer for iptables. This service comes with a default ruleset @code{%default-nftables-ruleset} that rejecting all incoming connections except those to the ssh port 22. To use it, simply write: @lisp (service nftables-service-type) @end lisp @end defvar @deftp {Data Type} nftables-configuration The data type representing the configuration of nftables. @table @asis @item @code{package} (default: @code{nftables}) The nftables package that provides @command{nft}. @item @code{ruleset} (default: @code{%default-nftables-ruleset}) The nftables ruleset to use. This may be any ``file-like'' object (@pxref{G-Expressions, file-like objects}). @end table @end deftp @cindex NTP (Network Time Protocol), service @cindex ntpd, service for the Network Time Protocol daemon @cindex real time clock @defvar ntp-service-type This is the type of the service running the @uref{https://www.ntp.org, Network Time Protocol (NTP)} daemon, @command{ntpd}. The daemon will keep the system clock synchronized with that of the specified NTP servers. The value of this service is an @code{ntpd-configuration} object, as described below. @end defvar @deftp {Data Type} ntp-configuration This is the data type for the NTP service configuration. @table @asis @item @code{servers} (default: @code{%ntp-servers}) This is the list of servers (@code{<ntp-server>} records) with which @command{ntpd} will be synchronized. See the @code{ntp-server} data type definition below. @item @code{allow-large-adjustment?} (default: @code{#t}) This determines whether @command{ntpd} is allowed to make an initial adjustment of more than 1,000 seconds. @item @code{ntp} (default: @code{ntp}) The NTP package to use. @end table @end deftp @defvar %ntp-servers List of host names used as the default NTP servers. These are servers of the @uref{https://www.ntppool.org/en/, NTP Pool Project}. @end defvar @deftp {Data Type} ntp-server The data type representing the configuration of a NTP server. @table @asis @item @code{type} (default: @code{'server}) The type of the NTP server, given as a symbol. One of @code{'pool}, @code{'server}, @code{'peer}, @code{'broadcast} or @code{'manycastclient}. @item @code{address} The address of the server, as a string. @item @code{options} NTPD options to use with that specific server, given as a list of option names and/or of option names and values tuples. The following example define a server to use with the options @option{iburst} and @option{prefer}, as well as @option{version} 3 and a @option{maxpoll} time of 16 seconds. @example (ntp-server (type 'server) (address "some.ntp.server.org") (options `(iburst (version 3) (maxpoll 16) prefer)))) @end example @end table @end deftp @cindex OpenNTPD @defvar openntpd-service-type Run the @command{ntpd}, the Network Time Protocol (NTP) daemon, as implemented by @uref{http://www.openntpd.org, OpenNTPD}. The daemon will keep the system clock synchronized with that of the given servers. @lisp (service openntpd-service-type (openntpd-configuration (listen-on '("127.0.0.1" "::1")) (sensor '("udcf0 correction 70000")) (constraint-from '("www.gnu.org")) (constraints-from '("https://www.google.com/")))) @end lisp @end defvar @defvar %openntpd-servers This variable is a list of the server addresses defined in @code{%ntp-servers}. @end defvar @deftp {Data Type} openntpd-configuration @table @asis @item @code{openntpd} (default: @code{openntpd}) The openntpd package to use. @item @code{listen-on} (default: @code{'("127.0.0.1" "::1")}) A list of local IP addresses or hostnames the ntpd daemon should listen on. @item @code{query-from} (default: @code{'()}) A list of local IP address the ntpd daemon should use for outgoing queries. @item @code{sensor} (default: @code{'()}) Specify a list of timedelta sensor devices ntpd should use. @code{ntpd} will listen to each sensor that actually exists and ignore non-existent ones. See @uref{https://man.openbsd.org/ntpd.conf, upstream documentation} for more information. @item @code{server} (default: @code{'()}) Specify a list of IP addresses or hostnames of NTP servers to synchronize to. @item @code{servers} (default: @code{%openntp-servers}) Specify a list of IP addresses or hostnames of NTP pools to synchronize to. @item @code{constraint-from} (default: @code{'()}) @code{ntpd} can be configured to query the ‘Date’ from trusted HTTPS servers via TLS. This time information is not used for precision but acts as an authenticated constraint, thereby reducing the impact of unauthenticated NTP man-in-the-middle attacks. Specify a list of URLs, IP addresses or hostnames of HTTPS servers to provide a constraint. @item @code{constraints-from} (default: @code{'()}) As with constraint from, specify a list of URLs, IP addresses or hostnames of HTTPS servers to provide a constraint. Should the hostname resolve to multiple IP addresses, @code{ntpd} will calculate a median constraint from all of them. @end table @end deftp @cindex inetd @defvar inetd-service-type This service runs the @command{inetd} (@pxref{inetd invocation,,, inetutils, GNU Inetutils}) daemon. @command{inetd} listens for connections on internet sockets, and lazily starts the specified server program when a connection is made on one of these sockets. The value of this service is an @code{inetd-configuration} object. The following example configures the @command{inetd} daemon to provide the built-in @command{echo} service, as well as an smtp service which forwards smtp traffic over ssh to a server @code{smtp-server} behind a gateway @code{hostname}: @lisp (service inetd-service-type (inetd-configuration (entries (list (inetd-entry (name "echo") (socket-type 'stream) (protocol "tcp") (wait? #f) (user "root")) (inetd-entry (node "127.0.0.1") (name "smtp") (socket-type 'stream) (protocol "tcp") (wait? #f) (user "root") (program (file-append openssh "/bin/ssh")) (arguments '("ssh" "-qT" "-i" "/path/to/ssh_key" "-W" "smtp-server:25" "user@@hostname"))))))) @end lisp See below for more details about @code{inetd-configuration}. @end defvar @deftp {Data Type} inetd-configuration Data type representing the configuration of @command{inetd}. @table @asis @item @code{program} (default: @code{(file-append inetutils "/libexec/inetd")}) The @command{inetd} executable to use. @item @code{entries} (default: @code{'()}) A list of @command{inetd} service entries. Each entry should be created by the @code{inetd-entry} constructor. @end table @end deftp @deftp {Data Type} inetd-entry Data type representing an entry in the @command{inetd} configuration. Each entry corresponds to a socket where @command{inetd} will listen for requests. @table @asis @item @code{node} (default: @code{#f}) Optional string, a comma-separated list of local addresses @command{inetd} should use when listening for this service. @xref{Configuration file,,, inetutils, GNU Inetutils} for a complete description of all options. @item @code{name} A string, the name must correspond to an entry in @code{/etc/services}. @item @code{socket-type} One of @code{'stream}, @code{'dgram}, @code{'raw}, @code{'rdm} or @code{'seqpacket}. @item @code{protocol} A string, must correspond to an entry in @code{/etc/protocols}. @item @code{wait?} (default: @code{#t}) Whether @command{inetd} should wait for the server to exit before listening to new service requests. @item @code{user} A string containing the user (and, optionally, group) name of the user as whom the server should run. The group name can be specified in a suffix, separated by a colon or period, i.e.@: @code{"user"}, @code{"user:group"} or @code{"user.group"}. @item @code{program} (default: @code{"internal"}) The server program which will serve the requests, or @code{"internal"} if @command{inetd} should use a built-in service. @item @code{arguments} (default: @code{'()}) A list strings or file-like objects, which are the server program's arguments, starting with the zeroth argument, i.e.@: the name of the program itself. For @command{inetd}'s internal services, this entry must be @code{'()} or @code{'("internal")}. @end table @xref{Configuration file,,, inetutils, GNU Inetutils} for a more detailed discussion of each configuration field. @end deftp @cindex opendht, distributed hash table network service @cindex dhtproxy, for use with jami @defvar opendht-service-type This is the type of the service running a @uref{https://opendht.net, OpenDHT} node, @command{dhtnode}. The daemon can be used to host your own proxy service to the distributed hash table (DHT), for example to connect to with Jami, among other applications. @quotation Important When using the OpenDHT proxy server, the IP addresses it ``sees'' from the clients should be addresses reachable from other peers. In practice this means that a publicly reachable address is best suited for a proxy server, outside of your private network. For example, hosting the proxy server on a IPv4 private local network and exposing it via port forwarding could work for external peers, but peers local to the proxy would have their private addresses shared with the external peers, leading to connectivity problems. @end quotation The value of this service is a @code{opendht-configuration} object, as described below. @end defvar @c The fields documentation has been auto-generated using the @c configuration->documentation procedure from @c (gnu services configuration). @deftp {Data Type} opendht-configuration Available @code{opendht-configuration} fields are: @table @asis @item @code{opendht} (default: @code{opendht}) (type: file-like) The @code{opendht} package to use. @item @code{peer-discovery?} (default: @code{#f}) (type: boolean) Whether to enable the multicast local peer discovery mechanism. @item @code{enable-logging?} (default: @code{#f}) (type: boolean) Whether to enable logging messages to syslog. It is disabled by default as it is rather verbose. @item @code{debug?} (default: @code{#f}) (type: boolean) Whether to enable debug-level logging messages. This has no effect if logging is disabled. @item @code{bootstrap-host} (default: @code{"bootstrap.jami.net:4222"}) (type: maybe-string) The node host name that is used to make the first connection to the network. A specific port value can be provided by appending the @code{:PORT} suffix. By default, it uses the Jami bootstrap nodes, but any host can be specified here. It's also possible to disable bootstrapping by explicitly setting this field to the @code{%unset-value} value. @item @code{port} (default: @code{4222}) (type: maybe-number) The UDP port to bind to. When left unspecified, an available port is automatically selected. @item @code{proxy-server-port} (type: maybe-number) Spawn a proxy server listening on the specified port. @item @code{proxy-server-port-tls} (type: maybe-number) Spawn a proxy server listening to TLS connections on the specified port. @end table @end deftp @cindex Tor @defvar tor-service-type Type for a service that runs the @uref{https://torproject.org, Tor} anonymous networking daemon. The service is configured using a @code{<tor-configuration>} record. By default, the Tor daemon runs as the @code{tor} unprivileged user, which is a member of the @code{tor} group. @cindex onion services, for Tor Services of this type can be extended by other services to specify @dfn{onion services} (in addition to those already specified in @code{tor-configuration}) as in this example: @lisp (simple-service 'my-extra-onion-service tor-service-type (list (tor-onion-service-configuration (name "extra-onion-service") (mapping '((80 . "127.0.0.1:8080")))))) @end lisp @end defvar @deftp {Data Type} tor-configuration @table @asis @item @code{tor} (default: @code{tor}) The package that provides the Tor daemon. This package is expected to provide the daemon at @file{bin/tor} relative to its output directory. The default package is the @uref{https://www.torproject.org, Tor Project's} implementation. @item @code{config-file} (default: @code{(plain-file "empty" "")}) The configuration file to use. It will be appended to a default configuration file, and the final configuration file will be passed to @code{tor} via its @code{-f} option. This may be any ``file-like'' object (@pxref{G-Expressions, file-like objects}). See @code{man tor} for details on the configuration file syntax. @item @code{hidden-services} (default: @code{'()}) The list of @code{<tor-onion-service-configuration>} records to use. For any onion service you include in this list, appropriate configuration to enable the onion service will be automatically added to the default configuration file. @item @code{socks-socket-type} (default: @code{'tcp}) The default socket type that Tor should use for its SOCKS socket. This must be either @code{'tcp} or @code{'unix}. If it is @code{'tcp}, then by default Tor will listen on TCP port 9050 on the loopback interface (i.e., localhost). If it is @code{'unix}, then Tor will listen on the UNIX domain socket @file{/var/run/tor/socks-sock}, which will be made writable by members of the @code{tor} group. If you want to customize the SOCKS socket in more detail, leave @code{socks-socket-type} at its default value of @code{'tcp} and use @code{config-file} to override the default by providing your own @code{SocksPort} option. @item @code{control-socket?} (default: @code{#f}) Whether or not to provide a ``control socket'' by which Tor can be controlled to, for instance, dynamically instantiate tor onion services. If @code{#t}, Tor will listen for control commands on the UNIX domain socket @file{/var/run/tor/control-sock}, which will be made writable by members of the @code{tor} group. @item @code{transport-plugins} (default: @code{'()}) The list of @code{<tor-transport-plugin>} records to use. For any transport plugin you include in this list, appropriate configuration line to enable transport plugin will be automatically added to the default configuration file. @end table @end deftp @cindex onion service, tor @deftp {Data Type} tor-onion-service-configuration Data Type representing a Tor @dfn{Onion Service} configuration. See @url{https://community.torproject.org/onion-services/, the Tor project's documentation} for more information. Available @code{tor-onion-service-configuration} fields are: @table @asis @item @code{name} (type: string) Name for this Onion Service. This creates a @file{/var/lib/tor/hidden-services/@var{name}} directory, where the @file{hostname} file contains the @indicateurl{.onion} host name for this Onion Service. @item @code{mapping} (type: alist) Association list of port to address mappings. The following example: @lisp '((22 . "127.0.0.1:22") (80 . "127.0.0.1:8080")) @end lisp maps ports 22 and 80 of the Onion Service to the local ports 22 and 8080. @end table @end deftp @cindex pluggable transports, tor @deftp {Data Type} tor-transport-plugin Data type representing a Tor pluggable transport plugin in @code{tor-configuration}. Plugguble transports are programs that disguise Tor traffic, which can be useful in case Tor is censored. See the the Tor project's @url{https://tb-manual.torproject.org/circumvention/, documentation} and @url{https://spec.torproject.org/pt-spec/index.html, specification} for more information. Each transport plugin corresponds either to @code{ClientTransportPlugin ...} or to @code{ServerTransportPlugin ...} line in the default configuration file, see @command{man tor}. Available @code{tor-transport-plugin} fields are: @table @asis @item @code{role} (default: @code{'client}) This must be either @code{'client} or @code{'server}. Otherwise, an error is raised. Set the @code{'server} value if you want to run a bridge to help censored users connect to the Tor network, see @url{https://community.torproject.org/relay/setup/bridge/, the Tor project's brige guide}. Set the @code{'client} value if you want to connect to somebody else's bridge, see @url{https://bridges.torproject.org/, the Tor project's ``Get Bridges'' page}. In both cases the required additional configuration should be provided via @code{#:config-file} option of @code{tor-configuration}. @item @code{protocol} (default: @code{"obfs4"}) A string that specifies a pluggable transport protocol. @item @code{program} This must be a ``file-like'' object or a string pointing to the pluggable transport plugin executable. This option allows the Tor daemon run inside the container to access the executable and all the references (e.g. package dependencies) attached to it. @end table Suppose you would like Tor daemon to use obfs4 type obfuscation and to connect to Tor network via obfs4 bridge (a nonpublic Tor relay with support for obfs4 type obfuscation). Then you may go to @url{https://bridges.torproject.org/, https://bridges.torproject.org/} and get there a couple of bridge lines (each starts with @code{obfs4 ...}) and use these lines in tor-service-type configuration as follows: @lisp (service tor-service-type (tor-configuration (config-file (plain-file "torrc" "\ UseBridges 1 Bridge obfs4 ... Bridge obfs4 ...")) (transport-plugins (list (tor-transport-plugin (program (file-append go-gitlab-torproject-org-tpo-anti-censorship-pluggable-transports-lyrebird "/bin/lyrebird"))))))) @end lisp @end deftp The @code{(gnu services rsync)} module provides the following services: You might want an rsync daemon if you have files that you want available so anyone (or just yourself) can download existing files or upload new files. @defvar rsync-service-type This is the service type for the @uref{https://rsync.samba.org, rsync} daemon, The value for this service type is a @command{rsync-configuration} record as in this example: @lisp ;; Export two directories over rsync. By default rsync listens on ;; all the network interfaces. (service rsync-service-type (rsync-configuration (modules (list (rsync-module (name "music") (file-name "/srv/zik") (read-only? #f)) (rsync-module (name "movies") (file-name "/home/charlie/movies")))))) @end lisp See below for details about @code{rsync-configuration}. @end defvar @deftp {Data Type} rsync-configuration Data type representing the configuration for @code{rsync-service}. @table @asis @item @code{package} (default: @var{rsync}) @code{rsync} package to use. @item @code{address} (default: @code{#f}) IP address on which @command{rsync} listens for incoming connections. If unspecified, it defaults to listening on all available addresses. @item @code{port-number} (default: @code{873}) TCP port on which @command{rsync} listens for incoming connections. If port is less than @code{1024} @command{rsync} needs to be started as the @code{root} user and group. @item @code{pid-file} (default: @code{"/var/run/rsyncd/rsyncd.pid"}) Name of the file where @command{rsync} writes its PID. @item @code{lock-file} (default: @code{"/var/run/rsyncd/rsyncd.lock"}) Name of the file where @command{rsync} writes its lock file. @item @code{log-file} (default: @code{"/var/log/rsyncd.log"}) Name of the file where @command{rsync} writes its log file. @item @code{user} (default: @code{"root"}) Owner of the @code{rsync} process. @item @code{group} (default: @code{"root"}) Group of the @code{rsync} process. @item @code{uid} (default: @code{"rsyncd"}) User name or user ID that file transfers to and from that module should take place as when the daemon was run as @code{root}. @item @code{gid} (default: @code{"rsyncd"}) Group name or group ID that will be used when accessing the module. @item @code{modules} (default: @code{%default-modules}) List of ``modules''---i.e., directories exported over rsync. Each element must be a @code{rsync-module} record, as described below. @end table @end deftp @deftp {Data Type} rsync-module This is the data type for rsync ``modules''. A module is a directory exported over the rsync protocol. The available fields are as follows: @table @asis @item @code{name} The module name. This is the name that shows up in URLs. For example, if the module is called @code{music}, the corresponding URL will be @code{rsync://host.example.org/music}. @item @code{file-name} Name of the directory being exported. @item @code{comment} (default: @code{""}) Comment associated with the module. Client user interfaces may display it when they obtain the list of available modules. @item @code{read-only?} (default: @code{#t}) Whether or not client will be able to upload files. If this is false, the uploads will be authorized if permissions on the daemon side permit it. @item @code{chroot?} (default: @code{#t}) When this is true, the rsync daemon changes root to the module's directory before starting file transfers with the client. This improves security, but requires rsync to run as root. @item @code{timeout} (default: @code{300}) Idle time in seconds after which the daemon closes a connection with the client. @end table @end deftp @cindex Syncthing, file synchronization service @cindex backup service, Syncthing The @code{(gnu services syncthing)} module provides the following services: @cindex syncthing You might want a syncthing daemon if you have files between two or more computers and want to sync them in real time, safely protected from prying eyes. @defvar syncthing-service-type This is the service type for the @uref{https://syncthing.net/, syncthing} daemon, The value for this service type is a @command{syncthing-configuration} record as in this example: @lisp (service syncthing-service-type (syncthing-configuration (user "alice"))) @end lisp @quotation Note This service is also available for Guix Home, where it runs directly with your user privileges (@pxref{Networking Home Services, @code{home-syncthing-service-type}}). @end quotation See below for details about @code{syncthing-configuration}. @end defvar @deftp {Data Type} syncthing-configuration Data type representing the configuration for @code{syncthing-service-type}. @table @asis @item @code{syncthing} (default: @var{syncthing}) @code{syncthing} package to use. @item @code{arguments} (default: @var{'()}) List of command-line arguments passing to @code{syncthing} binary. @item @code{logflags} (default: @var{0}) Sum of logging flags, see @uref{https://docs.syncthing.net/users/syncthing.html#cmdoption-logflags, Syncthing documentation logflags}. @item @code{user} (default: @var{#f}) The user as which the Syncthing service is to be run. This assumes that the specified user exists. @item @code{group} (default: @var{"users"}) The group as which the Syncthing service is to be run. This assumes that the specified group exists. @item @code{home} (default: @var{#f}) Common configuration and data directory. The default configuration directory is @file{$HOME} of the specified Syncthing @code{user}. @end table @end deftp Furthermore, @code{(gnu services ssh)} provides the following services. @cindex SSH @cindex SSH server @defvar lsh-service-type Type of the service that runs the GNU@tie{}lsh secure shell (SSH) daemon, @command{lshd}. The value for this service is a @code{<lsh-configuration>} object. @end defvar @deftp {Data Type} lsh-configuration Data type representing the configuration of @command{lshd}. @table @asis @item @code{lsh} (default: @code{lsh}) (type: file-like) The package object of the GNU@tie{}lsh secure shell (SSH) daemon. @item @code{daemonic?} (default: @code{#t}) (type: boolean) Whether to detach from the controlling terminal. @item @code{host-key} (default: @code{"/etc/lsh/host-key"}) (type: string) File containing the @dfn{host key}. This file must be readable by root only. @item @code{interfaces} (default: @code{'()}) (type: list) List of host names or addresses that @command{lshd} will listen on. If empty, @command{lshd} listens for connections on all the network interfaces. @item @code{port-number} (default: @code{22}) (type: integer) Port to listen on. @item @code{allow-empty-passwords?} (default: @code{#f}) (type: boolean) Whether to accept log-ins with empty passwords. @item @code{root-login?} (default: @code{#f}) (type: boolean) Whether to accept log-ins as root. @item @code{syslog-output?} (default: @code{#t}) (type: boolean) Whether to log @command{lshd} standard output to syslogd. This will make the service depend on the existence of a syslogd service. @item @code{pid-file?} (default: @code{#f}) (type: boolean) When @code{#t}, @command{lshd} writes its PID to the file specified in @var{pid-file}. @item @code{pid-file} (default: @code{"/var/run/lshd.pid"}) (type: string) File that @command{lshd} will write its PID to. @item @code{x11-forwarding?} (default: @code{#t}) (type: boolean) Whether to enable X11 forwarding. @item @code{tcp/ip-forwarding?} (default: @code{#t}) (type: boolean) Whether to enable TCP/IP forwarding. @item @code{password-authentication?} (default: @code{#t}) (type: boolean) Whether to accept log-ins using password authentication. @item @code{public-key-authentication?} (default: @code{#t}) (type: boolean) Whether to accept log-ins using public key authentication. @item @code{initialize?} (default: @code{#t}) (type: boolean) When @code{#f}, it is up to the user to initialize the randomness generator (@pxref{lsh-make-seed,,, lsh, LSH Manual}), and to create a key pair with the private key stored in file @var{host-key} (@pxref{lshd basics,,, lsh, LSH Manual}). @end table @end deftp @cindex SSH @cindex SSH server @defvar openssh-service-type This is the type for the @uref{http://www.openssh.org, OpenSSH} secure shell daemon, @command{sshd}. Its value must be an @code{openssh-configuration} record as in this example: @lisp (service openssh-service-type (openssh-configuration (x11-forwarding? #t) (permit-root-login 'prohibit-password) (authorized-keys `(("alice" ,(local-file "alice.pub")) ("bob" ,(local-file "bob.pub")))))) @end lisp See below for details about @code{openssh-configuration}. This service can be extended with extra authorized keys, as in this example: @lisp (service-extension openssh-service-type (const `(("charlie" ,(local-file "charlie.pub"))))) @end lisp @end defvar @deftp {Data Type} openssh-configuration This is the configuration record for OpenSSH's @command{sshd}. @table @asis @item @code{openssh} (default @var{openssh}) The OpenSSH package to use. @item @code{pid-file} (default: @code{"/var/run/sshd.pid"}) Name of the file where @command{sshd} writes its PID. @item @code{port-number} (default: @code{22}) TCP port on which @command{sshd} listens for incoming connections. @item @code{max-connections} (default: @code{200}) Hard limit on the maximum number of simultaneous client connections, enforced by the inetd-style Shepherd service (@pxref{Service De- and Constructors, @code{make-inetd-constructor},, shepherd, The GNU Shepherd Manual}). @item @code{permit-root-login} (default: @code{#f}) This field determines whether and when to allow logins as root. If @code{#f}, root logins are disallowed; if @code{#t}, they are allowed. If it's the symbol @code{'prohibit-password}, then root logins are permitted but not with password-based authentication. @item @code{allow-empty-passwords?} (default: @code{#f}) When true, users with empty passwords may log in. When false, they may not. @item @code{password-authentication?} (default: @code{#t}) When true, users may log in with their password. When false, they have other authentication methods. @item @code{public-key-authentication?} (default: @code{#t}) When true, users may log in using public key authentication. When false, users have to use other authentication method. Authorized public keys are stored in @file{~/.ssh/authorized_keys}. This is used only by protocol version 2. @item @code{x11-forwarding?} (default: @code{#f}) When true, forwarding of X11 graphical client connections is enabled---in other words, @command{ssh} options @option{-X} and @option{-Y} will work. @item @code{allow-agent-forwarding?} (default: @code{#t}) Whether to allow agent forwarding. @item @code{allow-tcp-forwarding?} (default: @code{#t}) Whether to allow TCP forwarding. @item @code{gateway-ports?} (default: @code{#f}) Whether to allow gateway ports. @item @code{challenge-response-authentication?} (default: @code{#f}) Specifies whether challenge response authentication is allowed (e.g.@: via PAM). @item @code{use-pam?} (default: @code{#t}) Enables the Pluggable Authentication Module interface. If set to @code{#t}, this will enable PAM authentication using @code{challenge-response-authentication?} and @code{password-authentication?}, in addition to PAM account and session module processing for all authentication types. Because PAM challenge response authentication usually serves an equivalent role to password authentication, you should disable either @code{challenge-response-authentication?} or @code{password-authentication?}. @item @code{print-last-log?} (default: @code{#t}) Specifies whether @command{sshd} should print the date and time of the last user login when a user logs in interactively. @item @code{subsystems} (default: @code{'(("sftp" "internal-sftp"))}) Configures external subsystems (e.g.@: file transfer daemon). This is a list of two-element lists, each of which containing the subsystem name and a command (with optional arguments) to execute upon subsystem request. The command @command{internal-sftp} implements an in-process SFTP server. Alternatively, one can specify the @command{sftp-server} command: @lisp (service openssh-service-type (openssh-configuration (subsystems `(("sftp" ,(file-append openssh "/libexec/sftp-server")))))) @end lisp @item @code{accepted-environment} (default: @code{'()}) List of strings describing which environment variables may be exported. Each string gets on its own line. See the @code{AcceptEnv} option in @code{man sshd_config}. This example allows ssh-clients to export the @env{COLORTERM} variable. It is set by terminal emulators, which support colors. You can use it in your shell's resource file to enable colors for the prompt and commands if this variable is set. @lisp (service openssh-service-type (openssh-configuration (accepted-environment '("COLORTERM")))) @end lisp @item @code{authorized-keys} (default: @code{'()}) @cindex authorized keys, SSH @cindex SSH authorized keys This is the list of authorized keys. Each element of the list is a user name followed by one or more file-like objects that represent SSH public keys. For example: @lisp (openssh-configuration (authorized-keys `(("rekado" ,(local-file "rekado.pub")) ("chris" ,(local-file "chris.pub")) ("root" ,(local-file "rekado.pub") ,(local-file "chris.pub"))))) @end lisp @noindent registers the specified public keys for user accounts @code{rekado}, @code{chris}, and @code{root}. Additional authorized keys can be specified @i{via} @code{service-extension}. Note that this does @emph{not} interfere with the use of @file{~/.ssh/authorized_keys}. @item @code{generate-host-keys?} (default: @code{#t}) Whether to generate host key pairs with @command{ssh-keygen -A} under @file{/etc/ssh} if there are none. Generating key pairs takes a few seconds when enough entropy is available and is only done once. You might want to turn it off for instance in a virtual machine that does not need it because host keys are provided in some other way, and where the extra boot time is a problem. @item @code{log-level} (default: @code{'info}) This is a symbol specifying the logging level: @code{quiet}, @code{fatal}, @code{error}, @code{info}, @code{verbose}, @code{debug}, etc. See the man page for @file{sshd_config} for the full list of level names. @item @code{extra-content} (default: @code{""}) This field can be used to append arbitrary text to the configuration file. It is especially useful for elaborate configurations that cannot be expressed otherwise. This configuration, for example, would generally disable root logins, but permit them from one specific IP address: @lisp (openssh-configuration (extra-content "\ Match Address 192.168.0.1 PermitRootLogin yes")) @end lisp @end table @end deftp @defvar dropbear-service-type Type of the service that runs the @url{https://matt.ucc.asn.au/dropbear/dropbear.html, Dropbear SSH daemon}, whose value is a @code{<dropbear-configuration>} object. For example, to specify a Dropbear service listening on port 1234: @lisp (service dropbear-service-type (dropbear-configuration (port-number 1234))) @end lisp @end defvar @deftp {Data Type} dropbear-configuration This data type represents the configuration of a Dropbear SSH daemon. @table @asis @item @code{dropbear} (default: @var{dropbear}) The Dropbear package to use. @item @code{port-number} (default: 22) The TCP port where the daemon waits for incoming connections. @item @code{syslog-output?} (default: @code{#t}) Whether to enable syslog output. @item @code{pid-file} (default: @code{"/var/run/dropbear.pid"}) File name of the daemon's PID file. @item @code{root-login?} (default: @code{#f}) Whether to allow @code{root} logins. @item @code{allow-empty-passwords?} (default: @code{#f}) Whether to allow empty passwords. @item @code{password-authentication?} (default: @code{#t}) Whether to enable password-based authentication. @end table @end deftp @cindex AutoSSH @defvar autossh-service-type This is the type for the @uref{https://www.harding.motd.ca/autossh, AutoSSH} program that runs a copy of @command{ssh} and monitors it, restarting it as necessary should it die or stop passing traffic. AutoSSH can be run manually from the command-line by passing arguments to the binary @command{autossh} from the package @code{autossh}, but it can also be run as a Guix service. This latter use case is documented here. AutoSSH can be used to forward local traffic to a remote machine using an SSH tunnel, and it respects the @file{~/.ssh/config} of the user it is run as. For example, to specify a service running autossh as the user @code{pino} and forwarding all local connections to port @code{8081} to @code{remote:8081} using an SSH tunnel, add this call to the operating system's @code{services} field: @lisp (service autossh-service-type (autossh-configuration (user "pino") (ssh-options (list "-T" "-N" "-L" "8081:localhost:8081" "remote.net")))) @end lisp @end defvar @deftp {Data Type} autossh-configuration This data type represents the configuration of an AutoSSH service. @table @asis @item @code{user} (default @code{"autossh"}) The user as which the AutoSSH service is to be run. This assumes that the specified user exists. @item @code{poll} (default @code{600}) Specifies the connection poll time in seconds. @item @code{first-poll} (default @code{#f}) Specifies how many seconds AutoSSH waits before the first connection test. After this first test, polling is resumed at the pace defined in @code{poll}. When set to @code{#f}, the first poll is not treated specially and will also use the connection poll specified in @code{poll}. @item @code{gate-time} (default @code{30}) Specifies how many seconds an SSH connection must be active before it is considered successful. @item @code{log-level} (default @code{1}) The log level, corresponding to the levels used by syslog---so @code{0} is the most silent while @code{7} is the chattiest. @item @code{max-start} (default @code{#f}) The maximum number of times SSH may be (re)started before AutoSSH exits. When set to @code{#f}, no maximum is configured and AutoSSH may restart indefinitely. @item @code{message} (default @code{""}) The message to append to the echo message sent when testing connections. @item @code{port} (default @code{"0"}) The ports used for monitoring the connection. When set to @code{"0"}, monitoring is disabled. When set to @code{"@var{n}"} where @var{n} is a positive integer, ports @var{n} and @var{n}+1 are used for monitoring the connection, such that port @var{n} is the base monitoring port and @code{n+1} is the echo port. When set to @code{"@var{n}:@var{m}"} where @var{n} and @var{m} are positive integers, the ports @var{n} and @var{m} are used for monitoring the connection, such that port @var{n} is the base monitoring port and @var{m} is the echo port. @item @code{ssh-options} (default @code{'()}) The list of command-line arguments to pass to @command{ssh} when it is run. Options @option{-f} and @option{-M} are reserved for AutoSSH and may cause undefined behaviour. @end table @end deftp @cindex WebSSH @defvar webssh-service-type This is the type for the @uref{https://webssh.huashengdun.org/, WebSSH} program that runs a web SSH client. WebSSH can be run manually from the command-line by passing arguments to the binary @command{wssh} from the package @code{webssh}, but it can also be run as a Guix service. This latter use case is documented here. For example, to specify a service running WebSSH on loopback interface on port @code{8888} with reject policy with a list of allowed to connection hosts, and NGINX as a reverse-proxy to this service listening for HTTPS connection, add this call to the operating system's @code{services} field: @lisp (service webssh-service-type (webssh-configuration (address "127.0.0.1") (port 8888) (policy 'reject) (known-hosts '("localhost ecdsa-sha2-nistp256 AAAA…" "127.0.0.1 ecdsa-sha2-nistp256 AAAA…")))) (service nginx-service-type (nginx-configuration (server-blocks (list (nginx-server-configuration (inherit %webssh-configuration-nginx) (server-name '("webssh.example.com")) (listen '("443 ssl")) (ssl-certificate (letsencrypt-certificate "webssh.example.com")) (ssl-certificate-key (letsencrypt-key "webssh.example.com")) (locations (cons (nginx-location-configuration (uri "/.well-known") (body '("root /var/www;"))) (nginx-server-configuration-locations %webssh-configuration-nginx)))))))) @end lisp @end defvar @deftp {Data Type} webssh-configuration Data type representing the configuration for @code{webssh-service}. @table @asis @item @code{package} (default: @var{webssh}) @code{webssh} package to use. @item @code{user-name} (default: @var{"webssh"}) User name or user ID that file transfers to and from that module should take place. @item @code{group-name} (default: @var{"webssh"}) Group name or group ID that will be used when accessing the module. @item @code{address} (default: @var{#f}) IP address on which @command{webssh} listens for incoming connections. @item @code{port} (default: @var{8888}) TCP port on which @command{webssh} listens for incoming connections. @item @code{policy} (default: @var{#f}) Connection policy. @var{reject} policy requires to specify @var{known-hosts}. @item @code{known-hosts} (default: @var{'()}) List of hosts which allowed for SSH connection from @command{webssh}. @item @code{log-file} (default: @file{"/var/log/webssh.log"}) Name of the file where @command{webssh} writes its log file. @item @code{log-level} (default: @var{#f}) Logging level. @end table @end deftp @defvar block-facebook-hosts-service-type This service type adds a list of known Facebook hosts to the @file{/etc/hosts} file. (@pxref{Host Names,,, libc, The GNU C Library Reference Manual}) Each line contains an entry that maps a known server name of the Facebook on-line service---e.g., @code{www.facebook.com}---to unroutable IPv4 and IPv6 addresses. This mechanism can prevent programs running locally, such as Web browsers, from accessing Facebook. @end defvar The @code{(gnu services avahi)} provides the following definition. @defvar avahi-service-type This is the service that runs @command{avahi-daemon}, a system-wide mDNS/DNS-SD responder that allows for service discovery and ``zero-configuration'' host name lookups (see @uref{https://avahi.org/}). Its value must be an @code{avahi-configuration} record---see below. This service extends the name service cache daemon (nscd) so that it can resolve @code{.local} host names using @uref{https://0pointer.de/lennart/projects/nss-mdns/, nss-mdns}. @xref{Name Service Switch}, for information on host name resolution. Additionally, add the @var{avahi} package to the system profile so that commands such as @command{avahi-browse} are directly usable. @end defvar @deftp {Data Type} avahi-configuration Data type representation the configuration for Avahi. @table @asis @item @code{host-name} (default: @code{#f}) If different from @code{#f}, use that as the host name to publish for this machine; otherwise, use the machine's actual host name. @item @code{publish?} (default: @code{#t}) When true, allow host names and services to be published (broadcast) over the network. @item @code{publish-workstation?} (default: @code{#t}) When true, @command{avahi-daemon} publishes the machine's host name and IP address via mDNS on the local network. To view the host names published on your local network, you can run: @example avahi-browse _workstation._tcp @end example @item @code{wide-area?} (default: @code{#f}) When true, DNS-SD over unicast DNS is enabled. @item @code{ipv4?} (default: @code{#t}) @itemx @code{ipv6?