;;; GNU Guix --- Functional package management for GNU ;;; Copyright © 2019 Jakob L. Kreuze <zerodaysfordays@sdf.org> ;;; Copyright © 2020-2023 Ludovic Courtès <ludo@gnu.org> ;;; ;;; This file is part of GNU Guix. ;;; ;;; GNU Guix is free software; you can redistribute it and/or modify it ;;; under the terms of the GNU General Public License as published by ;;; the Free Software Foundation; either version 3 of the License, or (at ;;; your option) any later version. ;;; ;;; GNU Guix is distributed in the hope that it will be useful, but ;;; WITHOUT ANY WARRANTY; without even the implied warranty of ;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the ;;; GNU General Public License for more details. ;;; ;;; You should have received a copy of the GNU General Public License ;;; along with GNU Guix. If not, see <http://www.gnu.org/licenses/>. (define-module (gnu machine ssh) #:use-module (gnu bootloader) #:use-module (gnu machine) #:autoload (gnu packages gnupg) (guile-gcrypt) #:use-module (gnu system) #:use-module (gnu system file-systems) #:use-module (gnu system uuid) #:use-module ((gnu services) #:select (sexp->system-provenance)) #:use-module (guix diagnostics) #:use-module (guix memoization) #:use-module (guix gexp) #:use-module (guix i18n) #:use-module (guix modules) #:use-module (guix monads) #:use-module (guix pki) #:use-module (guix records) #:use-module (guix remote) #:use-module (guix scripts system reconfigure) #:use-module (guix ssh) #:use-module (guix store) #:use-module (guix utils) #:use-module ((guix self) #:select (make-config.scm)) #:use-module ((guix inferior) #:select (inferior-exception? inferior-exception-arguments)) #:use-module ((guix platform) #:select (systems)) #:use-module (gcrypt pk-crypto) #:use-module (ice-9 format) #:use-module (ice-9 match) #:use-module (ice-9 textual-ports) #:use-module (srfi srfi-1) #:use-module (srfi srfi-9) #:use-module (srfi srfi-19) #:use-module (srfi srfi-26) #:use-module (srfi srfi-34) #:use-module (srfi srfi-35) #:export (managed-host-environment-type machine-ssh-configuration machine-ssh-configuration? machine-ssh-configuration machine-ssh-configuration-host-name machine-ssh-configuration-build-locally? machine-ssh-configuration-authorize? machine-ssh-configuration-allow-downgrades? machine-ssh-configuration-port machine-ssh-configuration-user machine-ssh-configuration-host-key machine-ssh-configuration-session)) ;;; Commentary: ;;; ;;; This module implements remote evaluation and system deployment for ;;; machines that are accessible over SSH and have a known host-name. In the ;;; sense of the broader "machine" interface, we describe the environment for ;;; such machines as 'managed-host. ;;; ;;; Code: ;;; ;;; Parameters for the SSH client. ;;; (define-record-type* <machine-ssh-configuration> machine-ssh-configuration make-machine-ssh-configuration machine-ssh-configuration? this-machine-ssh-configuration (host-name machine-ssh-configuration-host-name) ; string (system machine-ssh-configuration-system ; string (sanitize validate-system-type)) (build-locally? machine-ssh-configuration-build-locally? ; boolean (default #t)) (authorize? machine-ssh-configuration-authorize? ; boolean (default #t)) (allow-downgrades? machine-ssh-configuration-allow-downgrades? ; boolean (default #f)) (safety-checks? machine-ssh-configuration-safety-checks? ;boolean (default #t)) (port machine-ssh-configuration-port ; integer (default 22)) (user machine-ssh-configuration-user ; string (default "root")) (identity machine-ssh-configuration-identity ; path to a private key (default #f)) (session machine-ssh-configuration-session ; session (thunked) (default ;; By default, open the session once and cache it. (open-machine-ssh-session* this-machine-ssh-configuration))) (host-key machine-ssh-configuration-host-key ; #f | string (default #f))) (define-with-syntax-properties (validate-system-type (value properties)) ;; Raise an error if VALUE is not a valid system type. (unless (string? value) (raise (make-compound-condition (condition (&error-location (location (source-properties->location properties)))) (formatted-message (G_ "~a: invalid system type; must be a string") value)))) (unless (member value (systems)) (raise (apply make-compound-condition (condition (&error-location (location (source-properties->location properties)))) (formatted-message (G_ "~a: unknown system type") value) (let ((closest (string-closest value (systems) #:threshold 5))) (if closest (list (condition (&fix-hint (hint (format #f (G_ "Did you mean @code{~a}?") closest))))) '()))))) value) (define (open-machine-ssh-session config) "Open an SSH session for CONFIG, a <machine-ssh-configuration> record." (let ((host-name (machine-ssh-configuration-host-name config)) (user (machine-ssh-configuration-user config)) (port (machine-