} (default: @code{#t}) These fields determine whether to use IPv4/IPv6 sockets. @item @code{domains-to-browse} (default: @code{'()}) This is a list of domains to browse. @end table @end deftp @defvar openvswitch-service-type This is the type of the @uref{https://www.openvswitch.org, Open vSwitch} service, whose value should be an @code{openvswitch-configuration} object. @end defvar @deftp {Data Type} openvswitch-configuration Data type representing the configuration of Open vSwitch, a multilayer virtual switch which is designed to enable massive network automation through programmatic extension. @table @asis @item @code{package} (default: @var{openvswitch}) Package object of the Open vSwitch. @end table @end deftp @defvar pagekite-service-type This is the service type for the @uref{https://pagekite.net, PageKite} service, a tunneling solution for making localhost servers publicly visible, even from behind restrictive firewalls or NAT without forwarded ports. The value for this service type is a @code{pagekite-configuration} record. Here's an example exposing the local HTTP and SSH daemons: @lisp (service pagekite-service-type (pagekite-configuration (kites '("http:@@kitename:localhost:80:@@kitesecret" "raw/22:@@kitename:localhost:22:@@kitesecret")) (extra-file "/etc/pagekite.rc"))) @end lisp @end defvar @deftp {Data Type} pagekite-configuration Data type representing the configuration of PageKite. @table @asis @item @code{package} (default: @var{pagekite}) Package object of PageKite. @item @code{kitename} (default: @code{#f}) PageKite name for authenticating to the frontend server. @item @code{kitesecret} (default: @code{#f}) Shared secret for authenticating to the frontend server. You should probably put this inside @code{extra-file} instead. @item @code{frontend} (default: @code{#f}) Connect to the named PageKite frontend server instead of the @uref{https://pagekite.net,,pagekite.net} service. @item @code{kites} (default: @code{'("http:@@kitename:localhost:80:@@kitesecret")}) List of service kites to use. Exposes HTTP on port 80 by default. The format is @code{proto:kitename:host:port:secret}. @item @code{extra-file} (default: @code{#f}) Extra configuration file to read, which you are expected to create manually. Use this to add additional options and manage shared secrets out-of-band. @end table @end deftp @defvar yggdrasil-service-type The service type for connecting to the @uref{https://yggdrasil-network.github.io/, Yggdrasil network}, an early-stage implementation of a fully end-to-end encrypted IPv6 network. @quotation Yggdrasil provides name-independent routing with cryptographically generated addresses. Static addressing means you can keep the same address as long as you want, even if you move to a new location, or generate a new address (by generating new keys) whenever you want. @uref{https://yggdrasil-network.github.io/2018/07/28/addressing.html} @end quotation Pass it a value of @code{yggdrasil-configuration} to connect it to public peers and/or local peers. Here is an example using public peers and a static address. The static signing and encryption keys are defined in @file{/etc/yggdrasil-private.conf} (the default value for @code{config-file}). @lisp ;; part of the operating-system declaration (service yggdrasil-service-type (yggdrasil-configuration (autoconf? #f) ;; use only the public peers (json-config ;; choose one from ;; https://github.com/yggdrasil-network/public-peers '((peers . #("tcp://1.2.3.4:1337")))) ;; /etc/yggdrasil-private.conf is the default value for config-file )) @end lisp @example # sample content for /etc/yggdrasil-private.conf @{ # Your private key. DO NOT share this with anyone! PrivateKey: 5c750... @} @end example @end defvar @deftp {Data Type} yggdrasil-configuration Data type representing the configuration of Yggdrasil. @table @asis @item @code{package} (default: @code{yggdrasil}) Package object of Yggdrasil. @item @code{json-config} (default: @code{'()}) Contents of @file{/etc/yggdrasil.conf}. Will be merged with @file{/etc/yggdrasil-private.conf}. Note that these settings are stored in the Guix store, which is readable to all users. @strong{Do not store your private keys in it}. See the output of @code{yggdrasil -genconf} for a quick overview of valid keys and their default values. @item @code{autoconf?} (default: @code{#f}) Whether to use automatic mode. Enabling it makes Yggdrasil use a dynamic IP and peer with IPv6 neighbors. @item @code{log-level} (default: @code{'info}) How much detail to include in logs. Use @code{'debug} for more detail. @item @code{log-to} (default: @code{'stdout}) Where to send logs. By default, the service logs standard output to @file{/var/log/yggdrasil.log}. The alternative is @code{'syslog}, which sends output to the running syslog service. @item @code{config-file} (default: @code{"/etc/yggdrasil-private.conf"}) What HJSON file to load sensitive data from. This is where private keys should be stored, which are necessary to specify if you don't want a randomized address after each restart. Use @code{#f} to disable. Options defined in this file take precedence over @code{json-config}. Use the output of @code{yggdrasil -genconf} as a starting point. To configure a static address, delete everything except PrivateKey option. @end table @end deftp @cindex IPFS @defvar ipfs-service-type The service type for connecting to the @uref{https://ipfs.io,IPFS network}, a global, versioned, peer-to-peer file system. Pass it a @code{ipfs-configuration} to change the ports used for the gateway and API. Here's an example configuration, using some non-standard ports: @lisp (service ipfs-service-type (ipfs-configuration (gateway "/ip4/127.0.0.1/tcp/8880") (api "/ip4/127.0.0.1/tcp/8881"))) @end lisp @end defvar @deftp {Data Type} ipfs-configuration Data type representing the configuration of IPFS. @table @asis @item @code{package} (default: @code{go-ipfs}) Package object of IPFS. @item @code{gateway} (default: @code{"/ip4/127.0.0.1/tcp/8082"}) Address of the gateway, in ‘multiaddress’ format. @item @code{api} (default: @code{"/ip4/127.0.0.1/tcp/5001"}) Address of the API endpoint, in ‘multiaddress’ format. @end table @end deftp @cindex keepalived @defvar keepalived-service-type This is the type for the @uref{https://www.keepalived.org/, Keepalived} routing software, @command{keepalived}. Its value must be an @code{keepalived-configuration} record as in this example for master machine: @lisp (service keepalived-service-type (keepalived-configuration (config-file (local-file "keepalived-master.conf")))) @end lisp where @file{keepalived-master.conf}: @example vrrp_instance my-group @{ state MASTER interface enp9s0 virtual_router_id 100 priority 100 unicast_peer @{ 10.0.0.2 @} virtual_ipaddress @{ 10.0.0.4/24 @} @} @end example and for backup machine: @lisp (service keepalived-service-type (keepalived-configuration (config-file (local-file "keepalived-backup.conf")))) @end lisp where @file{keepalived-backup.conf}: @example vrrp_instance my-group @{ state BACKUP interface enp9s0 virtual_router_id 100 priority 99 unicast_peer @{ 10.0.0.3 @} virtual_ipaddress @{ 10.0.0.4/24 @} @} @end example @end defvar @node Unattended Upgrades @subsection Unattended Upgrades @cindex unattended upgrades @cindex upgrades, unattended Guix provides a service to perform @emph{unattended upgrades}: periodically, the system automatically reconfigures itself from the latest Guix. Guix System has several properties that make unattended upgrades safe: @itemize @item upgrades are transactional (either the upgrade succeeds or it fails, but you cannot end up with an ``in-between'' system state); @item the upgrade log is kept---you can view it with @command{guix system list-generations}---and you can roll back to any previous generation, should the upgraded system fail to behave as intended; @item channel code is authenticated so you know you can only run genuine code (@pxref{Channels}); @item @command{guix system reconfigure} prevents downgrades, which makes it immune to @dfn{downgrade attacks}. @end itemize To set up unattended upgrades, add an instance of @code{unattended-upgrade-service-type} like the one below to the list of your operating system services: @lisp (service unattended-upgrade-service-type) @end lisp The defaults above set up weekly upgrades: every Sunday at midnight. You do not need to provide the operating system configuration file: it uses @file{/run/current-system/configuration.scm}, which ensures it always uses your latest configuration---@pxref{provenance-service-type}, for more information about this file. There are several things that can be configured, in particular the periodicity and services (daemons) to be restarted upon completion. When the upgrade is successful, the service takes care of deleting system generations older that some threshold, as per @command{guix system delete-generations}. See the reference below for details. To ensure that upgrades are actually happening, you can run @command{guix system describe}. To investigate upgrade failures, visit the unattended upgrade log file (see below). @defvar unattended-upgrade-service-type This is the service type for unattended upgrades. It sets up an mcron job (@pxref{Scheduled Job Execution}) that runs @command{guix system reconfigure} from the latest version of the specified channels. Its value must be a @code{unattended-upgrade-configuration} record (see below). @end defvar @deftp {Data Type} unattended-upgrade-configuration This data type represents the configuration of the unattended upgrade service. The following fields are available: @table @asis @item @code{schedule} (default: @code{"30 01 * * 0"}) This is the schedule of upgrades, expressed as a gexp containing an mcron job schedule (@pxref{Guile Syntax, mcron job specifications,, mcron, GNU@tie{}mcron}). @item @code{channels} (default: @code{#~%default-channels}) This gexp specifies the channels to use for the upgrade (@pxref{Channels}). By default, the tip of the official @code{guix} channel is used. @item @code{operating-system-file} (default: @code{"/run/current-system/configuration.scm"}) This field specifies the operating system configuration file to use. The default is to reuse the config file of the current configuration. There are cases, though, where referring to @file{/run/current-system/configuration.scm} is not enough, for instance because that file refers to extra files (SSH public keys, extra configuration files, etc.) @i{via} @code{local-file} and similar constructs. For those cases, we recommend something along these lines: @lisp (unattended-upgrade-configuration (operating-system-file (file-append (local-file "." "config-dir" #:recursive? #t) "/config.scm"))) @end lisp The effect here is to import all of the current directory into the store, and to refer to @file{config.scm} within that directory. Therefore, uses of @code{local-file} within @file{config.scm} will work as expected. @xref{G-Expressions}, for information about @code{local-file} and @code{file-append}. @item @code{operating-system-expression} (default: @code{#f}) This field specifies an expression that evaluates to the operating system to use for the upgrade. If no value is provided the @code{operating-system-file} field value is used. @lisp (unattended-upgrade-configuration (operating-system-expression #~(@@ (guix system install) installation-os))) @end lisp @item @code{reboot?} (default: @code{#f}) This field specifies whether the system should reboot after completing an unattended upgrade. When @code{reboot?} is @code{#t}, services are not restarted before rebooting. This means that the value for @code{services-to-restart} is ignored. The updated services will be started after the system reboots. @item @code{services-to-restart} (default: @code{'(mcron)}) This field specifies the Shepherd services to restart when the upgrade completes. Those services are restarted right away upon completion, as with @command{herd restart}, which ensures that the latest version is running---remember that by default @command{guix system reconfigure} only restarts services that are not currently running, which is conservative: it minimizes disruption but leaves outdated services running. Use @command{herd status} to find out candidates for restarting. @xref{Services}, for general information about services. Common services to restart would include @code{ntpd} and @code{ssh-daemon}. By default, the @code{mcron} service is restarted. This ensures that the latest version of the unattended upgrade job will be used next time. @item @code{system-expiration} (default: @code{(* 3 30 24 3600)}) This is the expiration time in seconds for system generations. System generations older that this amount of time are deleted with @command{guix system delete-generations} when an upgrade completes. @quotation Note The unattended upgrade service does not run the garbage collector. You will probably want to set up your own mcron job to run @command{guix gc} periodically. @end quotation @item @code{maximum-duration} (default: @code{3600}) Maximum duration in seconds for the upgrade; past that time, the upgrade aborts. This is primarily useful to ensure the upgrade does not end up rebuilding or re-downloading ``the world''. @item @code{log-file} (default: @code{"/var/log/unattended-upgrade.log"}) File where unattended upgrades are logged. @end table @end deftp @node X Window @subsection X Window @cindex X11 @cindex X Window System @cindex login manager Support for the X Window graphical display system---specifically Xorg---is provided by the @code{(gnu services xorg)} module. Note that there is no @code{xorg-service} procedure. Instead, the X server is started by the @dfn{login manager}, by default the GNOME Display Manager (GDM). @cindex GDM @cindex GNOME, login manager @anchor{gdm} GDM of course allows users to log in into window managers and desktop environments other than GNOME; for those using GNOME, GDM is required for features such as automatic screen locking. @cindex window manager To use X11, you must install at least one @dfn{window manager}---for example the @code{windowmaker} or @code{openbox} packages---preferably by adding it to the @code{packages} field of your operating system definition (@pxref{operating-system Reference, system-wide packages}). @anchor{wayland-gdm} GDM also supports Wayland: it can itself use Wayland instead of X11 for its user interface, and it can also start Wayland sessions. Wayland support is enabled by default. To disable it, set @code{wayland?} to @code{#f} in @code{gdm-configuration}. @defvar gdm-service-type This is the type for the @uref{https://wiki.gnome.org/Projects/GDM/, GNOME Desktop Manager} (GDM), a program that manages graphical display servers and handles graphical user logins. Its value must be a @code{gdm-configuration} (see below). @cindex session types GDM looks for @dfn{session types} described by the @file{.desktop} files in @file{/run/current-system/profile/share/xsessions} (for X11 sessions) and @file{/run/current-system/profile/share/wayland-sessions} (for Wayland sessions) and allows users to choose a session from the log-in screen. Packages such as @code{gnome}, @code{xfce}, @code{i3} and @code{sway} provide @file{.desktop} files; adding them to the system-wide set of packages automatically makes them available at the log-in screen. In addition, @file{~/.xsession} files are honored. When available, @file{~/.xsession} must be an executable that starts a window manager and/or other X clients. @end defvar @deftp {Data Type} gdm-configuration @table @asis @item @code{auto-login?} (default: @code{#f}) @itemx @code{default-user} (default: @code{#f}) When @code{auto-login?} is false, GDM presents a log-in screen. When @code{auto-login?} is true, GDM logs in directly as @code{default-user}. @item @code{auto-suspend?} (default @code{#t}) When true, GDM will automatically suspend to RAM when nobody is physically connected. When a machine is used via remote desktop or SSH, this should be set to false to avoid GDM interrupting remote sessions or rendering the machine unavailable. @item @code{debug?} (default: @code{#f}) When true, GDM writes debug messages to its log. @item @code{gnome-shell-assets} (default: ...) List of GNOME Shell assets needed by GDM: icon theme, fonts, etc. @item @code{xorg-configuration} (default: @code{(xorg-configuration)}) Configuration of the Xorg graphical server. @item @code{x-session} (default: @code{(xinitrc)}) Script to run before starting a X session. @item @code{xdmcp?} (default: @code{#f}) When true, enable the X Display Manager Control Protocol (XDMCP). This should only be enabled in trusted environments, as the protocol is not secure. When enabled, GDM listens for XDMCP queries on the UDP port 177. @item @code{dbus-daemon} (default: @code{dbus-daemon-wrapper}) File name of the @code{dbus-daemon} executable. @item @code{gdm} (default: @code{gdm}) The GDM package to use. @item @code{wayland?} (default: @code{#t}) When true, enables Wayland in GDM, necessary to use Wayland sessions. @item @code{wayland-session} (default: @code{gdm-wayland-session-wrapper}) The Wayland session wrapper to use, needed to setup the environment. @end table @end deftp @defvar slim-service-type This is the type for the SLiM graphical login manager for X11. Like GDM, SLiM looks for session types described by @file{.desktop} files and allows users to choose a session from the log-in screen using @kbd{F1}. It also honors @file{~/.xsession} files. Unlike GDM, SLiM does not spawn the user session on a different VT after logging in, which means that you can only start one graphical session. If you want to be able to run multiple graphical sessions at the same time you have to add multiple SLiM services to your system services. The following example shows how to replace the default GDM service with two SLiM services on tty7 and tty8. @lisp (use-modules (gnu services) (gnu services desktop) (gnu services xorg)) (operating-system ;; ... (services (cons* (service slim-service-type (slim-configuration (display ":0") (vt "vt7"))) (service slim-service-type (slim-configuration (display ":1") (vt "vt8"))) (modify-services %desktop-services (delete gdm-service-type))))) @end lisp @end defvar @deftp {Data Type} slim-configuration Data type representing the configuration of @code{slim-service-type}. @table @asis @item @code{allow-empty-passwords?} (default: @code{#t}) Whether to allow logins with empty passwords. @item @code{gnupg?} (default: @code{#f}) If enabled, @code{pam-gnupg} will attempt to automatically unlock the user's GPG keys with the login password via @code{gpg-agent}. The keygrips of all keys to be unlocked should be written to @file{~/.pam-gnupg}, and can be queried with @code{gpg -K --with-keygrip}. Presetting passphrases must be enabled by adding @code{allow-preset-passphrase} in @file{~/.gnupg/gpg-agent.conf}. @item @code{auto-login?} (default: @code{#f}) @itemx @code{default-user} (default: @code{""}) When @code{auto-login?} is false, SLiM presents a log-in screen. When @code{auto-login?} is true, SLiM logs in directly as @code{default-user}. @item @code{theme} (default: @code{%default-slim-theme}) @itemx @code{theme-name} (default: @code{%default-slim-theme-name}) The graphical theme to use and its name. @item @code{auto-login-session} (default: @code{#f}) If true, this must be the name of the executable to start as the default session---e.g., @code{(file-append windowmaker "/bin/windowmaker")}. If false, a session described by one of the available @file{.desktop} files in @code{/run/current-system/profile} and @code{~/.guix-profile} will be used. @quotation Note You must install at least one window manager in the system profile or in your user profile. Failing to do that, if @code{auto-login-session} is false, you will be unable to log in. @end quotation @item @code{xorg-configuration} (default @code{(xorg-configuration)}) Configuration of the Xorg graphical server. @item @code{display} (default @code{":0"}) The display on which to start the Xorg graphical server. @item @code{vt} (default @code{"vt7"}) The VT on which to start the Xorg graphical server. @item @code{xauth} (default: @code{xauth}) The XAuth package to use. @item @code{shepherd} (default: @code{shepherd}) The Shepherd package used when invoking @command{halt} and @command{reboot}. @item @code{sessreg} (default: @code{sessreg}) The sessreg package used in order to register the session. @item @code{slim} (default: @code{slim}) The SLiM package to use. @end table @end deftp @defvar %default-theme @defvarx %default-theme-name The default SLiM theme and its name. @end defvar @cindex login manager @cindex X11 login @defvar sddm-service-type This is the type of the service to run the @uref{https://github.com/sddm/sddm,SDDM display manager}. Its value must be a @code{sddm-configuration} record (see below). Here's an example use: @lisp (service sddm-service-type (sddm-configuration (auto-login-user "alice") (auto-login-session "xfce.desktop"))) @end lisp @end defvar @deftp {Data Type} sddm-configuration This data type represents the configuration of the SDDM login manager. The available fields are: @table @asis @item @code{sddm} (default: @code{sddm}) The SDDM package to use. @quotation Note sddm has Qt6 enabled by default. If you want to still use a Qt5 theme, you need to set it to @code{sddm-qt5}. @end quotation @item @code{display-server} (default: "x11") Select display server to use for the greeter. Valid values are @samp{"x11"} or @samp{"wayland"}. @item @code{numlock} (default: "on") Valid values are @samp{"on"}, @samp{"off"} or @samp{"none"}. @item @code{halt-command} (default @code{#~(string-append #$shepherd "/sbin/halt")}) Command to run when halting. @item @code{reboot-command} (default @code{#~(string-append #$shepherd "/sbin/reboot")}) Command to run when rebooting. @item @code{theme} (default "maldives") Theme to use. Default themes provided by SDDM are @samp{"elarun"}, @samp{"maldives"} or @samp{"maya"}. @item @code{themes-directory} (default "/run/current-system/profile/share/sddm/themes") Directory to look for themes. @item @code{faces-directory} (default "/run/current-system/profile/share/sddm/faces") Directory to look for faces. @item @code{default-path} (default "/run/current-system/profile/bin") Default PATH to use. @item @code{minimum-uid} (default: 1000) Minimum UID displayed in SDDM and allowed for log-in. @item @code{maximum-uid} (default: 2000) Maximum UID to display in SDDM. @item @code{remember-last-user?} (default #t) Remember last user. @item @code{remember-last-session?} (default #t) Remember last session. @item @code{hide-users} (default "") Usernames to hide from SDDM greeter. @item @code{hide-shells} (default @code{#~(string-append #$shadow "/sbin/nologin")}) Users with shells listed will be hidden from the SDDM greeter. @item @code{session-command} (default @code{#~(string-append #$sddm "/share/sddm/scripts/wayland-session")}) Script to run before starting a wayland session. @item @code{sessions-directory} (default "/run/current-system/profile/share/wayland-sessions") Directory to look for desktop files starting wayland sessions. @item @code{xorg-configuration} (default @code{(xorg-configuration)}) Configuration of the Xorg graphical server. @item @code{xauth-path} (default @code{#~(string-append #$xauth "/bin/xauth")}) Path to xauth. @item @code{xephyr-path} (default @code{#~(string-append #$xorg-server "/bin/Xephyr")}) Path to Xephyr. @item @code{xdisplay-start} (default @code{#~(string-append #$sddm "/share/sddm/scripts/Xsetup")}) Script to run after starting xorg-server. @item @code{xdisplay-stop} (default @code{#~(string-append #$sddm "/share/sddm/scripts/Xstop")}) Script to run before stopping xorg-server. @item @code{xsession-command} (default: @code{xinitrc}) Script to run before starting a X session. @item @code{xsessions-directory} (default: "/run/current-system/profile/share/xsessions") Directory to look for desktop files starting X sessions. @item @code{minimum-vt} (default: 7) Minimum VT to use. @item @code{auto-login-user} (default "") User account that will be automatically logged in. Setting this to the empty string disables auto-login. @item @code{auto-login-session} (default "") The @file{.desktop} file name to use as the auto-login session, or the empty string. @item @code{relogin?} (default #f) Relogin after logout. @end table @end deftp @cindex lightdm, graphical login manager @cindex display manager, lightdm @anchor{lightdm} @defvar lightdm-service-type This is the type of the service to run the @url{https://github.com/canonical/lightdm,LightDM display manager}. Its value must be a @code{lightdm-configuration} record, which is documented below. Among its distinguishing features are TigerVNC integration for easily remoting your desktop as well as support for the XDMCP protocol, which can be used by remote clients to start a session from the login manager. In its most basic form, it can be used simply as: @lisp (service lightdm-service-type) @end lisp A more elaborate example making use of the VNC capabilities and enabling more features and verbose logs could look like: @lisp (service lightdm-service-type (lightdm-configuration (allow-empty-passwords? #t) (xdmcp? #t) (vnc-server? #t) (vnc-server-command (file-append tigervnc-server "/bin/Xvnc" " -SecurityTypes None")) (seats (list (lightdm-seat-configuration (name "*") (user-session "ratpoison")))))) @end lisp @end defvar @c The LightDM service documentation can be auto-generated via the @c 'generate-doc' procedure at the bottom of the (gnu services lightdm) @c module. @c %start of fragment @deftp {Data Type} lightdm-configuration Available @code{lightdm-configuration} fields are: @table @asis @item @code{lightdm} (default: @code{lightdm}) (type: file-like) The lightdm package to use. @item @code{allow-empty-passwords?} (default: @code{#f}) (type: boolean) Whether users not having a password set can login. @item @code{debug?} (default: @code{#f}) (type: boolean) Enable verbose output. @item @code{xorg-configuration} (type: xorg-configuration) The default Xorg server configuration to use to generate the Xorg server start script. It can be refined per seat via the @code{xserver-command} of the @code{<lightdm-seat-configuration>} record, if desired. @item @code{greeters} (type: list-of-greeter-configurations) The LightDM greeter configurations specifying the greeters to use. @item @code{seats} (type: list-of-seat-configurations) The seat configurations to use. A LightDM seat is akin to a user. @item @code{xdmcp?} (default: @code{#f}) (type: boolean) Whether a XDMCP server should listen on port UDP 177. @item @code{xdmcp-listen-address} (type: maybe-string) The host or IP address the XDMCP server listens for incoming connections. When unspecified, listen on for any hosts/IP addresses. @item @code{vnc-server?} (default: @code{#f}) (type: boolean) Whether a VNC server is started. @item @code{vnc-server-command} (type: file-like) The Xvnc command to use for the VNC server, it's possible to provide extra options not otherwise exposed along the command, for example to disable security: @lisp (vnc-server-command (file-append tigervnc-server "/bin/Xvnc" " -SecurityTypes None" )) @end lisp Or to set a PasswordFile for the classic (unsecure) VncAuth mechanism: @lisp (vnc-server-command (file-append tigervnc-server "/bin/Xvnc" " -PasswordFile /var/lib/lightdm/.vnc/passwd")) @end lisp The password file should be manually created using the @command{vncpasswd} command. Note that LightDM will create new sessions for VNC users, which means they need to authenticate in the same way as local users would. @item @code{vnc-server-listen-address} (type: maybe-string) The host or IP address the VNC server listens for incoming connections. When unspecified, listen for any hosts/IP addresses. @item @code{vnc-server-port} (default: @code{5900}) (type: number) The TCP port the VNC server should listen to. @item @code{extra-config} (default: @code{'()}) (type: list-of-strings) Extra configuration values to append to the LightDM configuration file. @end table @end deftp @c %end of fragment @c %start of fragment @deftp {Data Type} lightdm-gtk-greeter-configuration Available @code{lightdm-gtk-greeter-configuration} fields are: @table @asis @item @code{lightdm-gtk-greeter} (default: @code{lightdm-gtk-greeter}) (type: file-like) The lightdm-gtk-greeter package to use. @item @code{assets} (default: @code{(adwaita-icon-theme gnome-themes-extra hicolor-icon-theme)}) (type: list-of-file-likes) The list of packages complementing the greeter, such as package providing icon themes. @item @code{theme-name} (default: @code{"Adwaita"}) (type: string) The name of the theme to use. @item @code{icon-theme-name} (default: @code{"Adwaita"}) (type: string) The name of the icon theme to use. @item @code{cursor-theme-name} (default: @code{"Adwaita"}) (type: string) The name of the cursor theme to use. @item @code{cursor-theme-size} (default: @code{16}) (type: number) The size to use for the cursor theme. @item @code{allow-debugging?} (type: maybe-boolean) Set to #t to enable debug log level. @item @code{background} (type: file-like) The background image to use. @item @code{at-spi-enabled?} (default: @code{#f}) (type: boolean) Enable accessibility support through the Assistive Technology Service Provider Interface (AT-SPI). @item @code{a11y-states} (default: @code{(contrast font keyboard reader)}) (type: list-of-a11y-states) The accessibility features to enable, given as list of symbols. @item @code{reader} (type: maybe-file-like) The command to use to launch a screen reader. @item @code{extra-config} (default: @code{'()}) (type: list-of-strings) Extra configuration values to append to the LightDM GTK Greeter configuration file. @end table @end deftp @c %end of fragment @c %start of fragment @deftp {Data Type} lightdm-seat-configuration Available @code{lightdm-seat-configuration} fields are: @table @asis @item @code{name} (type: seat-name) The name of the seat. An asterisk (*) can be used in the name to apply the seat configuration to all the seat names it matches. @item @code{user-session} (type: maybe-string) The session to use by default. The session name must be provided as a lowercase string, such as @code{"gnome"}, @code{"ratpoison"}, etc. @item @code{type} (default: @code{local}) (type: seat-type) The type of the seat, either the @code{local} or @code{xremote} symbol. @item @code{autologin-user} (type: maybe-string) The username to automatically log in with by default. @item @code{greeter-session} (default: @code{lightdm-gtk-greeter}) (type: greeter-session) The greeter session to use, specified as a symbol. Currently, only @code{lightdm-gtk-greeter} is supported. @item @code{xserver-command} (type: maybe-file-like) The Xorg server command to run. @item @code{session-wrapper} (type: file-like) The xinitrc session wrapper to use. @item @code{extra-config} (default: @code{'()}) (type: list-of-strings) Extra configuration values to append to the seat configuration section. @end table @end deftp @c %end of fragment @cindex Xorg, configuration @deftp {Data Type} xorg-configuration This data type represents the configuration of the Xorg graphical display server. Note that there is no Xorg service; instead, the X server is started by a ``display manager'' such as GDM, SDDM, LightDM or SLiM@. Thus, the configuration of these display managers aggregates an @code{xorg-configuration} record. @table @asis @item @code{modules} (default: @code{%default-xorg-modules}) This is a list of @dfn{module packages} loaded by the Xorg server---e.g., @code{xf86-video-vesa}, @code{xf86-input-keyboard}, and so on. @item @code{fonts} (default: @code{%default-xorg-fonts}) This is a list of font directories to add to the server's @dfn{font path}. @item @code{drivers} (default: @code{'()}) This must be either the empty list, in which case Xorg chooses a graphics driver automatically, or a list of driver names that will be tried in this order---e.g., @code{'("modesetting" "vesa")}. @item @code{resolutions} (default: @code{'()}) When @code{resolutions} is the empty list, Xorg chooses an appropriate screen resolution. Otherwise, it must be a list of resolutions---e.g., @code{'((1024 768) (640 480))}. @cindex keyboard layout, for Xorg @cindex keymap, for Xorg @item @code{keyboard-layout} (default: @code{#f}) If this is @code{#f}, Xorg uses the default keyboard layout---usually US English (``qwerty'') for a 105-key PC keyboard. Otherwise this must be a @code{keyboard-layout} object specifying the keyboard layout in use when Xorg is running. @xref{Keyboard Layout}, for more information on how to specify the keyboard layout. @item @code{extra-config} (default: @code{'()}) This is a list of strings or objects appended to the configuration file. It is used to pass extra text to be added verbatim to the configuration file. @item @code{server} (default: @code{xorg-server}) This is the package providing the Xorg server. @item @code{server-arguments} (default: @code{%default-xorg-server-arguments}) This is the list of command-line arguments to pass to the X server. The default is @code{-nolisten tcp}. @end table @end deftp @deffn {Procedure} set-xorg-configuration config [login-manager-service-type] Tell the log-in manager (of type @var{login-manager-service-type}) to use @var{config}, an @code{<xorg-configuration>} record. Since the Xorg configuration is embedded in the log-in manager's configuration---e.g., @code{gdm-configuration}---this procedure provides a shorthand to set the Xorg configuration. @end deffn @deffn {Procedure} xorg-start-command [config] Return a @code{startx} script in which the modules, fonts, etc. specified in @var{config}, are available. The result should be used in place of @code{startx}. Usually the X server is started by a login manager. @end deffn @deffn {Procedure} xorg-start-command-xinit [config] Return a @code{startx} script in which the modules, fonts, etc. specified in @var{config} are available. The result should be used in place of @code{startx} and should be invoked by the user from a tty after login. Unlike @code{xorg-start-command}, this script calls xinit. Therefore it works well when executed from a tty. This script can be set up as @code{startx} using @code{startx-command-service-type} or @code{home-startx-command-service-type}. If you are using a desktop environment, you are unlikely to need this procedure. @end deffn @defvar screen-locker-service-type Type for a service that adds a package for a screen locker or screen saver to the set of privileged programs and/or add a PAM entry for it. The value for this service is a @code{<screen-locker-configuration>} object. While the default behavior is to setup both a privileged program and PAM entry, these two methods are redundant. Screen locker programs may not execute when PAM is configured and @code{setuid} is set on their executable. In this case, @code{using-setuid?} can be set to @code{#f}. For example, to make XlockMore usable: @lisp (service screen-locker-service-type (screen-locker-configuration (name "xlock") (program (file-append xlockmore "/bin/xlock")))) @end lisp makes the good ol' XlockMore usable. For example, swaylock fails to execute when compiled with PAM support and setuid enabled. One can thus disable setuid: @lisp (service screen-locker-service-type (screen-locker-configuration (name "swaylock") (program (file-append swaylock "/bin/swaylock")) (using-pam? #t) (using-setuid? #f))) @end lisp @end defvar @deftp {Data Type} screen-locker-configuration Available @code{screen-locker-configuration} fields are: @table @asis @item @code{name} (type: string) Name of the screen locker. @item @code{program} (type: file-like) Path to the executable for the screen locker as a G-Expression. @item @code{allow-empty-password?} (default: @code{#f}) (type: boolean) Whether to allow empty passwords. @item @code{using-pam?} (default: @code{#t}) (type: boolean) Whether to setup PAM entry. @item @code{using-setuid?} (default: @code{#t}) (type: boolean) Whether to setup program as setuid binary. @end table @end deftp @defvar startx-command-service-type Add @command{startx} to the system profile putting it onto @env{PATH}. The value for this service is a @code{<xorg-configuration>} object which is passed to the @code{xorg-start-command-xinit} procedure producing the @command{startx} used. Default value is @code{(xorg-configuration)}. @end defvar @node Printing Services @subsection Printing Services @cindex printer support with CUPS The @code{(gnu services cups)} module provides a Guix service definition for the CUPS printing service. To add printer support to a Guix system, add a @code{cups-service} to the operating system definition: @defvar cups-service-type The service type for the CUPS print server. Its value should be a valid CUPS configuration (see below). To use the default settings, simply write: @lisp (service cups-service-type) @end lisp @end defvar The CUPS configuration controls the basic things about your CUPS installation: what interfaces it listens on, what to do if a print job fails, how much logging to do, and so on. To actually add a printer, you have to visit the @url{http://localhost:631} URL, or use a tool such as GNOME's printer configuration services. By default, configuring a CUPS service will generate a self-signed certificate if needed, for secure connections to the print server. Suppose you want to enable the Web interface of CUPS and also add support for Epson printers @i{via} the @code{epson-inkjet-printer-escpr} package and for HP printers @i{via} the @code{hplip-minimal} package. You can do that directly, like this (you need to use the @code{(gnu packages cups)} module): @lisp (service cups-service-type (cups-configuration (web-interface? #t) (extensions (list cups-filters epson-inkjet-printer-escpr hplip-minimal)))) @end lisp @quotation Note If you wish to use the Qt5 based GUI which comes with the hplip package then it is suggested that you install the @code{hplip} package, either in your OS configuration file or as your user. @end quotation The available configuration parameters follow. Each parameter definition is preceded by its type; for example, @samp{string-list foo} indicates that the @code{foo} parameter should be specified as a list of strings. There is also a way to specify the configuration as a string, if you have an old @code{cupsd.conf} file that you want to port over from some other system; see the end for more details. @c The following documentation was initially generated by @c (generate-documentation) in (gnu services cups). Manually maintained @c documentation is better, so we shouldn't hesitate to edit below as @c needed. However if the change you want to make to this documentation @c can be done in an automated way, it's probably easier to change @c (generate-documentation) than to make it below and have to deal with @c the churn as CUPS updates. Available @code{cups-configuration} fields are: @deftypevr {@code{cups-configuration} parameter} package cups The CUPS package. @end deftypevr @deftypevr {@code{cups-configuration} parameter} package-list extensions (default: @code{(list brlaser cups-filters epson-inkjet-printer-escpr foomatic-filters hplip-minimal splix)}) Drivers and other extensions to the CUPS package. @end deftypevr @deftypevr {@code{cups-configuration} parameter} files-configuration files-configuration Configuration of where to write logs, what directories to use for print spools, and related privileged configuration parameters. Available @code{files-configuration} fields are: @deftypevr {@code{files-configuration} parameter} log-location access-log Defines the access log filename. Specifying a blank filename disables access log generation. The value @code{stderr} causes log entries to be sent to the standard error file when the scheduler is running in the foreground, or to the system log daemon when run in the background. The value @code{syslog} causes log entries to be sent to the system log daemon. The server name may be included in filenames using the string @code{%s}, as in @code{/var/log/cups/%s-access_log}. Defaults to @samp{"/var/log/cups/access_log"}. @end deftypevr @deftypevr {@code{files-configuration} parameter} file-name cache-dir Where CUPS should cache data. Defaults to @samp{"/var/cache/cups"}. @end deftypevr @deftypevr {@code{files-configuration} parameter} string config-file-perm Specifies the permissions for all configuration files that the scheduler writes. Note that the permissions for the printers.conf file are currently masked to only allow access from the scheduler user (typically root). This is done because printer device URIs sometimes contain sensitive authentication information that should not be generally known on the system. There is no way to disable this security feature. Defaults to @samp{"0640"}. @end deftypevr @deftypevr {@code{files-configuration} parameter} log-location error-log Defines the error log filename. Specifying a blank filename disables error log generation. The value @code{stderr} causes log entries to be sent to the standard error file when the scheduler is running in the foreground, or to the system log daemon when run in the background. The value @code{syslog} causes log entries to be sent to the system log daemon. The server name may be included in filenames using the string @code{%s}, as in @code{/var/log/cups/%s-error_log}. Defaults to @samp{"/var/log/cups/error_log"}. @end deftypevr @deftypevr {@code{files-configuration} parameter} string fatal-errors Specifies which errors are fatal, causing the scheduler to exit. The kind strings are: @table @code @item none No errors are fatal. @item all All of the errors below are fatal. @item browse Browsing initialization errors are fatal, for example failed connections to the DNS-SD daemon. @item config Configuration file syntax errors are fatal. @item listen Listen or Port errors are fatal, except for IPv6 failures on the loopback or @code{any} addresses. @item log Log file creation or write errors are fatal. @item permissions Bad startup file permissions are fatal, for example shared TLS certificate and key files with world-read permissions. @end table Defaults to @samp{"all -browse"}. @end deftypevr @deftypevr {@code{files-configuration} parameter} boolean file-device? Specifies whether the file pseudo-device can be used for new printer queues. The URI @uref{file:///dev/null} is always allowed. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{files-configuration} parameter} string group Specifies the group name or ID that will be used when executing external programs. Defaults to @samp{"lp"}. @end deftypevr @deftypevr {@code{files-configuration} parameter} string log-file-group Specifies the group name or ID that will be used for log files. Defaults to @samp{"lpadmin"}. @end deftypevr @deftypevr {@code{files-configuration} parameter} string log-file-perm Specifies the permissions for all log files that the scheduler writes. Defaults to @samp{"0644"}. @end deftypevr @deftypevr {@code{files-configuration} parameter} log-location page-log Defines the page log filename. Specifying a blank filename disables page log generation. The value @code{stderr} causes log entries to be sent to the standard error file when the scheduler is running in the foreground, or to the system log daemon when run in the background. The value @code{syslog} causes log entries to be sent to the system log daemon. The server name may be included in filenames using the string @code{%s}, as in @code{/var/log/cups/%s-page_log}. Defaults to @samp{"/var/log/cups/page_log"}. @end deftypevr @deftypevr {@code{files-configuration} parameter} string remote-root Specifies the username that is associated with unauthenticated accesses by clients claiming to be the root user. The default is @code{remroot}. Defaults to @samp{"remroot"}. @end deftypevr @deftypevr {@code{files-configuration} parameter} file-name request-root Specifies the directory that contains print jobs and other HTTP request data. Defaults to @samp{"/var/spool/cups"}. @end deftypevr @deftypevr {@code{files-configuration} parameter} sandboxing sandboxing Specifies the level of security sandboxing that is applied to print filters, backends, and other child processes of the scheduler; either @code{relaxed} or @code{strict}. This directive is currently only used/supported on macOS. Defaults to @samp{strict}. @end deftypevr @deftypevr {@code{files-configuration} parameter} file-name server-keychain Specifies the location of TLS certificates and private keys. CUPS will look for public and private keys in this directory: @file{.crt} files for PEM-encoded certificates and corresponding @file{.key} files for PEM-encoded private keys. Defaults to @samp{"/etc/cups/ssl"}. @end deftypevr @deftypevr {@code{files-configuration} parameter} file-name server-root Specifies the directory containing the server configuration files. Defaults to @samp{"/etc/cups"}. @end deftypevr @deftypevr {@code{files-configuration} parameter} boolean sync-on-close? Specifies whether the scheduler calls fsync(2) after writing configuration or state files. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{files-configuration} parameter} space-separated-string-list system-group Specifies the group(s) to use for @code{@@SYSTEM} group authentication. @end deftypevr @deftypevr {@code{files-configuration} parameter} file-name temp-dir Specifies the directory where temporary files are stored. Defaults to @samp{"/var/spool/cups/tmp"}. @end deftypevr @deftypevr {@code{files-configuration} parameter} string user Specifies the user name or ID that is used when running external programs. Defaults to @samp{"lp"}. @end deftypevr @deftypevr {@code{files-configuration} parameter} string set-env Set the specified environment variable to be passed to child processes. Defaults to @samp{"variable value"}. @end deftypevr @end deftypevr @deftypevr {@code{cups-configuration} parameter} access-log-level access-log-level Specifies the logging level for the AccessLog file. The @code{config} level logs when printers and classes are added, deleted, or modified and when configuration files are accessed or updated. The @code{actions} level logs when print jobs are submitted, held, released, modified, or canceled, and any of the conditions for @code{config}. The @code{all} level logs all requests. Defaults to @samp{actions}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} boolean auto-purge-jobs? Specifies whether to purge job history data automatically when it is no longer required for quotas. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} comma-separated-string-list browse-dns-sd-sub-types Specifies a list of DNS-SD sub-types to advertise for each shared printer. The default @samp{(list "_cups" "_print" "_universal")} tells clients that CUPS sharing, IPP Everywhere, AirPrint, and Mopria are supported. @end deftypevr @deftypevr {@code{cups-configuration} parameter} browse-local-protocols browse-local-protocols Specifies which protocols to use for local printer sharing. Defaults to @samp{dnssd}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} boolean browse-web-if? Specifies whether the CUPS web interface is advertised. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} boolean browsing? Specifies whether shared printers are advertised. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} default-auth-type default-auth-type Specifies the default type of authentication to use. Defaults to @samp{Basic}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} default-encryption default-encryption Specifies whether encryption will be used for authenticated requests. Defaults to @samp{Required}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} string default-language Specifies the default language to use for text and web content. Defaults to @samp{"en"}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} string default-paper-size Specifies the default paper size for new print queues. @samp{"Auto"} uses a locale-specific default, while @samp{"None"} specifies there is no default paper size. Specific size names are typically @samp{"Letter"} or @samp{"A4"}. Defaults to @samp{"Auto"}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} string default-policy Specifies the default access policy to use. Defaults to @samp{"default"}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} boolean default-shared? Specifies whether local printers are shared by default. Defaults to @samp{#t}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} non-negative-integer dirty-clean-interval Specifies the delay for updating of configuration and state files, in seconds. A value of 0 causes the update to happen as soon as possible, typically within a few milliseconds. Defaults to @samp{30}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} error-policy error-policy Specifies what to do when an error occurs. Possible values are @code{abort-job}, which will discard the failed print job; @code{retry-job}, which will retry the job at a later time; @code{retry-current-job}, which retries the failed job immediately; and @code{stop-printer}, which stops the printer. Defaults to @samp{stop-printer}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} non-negative-integer filter-limit Specifies the maximum cost of filters that are run concurrently, which can be used to minimize disk, memory, and CPU resource problems. A limit of 0 disables filter limiting. An average print to a non-PostScript printer needs a filter limit of about 200. A PostScript printer needs about half that (100). Setting the limit below these thresholds will effectively limit the scheduler to printing a single job at any time. Defaults to @samp{0}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} non-negative-integer filter-nice Specifies the scheduling priority of filters that are run to print a job. The nice value ranges from 0, the highest priority, to 19, the lowest priority. Defaults to @samp{0}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} host-name-lookups host-name-lookups Specifies whether to do reverse lookups on connecting clients. The @code{double} setting causes @code{cupsd} to verify that the hostname resolved from the address matches one of the addresses returned for that hostname. Double lookups also prevent clients with unregistered addresses from connecting to your server. Only set this option to @code{#t} or @code{double} if absolutely required. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} non-negative-integer job-kill-delay Specifies the number of seconds to wait before killing the filters and backend associated with a canceled or held job. Defaults to @samp{30}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} non-negative-integer job-retry-interval Specifies the interval between retries of jobs in seconds. This is typically used for fax queues but can also be used with normal print queues whose error policy is @code{retry-job} or @code{retry-current-job}. Defaults to @samp{30}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} non-negative-integer job-retry-limit Specifies the number of retries that are done for jobs. This is typically used for fax queues but can also be used with normal print queues whose error policy is @code{retry-job} or @code{retry-current-job}. Defaults to @samp{5}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} boolean keep-alive? Specifies whether to support HTTP keep-alive connections. Defaults to @samp{#t}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} non-negative-integer limit-request-body Specifies the maximum size of print files, IPP requests, and HTML form data. A limit of 0 disables the limit check. Defaults to @samp{0}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} multiline-string-list listen Listens on the specified interfaces for connections. Valid values are of the form @var{address}:@var{port}, where @var{address} is either an IPv6 address enclosed in brackets, an IPv4 address, or @code{*} to indicate all addresses. Values can also be file names of local UNIX domain sockets. The Listen directive is similar to the Port directive but allows you to restrict access to specific interfaces or networks. @end deftypevr @deftypevr {@code{cups-configuration} parameter} location-access-control-list location-access-controls Specifies a set of additional access controls. Available @code{location-access-controls} fields are: @deftypevr {@code{location-access-controls} parameter} file-name path Specifies the URI path to which the access control applies. @end deftypevr @deftypevr {@code{location-access-controls} parameter} access-control-list access-controls Access controls for all access to this path, in the same format as the @code{access-controls} of @code{operation-access-control}. Defaults to @samp{'()}. @end deftypevr @deftypevr {@code{location-access-controls} parameter} method-access-control-list method-access-controls Access controls for method-specific access to this path. Defaults to @samp{'()}. Available @code{method-access-controls} fields are: @deftypevr {@code{method-access-controls} parameter} boolean reverse? If @code{#t}, apply access controls to all methods except the listed methods. Otherwise apply to only the listed methods. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{method-access-controls} parameter} method-list methods Methods to which this access control applies. Defaults to @samp{'()}. @end deftypevr @deftypevr {@code{method-access-controls} parameter} access-control-list access-controls Access control directives, as a list of strings. Each string should be one directive, such as @samp{"Order allow,deny"}. Defaults to @samp{'()}. @end deftypevr @end deftypevr @end deftypevr @deftypevr {@code{cups-configuration} parameter} non-negative-integer log-debug-history Specifies the number of debugging messages that are retained for logging if an error occurs in a print job. Debug messages are logged regardless of the LogLevel setting. Defaults to @samp{100}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} log-level log-level Specifies the level of logging for the ErrorLog file. The value @code{none} stops all logging while @code{debug2} logs everything. Defaults to @samp{info}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} log-time-format log-time-format Specifies the format of the date and time in the log files. The value @code{standard} logs whole seconds while @code{usecs} logs microseconds. Defaults to @samp{standard}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} non-negative-integer max-clients Specifies the maximum number of simultaneous clients that are allowed by the scheduler. Defaults to @samp{100}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} non-negative-integer max-clients-per-host Specifies the maximum number of simultaneous clients that are allowed from a single address. Defaults to @samp{100}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} non-negative-integer max-copies Specifies the maximum number of copies that a user can print of each job. Defaults to @samp{9999}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} non-negative-integer max-hold-time Specifies the maximum time a job may remain in the @code{indefinite} hold state before it is canceled. A value of 0 disables cancellation of held jobs. Defaults to @samp{0}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} non-negative-integer max-jobs Specifies the maximum number of simultaneous jobs that are allowed. Set to 0 to allow an unlimited number of jobs. Defaults to @samp{500}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} non-negative-integer max-jobs-per-printer Specifies the maximum number of simultaneous jobs that are allowed per printer. A value of 0 allows up to @code{max-jobs} per printer. Defaults to @samp{0}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} non-negative-integer max-jobs-per-user Specifies the maximum number of simultaneous jobs that are allowed per user. A value of 0 allows up to @code{max-jobs} per user. Defaults to @samp{0}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} non-negative-integer max-job-time Specifies the maximum time a job may take to print before it is canceled, in seconds. Set to 0 to disable cancellation of ``stuck'' jobs. Defaults to @samp{10800}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} non-negative-integer max-log-size Specifies the maximum size of the log files before they are rotated, in bytes. The value 0 disables log rotation. Defaults to @samp{1048576}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} non-negative-integer max-subscriptions Specifies the maximum number of simultaneous event subscriptions that are allowed. Set to @samp{0} to allow an unlimited number of subscriptions. Defaults to @samp{0}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} non-negative-integer max-subscriptions-per-job Specifies the maximum number of simultaneous event subscriptions that are allowed per job. A value of @samp{0} allows up to @code{max-subscriptions} per job. Defaults to @samp{0}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} non-negative-integer max-subscriptions-per-printer Specifies the maximum number of simultaneous event subscriptions that are allowed per printer. A value of @samp{0} allows up to @code{max-subscriptions} per printer. Defaults to @samp{0}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} non-negative-integer max-subscriptions-per-user Specifies the maximum number of simultaneous event subscriptions that are allowed per user. A value of @samp{0} allows up to @code{max-subscriptions} per user. Defaults to @samp{0}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} non-negative-integer multiple-operation-timeout Specifies the maximum amount of time to allow between files in a multiple file print job, in seconds. Defaults to @samp{900}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} environment-variables environment-variables Passes the specified environment variable(s) to child processes; a list of strings. Defaults to @samp{'()}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} policy-configuration-list policies Specifies named access control policies. Available @code{policy-configuration} fields are: @deftypevr {@code{policy-configuration} parameter} string name Name of the policy. @end deftypevr @deftypevr {@code{policy-configuration} parameter} string job-private-access Specifies an access list for a job's private values. @code{@@ACL} maps to the printer's requesting-user-name-allowed or requesting-user-name-denied values. @code{@@OWNER} maps to the job's owner. @code{@@SYSTEM} maps to the groups listed for the @code{system-group} field of the @code{files-configuration}, which is reified into the @code{cups-files.conf(5)} file. Other possible elements of the access list include specific user names, and @code{@@@var{group}} to indicate members of a specific group. The access list may also be simply @code{all} or @code{default}. Defaults to @samp{"@@OWNER @@SYSTEM"}. @end deftypevr @deftypevr {@code{policy-configuration} parameter} string job-private-values Specifies the list of job values to make private, or @code{all}, @code{default}, or @code{none}. Defaults to @samp{"job-name job-originating-host-name job-originating-user-name phone"}. @end deftypevr @deftypevr {@code{policy-configuration} parameter} string subscription-private-access Specifies an access list for a subscription's private values. @code{@@ACL} maps to the printer's requesting-user-name-allowed or requesting-user-name-denied values. @code{@@OWNER} maps to the job's owner. @code{@@SYSTEM} maps to the groups listed for the @code{system-group} field of the @code{files-configuration}, which is reified into the @code{cups-files.conf(5)} file. Other possible elements of the access list include specific user names, and @code{@@@var{group}} to indicate members of a specific group. The access list may also be simply @code{all} or @code{default}. Defaults to @samp{"@@OWNER @@SYSTEM"}. @end deftypevr @deftypevr {@code{policy-configuration} parameter} string subscription-private-values Specifies the list of job values to make private, or @code{all}, @code{default}, or @code{none}. Defaults to @samp{"notify-events notify-pull-method notify-recipient-uri notify-subscriber-user-name notify-user-data"}. @end deftypevr @deftypevr {@code{policy-configuration} parameter} operation-access-control-list access-controls Access control by IPP operation. Defaults to @samp{'()}. @end deftypevr @end deftypevr @deftypevr {@code{cups-configuration} parameter} boolean-or-non-negative-integer preserve-job-files Specifies whether job files (documents) are preserved after a job is printed. If a numeric value is specified, job files are preserved for the indicated number of seconds after printing. Otherwise a boolean value applies indefinitely. Defaults to @samp{86400}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} boolean-or-non-negative-integer preserve-job-history Specifies whether the job history is preserved after a job is printed. If a numeric value is specified, the job history is preserved for the indicated number of seconds after printing. If @code{#t}, the job history is preserved until the MaxJobs limit is reached. Defaults to @samp{#t}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} comma-separated-string-list-or-#f ready-paper-sizes Specifies a list of potential paper sizes that are reported as ready, that is: loaded. The actual list will contain only the sizes that each printer supports. The default value of @code{#f} is a special case: CUPS will use @samp{(list \"Letter\" \"Legal\" \"Tabloid\" \"4x6\" \"Env10\")} if the default paper size is \"Letter\", and @samp{(list \"A3\" \"A4\" \"A5\" \"A6\" \"EnvDL\")} otherwise. @end deftypevr @deftypevr {@code{cups-configuration} parameter} non-negative-integer reload-timeout Specifies the amount of time to wait for job completion before restarting the scheduler. Defaults to @samp{30}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} string server-admin Specifies the email address of the server administrator. Defaults to @samp{"root@@localhost.localdomain"}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} host-name-list-or-* server-alias The ServerAlias directive is used for HTTP Host header validation when clients connect to the scheduler from external interfaces. Using the special name @code{*} can expose your system to known browser-based DNS rebinding attacks, even when accessing sites through a firewall. If the auto-discovery of alternate names does not work, we recommend listing each alternate name with a ServerAlias directive instead of using @code{*}. Defaults to @samp{*}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} string server-name Specifies the fully-qualified host name of the server. Defaults to @samp{"localhost"}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} server-tokens server-tokens Specifies what information is included in the Server header of HTTP responses. @code{None} disables the Server header. @code{ProductOnly} reports @code{CUPS}. @code{Major} reports @code{CUPS 2}. @code{Minor} reports @code{CUPS 2.0}. @code{Minimal} reports @code{CUPS 2.0.0}. @code{OS} reports @code{CUPS 2.0.0 (@var{uname})} where @var{uname} is the output of the @code{uname} command. @code{Full} reports @code{CUPS 2.0.0 (@var{uname}) IPP/2.0}. Defaults to @samp{Minimal}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} multiline-string-list ssl-listen Listens on the specified interfaces for encrypted connections. Valid values are of the form @var{address}:@var{port}, where @var{address} is either an IPv6 address enclosed in brackets, an IPv4 address, or @code{*} to indicate all addresses. Defaults to @samp{'()}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} ssl-options ssl-options Sets encryption options. By default, CUPS only supports encryption using TLS v1.0 or higher using known secure cipher suites. Security is reduced when @code{Allow} options are used, and enhanced when @code{Deny} options are used. The @code{AllowRC4} option enables the 128-bit RC4 cipher suites, which are required for some older clients. The @code{AllowSSL3} option enables SSL v3.0, which is required for some older clients that do not support TLS v1.0. The @code{DenyCBC} option disables all CBC cipher suites. The @code{DenyTLS1.0} option disables TLS v1.0 support - this sets the minimum protocol version to TLS v1.1. Defaults to @samp{'()}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} boolean strict-conformance? Specifies whether the scheduler requires clients to strictly adhere to the IPP specifications. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} non-negative-integer timeout Specifies the HTTP request timeout, in seconds. Defaults to @samp{900}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} boolean web-interface? Specifies whether the web interface is enabled. Defaults to @samp{#f}. @end deftypevr At this point you're probably thinking ``oh dear, Guix manual, I like you but you can stop already with the configuration options''. Indeed. However, one more point: it could be that you have an existing @code{cupsd.conf} that you want to use. In that case, you can pass an @code{opaque-cups-configuration} as the configuration of a @code{cups-service-type}. Available @code{opaque-cups-configuration} fields are: @deftypevr {@code{opaque-cups-configuration} parameter} package cups The CUPS package. @end deftypevr @deftypevr {@code{opaque-cups-configuration} parameter} string cupsd.conf The contents of the @code{cupsd.conf}, as a string. @end deftypevr @deftypevr {@code{opaque-cups-configuration} parameter} string cups-files.conf The contents of the @code{cups-files.conf} file, as a string. @end deftypevr For example, if your @code{cupsd.conf} and @code{cups-files.conf} are in strings of the same name, you could instantiate a CUPS service like this: @lisp (service cups-service-type (opaque-cups-configuration (cupsd.conf cupsd.conf) (cups-files.conf cups-files.conf))) @end lisp @node Desktop Services @subsection Desktop Services The @code{(gnu services desktop)} module provides services that are usually useful in the context of a ``desktop'' setup---that is, on a machine running a graphical display server, possibly with graphical user interfaces, etc. It also defines services that provide specific desktop environments like GNOME, Xfce or MATE. To simplify things, the module defines a variable containing the set of services that users typically expect on a machine with a graphical environment and networking: @defvar %desktop-services This is a list of services that builds upon @code{%base-services} and adds or adjusts services for a typical ``desktop'' setup. In particular, it adds a graphical login manager (@pxref{X Window, @code{gdm-service-type}}), screen lockers, a network management tool (@pxref{Networking Services, @code{network-manager-service-type}}) with modem support (@pxref{Networking Services, @code{modem-manager-service-type}}), energy and color management services, the @code{elogind} login and seat manager, the Polkit privilege service, the GeoClue location service, the AccountsService daemon that allows authorized users change system passwords, a NTP client (@pxref{Networking Services}) and the Avahi daemon. @end defvar The @code{%desktop-services} variable can be used as the @code{services} field of an @code{operating-system} declaration (@pxref{operating-system Reference, @code{services}}). Additionally, the following procedures add one (or more!) desktop environments to a system. @itemize @item @code{gnome-desktop-service-type} adds GNOME, @item @code{plasma-desktop-service-type} adds KDE Plasma, @item @code{enlightenment-desktop-service-type} adds Enlightenment, @item @code{lxqt-desktop-service-type} adds LXQt, @item @code{mate-desktop-service-type} adds MATE, and @item @code{xfce-desktop-service} adds Xfce. @end itemize These service types add ``metapackages'' such as @code{gnome} or @code{plasma} to the system profile, but most of them also set up other useful services that mere packages can't do. For example, they may elevate privileges on a limited number of special-purpose system interfaces and programs. This allows backlight adjustment helpers, power management utilities, screen lockers, and other integrated functionality to work as expected. The desktop environments in Guix use the Xorg display server by default. If you'd like to use the newer display server protocol called Wayland, you need to enable Wayland support in GDM (@pxref{wayland-gdm}). Another solution is to use the @code{sddm-service} instead of GDM as the graphical login manager. You should then select the ``GNOME (Wayland)'' session in SDDM@. Alternatively you can also try starting GNOME on Wayland manually from a TTY with the command ``XDG_SESSION_TYPE=wayland exec dbus-run-session gnome-session``. Currently only GNOME has support for Wayland. @defvar gnome-desktop-service-type This is the type of the service that adds the @uref{https://www.gnome.org, GNOME} desktop environment. Its value is a @code{gnome-desktop-configuration} object (see below). This service adds the @code{gnome} package to the system profile, and extends polkit with the actions from @code{gnome-settings-daemon}. @end defvar @deftp {Data Type} gnome-desktop-configuration Configuration record for the GNOME desktop environment. Available @code{gnome-desktop-configuration} fields are: @table @asis @item @code{core-services} (type: list-of-packages) A list of packages that the GNOME Shell and applications may rely on. @item @code{shell} (type: list-of-packages) A list of packages that constitute the GNOME Shell, without applications. @item @code{utilities} (type: list-of-packages) A list of packages that serve as applications to use on top of the GNOME Shell. @item @code{gnome} (type: maybe-package) This field used to be the only configuration point and specified a GNOME meta-package to install system-wide. Since the meta-package itself provides neither sources nor the actual packages and is only used to propagate them, this field is deprecated. @item @code{extra-packages} (type: list-of-packages) A list of GNOME-adjacent packages to also include. This field is intended for users to add their own packages to their GNOME experience. Note, that it already includes some packages that are considered essential by some (most?) GNOME users. @item @code{udev-ignorelist} (default: @code{()}) (type: list-of-strings) A list of regular expressions denoting udev rules or hardware file names provided by any package that should not be installed. By default, every udev rule and hardware file specified by any package referenced in the other fields are installed. @item @code{polkit-ignorelist} (default: @code{()}) (type: list-of-strings) A list of regular expressions denoting polkit rules provided by any package that should not be installed. By default, every polkit rule added by any package referenced in the other fields are installed. @end table @end deftp @defvar plasma-desktop-service-type This is the type of the service that adds the @uref{https://kde.org/plasma-desktop/, Plasma} desktop environment. Its value is a @code{plasma-desktop-configuration} object (see below). This service adds the @code{plasma} package to the system profile. @end defvar @deftp {Data Type} plasma-desktop-configuration Configuration record for the Plasma desktop environment. @table @asis @item @code{plasma} (default: @code{plasma}) The Plasma package to use. @end table @end deftp @defvar xfce-desktop-service-type This is the type of a service to run the @uref{Xfce, https://xfce.org/} desktop environment. Its value is an @code{xfce-desktop-configuration} object (see below). This service adds the @code{xfce} package to the system profile, and extends polkit with the ability for @code{thunar} to manipulate the file system as root from within a user session, after the user has authenticated with the administrator's password. Note that @code{xfce4-panel} and its plugin packages should be installed in the same profile to ensure compatibility. When using this service, you should add extra plugins (@code{xfce4-whiskermenu-plugin}, @code{xfce4-weather-plugin}, etc.) to the @code{packages} field of your @code{operating-system}. @end defvar @deftp {Data Type} xfce-desktop-configuration Configuration record for the Xfce desktop environment. @table @asis @item @code{xfce} (default: @code{xfce}) The Xfce package to use. @end table @end deftp @defvar mate-desktop-service-type This is the type of the service that runs the @uref{https://mate-desktop.org/, MATE desktop environment}. Its value is a @code{mate-desktop-configuration} object (see below). This service adds the @code{mate} package to the system profile, and extends polkit with the actions from @code{mate-settings-daemon}. @end defvar @deftp {Data Type} mate-desktop-configuration Configuration record for the MATE desktop environment. @table @asis @item @code{mate} (default: @code{mate}) The MATE package to use. @end table @end deftp @defvar lxqt-desktop-service-type This is the type of the service that runs the @uref{https://lxqt-project.org, LXQt desktop environment}. Its value is a @code{lxqt-desktop-configuration} object (see below). This service adds the @code{lxqt} package to the system profile. @end defvar @deftp {Data Type} lxqt-desktop-configuration Configuration record for the LXQt desktop environment. @table @asis @item @code{lxqt} (default: @code{lxqt}) The LXQT package to use. @end table @end deftp @defvar sugar-desktop-service-type This is the type of the service that runs the @uref{https://www.sugarlabs.org, Sugar desktop environment}. Its value is a @code{sugar-desktop-configuration} object (see below). This service adds the @code{sugar} package to the system profile, as well as any selected Sugar activities. By default it only includes a minimal set of activities. @end defvar @deftp {Data Type} sugar-desktop-configuration Configuration record for the Sugar desktop environment. @table @asis @item @code{sugar} (default: @code{sugar}) The Sugar package to use. @item @code{gobject-introspection} (default: @code{gobject-introspection}) The @code{gobject-introspection} package to use. This package is used to access libraries installed as dependencies of Sugar activities. @item @code{activities} (default: @code{(list sugar-help-activity)}) A list of Sugar activities to install. @end table @end deftp The following example configures the Sugar desktop environment with a number of useful activities: @lisp (use-modules (gnu)) (use-package-modules sugar) (use-service-modules desktop) (operating-system ... (services (cons* (service sugar-desktop-service-type (sugar-desktop-configuration (activities (list sugar-browse-activity sugar-help-activity sugar-jukebox-activity sugar-typing-turtle-activity)))) %desktop-services)) ...) @end lisp @defvar enlightenment-desktop-service-type Return a service that adds the @code{enlightenment} package to the system profile, and extends dbus with actions from @code{efl}. @end defvar @deftp {Data Type} enlightenment-desktop-service-configuration @table @asis @item @code{enlightenment} (default: @code{enlightenment}) The enlightenment package to use. @end table @end deftp Because the GNOME, Xfce and MATE desktop services pull in so many packages, the default @code{%desktop-services} variable doesn't include any of them by default. To add GNOME, Xfce or MATE, just @code{cons} them onto @code{%desktop-services} in the @code{services} field of your @code{operating-system}: @lisp (use-modules (gnu)) (use-service-modules desktop) (operating-system ... ;; cons* adds items to the list given as its last argument. (services (cons* (service gnome-desktop-service-type) (service xfce-desktop-service) %desktop-services)) ...) @end lisp These desktop environments will then be available as options in the graphical login window. The actual service definitions included in @code{%desktop-services} and provided by @code{(gnu services dbus)} and @code{(gnu services desktop)} are described below. @defvar dbus-root-service-type Type for a service that runs the D-Bus ``system bus''. @footnote{@uref{https://dbus.freedesktop.org/, D-Bus} is an inter-process communication facility. Its system bus is used to allow system services to communicate and to be notified of system-wide events.} The value for this service type is a @code{<dbus-configuration>} record. @end defvar @deftp {Data Type} dbus-configuration Data type representing the configuration for @code{dbus-root-service-type}. @table @asis @item @code{dbus} (default: @code{dbus}) (type: file-like) Package object for dbus. @item @code{services} (default: @code{'()}) (type: list) List of packages that provide an @file{etc/dbus-1/system.d} directory containing additional D-Bus configuration and policy files. For example, to allow avahi-daemon to use the system bus, @var{services} must be equal to @code{(list avahi)}. @item @code{verbose?} (default: @code{#f}) (type: boolean) When @code{#t}, D-Bus is launched with environment variable @samp{DBUS_VERBOSE} set to @samp{1}. A verbose-enabled D-Bus package such as @code{dbus-verbose} should be provided to @var{dbus} in this scenario. The verbose output is logged to @file{/var/log/dbus-daemon.log}. @end table @end deftp @subsubheading Elogind @uref{https://github.com/elogind/elogind, Elogind} is a login and seat management daemon that also handles most system-level power events for a computer, for example suspending the system when a lid is closed, or shutting it down when the power button is pressed. It also provides a D-Bus interface that can be used to know which users are logged in, know what kind of sessions they have open, suspend the system, inhibit system suspend, reboot the system, and other tasks. @defvar elogind-service-type Type of the service that runs @command{elogind}, a login and seat management daemon. The value for this service is a @code{<elogind-configuration>} object. @end defvar @c TODO: field descriptions. This is best done by refactoring @c elogind-configuration to use define-configuration which embeds the @c descriptions in the code and then use configuration->documentation. @deftp {Data Type} elogind-configuration Data type representing the configuration of @command{elogind}. @table @asis @item @code{elogind} (default: @code{elogind}) (type: file-like) ... @item @code{kill-user-processes?} (default: @code{#f}) (type: boolean) ... @item @code{kill-only-users} (default: @code{'()}) (type: list) ... @item @code{kill-exclude-users} (default: @code{'("root")}) (type: list-of-string) ... @item @code{inhibit-delay-max-seconds} (default: @code{5}) (type: integer) ... @item @code{handle-power-key} (default: @code{'poweroff}) (type: symbol) ... @item @code{handle-suspend-key} (default: @code{'suspend}) (type: symbol) ... @item @code{handle-hibernate-key} (default: @code{'hibernate}) (type: symbol) ... @item @code{handle-lid-switch} (default: @code{'suspend}) (type: symbol) ... @item @code{handle-lid-switch-docked} (default: @code{'ignore}) (type: symbol) ... @item @code{handle-lid-switch-external-power} (default: @code{*unspecified*}) (type: symbol) ... @item @code{power-key-ignore-inhibited?} (default: @code{#f}) (type: boolean) ... @item @code{suspend-key-ignore-inhibited?} (default: @code{#f}) (type: boolean) ... @item @code{hibernate-key-ignore-inhibited?} (default: @code{#f}) (type: boolean) ... @item @code{lid-switch-ignore-inhibited?} (default: @code{#t}) (type: boolean) ... @item @code{holdoff-timeout-seconds} (default: @code{30}) (type: integer) ... @item @code{idle-action} (default: @code{'ignore}) (type: symbol) ... @item @code{idle-action-seconds} (default: @code{(* 30 60)}) (type: integer) ... @item @code{runtime-directory-size-percent} (default: @code{10}) (type: integer) ... @item @code{runtime-directory-size} (default: @code{#f}) (type: integer) ... @item @code{remove-ipc?} (default: @code{#t}) (type: boolean) ... @item @code{suspend-state} (default: @code{'("mem" "standby" "freeze")}) (type: list) ... @item @code{suspend-mode} (default: @code{'()}) (type: list) ... @item @code{hibernate-state} (default: @code{'("disk")}) (type: list) ... @item @code{hibernate-mode} (default: @code{'("platform" "shutdown")}) (type: list) ... @item @code{hybrid-sleep-state} (default: @code{'("disk")}) (type: list) ... @item @code{hybrid-sleep-mode} (default: @code{'("suspend" "platform" "shutdown")}) (type: list) ... @item @code{hibernate-delay-seconds} (default: @code{*unspecified*}) (type: integer) ... @item @code{suspend-estimation-seconds} (default: @code{*unspecified*}) (type: integer) ... @end table @end deftp @defvar accountsservice-service-type Type for the service that runs AccountsService, a system service that can list available accounts, change their passwords, and so on. AccountsService integrates with PolicyKit to enable unprivileged users to acquire the capability to modify their system configuration. See @url{https://www.freedesktop.org/wiki/Software/AccountsService/, AccountsService} for more information. The value for this service is a file-like object, by default it is set to @code{accountsservice} (the package object for AccountsService). @end defvar @defvar polkit-service-type Type for the service that runs the @url{https://www.freedesktop.org/wiki/Software/polkit/, Polkit privilege management service}, which allows system administrators to grant access to privileged operations in a structured way. By querying the Polkit service, a privileged system component can know when it should grant additional capabilities to ordinary users. For example, an ordinary user can be granted the capability to suspend the system if the user is logged in locally. The value for this service is a @code{<polkit-configuration>} object. @end defvar @c TODO: Document <polkit-configuration>, preferably by refactoring this to use @c define-configuration and generating documentation from it. @defvar polkit-wheel-service Service that adds the @code{wheel} group as admins to the Polkit service. This makes it so that users in the @code{wheel} group are queried for their own passwords when performing administrative actions instead of @code{root}'s, similar to the behaviour used by @code{sudo}. @end defvar @defvar upower-service-type Service that runs @uref{https://upower.freedesktop.org/, @command{upowerd}}, a system-wide monitor for power consumption and battery levels, with the given configuration settings. It implements the @code{org.freedesktop.UPower} D-Bus interface, and is notably used by GNOME. @end defvar @deftp {Data Type} upower-configuration Data type representation the configuration for UPower. @table @asis @item @code{upower} (default: @var{upower}) Package to use for @code{upower}. @item @code{watts-up-pro?} (default: @code{#f}) Enable the Watts Up Pro device. @item @code{poll-batteries?} (default: @code{#t}) Enable polling the kernel for battery level changes. @item @code{ignore-lid?} (default: @code{#f}) Ignore the lid state, this can be useful if it's incorrect on a device. @item @code{use-percentage-for-policy?} (default: @code{#t}) Whether to use a policy based on battery percentage rather than on estimated time left. A policy based on battery percentage is usually more reliable. @item @code{percentage-low} (default: @code{20}) When @code{use-percentage-for-policy?} is @code{#t}, this sets the percentage at which the battery is considered low. @item @code{percentage-critical} (default: @code{5}) When @code{use-percentage-for-policy?} is @code{#t}, this sets the percentage at which the battery is considered critical. @item @code{percentage-action} (default: @code{2}) When @code{use-percentage-for-policy?} is @code{#t}, this sets the percentage at which action will be taken. @item @code{time-low} (default: @code{1200}) When @code{use-time-for-policy?} is @code{#f}, this sets the time remaining in seconds at which the battery is considered low. @item @code{time-critical} (default: @code{300}) When @code{use-time-for-policy?} is @code{#f}, this sets the time remaining in seconds at which the battery is considered critical. @item @code{time-action} (default: @code{120}) When @code{use-time-for-policy?} is @code{#f}, this sets the time remaining in seconds at which action will be taken. @item @code{critical-power-action} (default: @code{'hybrid-sleep}) The action taken when @code{percentage-action} or @code{time-action} is reached (depending on the configuration of @code{use-percentage-for-policy?}). Possible values are: @itemize @bullet @item @code{'power-off} @item @code{'hibernate} @item @code{'hybrid-sleep}. @end itemize @end table @end deftp @defvar udisks-service-type Type for the service that runs @uref{https://udisks.freedesktop.org/docs/latest/, UDisks}, a @dfn{disk management} daemon that provides user interfaces with notifications and ways to mount/unmount disks. Programs that talk to UDisks include the @command{udisksctl} command, part of UDisks, and GNOME Disks. Note that Udisks relies on the @command{mount} command, so it will only be able to use the file-system utilities installed in the system profile. For example if you want to be able to mount NTFS file-systems in read and write fashion, you'll need to have @code{ntfs-3g} installed system-wide. The value for this service is a @code{<udisks-configuration>} object. @end defvar @deftp {Data Type} udisks-configuration Data type representing the configuration for @code{udisks-service-type}. @table @asis @item @code{udisks} (default: @code{udisks}) (type: file-like) Package object for UDisks. @end table @end deftp @defvar gvfs-service-type Type for the service that provides virtual file systems for GIO applications, which enables support for @code{trash://}, @code{ftp://}, @code{sftp://} and many other location schemas in file managers like Nautilus (GNOME Files) and Thunar. The value for this service is a @code{<gvfs-configuration>} object. @end defvar @deftp {Data Type} gvfs-configuration Data type representing the configuration for @code{gvfs-service-type}. @table @asis @item @code{gvfs} (default: @code{gvfs}) (type: file-like) Package object for GVfs. @end table @end deftp @defvar colord-service-type This is the type of the service that runs @command{colord}, a system service with a D-Bus interface to manage the color profiles of input and output devices such as screens and scanners. It is notably used by the GNOME Color Manager graphical tool. See @uref{https://www.freedesktop.org/software/colord/, the colord web site} for more information. @end defvar @cindex scanner access @defvar sane-service-type This service provides access to scanners @i{via} @uref{http://www.sane-project.org, SANE} by installing the necessary udev rules. It is included in @code{%desktop-services} (@pxref{Desktop Services}) and relies by default on @code{sane-backends-minimal} package (see below) for hardware support. @end defvar @defvar sane-backends-minimal The default package which the @code{sane-service-type} installs. It supports many recent scanners. @end defvar @defvar sane-backends This package includes support for all scanners that @code{sane-backends-minimal} supports, plus older Hewlett-Packard scanners supported by @code{hplip} package. In order to use this on a system which relies on @code{%desktop-services}, you may use @code{modify-services} (@pxref{Service Reference, @code{modify-services}}) as illustrated below: @lisp (use-modules (gnu)) (use-service-modules @dots{} desktop) (use-package-modules @dots{} scanner) (define %my-desktop-services ;; List of desktop services that supports a broader range of scanners. (modify-services %desktop-services (sane-service-type _ => sane-backends))) (operating-system @dots{} (services %my-desktop-services)) @end lisp @end defvar @deffn {Procedure} geoclue-application name [#:allowed? #t] [#:system? #f] [#:users '()] Return a configuration allowing an application to access GeoClue location data. @var{name} is the Desktop ID of the application, without the @code{.desktop} part. If @var{allowed?} is true, the application will have access to location information by default. The boolean @var{system?} value indicates whether an application is a system component or not. Finally @var{users} is a list of UIDs of all users for which this application is allowed location info access. An empty users list means that all users are allowed. @end deffn @defvar %standard-geoclue-applications The standard list of well-known GeoClue application configurations, granting authority to the GNOME date-and-time utility to ask for the current location in order to set the time zone, and allowing the IceCat and Epiphany web browsers to request location information. IceCat and Epiphany both query the user before allowing a web page to know the user's location. @end defvar @defvar geoclue-service-type Type for the service that runs the @url{https://wiki.freedesktop.org/www/Software/GeoClue/, GeoClue} location service. This service provides a D-Bus interface to allow applications to request access to a user's physical location, and optionally to add information to online location databases. The value for this service is a @code{<geoclue-configuration>} object. @end defvar @c TODO: Document <geoclue-configuration>, preferably by refactoring this to use @c define-configuration and generating documentation from it. @defvar bluetooth-service-type This is the type for the @uref{https://bluez.org/, Linux Bluetooth Protocol Stack} (BlueZ) system, which generates the @file{/etc/bluetooth/main.conf} configuration file. The value for this type is a @command{bluetooth-configuration} record as in this example: @lisp (service bluetooth-service-type) @end lisp See below for details about @code{bluetooth-configuration}. @end defvar @deftp {Data Type} bluetooth-configuration Data type representing the configuration for @code{bluetooth-service}. @table @asis @item @code{bluez} (default: @code{bluez}) @code{bluez} package to use. @item @code{name} (default: @code{"BlueZ"}) Default adapter name. @item @code{class} (default: @code{#x000000}) Default device class. Only the major and minor device class bits are considered. @item @code{discoverable-timeout} (default: @code{180}) How long to stay in discoverable mode before going back to non-discoverable. The value is in seconds. @item @code{always-pairable?} (default: @code{#f}) Always allow pairing even if there are no agents registered. @item @code{pairable-timeout} (default: @code{0}) How long to stay in pairable mode before going back to non-discoverable. The value is in seconds. @item @code{device-id} (default: @code{#f}) Use vendor id source (assigner), vendor, product and version information for DID profile support. The values are separated by ":" and @var{assigner}, @var{VID}, @var{PID} and @var{version}. Possible values are: @itemize @bullet @item @code{#f} to disable it, @item @code{"assigner:1234:5678:abcd"}, where @var{assigner} is either @code{usb} (default) or @code{bluetooth}. @end itemize @item @code{reverse-service-discovery?} (default: @code{#t}) Do reverse service discovery for previously unknown devices that connect to us. For BR/EDR this option is really only needed for qualification since the BITE tester doesn't like us doing reverse SDP for some test cases, for LE this disables the GATT client functionally so it can be used in system which can only operate as peripheral. @item @code{name-resolving?} (default: @code{#t}) Enable name resolving after inquiry. Set it to @code{#f} if you don't need remote devices name and want shorter discovery cycle. @item @code{debug-keys?} (default: @code{#f}) Enable runtime persistency of debug link keys. Default is false which makes debug link keys valid only for the duration of the connection that they were created for. @item @code{controller-mode} (default: @code{'dual}) Restricts all controllers to the specified transport. @code{'dual} means both BR/EDR and LE are enabled (if supported by the hardware). Possible values are: @itemize @bullet @item @code{'dual} @item @code{'bredr} @item @code{'le} @end itemize @item @code{multi-profile} (default: @code{'off}) Enables Multi Profile Specification support. This allows to specify if system supports only Multiple Profiles Single Device (MPSD) configuration or both Multiple Profiles Single Device (MPSD) and Multiple Profiles Multiple Devices (MPMD) configurations. Possible values are: @itemize @bullet @item @code{'off} @item @code{'single} @item @code{'multiple} @end itemize @item @code{fast-connectable?} (default: @code{#f}) Permanently enables the Fast Connectable setting for adapters that support it. When enabled other devices can connect faster to us, however the tradeoff is increased power consumptions. This feature will fully work only on kernel version 4.1 and newer. @item @code{privacy} (default: @code{'off}) Default privacy settings. @itemize @bullet @item @code{'off}: Disable local privacy @item @code{'network/on}: A device will only accept advertising packets from peer devices that contain private addresses. It may not be compatible with some legacy devices since it requires the use of RPA(s) all the time @item @code{'device}: A device in device privacy mode is only concerned about the privacy of the device and will accept advertising packets from peer devices that contain their Identity Address as well as ones that contain a private address, even if the peer device has distributed its IRK in the past @end itemize and additionally, if @var{controller-mode} is set to @code{'dual}: @itemize @bullet @item @code{'limited-network}: Apply Limited Discoverable Mode to advertising, which follows the same policy as to BR/EDR that publishes the identity address when discoverable, and Network Privacy Mode for scanning @item @code{'limited-device}: Apply Limited Discoverable Mode to advertising, which follows the same policy as to BR/EDR that publishes the identity address when discoverable, and Device Privacy Mode for scanning. @end itemize @item @code{just-works-repairing} (default: @code{'never}) Specify the policy to the JUST-WORKS repairing initiated by peer. Possible values: @itemize @bullet @item @code{'never} @item @code{'confirm} @item @code{'always} @end itemize @item @code{temporary-timeout} (default: @code{30}) How long to keep temporary devices around. The value is in seconds. @code{0} disables the timer completely. @item @code{refresh-discovery?} (default: @code{#t}) Enables the device to issue an SDP request to update known services when profile is connected. @item @code{experimental} (default: @code{#f}) Enables experimental features and interfaces, alternatively a list of UUIDs can be given. Possible values: @itemize @bullet @item @code{#t} @item @code{#f} @item @code{(list (uuid <uuid-1>) (uuid <uuid-2>) ...)}. @end itemize List of possible UUIDs: @itemize @bullet @item @code{d4992530-b9ec-469f-ab01-6c481c47da1c}: BlueZ Experimental Debug, @item @code{671b10b5-42c0-4696-9227-eb28d1b049d6}: BlueZ Experimental Simultaneous Central and Peripheral, @item @code{15c0a148-c273-11ea-b3de-0242ac130004}: BlueZ Experimental LL privacy, @item @code{330859bc-7506-492d-9370-9a6f0614037f}: BlueZ Experimental Bluetooth Quality Report, @item @code{a6695ace-ee7f-4fb9-881a-5fac66c629af}: BlueZ Experimental Offload Codecs. @end itemize @item @code{remote-name-request-retry-delay} (default: @code{300}) The duration to avoid retrying to resolve a peer's name, if the previous try failed. @item @code{page-scan-type} (default: @code{#f}) BR/EDR Page scan activity type. @item @code{page-scan-interval} (default: @code{#f}) BR/EDR Page scan activity interval. @item @code{page-scan-window} (default: @code{#f}) BR/EDR Page scan activity window. @item @code{inquiry-scan-type} (default: @code{#f}) BR/EDR Inquiry scan activity type. @item @code{inquiry-scan-interval} (default: @code{#f}) BR/EDR Inquiry scan activity interval. @item @code{inquiry-scan-window} (default: @code{#f}) BR/EDR Inquiry scan activity window. @item @code{link-supervision-timeout} (default: @code{#f}) BR/EDR Link supervision timeout. @item @code{page-timeout} (default: @code{#f}) BR/EDR Page timeout. @item @code{min-sniff-interval} (default: @code{#f}) BR/EDR minimum sniff interval. @item @code{max-sniff-interval} (default: @code{#f}) BR/EDR maximum sniff interval. @item @code{min-advertisement-interval} (default: @code{#f}) LE minimum advertisement interval (used for legacy advertisement only). @item @code{max-advertisement-interval} (default: @code{#f}) LE maximum advertisement interval (used for legacy advertisement only). @item @code{multi-advertisement-rotation-interval} (default: @code{#f}) LE multiple advertisement rotation interval. @item @code{scan-interval-auto-connect} (default: @code{#f}) LE scanning interval used for passive scanning supporting auto connect. @item @code{scan-window-auto-connect} (default: @code{#f}) LE scanning window used for passive scanning supporting auto connect. @item @code{scan-interval-suspend} (default: @code{#f}) LE scanning interval used for active scanning supporting wake from suspend. @item @code{scan-window-suspend} (default: @code{#f}) LE scanning window used for active scanning supporting wake from suspend. @item @code{scan-interval-discovery} (default: @code{#f}) LE scanning interval used for active scanning supporting discovery. @item @code{scan-window-discovery} (default: @code{#f}) LE scanning window used for active scanning supporting discovery. @item @code{scan-interval-adv-monitor} (default: @code{#f}) LE scanning interval used for passive scanning supporting the advertisement monitor APIs. @item @code{scan-window-adv-monitor} (default: @code{#f}) LE scanning window used for passive scanning supporting the advertisement monitor APIs. @item @code{scan-interval-connect} (default: @code{#f}) LE scanning interval used for connection establishment. @item @code{scan-window-connect} (default: @code{#f}) LE scanning window used for connection establishment. @item @code{min-connection-interval} (default: @code{#f}) LE default minimum connection interval. This value is superseded by any specific value provided via the Load Connection Parameters interface. @item @code{max-connection-interval} (default: @code{#f}) LE default maximum connection interval. This value is superseded by any specific value provided via the Load Connection Parameters interface. @item @code{connection-latency} (default: @code{#f}) LE default connection latency. This value is superseded by any specific value provided via the Load Connection Parameters interface. @item @code{connection-supervision-timeout} (default: @code{#f}) LE default connection supervision timeout. This value is superseded by any specific value provided via the Load Connection Parameters interface. @item @code{autoconnect-timeout} (default: @code{#f}) LE default autoconnect timeout. This value is superseded by any specific value provided via the Load Connection Parameters interface. @item @code{adv-mon-allowlist-scan-duration} (default: @code{300}) Allowlist scan duration during interleaving scan. Only used when scanning for ADV monitors. The units are msec. @item @code{adv-mon-no-filter-scan-duration} (default: @code{500}) No filter scan duration during interleaving scan. Only used when scanning for ADV monitors. The units are msec. @item @code{enable-adv-mon-interleave-scan?} (default: @code{#t}) Enable/Disable Advertisement Monitor interleave scan for power saving. @item @code{cache} (default: @code{'always}) GATT attribute cache. Possible values are: @itemize @bullet @item @code{'always}: Always cache attributes even for devices not paired, this is recommended as it is best for interoperability, with more consistent reconnection times and enables proper tracking of notifications for all devices @item @code{'yes}: Only cache attributes of paired devices @item @code{'no}: Never cache attributes. @end itemize @item @code{key-size} (default: @code{0}) Minimum required Encryption Key Size for accessing secured characteristics. Possible values are: @itemize @bullet @item @code{0}: Don't care @item @code{7 <= N <= 16} @end itemize @item @code{exchange-mtu} (default: @code{517}) Exchange MTU size. Possible values are: @itemize @bullet @item @code{23 <= N <= 517} @end itemize @item @code{att-channels} (default: @code{3}) Number of ATT channels. Possible values are: @itemize @bullet @item @code{1}: Disables EATT @item @code{2 <= N <= 5} @end itemize @item @code{session-mode} (default: @code{'basic}) AVDTP L2CAP signalling channel mode. Possible values are: @itemize @bullet @item @code{'basic}: Use L2CAP basic mode @item @code{'ertm}: Use L2CAP enhanced retransmission mode. @end itemize @item @code{stream-mode} (default: @code{'basic}) AVDTP L2CAP transport channel mode. Possible values are: @itemize @bullet @item @code{'basic}: Use L2CAP basic mode @item @code{'streaming}: Use L2CAP streaming mode. @end itemize @item @code{reconnect-uuids} (default: @code{'()}) The ReconnectUUIDs defines the set of remote services that should try to be reconnected to in case of a link loss (link supervision timeout). The policy plugin should contain a sane set of values by default, but this list can be overridden here. By setting the list to empty the reconnection feature gets disabled. Possible values: @itemize @bullet @item @code{'()} @item @code{(list (uuid <uuid-1>) (uuid <uuid-2>) ...)}. @end itemize @item @code{reconnect-attempts} (default: @code{7}) Defines the number of attempts to reconnect after a link lost. Setting the value to 0 disables reconnecting feature. @item @code{reconnect-intervals} (default: @code{'(1 2 4 8 16 32 64)}) Defines a list of intervals in seconds to use in between attempts. If the number of attempts defined in @var{reconnect-attempts} is bigger than the list of intervals the last interval is repeated until the last attempt. @item @code{auto-enable?} (default: @code{#f}) Defines option to enable all controllers when they are found. This includes adapters present on start as well as adapters that are plugged in later on. @item @code{resume-delay} (default: @code{2}) Audio devices that were disconnected due to suspend will be reconnected on resume. @var{resume-delay} determines the delay between when the controller resumes from suspend and a connection attempt is made. A longer delay is better for better co-existence with Wi-Fi. The value is in seconds. @item @code{rssi-sampling-period} (default: @code{#xFF}) Default RSSI Sampling Period. This is used when a client registers an advertisement monitor and leaves the RSSISamplingPeriod unset. Possible values are: @itemize @bullet @item @code{#x0}: Report all advertisements @item @code{N = #xXX}: Report advertisements every N x 100 msec (range: #x01 to #xFE) @item @code{#xFF}: Report only one advertisement per device during monitoring period. @end itemize @end table @end deftp @defvar gnome-keyring-service-type This is the type of the service that adds the @uref{https://wiki.gnome.org/Projects/GnomeKeyring, GNOME Keyring}. Its value is a @code{gnome-keyring-configuration} object (see below). This service adds the @code{gnome-keyring} package to the system profile and extends PAM with entries using @code{pam_gnome_keyring.so}, unlocking a user's login keyring when they log in or setting its password with passwd. @end defvar @deftp {Data Type} gnome-keyring-configuration Configuration record for the GNOME Keyring service. @table @asis @item @code{keyring} (default: @code{gnome-keyring}) The GNOME keyring package to use. @item @code{pam-services} A list of @code{(@var{service} . @var{kind})} pairs denoting PAM services to extend, where @var{service} is the name of an existing service to extend and @var{kind} is one of @code{login} or @code{passwd}. If @code{login} is given, it adds an optional @code{pam_gnome_keyring.so} to the auth block without arguments and to the session block with @code{auto_start}. If @code{passwd} is given, it adds an optional @code{pam_gnome_keyring.so} to the password block without arguments. By default, this field contains ``gdm-password'' with the value @code{login} and ``passwd'' is with the value @code{passwd}. @end table @end deftp @defvar seatd-service-type @uref{https://sr.ht/~kennylevinsen/seatd/, seatd} is a minimal seat management daemon. Seat management takes care of mediating access to shared devices (graphics, input), without requiring the applications needing access to be root. @lisp (append (list ;; make sure seatd is running (service seatd-service-type)) ;; normally one would want %base-services %base-services) @end lisp @code{seatd} operates over a UNIX domain socket, with @code{libseat} providing the client side of the protocol. Applications that acquire access to the shared resources via @code{seatd} (e.g. @code{sway}) need to be able to talk to this socket. This can be achieved by adding the user they run under to the group owning @code{seatd}'s socket (usually ``seat''), like so: @lisp (user-account (name "alice") (group "users") (supplementary-groups '("wheel" ; allow use of sudo, etc. "seat" ; seat management "audio" ; sound card "video" ; video devices such as webcams "cdrom")) ; the good ol' CD-ROM (comment "Bob's sister")) @end lisp Depending on your setup, you will have to not only add regular users, but also system users to this group. For instance, some greetd greeters require graphics and therefore also need to negotiate with seatd. @end defvar @deftp {Data Type} seatd-configuration Configuration record for the seatd daemon service. @table @asis @item @code{seatd} (default: @code{seatd}) The seatd package to use. @item @code{group} (default: @samp{"seat"}) Group to own the seatd socket. @item @code{socket} (default: @samp{"/run/seatd.sock"}) Where to create the seatd socket. @item @code{logfile} (default: @samp{"/var/log/seatd.log"}) Log file to write to. @item @code{loglevel} (default: @samp{"error"}) Log level to output logs. Possible values: @samp{"silent"}, @samp{"error"}, @samp{"info"} and @samp{"debug"}. @end table @end deftp @node Sound Services @subsection Sound Services @cindex sound support @cindex ALSA @cindex PulseAudio, sound support The @code{(gnu services sound)} module provides a service to configure the Advanced Linux Sound Architecture (ALSA) system, which makes PulseAudio the preferred ALSA output driver. @defvar alsa-service-type This is the type for the @uref{https://alsa-project.org/, Advanced Linux Sound Architecture} (ALSA) system, which generates the @file{/etc/asound.conf} configuration file. The value for this type is a @command{alsa-configuration} record as in this example: @lisp (service alsa-service-type) @end lisp See below for details about @code{alsa-configuration}. @end defvar @deftp {Data Type} alsa-configuration Data type representing the configuration for @code{alsa-service}. @table @asis @item @code{alsa-plugins} (default: @var{alsa-plugins}) @code{alsa-plugins} package to use. @item @code{pulseaudio?} (default: @var{#t}) Whether ALSA applications should transparently be made to use the @uref{https://www.pulseaudio.org/, PulseAudio} sound server. Using PulseAudio allows you to run several sound-producing applications at the same time and to individual control them @i{via} @command{pavucontrol}, among other things. @item @code{extra-options} (default: @var{""}) String to append to the @file{/etc/asound.conf} file. @end table @end deftp Individual users who want to override the system configuration of ALSA can do it with the @file{~/.asoundrc} file: @example # In guix, we have to specify the absolute path for plugins. pcm_type.jack @{ lib "/home/alice/.guix-profile/lib/alsa-lib/libasound_module_pcm_jack.so" @} # Routing ALSA to jack: # <http://jackaudio.org/faq/routing_alsa.html>. pcm.rawjack @{ type jack playback_ports @{ 0 system:playback_1 1 system:playback_2 @} capture_ports @{ 0 system:capture_1 1 system:capture_2 @} @} pcm.!default @{ type plug slave @{ pcm "rawjack" @} @} @end example See @uref{https://www.alsa-project.org/main/index.php/Asoundrc} for the details. @defvar pulseaudio-service-type This is the type for the @uref{https://www.pulseaudio.org/, PulseAudio} sound server. It exists to allow system overrides of the default settings via @code{pulseaudio-configuration}, see below. @quotation Warning This service overrides per-user configuration files. If you want PulseAudio to honor configuration files in @file{~/.config/pulse}, you have to unset the environment variables @env{PULSE_CONFIG} and @env{PULSE_CLIENTCONFIG} in your @file{~/.bash_profile}. @end quotation @quotation Warning This service on its own does not ensure, that the @code{pulseaudio} package exists on your machine. It merely adds configuration files for it, as detailed below. In the (admittedly unlikely) case, that you find yourself without a @code{pulseaudio} package, consider enabling it through the @code{alsa-service-type} above. @end quotation @end defvar @deftp {Data Type} pulseaudio-configuration Data type representing the configuration for @code{pulseaudio-service}. @table @asis @item @code{client-conf} (default: @code{'()}) List of settings to set in @file{client.conf}. Accepts a list of strings or symbol-value pairs. A string will be inserted as-is with a newline added. A pair will be formatted as ``key = value'', again with a newline added. @item @code{daemon-conf} (default: @code{'((flat-volumes . no))}) List of settings to set in @file{daemon.conf}, formatted just like @var{client-conf}. @item @code{script-file} (default: @code{(file-append pulseaudio "/etc/pulse/default.pa")}) Script file to use as @file{default.pa}. In case the @code{extra-script-files} field below is used, an @code{.include} directive pointing to @file{/etc/pulse/default.pa.d} is appended to the provided script. @item @code{extra-script-files} (default: @code{'()}) A list of file-like objects defining extra PulseAudio scripts to run at the initialization of the @command{pulseaudio} daemon, after the main @code{script-file}. The scripts are deployed to the @file{/etc/pulse/default.pa.d} directory; they should have the @samp{.pa} file name extension. For a reference of the available commands, refer to @command{man pulse-cli-syntax}. @item @code{system-script-file} (default: @code{(file-append pulseaudio "/etc/pulse/system.pa")}) Script file to use as @file{system.pa}. @end table The example below sets the default PulseAudio card profile, the default sink and the default source to use for a old SoundBlaster Audigy sound card: @lisp (pulseaudio-configuration (extra-script-files (list (plain-file "audigy.pa" (string-append "\ set-card-profile alsa_card.pci-0000_01_01.0 \ output:analog-surround-40+input:analog-mono set-default-source alsa_input.pci-0000_01_01.0.analog-mono set-default-sink alsa_output.pci-0000_01_01.0.analog-surround-40\n"))))) @end lisp Note that @code{pulseaudio-service-type} is part of @code{%desktop-services}; if your operating system declaration was derived from one of the desktop templates, you'll want to adjust the above example to modify the existing @code{pulseaudio-service-type} via @code{modify-services} (@pxref{Service Reference, @code{modify-services}}), instead of defining a new one. @end deftp @defvar ladspa-service-type This service sets the @var{LADSPA_PATH} variable, so that programs, which respect it, e.g.@: PulseAudio, can load LADSPA plugins. The following example will setup the service to enable modules from the @code{swh-plugins} package: @lisp (service ladspa-service-type (ladspa-configuration (plugins (list swh-plugins)))) @end lisp See @uref{http://plugin.org.uk/ladspa-swh/docs/ladspa-swh.html} for the details. @end defvar @node File Search Services @subsection File Search Services @cindex file search @cindex searching for a file The services in this section populate @dfn{file databases} that let you search for files on your machine. These services are provided by the @code{(gnu services admin)} module. The first one, @code{file-database-service-type}, periodically runs the venerable @command{updatedb} command (@pxref{Invoking updatedb,,, find, GNU Findutils}). That command populates a database of file names that you can then search with the @command{locate} command (@pxref{Invoing locate,,, find, GNU Findutils}), as in this example: @example locate important-notes.txt @end example You can enable this service with its default settings by adding this snippet to your operating system services: @lisp (service file-database-service-type) @end lisp This updates the database once a week, excluding files from @file{/gnu/store}---these are more usefully handled by @command{guix locate} (@pxref{Invoking guix locate}). You can of course provide a custom configuration, as described below. @defvar file-database-service-type This is the type of the file database service, which runs @command{updatedb} periodically. Its associated value must be a @code{file-database-configuration} record, as described below. @end defvar @deftp {Data Type} file-database-configuration Record type for the @code{file-database-service-type} configuration, with the following fields: @table @asis @item @code{package} (default: @code{findutils}) The GNU@tie{}Findutils package from which the @command{updatedb} command is taken. @item @code{schedule} (default: @code{%default-file-database-update-schedule}) String or G-exp denoting an mcron schedule for the periodic @command{updatedb} job (@pxref{Guile Syntax,,, mcron, GNU@tie{}mcron}). @item @code{excluded-directories} (default @code{%default-file-database-excluded-directories}) List of regular expressions of directories to ignore when building the file database. By default, this includes @file{/tmp} and @file{/gnu/store}; the latter should instead be indexed by @command{guix locate} (@pxref{Invoking guix locate}). This list is passed to the @option{--prunepaths} option of @command{updatedb} (@pxref{Invoking updatedb,,, find, GNU@tie{}Findutils}). @end table @end deftp The second service, @code{package-database-service-type}, builds the database used by @command{guix locate}, which lets you search for packages that contain a given file (@pxref{Invoking guix locate}). The service periodically updates a system-wide database, which will be readily available to anyone running @command{guix locate} on the system. To use this service with its default settings, add this snippet to your service list: @lisp (service package-database-service-type) @end lisp This will run @command{guix locate --update} once a week. @defvar package-database-service-type This is the service type for periodic @command{guix locate} updates (@pxref{Invoking guix locate}). Its value must be a @code{package-database-configuration} record, as shown below. @end defvar @deftp {Data Type} package-database-configuration Data type to configure periodic package database updates. It has the following fields: @table @asis @item @code{package} (default: @code{guix}) The Guix package to use. @item @code{schedule} (default: @code{%default-package-database-update-schedule}) String or G-exp denoting an mcron schedule for the periodic @command{guix locate --update} job (@pxref{Guile Syntax,,, mcron, GNU@tie{}mcron}). @item @code{method} (default: @code{'store}) Indexing method for @command{guix locate}. The default value, @code{'store}, yields a more complete database but is relatively expensive in terms of CPU and input/output. @item @code{channels} (default: @code{#~%default-channels}) G-exp denoting the channels to use when updating the database (@pxref{Channels}). @end table @end deftp @node Database Services @subsection Database Services @cindex database @cindex SQL The @code{(gnu services databases)} module provides the following services. @subsubheading PostgreSQL @defvar postgresql-service-type The service type for the PostgreSQL database server. Its value should be a valid @code{postgresql-configuration} object, documented below. The following example describes a PostgreSQL service with the default configuration. @lisp (service postgresql-service-type (postgresql-configuration (postgresql postgresql))) @end lisp If the services fails to start, it may be due to an incompatible cluster already present in @var{data-directory}. Adjust it (or, if you don't need the cluster anymore, delete @var{data-directory}), then restart the service. Peer authentication is used by default and the @code{postgres} user account has no shell, which prevents the direct execution of @code{psql} commands as this user. To use @code{psql}, you can temporarily log in as @code{postgres} using a shell, create a PostgreSQL superuser with the same name as one of the system users and then create the associated database. @example sudo -u postgres -s /bin/sh createuser --interactive createdb $MY_USER_LOGIN # Replace appropriately. @end example @end defvar @deftp {Data Type} postgresql-configuration Data type representing the configuration for the @code{postgresql-service-type}. @table @asis @item @code{postgresql} PostgreSQL package to use for the service. @item @code{port} (default: @code{5432}) Port on which PostgreSQL should listen. @item @code{locale} (default: @code{"en_US.utf8"}) Locale to use as the default when creating the database cluster. @item @code{config-file} (default: @code{(postgresql-config-file)}) The configuration file to use when running PostgreSQL@. The default behaviour uses the postgresql-config-file record with the default values for the fields. @item @code{log-directory} (default: @code{"/var/log/postgresql"}) The directory where @command{pg_ctl} output will be written in a file named @code{"pg_ctl.log"}. This file can be useful to debug PostgreSQL configuration errors for instance. @item @code{data-directory} (default: @code{"/var/lib/postgresql/data"}) Directory in which to store the data. @item @code{extension-packages} (default: @code{'()}) @cindex postgresql extension-packages Additional extensions are loaded from packages listed in @var{extension-packages}. Extensions are available at runtime. For instance, to create a geographic database using the @code{postgis} extension, a user can configure the postgresql-service as in this example: @cindex postgis @lisp (use-package-modules databases geo) (operating-system ... ;; postgresql is required to run `psql' but postgis is not required for ;; proper operation. (packages (cons* postgresql %base-packages)) (services (cons* (service postgresql-service-type (postgresql-configuration (postgresql postgresql) (extension-packages (list postgis)))) %base-services))) @end lisp Then the extension becomes visible and you can initialise an empty geographic database in this way: @example psql -U postgres > create database postgistest; > \connect postgistest; > create extension postgis; > create extension postgis_topology; @end example There is no need to add this field for contrib extensions such as hstore or dblink as they are already loadable by postgresql. This field is only required to add extensions provided by other packages. @item @code{create-account?} (default: @code{#t}) Whether or not the @code{postgres} user and group should be created. @item @code{uid} (default: @code{#f}) Explicitly specify the UID of the @code{postgres} daemon account. You normally do not need to specify this, in which case a free UID will be automatically assigned. One situation where this option might be useful is if the @var{data-directory} is located on a mounted network share. @item @code{gid} (default: @code{#f}) Explicitly specify the GID of the @code{postgres} group. @end table @end deftp @deftp {Data Type} postgresql-config-file Data type representing the PostgreSQL configuration file. As shown in the following example, this can be used to customize the configuration of PostgreSQL@. Note that you can use any G-expression or filename in place of this record, if you already have a configuration file you'd like to use for example. @lisp (service postgresql-service-type (postgresql-configuration (config-file (postgresql-config-file (log-destination "stderr") (hba-file (plain-file "pg_hba.conf" " local all all trust host all all 127.0.0.1/32 md5 host all all ::1/128 md5")) (extra-config '(("session_preload_libraries" "auto_explain") ("random_page_cost" 2) ("auto_explain.log_min_duration" "100 ms") ("work_mem" "500 MB") ("logging_collector" #t) ("log_directory" "/var/log/postgresql"))))))) @end lisp @table @asis @item @code{log-destination} (default: @code{"syslog"}) The logging method to use for PostgreSQL@. Multiple values are accepted, separated by commas. @item @code{hba-file} (default: @code{%default-postgres-hba}) Filename or G-expression for the host-based authentication configuration. @item @code{ident-file} (default: @code{%default-postgres-ident}) Filename or G-expression for the user name mapping configuration. @item @code{socket-directory} (default: @code{"/var/run/postgresql"}) Specifies the directory of the Unix-domain socket(s) on which PostgreSQL is to listen for connections from client applications. If set to @code{""} PostgreSQL does not listen on any Unix-domain sockets, in which case only TCP/IP sockets can be used to connect to the server. By default, the @code{#false} value means the PostgreSQL default value will be used, which is currently @samp{/tmp}. @item @code{extra-config} (default: @code{'()}) List of additional keys and values to include in the PostgreSQL config file. Each entry in the list should be a list where the first element is the key, and the remaining elements are the values. The values can be numbers, booleans or strings and will be mapped to PostgreSQL parameters types @code{Boolean}, @code{String}, @code{Numeric}, @code{Numeric with Unit} and @code{Enumerated} described @uref{https://www.postgresql.org/docs/current/config-setting.html, here}. @end table @end deftp @defvar postgresql-role-service-type This service allows to create PostgreSQL roles and databases after PostgreSQL service start. Here is an example of its use. @lisp (service postgresql-role-service-type (postgresql-role-configuration (roles (list (postgresql-role (name "test") (create-database? #t)))))) @end lisp This service can be extended with extra roles, as in this example: @lisp (service-extension postgresql-role-service-type (const (postgresql-role (name "alice") (create-database? #t)))) @end lisp @end defvar @deftp {Data Type} postgresql-role PostgreSQL manages database access permissions using the concept of roles. A role can be thought of as either a database user, or a group of database users, depending on how the role is set up. Roles can own database objects (for example, tables) and can assign privileges on those objects to other roles to control who has access to which objects. @table @asis @item @code{name} The role name. @item @code{permissions} (default: @code{'(createdb login)}) The role permissions list. Supported permissions are @code{bypassrls}, @code{createdb}, @code{createrole}, @code{login}, @code{replication} and @code{superuser}. @item @code{create-database?} (default: @code{#f}) whether to create a database with the same name as the role. @item @code{encoding} (default: @code{"UTF8"}) The character set to use for storing text in the database. @item @code{collation} (default: @code{"en_US.utf8"}) The string sort order locale setting. @item @code{ctype} (default: @code{"en_US.utf8"}) The character classification locale setting. @item @code{template} (default: @code{"template1"}) The default template to copy the new database from when creating it. Use @code{"template0"} for a pristine database with no system-local modifications. @end table @end deftp @deftp {Data Type} postgresql-role-configuration Data type representing the configuration of @var{postgresql-role-service-type}. @table @asis @item @code{host} (default: @code{"/var/run/postgresql"}) The PostgreSQL host to connect to. @item @code{log} (default: @code{"/var/log/postgresql_roles.log"}) File name of the log file. @item @code{roles} (default: @code{'()}) The initial PostgreSQL roles to create. @end table @end deftp @subsubheading MariaDB/MySQL @defvar mysql-service-type This is the service type for a MySQL or MariaDB database server. Its value is a @code{mysql-configuration} object that specifies which package to use, as well as various settings for the @command{mysqld} daemon. @end defvar @deftp {Data Type} mysql-configuration Data type representing the configuration of @var{mysql-service-type}. @table @asis @item @code{mysql} (default: @var{mariadb}) Package object of the MySQL database server, can be either @var{mariadb} or @var{mysql}. For MySQL, a temporary root password will be displayed at activation time. For MariaDB, the root password is empty. @item @code{bind-address} (default: @code{"127.0.0.1"}) The IP on which to listen for network connections. Use @code{"0.0.0.0"} to bind to all available network interfaces. @item @code{port} (default: @code{3306}) TCP port on which the database server listens for incoming connections. @item @code{socket} (default: @code{"/run/mysqld/mysqld.sock"}) Socket file to use for local (non-network) connections. @item @code{extra-content} (default: @code{""}) Additional settings for the @file{my.cnf} configuration file. @item @code{extra-environment} (default: @code{#~'()}) List of environment variables passed to the @command{mysqld} process. @item @code{auto-upgrade?} (default: @code{#t}) Whether to automatically run @command{mysql_upgrade} after starting the service. This is necessary to upgrade the @dfn{system schema} after ``major'' updates (such as switching from MariaDB 10.4 to 10.5), but can be disabled if you would rather do that manually. @end table @end deftp @subsubheading Memcached @defvar memcached-service-type This is the service type for the @uref{https://memcached.org/, Memcached} service, which provides a distributed in memory cache. The value for the service type is a @code{memcached-configuration} object. @end defvar @lisp (service memcached-service-type) @end lisp @deftp {Data Type} memcached-configuration Data type representing the configuration of memcached. @table @asis @item @code{memcached} (default: @code{memcached}) The Memcached package to use. @item @code{interfaces} (default: @code{'("0.0.0.0")}) Network interfaces on which to listen. @item @code{tcp-port} (default: @code{11211}) Port on which to accept connections. @item @code{udp-port} (default: @code{11211}) Port on which to accept UDP connections on, a value of 0 will disable listening on a UDP socket. @item @code{additional-options} (default: @code{'()}) Additional command line options to pass to @code{memcached}. @end table @end deftp @subsubheading Redis @defvar redis-service-type This is the service type for the @uref{https://redis.io/, Redis} key/value store, whose value is a @code{redis-configuration} object. @end defvar @deftp {Data Type} redis-configuration Data type representing the configuration of redis. @table @asis @item @code{redis} (default: @code{redis}) The Redis package to use. @item @code{bind} (default: @code{"127.0.0.1"}) Network interface on which to listen. @item @code{port} (default: @code{6379}) Port on which to accept connections on, a value of 0 will disable listening on a TCP socket. @item @code{working-directory} (default: @code{"/var/lib/redis"}) Directory in which to store the database and related files. @end table @end deftp @node Mail Services @subsection Mail Services @cindex mail @cindex email The @code{(gnu services mail)} module provides Guix service definitions for email services: IMAP, POP3, and LMTP servers, as well as mail transport agents (MTAs). Lots of acronyms! These services are detailed in the subsections below. @subsubheading Dovecot Service @defvar dovecot-service-type Type for the service that runs the Dovecot IMAP/POP3/LMTP mail server, whose value is a @code{<dovecot-configuration>} object. @end defvar By default, Dovecot does not need much configuration; the default configuration object created by @code{(dovecot-configuration)} will suffice if your mail is delivered to @code{~/Maildir}. A self-signed certificate will be generated for TLS-protected connections, though Dovecot will also listen on cleartext ports by default. There are a number of options, though, which mail administrators might need to change, and as is the case with other services, Guix allows the system administrator to specify these parameters via a uniform Scheme interface. For example, to specify that mail is located at @code{maildir~/.mail}, one would instantiate the Dovecot service like this: @lisp (service dovecot-service-type (dovecot-configuration (mail-location "maildir:~/.mail"))) @end lisp The available configuration parameters follow. Each parameter definition is preceded by its type; for example, @samp{string-list foo} indicates that the @code{foo} parameter should be specified as a list of strings. There is also a way to specify the configuration as a string, if you have an old @code{dovecot.conf} file that you want to port over from some other system; see the end for more details. @c The following documentation was initially generated by @c (generate-documentation) in (gnu services mail). Manually maintained @c documentation is better, so we shouldn't hesitate to edit below as @c needed. However if the change you want to make to this documentation @c can be done in an automated way, it's probably easier to change @c (generate-documentation) than to make it below and have to deal with @c the churn as dovecot updates. Available @code{dovecot-configuration} fields are: @deftypevr {@code{dovecot-configuration} parameter} package dovecot The dovecot package. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} comma-separated-string-list listen A list of IPs or hosts where to listen for connections. @samp{*} listens on all IPv4 interfaces, @samp{::} listens on all IPv6 interfaces. If you want to specify non-default ports or anything more complex, customize the address and port fields of the @samp{inet-listener} of the specific services you are interested in. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} protocol-configuration-list protocols List of protocols we want to serve. Available protocols include @samp{imap}, @samp{pop3}, and @samp{lmtp}. Available @code{protocol-configuration} fields are: @deftypevr {@code{protocol-configuration} parameter} string name The name of the protocol. @end deftypevr @deftypevr {@code{protocol-configuration} parameter} string auth-socket-path UNIX socket path to the master authentication server to find users. This is used by imap (for shared users) and lda. It defaults to @samp{"/var/run/dovecot/auth-userdb"}. @end deftypevr @deftypevr {@code{protocol-configuration} parameter} boolean imap-metadata? Whether to enable the @code{IMAP METADATA} extension as defined in @uref{https://tools.ietf.org/html/rfc5464,RFC@tie{}5464}, which provides a means for clients to set and retrieve per-mailbox, per-user metadata and annotations over IMAP. If this is @samp{#t}, you must also specify a dictionary @i{via} the @code{mail-attribute-dict} setting. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{protocol-configuration} parameter} space-separated-string-list managesieve-notify-capabilities Which NOTIFY capabilities to report to clients that first connect to the ManageSieve service, before authentication. These may differ from the capabilities offered to authenticated users. If this field is left empty, report what the Sieve interpreter supports by default. Defaults to @samp{'()}. @end deftypevr @deftypevr {@code{protocol-configuration} parameter} space-separated-string-list managesieve-sieve-capability Which SIEVE capabilities to report to clients that first connect to the ManageSieve service, before authentication. These may differ from the capabilities offered to authenticated users. If this field is left empty, report what the Sieve interpreter supports by default. Defaults to @samp{'()}. @end deftypevr @deftypevr {@code{protocol-configuration} parameter} space-separated-string-list mail-plugins Space separated list of plugins to load. @end deftypevr @deftypevr {@code{protocol-configuration} parameter} non-negative-integer mail-max-userip-connections Maximum number of IMAP connections allowed for a user from each IP address. NOTE: The username is compared case-sensitively. Defaults to @samp{10}. @end deftypevr @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} service-configuration-list services List of services to enable. Available services include @samp{imap}, @samp{imap-login}, @samp{pop3}, @samp{pop3-login}, @samp{auth}, and @samp{lmtp}. Available @code{service-configuration} fields are: @deftypevr {@code{service-configuration} parameter} string kind The service kind. Valid values include @code{director}, @code{imap-login}, @code{pop3-login}, @code{lmtp}, @code{imap}, @code{pop3}, @code{auth}, @code{auth-worker}, @code{dict}, @code{tcpwrap}, @code{quota-warning}, or anything else. @end deftypevr @deftypevr {@code{service-configuration} parameter} listener-configuration-list listeners Listeners for the service. A listener is either a @code{unix-listener-configuration}, a @code{fifo-listener-configuration}, or an @code{inet-listener-configuration}. Defaults to @samp{'()}. Available @code{unix-listener-configuration} fields are: @deftypevr {@code{unix-listener-configuration} parameter} string path Path to the file, relative to @code{base-dir} field. This is also used as the section name. @end deftypevr @deftypevr {@code{unix-listener-configuration} parameter} string mode The access mode for the socket. Defaults to @samp{"0600"}. @end deftypevr @deftypevr {@code{unix-listener-configuration} parameter} string user The user to own the socket. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{unix-listener-configuration} parameter} string group The group to own the socket. Defaults to @samp{""}. @end deftypevr Available @code{fifo-listener-configuration} fields are: @deftypevr {@code{fifo-listener-configuration} parameter} string path Path to the file, relative to @code{base-dir} field. This is also used as the section name. @end deftypevr @deftypevr {@code{fifo-listener-configuration} parameter} string mode The access mode for the socket. Defaults to @samp{"0600"}. @end deftypevr @deftypevr {@code{fifo-listener-configuration} parameter} string user The user to own the socket. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{fifo-listener-configuration} parameter} string group The group to own the socket. Defaults to @samp{""}. @end deftypevr Available @code{inet-listener-configuration} fields are: @deftypevr {@code{inet-listener-configuration} parameter} string protocol The protocol to listen for. @end deftypevr @deftypevr {@code{inet-listener-configuration} parameter} string address The address on which to listen, or empty for all addresses. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{inet-listener-configuration} parameter} non-negative-integer port The port on which to listen. @end deftypevr @deftypevr {@code{inet-listener-configuration} parameter} boolean ssl? Whether to use SSL for this service; @samp{yes}, @samp{no}, or @samp{required}. Defaults to @samp{#t}. @end deftypevr @end deftypevr @deftypevr {@code{service-configuration} parameter} non-negative-integer client-limit Maximum number of simultaneous client connections per process. Once this number of connections is received, the next incoming connection will prompt Dovecot to spawn another process. If set to 0, @code{default-client-limit} is used instead. Defaults to @samp{0}. @end deftypevr @deftypevr {@code{service-configuration} parameter} non-negative-integer service-count Number of connections to handle before starting a new process. Typically the only useful values are 0 (unlimited) or 1. 1 is more secure, but 0 is faster. <doc/wiki/LoginProcess.txt>. Defaults to @samp{1}. @end deftypevr @deftypevr {@code{service-configuration} parameter} non-negative-integer process-limit Maximum number of processes that can exist for this service. If set to 0, @code{default-process-limit} is used instead. Defaults to @samp{0}. @end deftypevr @deftypevr {@code{service-configuration} parameter} non-negative-integer process-min-avail Number of processes to always keep waiting for more connections. Defaults to @samp{0}. @end deftypevr @deftypevr {@code{service-configuration} parameter} non-negative-integer vsz-limit If you set @samp{service-count 0}, you probably need to grow this. Defaults to @samp{256000000}. @end deftypevr @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} dict-configuration dict Dict configuration, as created by the @code{dict-configuration} constructor. Available @code{dict-configuration} fields are: @deftypevr {@code{dict-configuration} parameter} free-form-fields entries A list of key-value pairs that this dict should hold. Defaults to @samp{'()}. @end deftypevr @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} passdb-configuration-list passdbs A list of passdb configurations, each one created by the @code{passdb-configuration} constructor. Available @code{passdb-configuration} fields are: @deftypevr {@code{passdb-configuration} parameter} string driver The driver that the passdb should use. Valid values include @samp{pam}, @samp{passwd}, @samp{shadow}, @samp{bsdauth}, and @samp{static}. Defaults to @samp{"pam"}. @end deftypevr @deftypevr {@code{passdb-configuration} parameter} space-separated-string-list args Space separated list of arguments to the passdb driver. Defaults to @samp{""}. @end deftypevr @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} userdb-configuration-list userdbs List of userdb configurations, each one created by the @code{userdb-configuration} constructor. Available @code{userdb-configuration} fields are: @deftypevr {@code{userdb-configuration} parameter} string driver The driver that the userdb should use. Valid values include @samp{passwd} and @samp{static}. Defaults to @samp{"passwd"}. @end deftypevr @deftypevr {@code{userdb-configuration} parameter} space-separated-string-list args Space separated list of arguments to the userdb driver. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{userdb-configuration} parameter} free-form-args override-fields Override fields from passwd. Defaults to @samp{'()}. @end deftypevr @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} plugin-configuration plugin-configuration Plug-in configuration, created by the @code{plugin-configuration} constructor. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} list-of-namespace-configuration namespaces List of namespaces. Each item in the list is created by the @code{namespace-configuration} constructor. Available @code{namespace-configuration} fields are: @deftypevr {@code{namespace-configuration} parameter} string name Name for this namespace. @end deftypevr @deftypevr {@code{namespace-configuration} parameter} string type Namespace type: @samp{private}, @samp{shared} or @samp{public}. Defaults to @samp{"private"}. @end deftypevr @deftypevr {@code{namespace-configuration} parameter} string separator Hierarchy separator to use. You should use the same separator for all namespaces or some clients get confused. @samp{/} is usually a good one. The default however depends on the underlying mail storage format. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{namespace-configuration} parameter} string prefix Prefix required to access this namespace. This needs to be different for all namespaces. For example @samp{Public/}. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{namespace-configuration} parameter} string location Physical location of the mailbox. This is in the same format as mail_location, which is also the default for it. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{namespace-configuration} parameter} boolean inbox? There can be only one INBOX, and this setting defines which namespace has it. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{namespace-configuration} parameter} boolean hidden? If namespace is hidden, it's not advertised to clients via NAMESPACE extension. You'll most likely also want to set @samp{list? #f}. This is mostly useful when converting from another server with different namespaces which you want to deprecate but still keep working. For example you can create hidden namespaces with prefixes @samp{~/mail/}, @samp{~%u/mail/} and @samp{mail/}. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{namespace-configuration} parameter} boolean list? Show the mailboxes under this namespace with the LIST command. This makes the namespace visible for clients that do not support the NAMESPACE extension. The special @code{children} value lists child mailboxes, but hides the namespace prefix. Defaults to @samp{#t}. @end deftypevr @deftypevr {@code{namespace-configuration} parameter} boolean subscriptions? Namespace handles its own subscriptions. If set to @code{#f}, the parent namespace handles them. The empty prefix should always have this as @code{#t}). Defaults to @samp{#t}. @end deftypevr @deftypevr {@code{namespace-configuration} parameter} mailbox-configuration-list mailboxes List of predefined mailboxes in this namespace. Defaults to @samp{'()}. Available @code{mailbox-configuration} fields are: @deftypevr {@code{mailbox-configuration} parameter} string name Name for this mailbox. @end deftypevr @deftypevr {@code{mailbox-configuration} parameter} string auto @samp{create} will automatically create this mailbox. @samp{subscribe} will both create and subscribe to the mailbox. Defaults to @samp{"no"}. @end deftypevr @deftypevr {@code{mailbox-configuration} parameter} space-separated-string-list special-use List of IMAP @code{SPECIAL-USE} attributes as specified by RFC 6154. Valid values are @code{\All}, @code{\Archive}, @code{\Drafts}, @code{\Flagged}, @code{\Junk}, @code{\Sent}, and @code{\Trash}. Defaults to @samp{'()}. @end deftypevr @end deftypevr @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} file-name base-dir Base directory where to store runtime data. Defaults to @samp{"/var/run/dovecot/"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string login-greeting Greeting message for clients. Defaults to @samp{"Dovecot ready."}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list login-trusted-networks List of trusted network ranges. Connections from these IPs are allowed to override their IP addresses and ports (for logging and for authentication checks). @samp{disable-plaintext-auth} is also ignored for these networks. Typically you would specify your IMAP proxy servers here. Defaults to @samp{'()}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list login-access-sockets List of login access check sockets (e.g.@: tcpwrap). Defaults to @samp{'()}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} boolean verbose-proctitle? Show more verbose process titles (in ps). Currently shows user name and IP address. Useful for seeing who is actually using the IMAP processes (e.g.@: shared mailboxes or if the same uid is used for multiple accounts). Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} boolean shutdown-clients? Should all processes be killed when Dovecot master process shuts down. Setting this to @code{#f} means that Dovecot can be upgraded without forcing existing client connections to close (although that could also be a problem if the upgrade is e.g.@: due to a security fix). Defaults to @samp{#t}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer doveadm-worker-count If non-zero, run mail commands via this many connections to doveadm server, instead of running them directly in the same process. Defaults to @samp{0}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string doveadm-socket-path UNIX socket or host:port used for connecting to doveadm server. Defaults to @samp{"doveadm-server"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list import-environment List of environment variables that are preserved on Dovecot startup and passed down to all of its child processes. You can also give key=value pairs to always set specific settings. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} boolean disable-plaintext-auth? Disable LOGIN command and all other plaintext authentications unless SSL/TLS is used (LOGINDISABLED capability). Note that if the remote IP matches the local IP (i.e.@: you're connecting from the same computer), the connection is considered secure and plaintext authentication is allowed. See also the @samp{ssl=required} setting. Defaults to @samp{#t}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer auth-cache-size Authentication cache size (e.g.@: @samp{#e10e6}). 0 means it's disabled. Note that bsdauth, PAM and vpopmail require @samp{cache-key} to be set for caching to be used. Defaults to @samp{0}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string auth-cache-ttl Time to live for cached data. After TTL expires the cached record is no longer used, *except* if the main database lookup returns internal failure. We also try to handle password changes automatically: If user's previous authentication was successful, but this one wasn't, the cache isn't used. For now this works only with plaintext authentication. Defaults to @samp{"1 hour"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string auth-cache-negative-ttl TTL for negative hits (user not found, password mismatch). 0 disables caching them completely. Defaults to @samp{"1 hour"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list auth-realms List of realms for SASL authentication mechanisms that need them. You can leave it empty if you don't want to support multiple realms. Many clients simply use the first one listed here, so keep the default realm first. Defaults to @samp{'()}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string auth-default-realm Default realm/domain to use if none was specified. This is used for both SASL realms and appending @@domain to username in plaintext logins. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string auth-username-chars List of allowed characters in username. If the user-given username contains a character not listed in here, the login automatically fails. This is just an extra check to make sure user can't exploit any potential quote escaping vulnerabilities with SQL/LDAP databases. If you want to allow all characters, set this value to empty. Defaults to @samp{"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ01234567890.-_@@"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string auth-username-translation Username character translations before it's looked up from databases. The value contains series of from -> to characters. For example @samp{#@@/@@} means that @samp{#} and @samp{/} characters are translated to @samp{@@}. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string auth-username-format Username formatting before it's looked up from databases. You can use the standard variables here, e.g.@: %Lu would lowercase the username, %n would drop away the domain if it was given, or @samp{%n-AT-%d} would change the @samp{@@} into @samp{-AT-}. This translation is done after @samp{auth-username-translation} changes. Defaults to @samp{"%Lu"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string auth-master-user-separator If you want to allow master users to log in by specifying the master username within the normal username string (i.e.@: not using SASL mechanism's support for it), you can specify the separator character here. The format is then <username><separator><master username>. UW-IMAP uses @samp{*} as the separator, so that could be a good choice. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string auth-anonymous-username Username to use for users logging in with ANONYMOUS SASL mechanism. Defaults to @samp{"anonymous"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer auth-worker-max-count Maximum number of dovecot-auth worker processes. They're used to execute blocking passdb and userdb queries (e.g.@: MySQL and PAM). They're automatically created and destroyed as needed. Defaults to @samp{30}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string auth-gssapi-hostname Host name to use in GSSAPI principal names. The default is to use the name returned by gethostname(). Use @samp{$ALL} (with quotes) to allow all keytab entries. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string auth-krb5-keytab Kerberos keytab to use for the GSSAPI mechanism. Will use the system default (usually @file{/etc/krb5.keytab}) if not specified. You may need to change the auth service to run as root to be able to read this file. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} boolean auth-use-winbind? Do NTLM and GSS-SPNEGO authentication using Samba's winbind daemon and @samp{ntlm-auth} helper. <doc/wiki/Authentication/Mechanisms/Winbind.txt>. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} file-name auth-winbind-helper-path Path for Samba's @samp{ntlm-auth} helper binary. Defaults to @samp{"/usr/bin/ntlm_auth"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string auth-failure-delay Time to delay before replying to failed authentications. Defaults to @samp{"2 secs"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} boolean auth-ssl-require-client-cert? Require a valid SSL client certificate or the authentication fails. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} boolean auth-ssl-username-from-cert? Take the username from client's SSL certificate, using @code{X509_NAME_get_text_by_NID()} which returns the subject's DN's CommonName. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list auth-mechanisms List of wanted authentication mechanisms. Supported mechanisms are: @samp{plain}, @samp{login}, @samp{digest-md5}, @samp{cram-md5}, @samp{ntlm}, @samp{rpa}, @samp{apop}, @samp{anonymous}, @samp{gssapi}, @samp{otp}, @samp{skey}, and @samp{gss-spnego}. See also the @samp{disable-plaintext-auth} setting. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list director-servers List of IPs or hostnames to all director servers, including ourself. Ports can be specified as ip:port. The default port is the same as what director service's @samp{inet-listener} is using. Defaults to @samp{'()}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list director-mail-servers List of IPs or hostnames to all backend mail servers. Ranges are allowed too, like 10.0.0.10-10.0.0.30. Defaults to @samp{'()}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string director-user-expire How long to redirect users to a specific server after it no longer has any connections. Defaults to @samp{"15 min"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string director-username-hash How the username is translated before being hashed. Useful values include %Ln if user can log in with or without @@domain, %Ld if mailboxes are shared within domain. Defaults to @samp{"%Lu"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string log-path Log file to use for error messages. @samp{syslog} logs to syslog, @samp{/dev/stderr} logs to stderr. Defaults to @samp{"syslog"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string info-log-path Log file to use for informational messages. Defaults to @samp{log-path}. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string debug-log-path Log file to use for debug messages. Defaults to @samp{info-log-path}. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string syslog-facility Syslog facility to use if you're logging to syslog. Usually if you don't want to use @samp{mail}, you'll use local0..local7. Also other standard facilities are supported. Defaults to @samp{"mail"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} boolean auth-verbose? Log unsuccessful authentication attempts and the reasons why they failed. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string auth-verbose-passwords In case of password mismatches, log the attempted password. Valid values are no, plain and sha1. sha1 can be useful for detecting brute force password attempts vs. user simply trying the same password over and over again. You can also truncate the value to n chars by appending ":n" (e.g.@: sha1:6). Defaults to @samp{"no"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} boolean auth-debug? Even more verbose logging for debugging purposes. Shows for example SQL queries. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} boolean auth-debug-passwords? In case of password mismatches, log the passwords and used scheme so the problem can be debugged. Enabling this also enables @samp{auth-debug}. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} boolean mail-debug? Enable mail process debugging. This can help you figure out why Dovecot isn't finding your mails. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} boolean verbose-ssl? Show protocol level SSL errors. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string log-timestamp Prefix for each line written to log file. % codes are in strftime(3) format. Defaults to @samp{"\"%b %d %H:%M:%S \""}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list login-log-format-elements List of elements we want to log. The elements which have a non-empty variable value are joined together to form a comma-separated string. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string login-log-format Login log format. %s contains @samp{login-log-format-elements} string, %$ contains the data we want to log. Defaults to @samp{"%$: %s"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string mail-log-prefix Log prefix for mail processes. See doc/wiki/Variables.txt for list of possible variables you can use. Defaults to @samp{"\"%s(%u)<%@{pid@}><%@{session@}>: \""}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string deliver-log-format Format to use for logging mail deliveries. You can use variables: @table @code @item %$ Delivery status message (e.g.@: @samp{saved to INBOX}) @item %m Message-ID @item %s Subject @item %f From address @item %p Physical size @item %w Virtual size. @end table Defaults to @samp{"msgid=%m: %$"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string mail-location Location for users' mailboxes. The default is empty, which means that Dovecot tries to find the mailboxes automatically. This won't work if the user doesn't yet have any mail, so you should explicitly tell Dovecot the full location. If you're using mbox, giving a path to the INBOX file (e.g.@: @file{/var/mail/%u}) isn't enough. You'll also need to tell Dovecot where the other mailboxes are kept. This is called the @emph{root mail directory}, and it must be the first path given in the @samp{mail-location} setting. There are a few special variables you can use, e.g.: @table @samp @item %u username @item %n user part in user@@domain, same as %u if there's no domain @item %d domain part in user@@domain, empty if there's no domain @item %h home directory @end table See doc/wiki/Variables.txt for full list. Some examples: @table @samp @item maildir:~/Maildir @item mbox:~/mail:INBOX=/var/mail/%u @item mbox:/var/mail/%d/%1n/%n:INDEX=/var/indexes/%d/%1n/% @end table Defaults to @samp{""}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string mail-uid System user and group used to access mails. If you use multiple, userdb can override these by returning uid or gid fields. You can use either numbers or names. <doc/wiki/UserIds.txt>. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string mail-gid Defaults to @samp{""}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string mail-privileged-group Group to enable temporarily for privileged operations. Currently this is used only with INBOX when either its initial creation or dotlocking fails. Typically this is set to @samp{"mail"} to give access to @file{/var/mail}. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string mail-access-groups Grant access to these supplementary groups for mail processes. Typically these are used to set up access to shared mailboxes. Note that it may be dangerous to set these if users can create symlinks (e.g.@: if @samp{mail} group is set here, @code{ln -s /var/mail ~/mail/var} could allow a user to delete others' mailboxes, or @code{ln -s /secret/shared/box ~/mail/mybox} would allow reading it). Defaults to @samp{""}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string mail-attribute-dict The location of a dictionary used to store @code{IMAP METADATA} as defined by @uref{https://tools.ietf.org/html/rfc5464, RFC@tie{}5464}. The IMAP METADATA commands are available only if the ``imap'' protocol configuration's @code{imap-metadata?} field is @samp{#t}. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} boolean mail-full-filesystem-access? Allow full file system access to clients. There's no access checks other than what the operating system does for the active UID/GID@. It works with both maildir and mboxes, allowing you to prefix mailboxes names with e.g.@: @file{/path/} or @file{~user/}. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} boolean mmap-disable? Don't use @code{mmap()} at all. This is required if you store indexes to shared file systems (NFS or clustered file system). Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} boolean dotlock-use-excl? Rely on @samp{O_EXCL} to work when creating dotlock files. NFS supports @samp{O_EXCL} since version 3, so this should be safe to use nowadays by default. Defaults to @samp{#t}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string mail-fsync When to use fsync() or fdatasync() calls: @table @code @item optimized Whenever necessary to avoid losing important data @item always Useful with e.g.@: NFS when @code{write()}s are delayed @item never Never use it (best performance, but crashes can lose data). @end table Defaults to @samp{"optimized"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} boolean mail-nfs-storage? Mail storage exists in NFS@. Set this to yes to make Dovecot flush NFS caches whenever needed. If you're using only a single mail server this isn't needed. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} boolean mail-nfs-index? Mail index files also exist in NFS@. Setting this to yes requires @samp{mmap-disable? #t} and @samp{fsync-disable? #f}. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string lock-method Locking method for index files. Alternatives are fcntl, flock and dotlock. Dotlocking uses some tricks which may create more disk I/O than other locking methods. NFS users: flock doesn't work, remember to change @samp{mmap-disable}. Defaults to @samp{"fcntl"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} file-name mail-temp-dir Directory in which LDA/LMTP temporarily stores incoming mails >128 kB. Defaults to @samp{"/tmp"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer first-valid-uid Valid UID range for users. This is mostly to make sure that users can't log in as daemons or other system users. Note that denying root logins is hardcoded to dovecot binary and can't be done even if @samp{first-valid-uid} is set to 0. Defaults to @samp{500}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer last-valid-uid Defaults to @samp{0}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer first-valid-gid Valid GID range for users. Users having non-valid GID as primary group ID aren't allowed to log in. If user belongs to supplementary groups with non-valid GIDs, those groups are not set. Defaults to @samp{1}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer last-valid-gid Defaults to @samp{0}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer mail-max-keyword-length Maximum allowed length for mail keyword name. It's only forced when trying to create new keywords. Defaults to @samp{50}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} colon-separated-file-name-list valid-chroot-dirs List of directories under which chrooting is allowed for mail processes (i.e.@: @file{/var/mail} will allow chrooting to @file{/var/mail/foo/bar} too). This setting doesn't affect @samp{login-chroot} @samp{mail-chroot} or auth chroot settings. If this setting is empty, @samp{/./} in home dirs are ignored. WARNING: Never add directories here which local users can modify, that may lead to root exploit. Usually this should be done only if you don't allow shell access for users. <doc/wiki/Chrooting.txt>. Defaults to @samp{'()}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string mail-chroot Default chroot directory for mail processes. This can be overridden for specific users in user database by giving @samp{/./} in user's home directory (e.g.@: @samp{/home/./user} chroots into @file{/home}). Note that usually there is no real need to do chrooting, Dovecot doesn't allow users to access files outside their mail directory anyway. If your home directories are prefixed with the chroot directory, append @samp{/.} to @samp{mail-chroot}. <doc/wiki/Chrooting.txt>. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} file-name auth-socket-path UNIX socket path to master authentication server to find users. This is used by imap (for shared users) and lda. Defaults to @samp{"/var/run/dovecot/auth-userdb"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} file-name mail-plugin-dir Directory where to look up mail plugins. Defaults to @samp{"/usr/lib/dovecot"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list mail-plugins List of plugins to load for all services. Plugins specific to IMAP, LDA, etc.@: are added to this list in their own .conf files. Defaults to @samp{'()}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer mail-cache-min-mail-count The minimum number of mails in a mailbox before updates are done to cache file. This allows optimizing Dovecot's behavior to do less disk writes at the cost of more disk reads. Defaults to @samp{0}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string mailbox-idle-check-interval When IDLE command is running, mailbox is checked once in a while to see if there are any new mails or other changes. This setting defines the minimum time to wait between those checks. Dovecot can also use dnotify, inotify and kqueue to find out immediately when changes occur. Defaults to @samp{"30 secs"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} boolean mail-save-crlf? Save mails with CR+LF instead of plain LF@. This makes sending those mails take less CPU, especially with sendfile() syscall with Linux and FreeBSD@. But it also creates a bit more disk I/O which may just make it slower. Also note that if other software reads the mboxes/maildirs, they may handle the extra CRs wrong and cause problems. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} boolean maildir-stat-dirs? By default LIST command returns all entries in maildir beginning with a dot. Enabling this option makes Dovecot return only entries which are directories. This is done by stat()ing each entry, so it causes more disk I/O. (For systems setting struct @samp{dirent->d_type} this check is free and it's done always regardless of this setting). Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} boolean maildir-copy-with-hardlinks? When copying a message, do it with hard links whenever possible. This makes the performance much better, and it's unlikely to have any side effects. Defaults to @samp{#t}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} boolean maildir-very-dirty-syncs? Assume Dovecot is the only MUA accessing Maildir: Scan cur/ directory only when its mtime changes unexpectedly or when we can't find the mail otherwise. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list mbox-read-locks Which locking methods to use for locking mbox. There are four available: @table @code @item dotlock Create <mailbox>.lock file. This is the oldest and most NFS-safe solution. If you want to use /var/mail/ like directory, the users will need write access to that directory. @item dotlock-try Same as dotlock, but if it fails because of permissions or because there isn't enough disk space, just skip it. @item fcntl Use this if possible. Works with NFS too if lockd is used. @item flock May not exist in all systems. Doesn't work with NFS. @item lockf May not exist in all systems. Doesn't work with NFS. @end table You can use multiple locking methods; if you do the order they're declared in is important to avoid deadlocks if other MTAs/MUAs are using multiple locking methods as well. Some operating systems don't allow using some of them simultaneously. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list mbox-write-locks @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string mbox-lock-timeout Maximum time to wait for lock (all of them) before aborting. Defaults to @samp{"5 mins"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string mbox-dotlock-change-timeout If dotlock exists but the mailbox isn't modified in any way, override the lock file after this much time. Defaults to @samp{"2 mins"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} boolean mbox-dirty-syncs? When mbox changes unexpectedly we have to fully read it to find out what changed. If the mbox is large this can take a long time. Since the change is usually just a newly appended mail, it'd be faster to simply read the new mails. If this setting is enabled, Dovecot does this but still safely fallbacks to re-reading the whole mbox file whenever something in mbox isn't how it's expected to be. The only real downside to this setting is that if some other MUA changes message flags, Dovecot doesn't notice it immediately. Note that a full sync is done with SELECT, EXAMINE, EXPUNGE and CHECK commands. Defaults to @samp{#t}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} boolean mbox-very-dirty-syncs? Like @samp{mbox-dirty-syncs}, but don't do full syncs even with SELECT, EXAMINE, EXPUNGE or CHECK commands. If this is set, @samp{mbox-dirty-syncs} is ignored. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} boolean mbox-lazy-writes? Delay writing mbox headers until doing a full write sync (EXPUNGE and CHECK commands and when closing the mailbox). This is especially useful for POP3 where clients often delete all mails. The downside is that our changes aren't immediately visible to other MUAs. Defaults to @samp{#t}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer mbox-min-index-size If mbox size is smaller than this (e.g.@: 100k), don't write index files. If an index file already exists it's still read, just not updated. Defaults to @samp{0}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer mdbox-rotate-size Maximum dbox file size until it's rotated. Defaults to @samp{10000000}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string mdbox-rotate-interval Maximum dbox file age until it's rotated. Typically in days. Day begins from midnight, so 1d = today, 2d = yesterday, etc. 0 = check disabled. Defaults to @samp{"1d"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} boolean mdbox-preallocate-space? When creating new mdbox files, immediately preallocate their size to @samp{mdbox-rotate-size}. This setting currently works only in Linux with some file systems (ext4, xfs). Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string mail-attachment-dir sdbox and mdbox support saving mail attachments to external files, which also allows single instance storage for them. Other backends don't support this for now. WARNING: This feature hasn't been tested much yet. Use at your own risk. Directory root where to store mail attachments. Disabled, if empty. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer mail-attachment-min-size Attachments smaller than this aren't saved externally. It's also possible to write a plugin to disable saving specific attachments externally. Defaults to @samp{128000}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string mail-attachment-fs File system backend to use for saving attachments: @table @code @item posix No SiS done by Dovecot (but this might help FS's own deduplication) @item sis posix SiS with immediate byte-by-byte comparison during saving @item sis-queue posix SiS with delayed comparison and deduplication. @end table Defaults to @samp{"sis posix"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string mail-attachment-hash Hash format to use in attachment filenames. You can add any text and variables: @code{%@{md4@}}, @code{%@{md5@}}, @code{%@{sha1@}}, @code{%@{sha256@}}, @code{%@{sha512@}}, @code{%@{size@}}. Variables can be truncated, e.g.@: @code{%@{sha256:80@}} returns only first 80 bits. Defaults to @samp{"%@{sha1@}"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer default-process-limit Defaults to @samp{100}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer default-client-limit Defaults to @samp{1000}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer default-vsz-limit Default VSZ (virtual memory size) limit for service processes. This is mainly intended to catch and kill processes that leak memory before they eat up everything. Defaults to @samp{256000000}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string default-login-user Login user is internally used by login processes. This is the most untrusted user in Dovecot system. It shouldn't have access to anything at all. Defaults to @samp{"dovenull"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string default-internal-user Internal user is used by unprivileged processes. It should be separate from login user, so that login processes can't disturb other processes. Defaults to @samp{"dovecot"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string ssl? SSL/TLS support: yes, no, required. <doc/wiki/SSL.txt>. Defaults to @samp{"required"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string ssl-cert PEM encoded X.509 SSL/TLS certificate (public key). Defaults to @samp{"</etc/dovecot/default.pem"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string ssl-key PEM encoded SSL/TLS private key. The key is opened before dropping root privileges, so keep the key file unreadable by anyone but root. Defaults to @samp{"</etc/dovecot/private/default.pem"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string ssl-key-password If key file is password protected, give the password here. Alternatively give it when starting dovecot with -p parameter. Since this file is often world-readable, you may want to place this setting instead to a different. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string ssl-ca PEM encoded trusted certificate authority. Set this only if you intend to use @samp{ssl-verify-client-cert? #t}. The file should contain the CA certificate(s) followed by the matching CRL(s). (e.g.@: @samp{ssl-ca </etc/ssl/certs/ca.pem}). Defaults to @samp{""}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} boolean ssl-require-crl? Require that CRL check succeeds for client certificates. Defaults to @samp{#t}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} boolean ssl-verify-client-cert? Request client to send a certificate. If you also want to require it, set @samp{auth-ssl-require-client-cert? #t} in auth section. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string ssl-cert-username-field Which field from certificate to use for username. commonName and x500UniqueIdentifier are the usual choices. You'll also need to set @samp{auth-ssl-username-from-cert? #t}. Defaults to @samp{"commonName"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string ssl-min-protocol Minimum SSL protocol version to accept. Defaults to @samp{"TLSv1"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string ssl-cipher-list SSL ciphers to use. Defaults to @samp{"ALL:!kRSA:!SRP:!kDHd:!DSS:!aNULL:!eNULL:!EXPORT:!DES:!3DES:!MD5:!PSK:!RC4:!ADH:!LOW@@STRENGTH"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string ssl-crypto-device SSL crypto device to use, for valid values run "openssl engine". Defaults to @samp{""}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string postmaster-address Address to use when sending rejection mails. %d expands to recipient domain. Defaults to @samp{"postmaster@@%d"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string hostname Hostname to use in various parts of sent mails (e.g.@: in Message-Id) and in LMTP replies. Default is the system's real hostname@@domain. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} boolean quota-full-tempfail? If user is over quota, return with temporary failure instead of bouncing the mail. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} file-name sendmail-path Binary to use for sending mails. Defaults to @samp{"/usr/sbin/sendmail"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string submission-host If non-empty, send mails via this SMTP host[:port] instead of sendmail. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string rejection-subject Subject: header to use for rejection mails. You can use the same variables as for @samp{rejection-reason} below. Defaults to @samp{"Rejected: %s"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string rejection-reason Human readable error message for rejection mails. You can use variables: @table @code @item %n CRLF @item %r reason @item %s original subject @item %t recipient @end table Defaults to @samp{"Your message to <%t> was automatically rejected:%n%r"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string recipient-delimiter Delimiter character between local-part and detail in email address. Defaults to @samp{"+"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string lda-original-recipient-header Header where the original recipient address (SMTP's RCPT TO: address) is taken from if not available elsewhere. With dovecot-lda -a parameter overrides this. A commonly used header for this is X-Original-To. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} boolean lda-mailbox-autocreate? Should saving a mail to a nonexistent mailbox automatically create it?. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} boolean lda-mailbox-autosubscribe? Should automatically created mailboxes be also automatically subscribed?. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer imap-max-line-length Maximum IMAP command line length. Some clients generate very long command lines with huge mailboxes, so you may need to raise this if you get "Too long argument" or "IMAP command line too large" errors often. Defaults to @samp{64000}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string imap-logout-format IMAP logout format string: @table @code @item %i total number of bytes read from client @item %o total number of bytes sent to client. @end table See @file{doc/wiki/Variables.txt} for a list of all the variables you can use. Defaults to @samp{"in=%i out=%o deleted=%@{deleted@} expunged=%@{expunged@} trashed=%@{trashed@} hdr_count=%@{fetch_hdr_count@} hdr_bytes=%@{fetch_hdr_bytes@} body_count=%@{fetch_body_count@} body_bytes=%@{fetch_body_bytes@}"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string imap-capability Override the IMAP CAPABILITY response. If the value begins with '+', add the given capabilities on top of the defaults (e.g.@: +XFOO XBAR). Defaults to @samp{""}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string imap-idle-notify-interval How long to wait between "OK Still here" notifications when client is IDLEing. Defaults to @samp{"2 mins"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string imap-id-send ID field names and values to send to clients. Using * as the value makes Dovecot use the default value. The following fields have default values currently: name, version, os, os-version, support-url, support-email. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string imap-id-log ID fields sent by client to log. * means everything. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list imap-client-workarounds Workarounds for various client bugs: @table @code @item delay-newmail Send EXISTS/RECENT new mail notifications only when replying to NOOP and CHECK commands. Some clients ignore them otherwise, for example OSX Mail (<v2.1). Outlook Express breaks more badly though, without this it may show user "Message no longer in server" errors. Note that OE6 still breaks even with this workaround if synchronization is set to "Headers Only". @item tb-extra-mailbox-sep Thunderbird gets somehow confused with LAYOUT=fs (mbox and dbox) and adds extra @samp{/} suffixes to mailbox names. This option causes Dovecot to ignore the extra @samp{/} instead of treating it as invalid mailbox name. @item tb-lsub-flags Show \Noselect flags for LSUB replies with LAYOUT=fs (e.g.@: mbox). This makes Thunderbird realize they aren't selectable and show them greyed out, instead of only later giving "not selectable" popup error. @end table Defaults to @samp{'()}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string imap-urlauth-host Host allowed in URLAUTH URLs sent by client. "*" allows all. Defaults to @samp{""}. @end deftypevr Whew! Lots of configuration options. The nice thing about it though is that Guix has a complete interface to Dovecot's configuration language. This allows not only a nice way to declare configurations, but also offers reflective capabilities as well: users can write code to inspect and transform configurations from within Scheme. However, it could be that you just want to get a @code{dovecot.conf} up and running. In that case, you can pass an @code{opaque-dovecot-configuration} as the @code{#:config} parameter to @code{dovecot-service}. As its name indicates, an opaque configuration does not have easy reflective capabilities. Available @code{opaque-dovecot-configuration} fields are: @deftypevr {@code{opaque-dovecot-configuration} parameter} package dovecot The dovecot package. @end deftypevr @deftypevr {@code{opaque-dovecot-configuration} parameter} string string The contents of the @code{dovecot.conf}, as a string. @end deftypevr For example, if your @code{dovecot.conf} is just the empty string, you could instantiate a dovecot service like this: @lisp (dovecot-service #:config (opaque-dovecot-configuration (string ""))) @end lisp @subsubheading OpenSMTPD Service @defvar opensmtpd-service-type This is the type of the @uref{https://www.opensmtpd.org, OpenSMTPD} service, whose value should be an @code{opensmtpd-configuration} object as in this example: @lisp (service opensmtpd-service-type (opensmtpd-configuration (config-file (local-file "./my-smtpd.conf")))) @end lisp @end defvar @deftp {Data Type} opensmtpd-configuration Data type representing the configuration of opensmtpd. @table @asis @item @code{package} (default: @var{opensmtpd}) Package object of the OpenSMTPD SMTP server. @item @code{shepherd-requirement} (default: @code{'()}) This option can be used to provide a list of symbols naming Shepherd services that this service will depend on, such as @code{'networking} if you want to configure OpenSMTPD to listen on non-loopback interfaces. @item @code{config-file} (default: @code{%default-opensmtpd-config-file}) File-like object of the OpenSMTPD configuration file to use. By default it listens on the loopback network interface, and allows for mail from users and daemons on the local machine, as well as permitting email to remote servers. Run @command{man smtpd.conf} for more information. @item @code{setgid-commands?} (default: @code{#t}) Make the following commands setgid to @code{smtpq} so they can be executed: @command{smtpctl}, @command{sendmail}, @command{send-mail}, @command{makemap}, @command{mailq}, and @command{newaliases}. @xref{Privileged Programs}, for more information on setgid programs. @end table @end deftp @subsubheading Exim Service @cindex mail transfer agent (MTA) @cindex MTA (mail transfer agent) @cindex SMTP @defvar exim-service-type This is the type of the @uref{https://exim.org, Exim} mail transfer agent (MTA), whose value should be an @code{exim-configuration} object as in this example: @lisp (service exim-service-type (exim-configuration (config-file (local-file "./my-exim.conf")))) @end lisp @end defvar In order to use an @code{exim-service-type} service you must also have a @code{mail-aliases-service-type} service present in your @code{operating-system} (even if it has no aliases). @deftp {Data Type} exim-configuration Data type representing the configuration of exim. @table @asis @item @code{package} (default: @var{exim}) Package object of the Exim server. @item @code{config-file} (default: @code{#f}) File-like object of the Exim configuration file to use. If its value is @code{#f} then use the default configuration file from the package provided in @code{package}. The resulting configuration file is loaded after setting the @code{exim_user} and @code{exim_group} configuration variables. @end table @end deftp @subsubheading Getmail service @cindex IMAP @cindex POP @defvar getmail-service-type This is the type of the @uref{http://pyropus.ca/software/getmail/, Getmail} mail retriever, whose value should be a @code{getmail-configuration}. @end defvar Available @code{getmail-configuration} fields are: @deftypevr {@code{getmail-configuration} parameter} symbol name A symbol to identify the getmail service. Defaults to @samp{"unset"}. @end deftypevr @deftypevr {@code{getmail-configuration} parameter} package package The getmail package to use. @end deftypevr @deftypevr {@code{getmail-configuration} parameter} string user The user to run getmail as. Defaults to @samp{"getmail"}. @end deftypevr @deftypevr {@code{getmail-configuration} parameter} string group The group to run getmail as. Defaults to @samp{"getmail"}. @end deftypevr @deftypevr {@code{getmail-configuration} parameter} string directory The getmail directory to use. Defaults to @samp{"/var/lib/getmail/default"}. @end deftypevr @deftypevr {@code{getmail-configuration} parameter} getmail-configuration-file rcfile The getmail configuration file to use. Available @code{getmail-configuration-file} fields are: @deftypevr {@code{getmail-configuration-file} parameter} getmail-retriever-configuration retriever What mail account to retrieve mail from, and how to access that account. Available @code{getmail-retriever-configuration} fields are: @deftypevr {@code{getmail-retriever-configuration} parameter} string type The type of mail retriever to use. Valid values include @samp{passwd} and @samp{static}. Defaults to @samp{"SimpleIMAPSSLRetriever"}. @end deftypevr @deftypevr {@code{getmail-retriever-configuration} parameter} string server Username to login to the mail server with. Defaults to @samp{unset}. @end deftypevr @deftypevr {@code{getmail-retriever-configuration} parameter} string username Username to login to the mail server with. Defaults to @samp{unset}. @end deftypevr @deftypevr {@code{getmail-retriever-configuration} parameter} non-negative-integer port Port number to connect to. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{getmail-retriever-configuration} parameter} string password Override fields from passwd. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{getmail-retriever-configuration} parameter} list password-command Override fields from passwd. Defaults to @samp{'()}. @end deftypevr @deftypevr {@code{getmail-retriever-configuration} parameter} string keyfile PEM-formatted key file to use for the TLS negotiation. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{getmail-retriever-configuration} parameter} string certfile PEM-formatted certificate file to use for the TLS negotiation. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{getmail-retriever-configuration} parameter} string ca-certs CA certificates to use. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{getmail-retriever-configuration} parameter} parameter-alist extra-parameters Extra retriever parameters. Defaults to @samp{'()}. @end deftypevr @end deftypevr @deftypevr {@code{getmail-configuration-file} parameter} getmail-destination-configuration destination What to do with retrieved messages. Available @code{getmail-destination-configuration} fields are: @deftypevr {@code{getmail-destination-configuration} parameter} string type The type of mail destination. Valid values include @samp{Maildir}, @samp{Mboxrd} and @samp{MDA_external}. Defaults to @samp{unset}. @end deftypevr @deftypevr {@code{getmail-destination-configuration} parameter} string-or-filelike path The path option for the mail destination. The behaviour depends on the chosen type. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{getmail-destination-configuration} parameter} parameter-alist extra-parameters Extra destination parameters Defaults to @samp{'()}. @end deftypevr @end deftypevr @deftypevr {@code{getmail-configuration-file} parameter} getmail-options-configuration options Configure getmail. Available @code{getmail-options-configuration} fields are: @deftypevr {@code{getmail-options-configuration} parameter} non-negative-integer verbose If set to @samp{0}, getmail will only print warnings and errors. A value of @samp{1} means that messages will be printed about retrieving and deleting messages. If set to @samp{2}, getmail will print messages about each of its actions. Defaults to @samp{1}. @end deftypevr @deftypevr {@code{getmail-options-configuration} parameter} boolean read-all If true, getmail will retrieve all available messages. Otherwise it will only retrieve messages it hasn't seen previously. Defaults to @samp{#t}. @end deftypevr @deftypevr {@code{getmail-options-configuration} parameter} boolean delete If set to true, messages will be deleted from the server after retrieving and successfully delivering them. Otherwise, messages will be left on the server. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{getmail-options-configuration} parameter} non-negative-integer delete-after Getmail will delete messages this number of days after seeing them, if they have been delivered. This means messages will be left on the server this number of days after delivering them. A value of @samp{0} disabled this feature. Defaults to @samp{0}. @end deftypevr @deftypevr {@code{getmail-options-configuration} parameter} non-negative-integer delete-bigger-than Delete messages larger than this of bytes after retrieving them, even if the delete and delete-after options are disabled. A value of @samp{0} disables this feature. Defaults to @samp{0}. @end deftypevr @deftypevr {@code{getmail-options-configuration} parameter} non-negative-integer max-bytes-per-session Retrieve messages totalling up to this number of bytes before closing the session with the server. A value of @samp{0} disables this feature. Defaults to @samp{0}. @end deftypevr @deftypevr {@code{getmail-options-configuration} parameter} non-negative-integer max-message-size Don't retrieve messages larger than this number of bytes. A value of @samp{0} disables this feature. Defaults to @samp{0}. @end deftypevr @deftypevr {@code{getmail-options-configuration} parameter} boolean delivered-to If true, getmail will add a Delivered-To header to messages. Defaults to @samp{#t}. @end deftypevr @deftypevr {@code{getmail-options-configuration} parameter} boolean received If set, getmail adds a Received header to the messages. Defaults to @samp{#t}. @end deftypevr @deftypevr {@code{getmail-options-configuration} parameter} string message-log Getmail will record a log of its actions to the named file. A value of @samp{""} disables this feature. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{getmail-options-configuration} parameter} boolean message-log-syslog If true, getmail will record a log of its actions using the system logger. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{getmail-options-configuration} parameter} boolean message-log-verbose If true, getmail will log information about messages not retrieved and the reason for not retrieving them, as well as starting and ending information lines. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{getmail-options-configuration} parameter} parameter-alist extra-parameters Extra options to include. Defaults to @samp{'()}. @end deftypevr @end deftypevr @end deftypevr @deftypevr {@code{getmail-configuration} parameter} list idle A list of mailboxes that getmail should wait on the server for new mail notifications. This depends on the server supporting the IDLE extension. Defaults to @samp{'()}. @end deftypevr @deftypevr {@code{getmail-configuration} parameter} list environment-variables Environment variables to set for getmail. Defaults to @samp{'()}. @end deftypevr @subsubheading Mail Aliases Service @cindex email aliases @cindex aliases, for email addresses @defvar mail-aliases-service-type This is the type of the service which provides @code{/etc/aliases}, specifying how to deliver mail to users on this system. @lisp (service mail-aliases-service-type '(("postmaster" "bob") ("bob" "bob@@example.com" "bob@@example2.com"))) @end lisp @end defvar The configuration for a @code{mail-aliases-service-type} service is an association list denoting how to deliver mail that comes to this system. Each entry is of the form @code{(alias addresses ...)}, with @code{alias} specifying the local alias and @code{addresses} specifying where to deliver this user's mail. The aliases aren't required to exist as users on the local system. In the above example, there doesn't need to be a @code{postmaster} entry in the @code{operating-system}'s @code{user-accounts} in order to deliver the @code{postmaster} mail to @code{bob} (which subsequently would deliver mail to @code{bob@@example.com} and @code{bob@@example2.com}). @subsubheading GNU Mailutils IMAP4 Daemon @cindex GNU Mailutils IMAP4 Daemon @defvar imap4d-service-type This is the type of the GNU Mailutils IMAP4 Daemon (@pxref{imap4d,,, mailutils, GNU Mailutils Manual}), whose value should be an @code{imap4d-configuration} object as in this example: @lisp (service imap4d-service-type (imap4d-configuration (config-file (local-file "imap4d.conf")))) @end lisp @end defvar @deftp {Data Type} imap4d-configuration Data type representing the configuration of @command{imap4d}. @table @asis @item @code{package} (default: @code{mailutils}) The package that provides @command{imap4d}. @item @code{config-file} (default: @code{%default-imap4d-config-file}) File-like object of the configuration file to use, by default it will listen on TCP port 143 of @code{localhost}. @xref{Conf-imap4d,,, mailutils, GNU Mailutils Manual}, for details. @end table @end deftp @subsubheading Radicale Service @cindex CalDAV @cindex CardDAV @defvar radicale-service-type This is the type of the @uref{https://radicale.org, Radicale} CalDAV/CardDAV server whose value should be a @code{radicale-configuration}. The default configuration matches the @uref{https://radicale.org/v3.html#configuration, upstream documentation}. @end defvar @deftp {Data Type} radicale-configuration Data type representing the configuration of @command{radicale}. Available @code{radicale-configuration} fields are: @table @asis @item @code{package} (default: @code{radicale}) (type: package) Package that provides @command{radicale}. @item @code{auth} (default: @code{'()}) (type: radicale-auth-configuration) Configuration for auth-related variables. @deftp {Data Type} radicale-auth-configuration Data type representing the @code{auth} section of a @command{radicale} configuration file. Available @code{radicale-auth-configuration} fields are: @table @asis @item @code{type} (default: @code{'none}) (type: symbol) The method to verify usernames and passwords. Options are @code{none}, @code{htpasswd}, @code{remote-user}, and @code{http-x-remote-user}. This value is tied to @code{htpasswd-filename} and @code{htpasswd-encryption}. @item @code{htpasswd-filename} (default: @code{"/etc/radicale/users"}) (type: file-name) Path to the htpasswd file. Use htpasswd or similar to generate this file. @item @code{htpasswd-encryption} (default: @code{'md5}) (type: symbol) Encryption method used in the htpasswd file. Options are @code{plain}, @code{bcrypt}, and @code{md5}. @item @code{delay} (default: @code{1}) (type: non-negative-integer) Average delay after failed login attempts in seconds. @item @code{realm} (default: @code{"Radicale - Password Required"}) (type: string) Message displayed in the client when a password is needed. @end table @end deftp @item @code{encoding} (default: @code{'()}) (type: radicale-encoding-configuration) Configuration for encoding-related variables. @deftp {Data Type} radicale-encoding-configuration Data type representing the @code{encoding} section of a @command{radicale} configuration file. Available @code{radicale-encoding-configuration} fields are: @table @asis @item @code{request} (default: @code{'utf-8}) (type: symbol) Encoding for responding requests. @item @code{stock} (default: @code{'utf-8}) (type: symbol) Encoding for storing local collections. @end table @end deftp @item @code{headers-file} (default: none) (type: file-like) Custom HTTP headers. @item @code{logging} (default: @code{'()}) (type: radicale-logging-configuration) Configuration for logging-related variables. @deftp {Data Type} radicale-logging-configuration Data type representing the @code{logging} section of a @command{radicale} configuration file. Available @code{radicale-logging-configuration} fields are: @table @asis @item @code{level} (default: @code{'warning}) (type: symbol) Set the logging level. One of @code{debug}, @code{info}, @code{warning}, @code{error}, or @code{critical}. @item @code{mask-passwords?} (default: @code{#t}) (type: boolean) Whether to include passwords in logs. @end table @end deftp @item @code{rights} (default: @code{'()}) (type: radicale-rights-configuration) Configuration for rights-related variables. This should be a @code{radicale-rights-configuration}. @deftp {Data Type} radicale-rights-configuration Data type representing the @code{rights} section of a @command{radicale} configuration file. Available @code{radicale-rights-configuration} fields are: @table @asis @item @code{type} (default: @code{'owner-only}) (type: symbol) Backend used to check collection access rights. The recommended backend is @code{owner-only}. If access to calendars and address books outside the home directory of users is granted, clients won't detect these collections and will not show them to the user. Choosing any other method is only useful if you access calendars and address books directly via URL. Options are @code{authenticate}, @code{owner-only}, @code{owner-write}, and @code{from-file}. @item @code{file} (default: @code{""}) (type: file-name) File for the rights backend @code{from-file}. @end table @end deftp @item @code{server} (default: @code{'()}) (type: radicale-server-configuration) Configuration for server-related variables. Ignored if WSGI is used. @deftp {Data Type} radicale-server-configuration Data type representing the @code{server} section of a @command{radicale} configuration file. Available @code{radicale-server-configuration} fields are: @table @asis @item @code{hosts} (default: @code{(list "localhost:5232")}) (type: list-of-ip-addresses) List of IP addresses that the server will bind to. @item @code{max-connections} (default: @code{8}) (type: non-negative-integer) Maximum number of parallel connections. Set to 0 to disable the limit. @item @code{max-content-length} (default: @code{100000000}) (type: non-negative-integer) Maximum size of the request body in bytes. @item @code{timeout} (default: @code{30}) (type: non-negative-integer) Socket timeout in seconds. @item @code{ssl?} (default: @code{#f}) (type: boolean) Whether to enable transport layer encryption. @item @code{certificate} (default: @code{"/etc/ssl/radicale.cert.pem"}) (type: file-name) Path of the SSL certificate. @item @code{key} (default: @code{"/etc/ssl/radicale.key.pem"}) (type: file-name) Path to the private key for SSL. Only effective if @code{ssl?} is @code{#t}. @item @code{certificate-authority} (default: @code{""}) (type: file-name) Path to CA certificate for validating client certificates. This can be used to secure TCP traffic between Radicale and a reverse proxy. If you want to authenticate users with client-side certificates, you also have to write an authentication plugin that extracts the username from the certificate. @end table @end deftp @item @code{storage} (default: @code{'()}) (type: radicale-storage-configuration) Configuration for storage-related variables. @deftp {Data Type} radicale-storage-configuration Data type representing the @code{storage} section of a @command{radicale} configuration file. Available @code{radicale-storage-configuration} fields are: @table @asis @item @code{type} (default: @code{'multifilesystem}) (type: symbol) Backend used to store data. Options are @code{multifilesystem} and @code{multifilesystem-nolock}. @item @code{filesystem-folder} (default: @code{"/var/lib/radicale/collections"}) (type: file-name) Folder for storing local collections. Created if not present. @item @code{max-sync-token-age} (default: @code{2592000}) (type: non-negative-integer) Delete sync-tokens that are older than the specified time in seconds. @item @code{hook} (default: @code{""}) (type: string) Command run after changes to storage. @end table @end deftp @item @code{web-interface?} (default: @code{#t}) (type: boolean) Whether to use Radicale's built-in web interface. @end table @end deftp @subsubheading Rspamd Service @cindex email @cindex spam @defvar rspamd-service-type This is the type of the @uref{https://rspamd.com/, Rspamd} filtering system whose value should be a @code{rspamd-configuration}. @end defvar @c %start of fragment @deftp {Data Type} rspamd-configuration Available @code{rspamd-configuration} fields are: @table @asis @item @code{package} (default: @code{rspamd}) (type: file-like) The package that provides rspamd. @item @code{config-file} (default: @code{%default-rspamd-config-file}) (type: file-like) File-like object of the configuration file to use. By default all workers are enabled except fuzzy and they are binded to their usual ports, e.g localhost:11334, localhost:11333 and so on @item @code{local.d-files} (default: @code{()}) (type: directory-tree) Configuration files in local.d, provided as a list of two element lists where the first element is the filename and the second one is a file-like object. Settings in these files will be merged with the defaults. @item @code{override.d-files} (default: @code{()}) (type: directory-tree) Configuration files in override.d, provided as a list of two element lists where the first element is the filename and the second one is a file-like object. Settings in these files will override the defaults. @item @code{user} (default: @code{%default-rspamd-account}) (type: user-account) The user to run rspamd as. @item @code{group} (default: @code{%default-rspamd-group}) (type: user-group) The group to run rspamd as. @item @code{debug?} (default: @code{#f}) (type: boolean) Force debug output. @item @code{insecure?} (default: @code{#f}) (type: boolean) Ignore running workers as privileged users. @item @code{skip-template?} (default: @code{#f}) (type: boolean) Do not apply Jinja templates. @item @code{shepherd-requirements} (default: @code{(loopback)}) (type: list-of-symbols) This is a list of symbols naming Shepherd services that this service will depend on. @end table @end deftp @c %end of fragment @node Messaging Services @subsection Messaging Services @cindex messaging @cindex jabber @cindex XMPP The @code{(gnu services messaging)} module provides Guix service definitions for messaging services. Currently it provides the following services: @subsubheading Prosody Service @defvar prosody-service-type This is the type for the @uref{https://prosody.im, Prosody XMPP communication server}. Its value must be a @code{prosody-configuration} record as in this example: @lisp (service prosody-service-type (prosody-configuration (modules-enabled (cons* "groups" "mam" %default-modules-enabled)) (int-components (list (int-component-configuration (hostname "conference.example.net") (plugin "muc") (mod-muc (mod-muc-configuration))))) (virtualhosts (list (virtualhost-configuration (domain "example.net")))))) @end lisp See below for details about @code{prosody-configuration}. @end defvar By default, Prosody does not need much configuration. Only one @code{virtualhosts} field is needed: it specifies the domain you wish Prosody to serve. You can perform various sanity checks on the generated configuration with the @code{prosodyctl check} command. Prosodyctl will also help you to import certificates from the @code{letsencrypt} directory so that the @code{prosody} user can access them. See @url{https://prosody.im/doc/letsencrypt}. @example prosodyctl --root cert import /etc/certs @end example The available configuration parameters follow. Each parameter definition is preceded by its type; for example, @samp{string-list foo} indicates that the @code{foo} parameter should be specified as a list of strings. Types starting with @code{maybe-} denote parameters that won't show up in @code{prosody.cfg.lua} when their value is left unspecified. There is also a way to specify the configuration as a string, if you have an old @code{prosody.cfg.lua} file that you want to port over from some other system; see the end for more details. The @code{file-object} type designates either a file-like object (@pxref{G-Expressions, file-like objects}) or a file name. @c The following documentation was initially generated by @c (generate-documentation) in (gnu services messaging). Manually maintained @c documentation is better, so we shouldn't hesitate to edit below as @c needed. However if the change you want to make to this documentation @c can be done in an automated way, it's probably easier to change @c (generate-documentation) than to make it below and have to deal with @c the churn as Prosody updates. Available @code{prosody-configuration} fields are: @deftypevr {@code{prosody-configuration} parameter} package prosody The Prosody package. @end deftypevr @deftypevr {@code{prosody-configuration} parameter} file-name data-path Location of the Prosody data storage directory. See @url{https://prosody.im/doc/configure}. Defaults to @samp{"/var/lib/prosody"}. @end deftypevr @deftypevr {@code{prosody-configuration} parameter} file-object-list plugin-paths Additional plugin directories. They are searched in all the specified paths in order. See @url{https://prosody.im/doc/plugins_directory}. Defaults to @samp{'()}. @end deftypevr @deftypevr {@code{prosody-configuration} parameter} file-name certificates Every virtual host and component needs a certificate so that clients and servers can securely verify its identity. Prosody will automatically load certificates/keys from the directory specified here. Defaults to @samp{"/etc/prosody/certs"}. @end deftypevr @deftypevr {@code{prosody-configuration} parameter} string-list admins This is a list of accounts that are admins for the server. Note that you must create the accounts separately. See @url{https://prosody.im/doc/admins} and @url{https://prosody.im/doc/creating_accounts}. Example: @code{(admins '("user1@@example.com" "user2@@example.net"))} Defaults to @samp{'()}. @end deftypevr @deftypevr {@code{prosody-configuration} parameter} boolean use-libevent? Enable use of libevent for better performance under high load. See @url{https://prosody.im/doc/libevent}. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{prosody-configuration} parameter} module-list modules-enabled This is the list of modules Prosody will load on startup. It looks for @code{mod_modulename.lua} in the plugins folder, so make sure that exists too. Documentation on modules can be found at: @url{https://prosody.im/doc/modules}. Defaults to @samp{'("roster" "saslauth" "tls" "dialback" "disco" "carbons" "private" "blocklist" "vcard" "version" "uptime" "time" "ping" "pep" "register" "admin_adhoc")}. @end deftypevr @deftypevr {@code{prosody-configuration} parameter} string-list modules-disabled @samp{"offline"}, @samp{"c2s"} and @samp{"s2s"} are auto-loaded, but should you want to disable them then add them to this list. Defaults to @samp{'()}. @end deftypevr @deftypevr {@code{prosody-configuration} parameter} file-object groups-file Path to a text file where the shared groups are defined. If this path is empty then @samp{mod_groups} does nothing. See @url{https://prosody.im/doc/modules/mod_groups}. Defaults to @samp{"/var/lib/prosody/sharedgroups.txt"}. @end deftypevr @deftypevr {@code{prosody-configuration} parameter} boolean allow-registration? Disable account creation by default, for security. See @url{https://prosody.im/doc/creating_accounts}. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{prosody-configuration} parameter} maybe-ssl-configuration ssl These are the SSL/TLS-related settings. Most of them are disabled so to use Prosody's defaults. If you do not completely understand these options, do not add them to your config, it is easy to lower the security of your server using them. See @url{https://prosody.im/doc/advanced_ssl_config}. Available @code{ssl-configuration} fields are: @deftypevr {@code{ssl-configuration} parameter} maybe-string protocol This determines what handshake to use. @end deftypevr @deftypevr {@code{ssl-configuration} parameter} maybe-file-name key Path to your private key file. @end deftypevr @deftypevr {@code{ssl-configuration} parameter} maybe-file-name certificate Path to your certificate file. @end deftypevr @deftypevr {@code{ssl-configuration} parameter} file-object capath Path to directory containing root certificates that you wish Prosody to trust when verifying the certificates of remote servers. Defaults to @samp{"/etc/ssl/certs"}. @end deftypevr @deftypevr {@code{ssl-configuration} parameter} maybe-file-object cafile Path to a file containing root certificates that you wish Prosody to trust. Similar to @code{capath} but with all certificates concatenated together. @end deftypevr @deftypevr {@code{ssl-configuration} parameter} maybe-string-list verify A list of verification options (these mostly map to OpenSSL's @code{set_verify()} flags). @end deftypevr @deftypevr {@code{ssl-configuration} parameter} maybe-string-list options A list of general options relating to SSL/TLS@. These map to OpenSSL's @code{set_options()}. For a full list of options available in LuaSec, see the LuaSec source. @end deftypevr @deftypevr {@code{ssl-configuration} parameter} maybe-non-negative-integer depth How long a chain of certificate authorities to check when looking for a trusted root certificate. @end deftypevr @deftypevr {@code{ssl-configuration} parameter} maybe-string ciphers An OpenSSL cipher string. This selects what ciphers Prosody will offer to clients, and in what order. @end deftypevr @deftypevr {@code{ssl-configuration} parameter} maybe-file-name dhparam A path to a file containing parameters for Diffie-Hellman key exchange. You can create such a file with: @code{openssl dhparam -out /etc/prosody/certs/dh-2048.pem 2048} @end deftypevr @deftypevr {@code{ssl-configuration} parameter} maybe-string curve Curve for Elliptic curve Diffie-Hellman. Prosody's default is @samp{"secp384r1"}. @end deftypevr @deftypevr {@code{ssl-configuration} parameter} maybe-string-list verifyext A list of ``extra'' verification options. @end deftypevr @deftypevr {@code{ssl-configuration} parameter} maybe-string password Password for encrypted private keys. @end deftypevr @end deftypevr @deftypevr {@code{prosody-configuration} parameter} boolean c2s-require-encryption? Whether to force all client-to-server connections to be encrypted or not. See @url{https://prosody.im/doc/modules/mod_tls}. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{prosody-configuration} parameter} string-list disable-sasl-mechanisms Set of mechanisms that will never be offered. See @url{https://prosody.im/doc/modules/mod_saslauth}. Defaults to @samp{'("DIGEST-MD5")}. @end deftypevr @deftypevr {@code{prosody-configuration} parameter} string-list insecure-sasl-mechanisms Set of mechanisms that will not be offered on unencrypted connections. See @url{https://prosody.im/doc/modules/mod_saslauth}. Defaults to @samp{'("PLAIN" "LOGIN")}. @end deftypevr @deftypevr {@code{prosody-configuration} parameter} boolean s2s-require-encryption? Whether to force all server-to-server connections to be encrypted or not. See @url{https://prosody.im/doc/modules/mod_tls}. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{prosody-configuration} parameter} boolean s2s-secure-auth? Whether to require encryption and certificate authentication. This provides ideal security, but requires servers you communicate with to support encryption AND present valid, trusted certificates. See @url{https://prosody.im/doc/s2s#security}. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{prosody-configuration} parameter} string-list s2s-insecure-domains Many servers don't support encryption or have invalid or self-signed certificates. You can list domains here that will not be required to authenticate using certificates. They will be authenticated using DNS@. See @url{https://prosody.im/doc/s2s#security}. Defaults to @samp{'()}. @end deftypevr @deftypevr {@code{prosody-configuration} parameter} string-list s2s-secure-domains Even if you leave @code{s2s-secure-auth?} disabled, you can still require valid certificates for some domains by specifying a list here. See @url{https://prosody.im/doc/s2s#security}. Defaults to @samp{'()}. @end deftypevr @deftypevr {@code{prosody-configuration} parameter} string authentication Select the authentication backend to use. The default provider stores passwords in plaintext and uses Prosody's configured data storage to store the authentication data. If you do not trust your server please see @url{https://prosody.im/doc/modules/mod_auth_internal_hashed} for information about using the hashed backend. See also @url{https://prosody.im/doc/authentication} Defaults to @samp{"internal_plain"}. @end deftypevr @deftypevr {@code{prosody-configuration} parameter} maybe-string log Set logging options. Advanced logging configuration is not yet supported by the Prosody service. See @url{https://prosody.im/doc/logging}. Defaults to @samp{"*syslog"}. @end deftypevr @deftypevr {@code{prosody-configuration} parameter} file-name pidfile File to write pid in. See @url{https://prosody.im/doc/modules/mod_posix}. Defaults to @samp{"/var/run/prosody/prosody.pid"}. @end deftypevr @deftypevr {@code{prosody-configuration} parameter} maybe-non-negative-integer http-max-content-size Maximum allowed size of the HTTP body (in bytes). @end deftypevr @deftypevr {@code{prosody-configuration} parameter} maybe-string http-external-url Some modules expose their own URL in various ways. This URL is built from the protocol, host and port used. If Prosody sits behind a proxy, the public URL will be @code{http-external-url} instead. See @url{https://prosody.im/doc/http#external_url}. @end deftypevr @deftypevr {@code{prosody-configuration} parameter} virtualhost-configuration-list virtualhosts A host in Prosody is a domain on which user accounts can be created. For example if you want your users to have addresses like @samp{"john.smith@@example.com"} then you need to add a host @samp{"example.com"}. All options in this list will apply only to this host. @quotation Note The name @emph{virtual} host is used in configuration to avoid confusion with the actual physical host that Prosody is installed on. A single Prosody instance can serve many domains, each one defined as a VirtualHost entry in Prosody's configuration. Conversely a server that hosts a single domain would have just one VirtualHost entry. See @url{https://prosody.im/doc/configure#virtual_host_settings}. @end quotation Available @code{virtualhost-configuration} fields are: all these @code{prosody-configuration} fields: @code{admins}, @code{use-libevent?}, @code{modules-enabled}, @code{modules-disabled}, @code{groups-file}, @code{allow-registration?}, @code{ssl}, @code{c2s-require-encryption?}, @code{disable-sasl-mechanisms}, @code{insecure-sasl-mechanisms}, @code{s2s-require-encryption?}, @code{s2s-secure-auth?}, @code{s2s-insecure-domains}, @code{s2s-secure-domains}, @code{authentication}, @code{log}, @code{http-max-content-size}, @code{http-external-url}, @code{raw-content}, plus: @deftypevr {@code{virtualhost-configuration} parameter} string domain Domain you wish Prosody to serve. @end deftypevr @end deftypevr @deftypevr {@code{prosody-configuration} parameter} int-component-configuration-list int-components Components are extra services on a server which are available to clients, usually on a subdomain of the main server (such as @samp{"mycomponent.example.com"}). Example components might be chatroom servers, user directories, or gateways to other protocols. Internal components are implemented with Prosody-specific plugins. To add an internal component, you simply fill the hostname field, and the plugin you wish to use for the component. See @url{https://prosody.im/doc/components}. Defaults to @samp{'()}. Available @code{int-component-configuration} fields are: all these @code{prosody-configuration} fields: @code{admins}, @code{use-libevent?}, @code{modules-enabled}, @code{modules-disabled}, @code{groups-file}, @code{allow-registration?}, @code{ssl}, @code{c2s-require-encryption?}, @code{disable-sasl-mechanisms}, @code{insecure-sasl-mechanisms}, @code{s2s-require-encryption?}, @code{s2s-secure-auth?}, @code{s2s-insecure-domains}, @code{s2s-secure-domains}, @code{authentication}, @code{log}, @code{http-max-content-size}, @code{http-external-url}, @code{raw-content}, plus: @deftypevr {@code{int-component-configuration} parameter} string hostname Hostname of the component. @end deftypevr @deftypevr {@code{int-component-configuration} parameter} string plugin Plugin you wish to use for the component. @end deftypevr @deftypevr {@code{int-component-configuration} parameter} maybe-mod-muc-configuration mod-muc Multi-user chat (MUC) is Prosody's module for allowing you to create hosted chatrooms/conferences for XMPP users. General information on setting up and using multi-user chatrooms can be found in the ``Chatrooms'' documentation (@url{https://prosody.im/doc/chatrooms}), which you should read if you are new to XMPP chatrooms. See also @url{https://prosody.im/doc/modules/mod_muc}. Available @code{mod-muc-configuration} fields are: @deftypevr {@code{mod-muc-configuration} parameter} string name The name to return in service discovery responses. Defaults to @samp{"Prosody Chatrooms"}. @end deftypevr @deftypevr {@code{mod-muc-configuration} parameter} string-or-boolean restrict-room-creation If @samp{#t}, this will only allow admins to create new chatrooms. Otherwise anyone can create a room. The value @samp{"local"} restricts room creation to users on the service's parent domain. E.g.@: @samp{user@@example.com} can create rooms on @samp{rooms.example.com}. The value @samp{"admin"} restricts to service administrators only. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{mod-muc-configuration} parameter} non-negative-integer max-history-messages Maximum number of history messages that will be sent to the member that has just joined the room. Defaults to @samp{20}. @end deftypevr @end deftypevr @end deftypevr @deftypevr {@code{prosody-configuration} parameter} ext-component-configuration-list ext-components External components use XEP-0114, which most standalone components support. To add an external component, you simply fill the hostname field. See @url{https://prosody.im/doc/components}. Defaults to @samp{'()}. Available @code{ext-component-configuration} fields are: all these @code{prosody-configuration} fields: @code{admins}, @code{use-libevent?}, @code{modules-enabled}, @code{modules-disabled}, @code{groups-file}, @code{allow-registration?}, @code{ssl}, @code{c2s-require-encryption?}, @code{disable-sasl-mechanisms}, @code{insecure-sasl-mechanisms}, @code{s2s-require-encryption?}, @code{s2s-secure-auth?}, @code{s2s-insecure-domains}, @code{s2s-secure-domains}, @code{authentication}, @code{log}, @code{http-max-content-size}, @code{http-external-url}, @code{raw-content}, plus: @deftypevr {@code{ext-component-configuration} parameter} string component-secret Password which the component will use to log in. @end deftypevr @deftypevr {@code{ext-component-configuration} parameter} string hostname Hostname of the component. @end deftypevr @end deftypevr @deftypevr {@code{prosody-configuration} parameter} non-negative-integer-list component-ports Port(s) Prosody listens on for component connections. Defaults to @samp{'(5347)}. @end deftypevr @deftypevr {@code{prosody-configuration} parameter} string component-interface Interface Prosody listens on for component connections. Defaults to @samp{"127.0.0.1"}. @end deftypevr @deftypevr {@code{prosody-configuration} parameter} maybe-raw-content raw-content Raw content that will be added to the configuration file. @end deftypevr It could be that you just want to get a @code{prosody.cfg.lua} up and running. In that case, you can pass an @code{opaque-prosody-configuration} record as the value of @code{prosody-service-type}. As its name indicates, an opaque configuration does not have easy reflective capabilities. Available @code{opaque-prosody-configuration} fields are: @deftypevr {@code{opaque-prosody-configuration} parameter} package prosody The prosody package. @end deftypevr @deftypevr {@code{opaque-prosody-configuration} parameter} string prosody.cfg.lua The contents of the @code{prosody.cfg.lua} to use. @end deftypevr For example, if your @code{prosody.cfg.lua} is just the empty string, you could instantiate a prosody service like this: @lisp (service prosody-service-type (opaque-prosody-configuration (prosody.cfg.lua ""))) @end lisp @c end of Prosody auto-generated documentation @subsubheading BitlBee Service @cindex IRC (Internet Relay Chat) @cindex IRC gateway @url{https://bitlbee.org,BitlBee} is a gateway that provides an IRC interface to a variety of messaging protocols such as XMPP. @defvar bitlbee-service-type This is the service type for the @url{https://bitlbee.org,BitlBee} IRC gateway daemon. Its value is a @code{bitlbee-configuration} (see below). To have BitlBee listen on port 6667 on localhost, add this line to your services: @lisp (service bitlbee-service-type) @end lisp @end defvar @deftp {Data Type} bitlbee-configuration This is the configuration for BitlBee, with the following fields: @table @asis @item @code{interface} (default: @code{"127.0.0.1"}) @itemx @code{port} (default: @code{6667}) Listen on the network interface corresponding to the IP address specified in @var{interface}, on @var{port}. When @var{interface} is @code{127.0.0.1}, only local clients can connect; when it is @code{0.0.0.0}, connections can come from any networking interface. @item @code{bitlbee} (default: @code{bitlbee}) The BitlBee package to use. @item @code{plugins} (default: @code{'()}) List of plugin packages to use---e.g., @code{bitlbee-discord}. @item @code{extra-settings} (default: @code{""}) Configuration snippet added as-is to the BitlBee configuration file. @end table @end deftp @subsubheading Quassel Service @cindex IRC (Internet Relay Chat) @url{https://quassel-irc.org/,Quassel} is a distributed IRC client, meaning that one or more clients can attach to and detach from the central core. @defvar quassel-service-type This is the service type for the @url{https://quassel-irc.org/,Quassel} IRC backend daemon. Its value is a @code{quassel-configuration} (see below). @end defvar @deftp {Data Type} quassel-configuration This is the configuration for Quassel, with the following fields: @table @asis @item @code{quassel} (default: @code{quassel}) The Quassel package to use. @item @code{interface} (default: @code{"::,0.0.0.0"}) @item @code{port} (default: @code{4242}) Listen on the network interface(s) corresponding to the IPv4 or IPv6 interfaces specified in the comma delimited @var{interface}, on @var{port}. @item @code{loglevel} (default: @code{"Info"}) The level of logging desired. Accepted values are Debug, Info, Warning and Error. @end table @end deftp @node Telephony Services @subsection Telephony Services @cindex telephony, services The @code{(gnu services telephony)} module contains Guix service definitions for telephony services. Currently it provides the following services: @subsubheading Jami @defvar jami-service-type The service type for running Jami as a service. It takes a @code{jami-configuration} object as a value, documented below. This section describes how to configure a Jami server that can be used to host video (or audio) conferences, among other uses. The following example demonstrates how to specify Jami account archives (backups) to be provisioned automatically: @lisp (service jami-service-type (jami-configuration (accounts (list (jami-account (archive "/etc/jami/unencrypted-account-1.gz")) (jami-account (archive "/etc/jami/unencrypted-account-2.gz")))))) @end lisp When the accounts field is specified, the Jami account files of the service found under @file{/var/lib/jami} are recreated every time the service starts. Jami accounts and their corresponding backup archives can be generated using the @code{jami} or @code{jami-gnome} Jami clients. The accounts should not be password-protected, but it is wise to ensure their files are only readable by @samp{root}. The next example shows how to declare that only some contacts should be allowed to communicate with a given account: @lisp (service jami-service-type (jami-configuration (accounts (list (jami-account (archive "/etc/jami/unencrypted-account-1.gz") (peer-discovery? #t) (rendezvous-point? #t) (allowed-contacts '("1dbcb0f5f37324228235564b79f2b9737e9a008f" "2dbcb0f5f37324228235564b79f2b9737e9a008f"))))))) @end lisp In this mode, only the declared @code{allowed-contacts} can initiate communication with the Jami account. This can be used, for example, with rendezvous point accounts to create a private video conferencing space. To put the system administrator in full control of the conferences hosted on their system, the Jami service supports the following actions: @example sh # herd doc jami list-actions (list-accounts list-account-details list-banned-contacts list-contacts list-moderators add-moderator ban-contact enable-account disable-account) @end example The above actions aim to provide the most valuable actions for moderation purposes, not to cover the whole Jami API. Users wanting to interact with the Jami daemon from Guile may be interested in experimenting with the @code{(gnu build jami-service)} module, which powers the above Shepherd actions. @c TODO: This should be auto-generated from the doc already defined on @c the shepherd-actions themselves in (gnu services telephony). The @code{add-moderator} and @code{ban-contact} actions accept a contact @emph{fingerprint} (40 characters long hash) as first argument and an account fingerprint or username as second argument: @example sh # herd add-moderator jami 1dbcb0f5f37324228235564b79f2b9737e9a008f \ f3345f2775ddfe07a4b0d95daea111d15fbc1199 # herd list-moderators jami Moderators for account f3345f2775ddfe07a4b0d95daea111d15fbc1199: - 1dbcb0f5f37324228235564b79f2b9737e9a008f @end example In the case of @code{ban-contact}, the second username argument is optional; when omitted, the account is banned from all Jami accounts: @example sh # herd ban-contact jami 1dbcb0f5f37324228235564b79f2b9737e9a008f # herd list-banned-contacts jami Banned contacts for account f3345f2775ddfe07a4b0d95daea111d15fbc1199: - 1dbcb0f5f37324228235564b79f2b9737e9a008f @end example Banned contacts are also stripped from their moderation privileges. The @code{disable-account} action allows to completely disconnect an account from the network, making it unreachable, while @code{enable-account} does the inverse. They accept a single account username or fingerprint as first argument: @example sh # herd disable-account jami f3345f2775ddfe07a4b0d95daea111d15fbc1199 # herd list-accounts jami The following Jami accounts are available: - f3345f2775ddfe07a4b0d95daea111d15fbc1199 (dummy) [disabled] @end example The @code{list-account-details} action prints the detailed parameters of each accounts in the Recutils format, which means the @command{recsel} command can be used to select accounts of interest (@pxref{Selection Expressions,,,recutils, GNU recutils manual}). Note that period characters (@samp{.}) found in the account parameter keys are mapped to underscores (@samp{_}) in the output, to meet the requirements of the Recutils format. The following example shows how to print the account fingerprints for all accounts operating in the rendezvous point mode: @example sh # herd list-account-details jami | \ recsel -p Account.username -e 'Account.rendezVous ~ "true"' Account_username: f3345f2775ddfe07a4b0d95daea111d15fbc1199 @end example The remaining actions should be self-explanatory. The complete set of available configuration options is detailed below. @end defvar @c TODO: Ideally, the following fragments would be auto-generated at @c build time, so that they needn't be manually duplicated. @c Auto-generated via (configuration->documentation 'jami-configuration) @deftp {Data Type} jami-configuration Available @code{jami-configuration} fields are: @table @asis @item @code{libjami} (default: @code{libjami}) (type: package) The Jami daemon package to use. @item @code{dbus} (default: @code{dbus-for-jami}) (type: package) The D-Bus package to use to start the required D-Bus session. @item @code{nss-certs} (default: @code{nss-certs}) (type: package) The nss-certs package to use to provide TLS certificates. @item @code{enable-logging?} (default: @code{#t}) (type: boolean) Whether to enable logging to syslog. @item @code{debug?} (default: @code{#f}) (type: boolean) Whether to enable debug level messages. @item @code{auto-answer?} (default: @code{#f}) (type: boolean) Whether to force automatic answer to incoming calls. @item @code{accounts} (type: maybe-jami-account-list) A list of Jami accounts to be (re-)provisioned every time the Jami daemon service starts. When providing this field, the account directories under @file{/var/lib/jami/} are recreated every time the service starts, ensuring a consistent state. @end table @end deftp @c Auto-generated via (configuration->documentation 'jami-account) @deftp {Data Type} jami-account Available @code{jami-account} fields are: @table @asis @item @code{archive} (type: string-or-computed-file) The account archive (backup) file name of the account. This is used to provision the account when the service starts. The account archive should @emph{not} be encrypted. It is highly recommended to make it readable only to the @samp{root} user (i.e., not in the store), to guard against leaking the secret key material of the Jami account it contains. @item @code{allowed-contacts} (type: maybe-account-fingerprint-list) The list of allowed contacts for the account, entered as their 40 characters long fingerprint. Messages or calls from accounts not in that list will be rejected. When left specified, the configuration of the account archive is used as-is with respect to contacts and public inbound calls/messaging allowance, which typically defaults to allow any contact to communicate with the account. @item @code{moderators} (type: maybe-account-fingerprint-list) The list of contacts that should have moderation privileges (to ban, mute, etc. other users) in rendezvous conferences, entered as their 40 characters long fingerprint. When left unspecified, the configuration of the account archive is used as-is with respect to moderation, which typically defaults to allow anyone to moderate. @item @code{rendezvous-point?} (type: maybe-boolean) Whether the account should operate in the rendezvous mode. In this mode, all the incoming audio/video calls are mixed into a conference. When left unspecified, the value from the account archive prevails. @item @code{peer-discovery?} (type: maybe-boolean) Whether peer discovery should be enabled. Peer discovery is used to discover other OpenDHT nodes on the local network, which can be useful to maintain communication between devices on such network even when the connection to the Internet has been lost. When left unspecified, the value from the account archive prevails. @item @code{bootstrap-hostnames} (type: maybe-list-of-strings) A list of hostnames or IPs pointing to OpenDHT nodes, that should be used to initially join the OpenDHT network. When left unspecified, the value from the account archive prevails. @item @code{name-server-uri} (type: maybe-string) The URI of the name server to use, that can be used to retrieve the account fingerprint for a registered username. @end table @end deftp @subsubheading Mumble server @cindex Mumble @cindex Murmur @cindex VoIP server This section describes how to set up and run a @uref{https://mumble.info, Mumble} server (formerly known as Murmur). @defvar mumble-server-service-type This is the service to run a Mumble server. It takes a @code{mumble-server-configuration} object as its value, defined below. @end defvar @deftp {Data Type} mumble-server-configuration The service type for the Mumble server. An example configuration can look like this: @lisp (service mumble-server-service-type (mumble-server-configuration (welcome-text "Welcome to this Mumble server running on Guix!") (cert-required? #t) ;disallow text password logins (ssl-cert "/etc/certs/mumble.example.com/fullchain.pem") (ssl-key "/etc/certs/mumble.example.com/privkey.pem"))) @end lisp After reconfiguring your system, you can manually set the mumble-server @code{SuperUser} password with the command that is printed during the activation phase. It is recommended to register a normal Mumble user account and grant it admin or moderator rights. You can use the @code{mumble} client to login as new normal user, register yourself, and log out. For the next step login with the name @code{SuperUser} use the @code{SuperUser} password that you set previously, and grant your newly registered mumble user administrator or moderator rights and create some channels. Available @code{mumble-server-configuration} fields are: @table @asis @item @code{package} (default: @code{mumble}) Package that contains @code{bin/mumble-server}. @item @code{user} (default: @code{"mumble-server"}) User who will run the Mumble-Server server. @item @code{group} (default: @code{"mumble-server"}) Group of the user who will run the mumble-server server. @item @code{port} (default: @code{64738}) Port on which the server will listen. @item @code{welcome-text} (default: @code{""}) Welcome text sent to clients when they connect. @item @code{server-password} (default: @code{""}) Password the clients have to enter in order to connect. @item @code{max-users} (default: @code{100}) Maximum of users that can be connected to the server at once. @item @code{max-user-bandwidth} (default: @code{#f}) Maximum voice traffic a user can send per second. @item @code{database-file} (default: @code{"/var/lib/mumble-server/db.sqlite"}) File name of the sqlite database. The service's user will become the owner of the directory. @item @code{log-file} (default: @code{"/var/log/mumble-server/mumble-server.log"}) File name of the log file. The service's user will become the owner of the directory. @item @code{autoban-attempts} (default: @code{10}) Maximum number of logins a user can make in @code{autoban-timeframe} without getting auto banned for @code{autoban-time}. @item @code{autoban-timeframe} (default: @code{120}) Timeframe for autoban in seconds. @item @code{autoban-time} (default: @code{300}) Amount of time in seconds for which a client gets banned when violating the autoban limits. @item @code{opus-threshold} (default: @code{100}) Percentage of clients that need to support opus before switching over to opus audio codec. @item @code{channel-nesting-limit} (default: @code{10}) How deep channels can be nested at maximum. @item @code{channelname-regex} (default: @code{#f}) A string in form of a Qt regular expression that channel names must conform to. @item @code{username-regex} (default: @code{#f}) A string in form of a Qt regular expression that user names must conform to. @item @code{text-message-length} (default: @code{5000}) Maximum size in bytes that a user can send in one text chat message. @item @code{image-message-length} (default: @code{(* 128 1024)}) Maximum size in bytes that a user can send in one image message. @item @code{cert-required?} (default: @code{#f}) If it is set to @code{#t} clients that use weak password authentication will not be accepted. Users must have completed the certificate wizard to join. @item @code{remember-channel?} (default: @code{#f}) Should mumble-server remember the last channel each user was in when they disconnected and put them into the remembered channel when they rejoin. @item @code{allow-html?} (default: @code{#f}) Should html be allowed in text messages, user comments, and channel descriptions. @item @code{allow-ping?} (default: @code{#f}) Setting to true exposes the current user count, the maximum user count, and the server's maximum bandwidth per client to unauthenticated users. In the Mumble client, this information is shown in the Connect dialog. Disabling this setting will prevent public listing of the server. @item @code{bonjour?} (default: @code{#f}) Should the server advertise itself in the local network through the bonjour protocol. @item @code{send-version?} (default: @code{#f}) Should the mumble-server server version be exposed in ping requests. @item @code{log-days} (default: @code{31}) Mumble also stores logs in the database, which are accessible via RPC. The default is 31 days of months, but you can set this setting to 0 to keep logs forever, or -1 to disable logging to the database. @item @code{obfuscate-ips?} (default: @code{#t}) Should logged ips be obfuscated to protect the privacy of users. @item @code{ssl-cert} (default: @code{#f}) File name of the SSL/TLS certificate used for encrypted connections. @lisp (ssl-cert "/etc/certs/example.com/fullchain.pem") @end lisp @item @code{ssl-key} (default: @code{#f}) Filepath to the ssl private key used for encrypted connections. @lisp (ssl-key "/etc/certs/example.com/privkey.pem") @end lisp @item @code{ssl-dh-params} (default: @code{#f}) File name of a PEM-encoded file with Diffie-Hellman parameters for the SSL/TLS encryption. Alternatively you set it to @code{"@@ffdhe2048"}, @code{"@@ffdhe3072"}, @code{"@@ffdhe4096"}, @code{"@@ffdhe6144"} or @code{"@@ffdhe8192"} to use bundled parameters from RFC 7919. @item @code{ssl-ciphers} (default: @code{#f}) The @code{ssl-ciphers} option chooses the cipher suites to make available for use in SSL/TLS. This option is specified using @uref{https://www.openssl.org/docs/apps/ciphers.html#CIPHER-LIST-FORMAT, OpenSSL cipher list notation}. It is recommended that you try your cipher string using 'openssl ciphers <string>' before setting it here, to get a feel for which cipher suites you will get. After setting this option, it is recommend that you inspect your Mumble server log to ensure that Mumble is using the cipher suites that you expected it to. @quotation Note Changing this option may impact the backwards compatibility of your Mumble-Server server, and can remove the ability for older Mumble clients to be able to connect to it. @end quotation @item @code{public-registration} (default: @code{#f}) Must be a @code{<mumble-server-public-registration-configuration>} record or @code{#f}. You can optionally register your server in the public server list that the @code{mumble} client shows on startup. You cannot register your server if you have set a @code{server-password}, or set @code{allow-ping} to @code{#f}. It might take a few hours until it shows up in the public list. @item @code{file} (default: @code{#f}) Optional alternative override for this configuration. @end table @end deftp @deftp {Data Type} mumble-server-public-registration-configuration Configuration for public registration of a mumble-server service. @table @asis @item @code{name} This is a display name for your server. Not to be confused with the hostname. @item @code{password} A password to identify your registration. Subsequent updates will need the same password. Don't lose your password. @item @code{url} This should be a @code{http://} or @code{https://} link to your web site. @item @code{hostname} (default: @code{#f}) By default your server will be listed by its IP address. If it is set your server will be linked by this host name instead. @end table @end deftp @quotation Deprecation notice Due to historical reasons, all of the above @code{mumble-server-} procedures are also exported with the @code{murmur-} prefix. It is recommended that you switch to using @code{mumble-server-} going forward. @end quotation @node File-Sharing Services @subsection File-Sharing Services The @code{(gnu services file-sharing)} module provides services that assist with transferring files over peer-to-peer file-sharing networks. @subsubheading Transmission Daemon Service @uref{https://transmissionbt.com/, Transmission} is a flexible BitTorrent client that offers a variety of graphical and command-line interfaces. A @code{transmission-daemon-service-type} service provides Transmission's headless variant, @command{transmission-daemon}, as a system service, allowing users to share files via BitTorrent even when they are not logged in. @defvar transmission-daemon-service-type The service type for the Transmission Daemon BitTorrent client. Its value must be a @code{transmission-daemon-configuration} object as in this example: @lisp (service transmission-daemon-service-type (transmission-daemon-configuration ;; Restrict access to the RPC ("control") interface (rpc-authentication-required? #t) (rpc-username "transmission") (rpc-password (transmission-password-hash "transmission" ; desired password "uKd1uMs9")) ; arbitrary salt value ;; Accept requests from this and other hosts on the ;; local network (rpc-whitelist-enabled? #t) (rpc-whitelist '("::1" "127.0.0.1" "192.168.0.*")) ;; Limit bandwidth use during work hours (alt-speed-down (* 1024 2)) ; 2 MB/s (alt-speed-up 512) ; 512 kB/s (alt-speed-time-enabled? #t) (alt-speed-time-day 'weekdays) (alt-speed-time-begin (+ (* 60 8) 30)) ; 8:30 am (alt-speed-time-end (+ (* 60 (+ 12 5)) 30)))) ; 5:30 pm @end lisp @end defvar Once the service is started, users can interact with the daemon through its Web interface (at @code{http://localhost:9091/}) or by using the @command{transmission-remote} command-line tool, available in the @code{transmission} package. (Emacs users may want to also consider the @code{emacs-transmission} package.) Both communicate with the daemon through its remote procedure call (RPC) interface, which by default is available to all users on the system; you may wish to change this by assigning values to the @code{rpc-authentication-required?}, @code{rpc-username} and @code{rpc-password} settings, as shown in the example above and documented further below. The value for @code{rpc-password} must be a password hash of the type generated and used by Transmission clients. This can be copied verbatim from an existing @file{settings.json} file, if another Transmission client is already being used. Otherwise, the @code{transmission-password-hash} and @code{transmission-random-salt} procedures provided by this module can be used to obtain a suitable hash value. @deffn {Procedure} transmission-password-hash password salt Returns a string containing the result of hashing @var{password} together with @var{salt}, in the format recognized by Transmission clients for their @code{rpc-password} configuration setting. @var{salt} must be an eight-character string. The @code{transmission-random-salt} procedure can be used to generate a suitable salt value at random. @end deffn @deffn {Procedure} transmission-random-salt Returns a string containing a random, eight-character salt value of the type generated and used by Transmission clients, suitable for passing to the @code{transmission-password-hash} procedure. @end deffn These procedures are accessible from within a Guile REPL started with the @command{guix repl} command (@pxref{Invoking guix repl}). This is useful for obtaining a random salt value to provide as the second parameter to `transmission-password-hash`, as in this example session: @example $ guix repl scheme@@(guix-user)> ,use (gnu services file-sharing) scheme@@(guix-user)> (transmission-random-salt) $1 = "uKd1uMs9" @end example Alternatively, a complete password hash can generated in a single step: @example scheme@@(guix-user)> (transmission-password-hash "transmission" (transmission-random-salt)) $2 = "@{c8bbc6d1740cd8dc819a6e25563b67812c1c19c9VtFPfdsX" @end example The resulting string can be used as-is for the value of @code{rpc-password}, allowing the password to be kept hidden even in the operating-system configuration. Torrent files downloaded by the daemon are directly accessible only to users in the ``transmission'' user group, who receive read-only access to the directory specified by the @code{download-dir} configuration setting (and also the directory specified by @code{incomplete-dir}, if @code{incomplete-dir-enabled?} is @code{#t}). Downloaded files can be moved to another directory or deleted altogether using @command{transmission-remote} with its @code{--move} and @code{--remove-and-delete} options. If the @code{watch-dir-enabled?} setting is set to @code{#t}, users in the ``transmission'' group are able also to place @file{.torrent} files in the directory specified by @code{watch-dir} to have the corresponding torrents added by the daemon. (The @code{trash-original-torrent-files?} setting controls whether the daemon deletes these files after processing them.) Some of the daemon's configuration settings can be changed temporarily by @command{transmission-remote} and similar tools. To undo these changes, use the service's @code{reload} action to have the daemon reload its settings from disk: @example # herd reload transmission-daemon @end example The full set of available configuration settings is defined by the @code{transmission-daemon-configuration} data type. @deftp {Data Type} transmission-daemon-configuration The data type representing configuration settings for Transmission Daemon. These correspond directly to the settings recognized by Transmission clients in their @file{settings.json} file. @end deftp @c The following documentation was initially generated by @c (generate-transmission-daemon-documentation) in (gnu services @c file-sharing). Manually maintained documentation is better, so we @c shouldn't hesitate to edit below as needed. However if the change @c you want to make to this documentation can be done in an automated @c way, it's probably easier to change (generate-documentation) than to @c make it below and have to deal with the churn as Transmission Daemon @c updates. @c %start of fragment Available @code{transmission-daemon-configuration} fields are: @deftypevr {@code{transmission-daemon-configuration} parameter} package transmission The Transmission package to use. @end deftypevr @deftypevr {@code{transmission-daemon-configuration} parameter} non-negative-integer stop-wait-period The period, in seconds, to wait when stopping the service for @command{transmission-daemon} to exit before killing its process. This allows the daemon time to complete its housekeeping and send a final update to trackers as it shuts down. On slow hosts, or hosts with a slow network connection, this value may need to be increased. Defaults to @samp{10}. @end deftypevr @deftypevr {@code{transmission-daemon-configuration} parameter} string download-dir The directory to which torrent files are downloaded. Defaults to @samp{"/var/lib/transmission-daemon/downloads"}. @end deftypevr @deftypevr {@code{transmission-daemon-configuration} parameter} boolean incomplete-dir-enabled? If @code{#t}, files will be held in @code{incomplete-dir} while their torrent is being downloaded, then moved to @code{download-dir} once the torrent is complete. Otherwise, files for all torrents (including those still being downloaded) will be placed in @code{download-dir}. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{transmission-daemon-configuration} parameter} maybe-string incomplete-dir The directory in which files from incompletely downloaded torrents will be held when @code{incomplete-dir-enabled?} is @code{#t}. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{transmission-daemon-configuration} parameter} umask umask The file mode creation mask used for downloaded files. (See the @command{umask} man page for more information.) Defaults to @samp{18}. @end deftypevr @deftypevr {@code{transmission-daemon-configuration} parameter} boolean rename-partial-files? When @code{#t}, ``.part'' is appended to the name of partially downloaded files. Defaults to @samp{#t}. @end deftypevr @deftypevr {@code{transmission-daemon-configuration} parameter} preallocation-mode preallocation The mode by which space should be preallocated for downloaded files, one of @code{none}, @code{fast} (or @code{sparse}) and @code{full}. Specifying @code{full} will minimize disk fragmentation at a cost to file-creation speed. Defaults to @samp{fast}. @end deftypevr @deftypevr {@code{transmission-daemon-configuration} parameter} boolean watch-dir-enabled? If @code{#t}, the directory specified by @code{watch-dir} will be watched for new @file{.torrent} files and the torrents they describe added automatically (and the original files removed, if @code{trash-original-torrent-files?} is @code{#t}). Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{transmission-daemon-configuration} parameter} maybe-string watch-dir The directory to be watched for @file{.torrent} files indicating new torrents to be added, when @code{watch-dir-enabled} is @code{#t}. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{transmission-daemon-configuration} parameter} boolean trash-original-torrent-files? When @code{#t}, @file{.torrent} files will be deleted from the watch directory once their torrent has been added (see @code{watch-directory-enabled?}). Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{transmission-daemon-configuration} parameter} boolean speed-limit-down-enabled? When @code{#t}, the daemon's download speed will be limited to the rate specified by @code{speed-limit-down}. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{transmission-daemon-configuration} parameter} non-negative-integer speed-limit-down The default global-maximum download speed, in kilobytes per second. Defaults to @samp{100}. @end deftypevr @deftypevr {@code{transmission-daemon-configuration} parameter} boolean speed-limit-up-enabled? When @code{#t}, the daemon's upload speed will be limited to the rate specified by @code{speed-limit-up}. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{transmission-daemon-configuration} parameter} non-negative-integer speed-limit-up The default global-maximum upload speed, in kilobytes per second. Defaults to @samp{100}. @end deftypevr @deftypevr {@code{transmission-daemon-configuration} parameter} boolean alt-speed-enabled? When @code{#t}, the alternate speed limits @code{alt-speed-down} and @code{alt-speed-up} are used (in place of @code{speed-limit-down} and @code{speed-limit-up}, if they are enabled) to constrain the daemon's bandwidth usage. This can be scheduled to occur automatically at certain times during the week; see @code{alt-speed-time-enabled?}. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{transmission-daemon-configuration} parameter} non-negative-integer alt-speed-down The alternate global-maximum download speed, in kilobytes per second. Defaults to @samp{50}. @end deftypevr @deftypevr {@code{transmission-daemon-configuration} parameter} non-negative-integer alt-speed-up The alternate global-maximum upload speed, in kilobytes per second. Defaults to @samp{50}. @end deftypevr @deftypevr {@code{transmission-daemon-configuration} parameter} boolean alt-speed-time-enabled? When @code{#t}, the alternate speed limits @code{alt-speed-down} and @code{alt-speed-up} will be enabled automatically during the periods specified by @code{alt-speed-time-day}, @code{alt-speed-time-begin} and @code{alt-time-speed-end}. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{transmission-daemon-configuration} parameter} day-list alt-speed-time-day The days of the week on which the alternate-speed schedule should be used, specified either as a list of days (@code{sunday}, @code{monday}, and so on) or using one of the symbols @code{weekdays}, @code{weekends} or @code{all}. Defaults to @samp{all}. @end deftypevr @deftypevr {@code{transmission-daemon-configuration} parameter} non-negative-integer alt-speed-time-begin The time of day at which to enable the alternate speed limits, expressed as a number of minutes since midnight. Defaults to @samp{540}. @end deftypevr @deftypevr {@code{transmission-daemon-configuration} parameter} non-negative-integer alt-speed-time-end The time of day at which to disable the alternate speed limits, expressed as a number of minutes since midnight. Defaults to @samp{1020}. @end deftypevr @deftypevr {@code{transmission-daemon-configuration} parameter} string bind-address-ipv4 The IP address at which to listen for peer connections, or ``0.0.0.0'' to listen at all available IP addresses. Defaults to @samp{"0.0.0.0"}. @end deftypevr @deftypevr {@code{transmission-daemon-configuration} parameter} string bind-address-ipv6 The IPv6 address at which to listen for peer connections, or ``::'' to listen at all available IPv6 addresses. Defaults to @samp{"::"}. @end deftypevr @deftypevr {@code{transmission-daemon-configuration} parameter} boolean peer-port-random-on-start? If @code{#t}, when the daemon starts it will select a port at random on which to listen for peer connections, from the range specified (inclusively) by @code{peer-port-random-low} and @code{peer-port-random-high}. Otherwise, it listens on the port specified by @code{peer-port}. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{transmission-daemon-configuration} parameter} port-number peer-port-random-low The lowest selectable port number when @code{peer-port-random-on-start?} is @code{#t}. Defaults to @samp{49152}. @end deftypevr @deftypevr {@code{transmission-daemon-configuration} parameter} port-number peer-port-random-high The highest selectable port number when @code{peer-port-random-on-start} is @code{#t}. Defaults to @samp{65535}. @end deftypevr @deftypevr {@code{transmission-daemon-configuration} parameter} port-number peer-port The port on which to listen for peer connections when @code{peer-port-random-on-start?} is @code{#f}. Defaults to @samp{51413}. @end deftypevr @deftypevr {@code{transmission-daemon-configuration} parameter} boolean port-forwarding-enabled? If @code{#t}, the daemon will attempt to configure port-forwarding on an upstream gateway automatically using @acronym{UPnP} and @acronym{NAT-PMP}. Defaults to @samp{#t}. @end deftypevr @deftypevr {@code{transmission-daemon-configuration} parameter} encryption-mode encryption The encryption preference for peer connections, one of @code{prefer-unencrypted-connections}, @code{prefer-encrypted-connections} or @code{require-encrypted-connections}. Defaults to @samp{prefer-encrypted-connections}. @end deftypevr @deftypevr {@code{transmission-daemon-configuration} parameter} maybe-string peer-congestion-algorithm The TCP congestion-control algorithm to use for peer connections, specified using a string recognized by the operating system in calls to @code{setsockopt}. When left unspecified, the operating-system default is used. Note that on GNU/Linux systems, the kernel must be configured to allow processes to use a congestion-control algorithm not in the default set; otherwise, it will deny these requests with ``Operation not permitted''. To see which algorithms are available on your system and which are currently permitted for use, look at the contents of the files @file{tcp_available_congestion_control} and @file{tcp_allowed_congestion_control} in the @file{/proc/sys/net/ipv4} directory. As an example, to have Transmission Daemon use @uref{http://www-ece.rice.edu/networks/TCP-LP/,the TCP Low Priority congestion-control algorithm}, you'll need to modify your kernel configuration to build in support for the algorithm, then update your operating-system configuration to allow its use by adding a @code{sysctl-service-type} service (or updating the existing one's configuration) with lines like the following: @lisp (service sysctl-service-type (sysctl-configuration (settings ("net.ipv4.tcp_allowed_congestion_control" . "reno cubic lp")))) @end lisp The Transmission Daemon configuration can then be updated with @lisp (peer-congestion-algorithm "lp") @end lisp and the system reconfigured to have the changes take effect. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{transmission-daemon-configuration} parameter} tcp-type-of-service peer-socket-tos The type of service to request in outgoing @acronym{TCP} packets, one of @code{default}, @code{low-cost}, @code{throughput}, @code{low-delay} and @code{reliability}. Defaults to @samp{default}. @end deftypevr @deftypevr {@code{transmission-daemon-configuration} parameter} non-negative-integer peer-limit-global The global limit on the number of connected peers. Defaults to @samp{200}. @end deftypevr @deftypevr {@code{transmission-daemon-configuration} parameter} non-negative-integer peer-limit-per-torrent The per-torrent limit on the number of connected peers. Defaults to @samp{50}. @end deftypevr @deftypevr {@code{transmission-daemon-configuration} parameter} non-negative-integer upload-slots-per-torrent The maximum number of peers to which the daemon will upload data simultaneously for each torrent. Defaults to @samp{14}. @end deftypevr @deftypevr {@code{transmission-daemon-configuration} parameter} non-negative-integer peer-id-ttl-hours The maximum lifespan, in hours, of the peer ID associated with each public torrent before it is regenerated. Defaults to @samp{6}. @end deftypevr @deftypevr {@code{transmission-daemon-configuration} parameter} boolean blocklist-enabled? When @code{#t}, the daemon will ignore peers mentioned in the blocklist it has most recently downloaded from @code{blocklist-url}. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{transmission-daemon-configuration} parameter} maybe-string blocklist-url The URL of a peer blocklist (in @acronym{P2P}-plaintext or eMule @file{.dat} format) to be periodically downloaded and applied when @code{blocklist-enabled?} is @code{#t}. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{transmission-daemon-configuration} parameter} boolean download-queue-enabled? If @code{#t}, the daemon will be limited to downloading at most @code{download-queue-size} non-stalled torrents simultaneously. Defaults to @samp{#t}. @end deftypevr @deftypevr {@code{transmission-daemon-configuration} parameter} non-negative-integer download-queue-size The size of the daemon's download queue, which limits the number of non-stalled torrents it will download at any one time when @code{download-queue-enabled?} is @code{#t}. Defaults to @samp{5}. @end deftypevr @deftypevr {@code{transmission-daemon-configuration} parameter} boolean seed-queue-enabled? If @code{#t}, the daemon will be limited to seeding at most @code{seed-queue-size} non-stalled torrents simultaneously. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{transmission-daemon-configuration} parameter} non-negative-integer seed-queue-size The size of the daemon's seed queue, which limits the number of non-stalled torrents it will seed at any one time when @code{seed-queue-enabled?} is @code{#t}. Defaults to @samp{10}. @end deftypevr @deftypevr {@code{transmission-daemon-configuration} parameter} boolean queue-stalled-enabled? When @code{#t}, the daemon will consider torrents for which it has not shared data in the past @code{queue-stalled-minutes} minutes to be stalled and not count them against its @code{download-queue-size} and @code{seed-queue-size} limits. Defaults to @samp{#t}. @end deftypevr @deftypevr {@code{transmission-daemon-configuration} parameter} non-negative-integer queue-stalled-minutes The maximum period, in minutes, a torrent may be idle before it is considered to be stalled, when @code{queue-stalled-enabled?} is @code{#t}. Defaults to @samp{30}. @end deftypevr @deftypevr {@code{transmission-daemon-configuration} parameter} boolean ratio-limit-enabled? When @code{#t}, a torrent being seeded will automatically be paused once it reaches the ratio specified by @code{ratio-limit}. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{transmission-daemon-configuration} parameter} non-negative-rational ratio-limit The ratio at which a torrent being seeded will be paused, when @code{ratio-limit-enabled?} is @code{#t}. Defaults to @samp{2.0}. @end deftypevr @deftypevr {@code{transmission-daemon-configuration} parameter} boolean idle-seeding-limit-enabled? When @code{#t}, a torrent being seeded will automatically be paused once it has been idle for @code{idle-seeding-limit} minutes. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{transmission-daemon-configuration} parameter} non-negative-integer idle-seeding-limit The maximum period, in minutes, a torrent being seeded may be idle before it is paused, when @code{idle-seeding-limit-enabled?} is @code{#t}. Defaults to @samp{30}. @end deftypevr @deftypevr {@code{transmission-daemon-configuration} parameter} boolean dht-enabled? Enable @uref{http://bittorrent.org/beps/bep_0005.html,the distributed hash table (@acronym{DHT}) protocol}, which supports the use of trackerless torrents. Defaults to @samp{#t}. @end deftypevr @deftypevr {@code{transmission-daemon-configuration} parameter} boolean lpd-enabled? Enable @uref{https://en.wikipedia.org/wiki/Local_Peer_Discovery,local peer discovery} (@acronym{LPD}), which allows the discovery of peers on the local network and may reduce the amount of data sent over the public Internet. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{transmission-daemon-configuration} parameter} boolean pex-enabled? Enable @uref{https://en.wikipedia.org/wiki/Peer_exchange,peer exchange} (@acronym{PEX}), which reduces the daemon's reliance on external trackers and may improve its performance. Defaults to @samp{#t}. @end deftypevr @deftypevr {@code{transmission-daemon-configuration} parameter} boolean utp-enabled? Enable @uref{http://bittorrent.org/beps/bep_0029.html,the micro transport protocol} (@acronym{uTP}), which aims to reduce the impact of BitTorrent traffic on other users of the local network while maintaining full utilization of the available bandwidth. Defaults to @samp{#t}. @end deftypevr @deftypevr {@code{transmission-daemon-configuration} parameter} boolean rpc-enabled? If @code{#t}, enable the remote procedure call (@acronym{RPC}) interface, which allows remote control of the daemon via its Web interface, the @command{transmission-remote} command-line client, and similar tools. Defaults to @samp{#t}. @end deftypevr @deftypevr {@code{transmission-daemon-configuration} parameter} string rpc-bind-address The IP address at which to listen for @acronym{RPC} connections, or ``0.0.0.0'' to listen at all available IP addresses. Defaults to @samp{"0.0.0.0"}. @end deftypevr @deftypevr {@code{transmission-daemon-configuration} parameter} port-number rpc-port The port on which to listen for @acronym{RPC} connections. Defaults to @samp{9091}. @end deftypevr @deftypevr {@code{transmission-daemon-configuration} parameter} string rpc-url The path prefix to use in the @acronym{RPC}-endpoint @acronym{URL}. Defaults to @samp{"/transmission/"}. @end deftypevr @deftypevr {@code{transmission-daemon-configuration} parameter} boolean rpc-authentication-required? When @code{#t}, clients must authenticate (see @code{rpc-username} and @code{rpc-password}) when using the @acronym{RPC} interface. Note this has the side effect of disabling host-name whitelisting (see @code{rpc-host-whitelist-enabled?}. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{transmission-daemon-configuration} parameter} maybe-string rpc-username The username required by clients to access the @acronym{RPC} interface when @code{rpc-authentication-required?} is @code{#t}. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{transmission-daemon-configuration} parameter} maybe-transmission-password-hash rpc-password The password required by clients to access the @acronym{RPC} interface when @code{rpc-authentication-required?} is @code{#t}. This must be specified using a password hash in the format recognized by Transmission clients, either copied from an existing @file{settings.json} file or generated using the @code{transmission-password-hash} procedure. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{transmission-daemon-configuration} parameter} boolean rpc-whitelist-enabled? When @code{#t}, @acronym{RPC} requests will be accepted only when they originate from an address specified in @code{rpc-whitelist}. Defaults to @samp{#t}. @end deftypevr @deftypevr {@code{transmission-daemon-configuration} parameter} string-list rpc-whitelist The list of IP and IPv6 addresses from which @acronym{RPC} requests will be accepted when @code{rpc-whitelist-enabled?} is @code{#t}. Wildcards may be specified using @samp{*}. Defaults to @samp{'("127.0.0.1" "::1")}. @end deftypevr @deftypevr {@code{transmission-daemon-configuration} parameter} boolean rpc-host-whitelist-enabled? When @code{#t}, @acronym{RPC} requests will be accepted only when they are addressed to a host named in @code{rpc-host-whitelist}. Note that requests to ``localhost'' or ``localhost.'', or to a numeric address, are always accepted regardless of these settings. Note also this functionality is disabled when @code{rpc-authentication-required?} is @code{#t}. Defaults to @samp{#t}. @end deftypevr @deftypevr {@code{transmission-daemon-configuration} parameter} string-list rpc-host-whitelist The list of host names recognized by the @acronym{RPC} server when @code{rpc-host-whitelist-enabled?} is @code{#t}. Defaults to @samp{'()}. @end deftypevr @deftypevr {@code{transmission-daemon-configuration} parameter} message-level message-level The minimum severity level of messages to be logged (to @file{/var/log/transmission.log}) by the daemon, one of @code{none} (no logging), @code{error}, @code{info} and @code{debug}. Defaults to @samp{info}. @end deftypevr @deftypevr {@code{transmission-daemon-configuration} parameter} boolean start-added-torrents? When @code{#t}, torrents are started as soon as they are added; otherwise, they are added in ``paused'' state. Defaults to @samp{#t}. @end deftypevr @deftypevr {@code{transmission-daemon-configuration} parameter} boolean script-torrent-done-enabled? When @code{#t}, the script specified by @code{script-torrent-done-filename} will be invoked each time a torrent completes. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{transmission-daemon-configuration} parameter} maybe-file-object script-torrent-done-filename A file name or file-like object specifying a script to run each time a torrent completes, when @code{script-torrent-done-enabled?} is @code{#t}. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{transmission-daemon-configuration} parameter} boolean scrape-paused-torrents-enabled? When @code{#t}, the daemon will scrape trackers for a torrent even when the torrent is paused. Defaults to @samp{#t}. @end deftypevr @deftypevr {@code{transmission-daemon-configuration} parameter} non-negative-integer cache-size-mb The amount of memory, in megabytes, to allocate for the daemon's in-memory cache. A larger value may increase performance by reducing the frequency of disk I/O. Defaults to @samp{4}. @end deftypevr @deftypevr {@code{transmission-daemon-configuration} parameter} boolean prefetch-enabled? When @code{#t}, the daemon will try to improve I/O performance by hinting to the operating system which data is likely to be read next from disk to satisfy requests from peers. Defaults to @samp{#t}. @end deftypevr @c %end of fragment @node Monitoring Services @subsection Monitoring Services @subsubheading Tailon Service @uref{https://tailon.readthedocs.io/, Tailon} is a web application for viewing and searching log files. The following example will configure the service with default values. By default, Tailon can be accessed on port 8080 (@code{http://localhost:8080}). @lisp (service tailon-service-type) @end lisp The following example customises more of the Tailon configuration, adding @command{sed} to the list of allowed commands. @lisp (service tailon-service-type (tailon-configuration (config-file (tailon-configuration-file (allowed-commands '("tail" "grep" "awk" "sed")))))) @end lisp @deftp {Data Type} tailon-configuration Data type representing the configuration of Tailon. This type has the following parameters: @table @asis @item @code{config-file} (default: @code{(tailon-configuration-file)}) The configuration file to use for Tailon. This can be set to a @dfn{tailon-configuration-file} record value, or any gexp (@pxref{G-Expressions}). For example, to instead use a local file, the @code{local-file} function can be used: @lisp (service tailon-service-type (tailon-configuration (config-file (local-file "./my-tailon.conf")))) @end lisp @item @code{package} (default: @code{tailon}) The tailon package to use. @end table @end deftp @deftp {Data Type} tailon-configuration-file Data type representing the configuration options for Tailon. This type has the following parameters: @table @asis @item @code{files} (default: @code{(list "/var/log")}) List of files to display. The list can include strings for a single file or directory, or a list, where the first item is the name of a subsection, and the remaining items are the files or directories in that subsection. @item @code{bind} (default: @code{"localhost:8080"}) Address and port to which Tailon should bind on. @item @code{relative-root} (default: @code{#f}) URL path to use for Tailon, set to @code{#f} to not use a path. @item @code{allow-transfers?} (default: @code{#t}) Allow downloading the log files in the web interface. @item @code{follow-names?} (default: @code{#t}) Allow tailing of not-yet existent files. @item @code{tail-lines} (default: @code{200}) Number of lines to read initially from each file. @item @code{allowed-commands} (default: @code{(list "tail" "grep" "awk")}) Commands to allow running. By default, @code{sed} is disabled. @item @code{debug?} (default: @code{#f}) Set @code{debug?} to @code{#t} to show debug messages. @item @code{wrap-lines} (default: @code{#t}) Initial line wrapping state in the web interface. Set to @code{#t} to initially wrap lines (the default), or to @code{#f} to initially not wrap lines. @item @code{http-auth} (default: @code{#f}) HTTP authentication type to use. Set to @code{#f} to disable authentication (the default). Supported values are @code{"digest"} or @code{"basic"}. @item @code{users} (default: @code{#f}) If HTTP authentication is enabled (see @code{http-auth}), access will be restricted to the credentials provided here. To configure users, use a list of pairs, where the first element of the pair is the username, and the 2nd element of the pair is the password. @lisp (tailon-configuration-file (http-auth "basic") (users '(("user1" . "password1") ("user2" . "password2")))) @end lisp @end table @end deftp @subsubheading Darkstat Service @cindex darkstat Darkstat is a packet sniffer that captures network traffic, calculates statistics about usage, and serves reports over HTTP. @defvar darkstat-service-type This is the service type for the @uref{https://unix4lyfe.org/darkstat/, darkstat} service, its value must be a @code{darkstat-configuration} record as in this example: @lisp (service darkstat-service-type (darkstat-configuration (interface "eno1"))) @end lisp @end defvar @deftp {Data Type} darkstat-configuration Data type representing the configuration of @command{darkstat}. @table @asis @item @code{package} (default: @code{darkstat}) The darkstat package to use. @item @code{interface} Capture traffic on the specified network interface. @item @code{port} (default: @code{"667"}) Bind the web interface to the specified port. @item @code{bind-address} (default: @code{"127.0.0.1"}) Bind the web interface to the specified address. @item @code{base} (default: @code{"/"}) Specify the path of the base URL@. This can be useful if @command{darkstat} is accessed via a reverse proxy. @end table @end deftp @anchor{prometheus-node-exporter} @subsubheading Prometheus Node Exporter Service @cindex prometheus-node-exporter The Prometheus ``node exporter'' makes hardware and operating system statistics provided by the Linux kernel available for the Prometheus monitoring system. This service should be deployed on all physical nodes and virtual machines, where monitoring these statistics is desirable. @defvar prometheus-node-exporter-service-type This is the service type for the @uref{https://github.com/prometheus/node_exporter/, prometheus-node-exporter} service, its value must be a @code{prometheus-node-exporter-configuration}. @lisp (service prometheus-node-exporter-service-type) @end lisp @end defvar @deftp {Data Type} prometheus-node-exporter-configuration Data type representing the configuration of @command{node_exporter}. @table @asis @item @code{package} (default: @code{go-github-com-prometheus-node-exporter}) The prometheus-node-exporter package to use. @item @code{web-listen-address} (default: @code{":9100"}) Bind the web interface to the specified address. @item @code{textfile-directory} (default: @code{"/var/lib/prometheus/node-exporter"}) This directory can be used to export metrics specific to this machine. Files containing metrics in the text format, with the filename ending in @code{.prom} should be placed in this directory. @item @code{extra-options} (default: @code{'()}) Extra options to pass to the Prometheus node exporter. @end table @end deftp @anchor{vnstat} @subsubheading vnStat Network Traffic Monitor @cindex vnstat vnStat is a network traffic monitor that uses interface statistics provided by the kernel rather than traffic sniffing. This makes it a light resource monitor, regardless of network traffic rate. @defvar vnstat-service-type This is the service type for the @uref{https://humdi.net/vnstat/,vnStat} daemon and accepts a @code{vnstat-configuration} value. The following example will configure the service with default values: @lisp (service vnstat-service-type) @end lisp @end defvar @c %start of fragment @deftp {Data Type} vnstat-configuration Available @code{vnstat-configuration} fields are: @table @asis @item @code{package} (default: @code{vnstat}) (type: file-like) The vnstat package. @item @code{database-directory} (default: @code{"/var/lib/vnstat"}) (type: string) Specifies the directory where the database is to be stored. A full path must be given and a leading '/' isn't required. @item @code{5-minute-hours} (default: @code{48}) (type: maybe-integer) Data retention duration for the 5 minute resolution entries. The configuration defines for how many past hours entries will be stored. Set to @code{-1} for unlimited entries or to @code{0} to disable the data collection of this resolution. @item @code{64bit-interface-counters} (default: @code{-2}) (type: maybe-integer) Select interface counter handling. Set to @code{1} for defining that all interfaces use 64-bit counters on the kernel side and @code{0} for defining 32-bit counter. Set to @code{-1} for using the old style logic used in earlier versions where counter values within 32-bits are assumed to be 32-bit and anything larger is assumed to be a 64-bit counter. This may produce false results if a 64-bit counter is reset within the 32-bits. Set to @code{-2} for using automatic detection based on available kernel datastructures. @item @code{always-add-new-interfaces?} (default: @code{#t}) (type: maybe-boolean) Enable or disable automatic creation of new database entries for interfaces not currently in the database even if the database file already exists when the daemon is started. New database entries will also get created for new interfaces seen while the daemon is running. Pseudo interfaces @samp{lo}, @samp{lo0} and @samp{sit0} are always excluded from getting added. @item @code{bandwidth-detection?} (default: @code{#t}) (type: maybe-boolean) Try to automatically detect @var{max-bandwidth} value for each monitored interface. Mostly only ethernet interfaces support this feature. @var{max-bandwidth} will be used as fallback value if detection fails. Any interface specific @var{max-BW} configuration will disable the detection for the specified interface. In Linux, the detection is disabled for tun interfaces due to the Linux kernel always reporting 10 Mbit regardless of the used real interface. @item @code{bandwidth-detection-interval} (default: @code{5}) (type: maybe-integer) How often in minutes interface specific detection of @var{max-bandwidth} is done for detecting possible changes when @var{bandwidth-detection} is enabled. Can be disabled by setting to @code{0}. Value range: @samp{0}..@samp{30} @item @code{boot-variation} (default: @code{15}) (type: maybe-integer) Time in seconds how much the boot time reported by system kernel can variate between updates. Value range: @samp{0}..@samp{300} @item @code{check-disk-space?} (default: @code{#t}) (type: maybe-boolean) Enable or disable the availability check of at least some free disk space before a database write. @item @code{create-directories?} (default: @code{#t}) (type: maybe-boolean) Enable or disable the creation of directories when a configured path doesn't exist. This includes @var{database-directory}. @item @code{daemon-group} (type: maybe-user-group) Specify the group to which the daemon process should switch during startup. Set to @code{%unset-value} to disable group switching. @item @code{daemon-user} (type: maybe-user-account) Specify the user to which the daemon process should switch during startup. Set to @code{%unset-value} to disable user switching. @item @code{daily-days} (default: @code{62}) (type: maybe-integer) Data retention duration for the one day resolution entries. The configuration defines for how many past days entries will be stored. Set to @code{-1} for unlimited entries or to @code{0} to disable the data collection of this resolution. @item @code{database-synchronous} (default: @code{-1}) (type: maybe-integer) Change the setting of the SQLite "synchronous" flag which controls how much care is taken to ensure disk writes have fully completed when writing data to the database before continuing other actions. Higher values take extra steps to ensure data safety at the cost of slower performance. A value of @code{0} will result in all handling being left to the filesystem itself. Set to @code{-1} to select the default value according to database mode controlled by @var{database-write-ahead-logging} setting. See SQLite documentation for more details regarding values from @code{1} to @code{3}. Value range: @samp{-1}..@samp{3} @item @code{database-write-ahead-logging?} (default: @code{#f}) (type: maybe-boolean) Enable or disable SQLite Write-Ahead Logging mode for the database. See SQLite documentation for more details and note that support for read-only operations isn't available in older SQLite versions. @item @code{hourly-days} (default: @code{4}) (type: maybe-integer) Data retention duration for the one hour resolution entries. The configuration defines for how many past days entries will be stored. Set to @code{-1} for unlimited entries or to @code{0} to disable the data collection of this resolution. @item @code{log-file} (type: maybe-string) Specify log file path and name to be used if @var{use-logging} is set to @code{1}. @item @code{max-bandwidth} (type: maybe-integer) Maximum bandwidth for all interfaces. If the interface specific traffic exceeds the given value then the data is assumed to be invalid and rejected. Set to 0 in order to disable the feature. Value range: @samp{0}..@samp{50000} @item @code{max-bw} (type: maybe-alist) Same as @var{max-bandwidth} but can be used for setting individual limits for selected interfaces. This is an association list of interfaces as strings to integer values. For example, @lisp (max-bw `(("eth0" . 15000) ("ppp0" . 10000))) @end lisp @var{bandwidth-detection} is disabled on an interface specific level for each @var{max-bw} configuration. Value range: @samp{0}..@samp{50000} @item @code{monthly-months} (default: @code{25}) (type: maybe-integer) Data retention duration for the one month resolution entries. The configuration defines for how many past months entries will be stored. Set to @code{-1} for unlimited entries or to @code{0} to disable the data collection of this resolution. @item @code{month-rotate} (default: @code{1}) (type: maybe-integer) Day of month that months are expected to change. Usually set to 1 but can be set to alternative values for example for tracking monthly billed traffic where the billing period doesn't start on the first day. For example, if set to 7, days of February up to and including the 6th will count for January. Changing this option will not cause existing data to be recalculated. Value range: @samp{1}..@samp{28} @item @code{month-rotate-affects-years?} (default: @code{#f}) (type: maybe-boolean) Enable or disable @var{month-rotate} also affecting yearly data. Applicable only when @var{month-rotate} has a value greater than one. @item @code{offline-save-interval} (default: @code{30}) (type: maybe-integer) How often in minutes cached interface data is saved to file when all monitored interfaces are offline. Value range: @var{save-interval}..@samp{60} @item @code{pid-file} (default: @code{"/var/run/vnstatd.pid"}) (type: maybe-string) Specify pid file path and name to be used. @item @code{poll-interval} (default: @code{5}) (type: maybe-integer) How often in seconds interfaces are checked for status changes. Value range: @samp{2}..@samp{60} @item @code{rescan-database-on-save?} (type: maybe-boolean) Automatically discover added interfaces from the database and start monitoring. The rescan is done every @var{save-interval} or @var{offline-save-interval} minutes depending on the current activity state. @item @code{save-interval} (default: @code{5}) (type: maybe-integer) How often in minutes cached interface data is saved to file. Value range: ( @var{update-interval} / 60 )..@samp{60} @item @code{save-on-status-change?} (default: @code{#t}) (type: maybe-boolean) Enable or disable the additional saving to file of cached interface data when the availability of an interface changes, i.e., when an interface goes offline or comes online. @item @code{time-sync-wait} (default: @code{5}) (type: maybe-integer) How many minutes to wait during daemon startup for system clock to sync if most recent database update appears to be in the future. This may be needed in systems without a real-time clock (RTC) which require some time after boot to query and set the correct time. @code{0} = wait disabled. Value range: @samp{0}..@samp{60} @item @code{top-day-entries} (default: @code{20}) (type: maybe-integer) Data retention duration for the top day entries. The configuration defines how many of the past top day entries will be stored. Set to @code{-1} for unlimited entries or to @code{0} to disable the data collection of this resolution. @item @code{trafficless-entries?} (default: @code{#t}) (type: maybe-boolean) Create database entries even when there is no traffic during the entry's time period. @item @code{update-file-owner?} (default: @code{#t}) (type: maybe-boolean) Enable or disable the update of file ownership during daemon process startup. During daemon startup, only database, log and pid files will be modified if the user or group change feature ( @var{daemon-user} or @var{daemon-group} ) is enabled and the files don't match the requested user or group. During manual database creation, this option will cause file ownership to be inherited from the database directory if the directory already exists. This option only has effect when the process is started as root or via sudo. @item @code{update-interval} (default: @code{20}) (type: maybe-integer) How often in seconds the interface data is updated. Value range: @var{poll-interval}..@samp{300} @item @code{use-logging} (default: @code{2}) (type: maybe-integer) Enable or disable logging. Accepted values are: @code{0} = disabled, @code{1} = logfile and @code{2} = syslog. @item @code{use-utc?} (type: maybe-boolean) Enable or disable using UTC as timezone in the database for all entries. When enabled, all entries added to the database will use UTC regardless of the configured system timezone. When disabled, the configured system timezone will be used. Changing this setting will not result in already existing data to be modified. @item @code{yearly-years} (default: @code{-1}) (type: maybe-integer) Data retention duration for the one year resolution entries. The configuration defines for how many past years entries will be stored. Set to @code{-1} for unlimited entries or to @code{0} to disable the data collection of this resolution. @end table @end deftp @c %end of fragment @subsubheading Zabbix server @cindex zabbix zabbix-server Zabbix is a high performance monitoring system that can collect data from a variety of sources and provide the results in a web-based interface. Alerting and reporting is built-in, as well as @dfn{templates} for common operating system metrics such as network utilization, CPU load, and disk space consumption. This service provides the central Zabbix monitoring service; you also need @ref{zabbix-front-end,@code{zabbix-front-end-service-type}} to configure Zabbix and display results, and optionally @ref{zabbix-agent, @code{zabbix-agent-service-type}} on machines that should be monitored (other data sources are supported, such as @ref{prometheus-node-exporter, Prometheus Node Exporter}). @defvar zabbix-server-service-type This is the service type for the Zabbix server service. Its value must be a @code{zabbix-server-configuration} record, shown below. @end defvar @c %start of fragment @deftp {Data Type} zabbix-server-configuration Available @code{zabbix-server-configuration} fields are: @table @asis @item @code{zabbix-server} (default: @code{zabbix-server}) (type: file-like) The zabbix-server package. @item @code{user} (default: @code{"zabbix"}) (type: string) User who will run the Zabbix server. @item @code{group} (default: @code{"zabbix"}) (type: string) Group who will run the Zabbix server. @item @code{db-host} (default: @code{"127.0.0.1"}) (type: string) Database host name. @item @code{db-name} (default: @code{"zabbix"}) (type: string) Database name. @item @code{db-user} (default: @code{"zabbix"}) (type: string) Database user. @item @code{db-password} (default: @code{""}) (type: string) Database password. Please, use @code{include-files} with @code{DBPassword=SECRET} inside a specified file instead. @item @code{db-port} (default: @code{5432}) (type: number) Database port. @item @code{log-type} (default: @code{""}) (type: string) Specifies where log messages are written to: @itemize @bullet @item @code{system} - syslog. @item @code{file} - file specified with @code{log-file} parameter. @item @code{console} - standard output. @end itemize @item @code{log-file} (default: @code{"/var/log/zabbix/server.log"}) (type: string) Log file name for @code{log-type} @code{file} parameter. @item @code{pid-file} (default: @code{"/var/run/zabbix/zabbix_server.pid"}) (type: string) Name of PID file. @item @code{ssl-ca-location} (default: @code{"/etc/ssl/certs/ca-certificates.crt"}) (type: string) The location of certificate authority (CA) files for SSL server certificate verification. @item @code{ssl-cert-location} (default: @code{"/etc/ssl/certs"}) (type: string) Location of SSL client certificates. @item @code{extra-options} (default: @code{""}) (type: extra-options) Extra options will be appended to Zabbix server configuration file. @item @code{include-files} (default: @code{'()}) (type: include-files) You may include individual files or all files in a directory in the configuration file. @end table @end deftp @c %end of fragment @anchor{zabbix-agent} @subsubheading Zabbix agent @cindex zabbix zabbix-agent The Zabbix agent gathers information about the running system for the Zabbix monitoring server. It has a variety of built-in checks, and can be extended with custom @uref{https://www.zabbix.com/documentation/current/en/manual/config/items/userparameters, @dfn{user parameters}}. @defvar zabbix-agent-service-type This is the service type for the Zabbix agent service. Its value must be a @code{zabbix-agent-configuration} record, shown below. @end defvar @c %start of fragment @deftp {Data Type} zabbix-agent-configuration Available @code{zabbix-agent-configuration} fields are: @table @asis @item @code{zabbix-agent} (default: @code{zabbix-agentd}) (type: file-like) The zabbix-agent package. @item @code{user} (default: @code{"zabbix"}) (type: string) User who will run the Zabbix agent. @item @code{group} (default: @code{"zabbix"}) (type: string) Group who will run the Zabbix agent. @item @code{hostname} (default: @code{""}) (type: string) Unique, case sensitive hostname which is required for active checks and must match hostname as configured on the server. @item @code{log-type} (default: @code{""}) (type: string) Specifies where log messages are written to: @itemize @bullet @item @code{system} - syslog. @item @code{file} - file specified with @code{log-file} parameter. @item @code{console} - standard output. @end itemize @item @code{log-file} (default: @code{"/var/log/zabbix/agent.log"}) (type: string) Log file name for @code{log-type} @code{file} parameter. @item @code{pid-file} (default: @code{"/var/run/zabbix/zabbix_agent.pid"}) (type: string) Name of PID file. @item @code{server} (default: @code{'("127.0.0.1")}) (type: list) List of IP addresses, optionally in CIDR notation, or hostnames of Zabbix servers and Zabbix proxies. Incoming connections will be accepted only from the hosts listed here. @item @code{server-active} (default: @code{'("127.0.0.1")}) (type: list) List of IP:port (or hostname:port) pairs of Zabbix servers and Zabbix proxies for active checks. If port is not specified, default port is used. If this parameter is not specified, active checks are disabled. @item @code{extra-options} (default: @code{""}) (type: extra-options) Extra options will be appended to Zabbix server configuration file. @item @code{include-files} (default: @code{'()}) (type: include-files) You may include individual files or all files in a directory in the configuration file. @end table @end deftp @c %end of fragment @anchor{zabbix-front-end} @subsubheading Zabbix front-end @cindex zabbix zabbix-front-end The Zabbix front-end provides a web interface to Zabbix. It does not need to run on the same machine as the Zabbix server. This service works by extending the @ref{PHP-FPM} and @ref{NGINX} services with the configuration necessary for loading the Zabbix user interface. @defvar zabbix-front-end-service-type This is the service type for the Zabbix web frontend. Its value must be a @code{zabbix-front-end-configuration} record, shown below. @end defvar @c %start of fragment @deftp {Data Type} zabbix-front-end-configuration Available @code{zabbix-front-end-configuration} fields are: @table @asis @item @code{zabbix-server} (default: @code{zabbix-server}) (type: file-like) The Zabbix server package to use. @item @code{nginx} (default: @code{'()}) (type: list) List of @ref{nginx-server-configuration,@code{nginx-server-configuration}} blocks for the Zabbix front-end. When empty, a default that listens on port 80 is used. @item @code{db-host} (default: @code{"localhost"}) (type: string) Database host name. @item @code{db-port} (default: @code{5432}) (type: number) Database port. @item @code{db-name} (default: @code{"zabbix"}) (type: string) Database name. @item @code{db-user} (default: @code{"zabbix"}) (type: string) Database user. @item @code{db-password} (default: @code{""}) (type: string) Database password. Please, use @code{db-secret-file} instead. @item @code{db-secret-file} (default: @code{""}) (type: string) Secret file which will be appended to @file{zabbix.conf.php} file. This file contains credentials for use by Zabbix front-end. You are expected to create it manually. @item @code{zabbix-host} (default: @code{"localhost"}) (type: string) Zabbix server hostname. @item @code{zabbix-port} (default: @code{10051}) (type: number) Zabbix server port. @end table @end deftp @c %end of fragment @node Kerberos Services @subsection Kerberos Services @cindex Kerberos The @code{(gnu services kerberos)} module provides services relating to the authentication protocol @dfn{Kerberos}. @subsubheading Krb5 Service Programs using a Kerberos client library normally expect a configuration file in @file{/etc/krb5.conf}. This service generates such a file from a definition provided in the operating system declaration. It does not cause any daemon to be started. No ``keytab'' files are provided by this service---you must explicitly create them. This service is known to work with the MIT client library, @code{mit-krb5}. Other implementations have not been tested. @defvar krb5-service-type A service type for Kerberos 5 clients. @end defvar @noindent Here is an example of its use: @lisp (service krb5-service-type (krb5-configuration (default-realm "EXAMPLE.COM") (allow-weak-crypto? #t) (realms (list (krb5-realm (name "EXAMPLE.COM") (admin-server "groucho.example.com") (kdc "karl.example.com")) (krb5-realm (name "ARGRX.EDU") (admin-server "kerb-admin.argrx.edu") (kdc "keys.argrx.edu")))))) @end lisp @noindent This example provides a Kerberos@tie{}5 client configuration which: @itemize @item Recognizes two realms, @i{viz:} ``EXAMPLE.COM'' and ``ARGRX.EDU'', both of which have distinct administration servers and key distribution centers; @item Will default to the realm ``EXAMPLE.COM'' if the realm is not explicitly specified by clients; @item Accepts services which only support encryption types known to be weak. @end itemize The @code{krb5-realm} and @code{krb5-configuration} types have many fields. Only the most commonly used ones are described here. For a full list, and more detailed explanation of each, see the MIT @uref{https://web.mit.edu/kerberos/krb5-devel/doc/admin/conf_files/krb5_conf.html,,krb5.conf} documentation. @deftp {Data Type} krb5-realm @cindex realm, kerberos @table @asis @item @code{name} This field is a string identifying the name of the realm. A common convention is to use the fully qualified DNS name of your organization, converted to upper case. @item @code{admin-server} This field is a string identifying the host where the administration server is running. @item @code{kdc} This field is a string identifying the key distribution center for the realm. @end table @end deftp @deftp {Data Type} krb5-configuration @table @asis @item @code{allow-weak-crypto?} (default: @code{#f}) If this flag is @code{#t} then services which only offer encryption algorithms known to be weak will be accepted. @item @code{default-realm} (default: @code{#f}) This field should be a string identifying the default Kerberos realm for the client. You should set this field to the name of your Kerberos realm. If this value is @code{#f} then a realm must be specified with every Kerberos principal when invoking programs such as @command{kinit}. @item @code{realms} This should be a non-empty list of @code{krb5-realm} objects, which clients may access. Normally, one of them will have a @code{name} field matching the @code{default-realm} field. @end table @end deftp @subsubheading PAM krb5 Service @cindex pam-krb5 The @code{pam-krb5} service allows for login authentication and password management via Kerberos. You will need this service if you want PAM enabled applicati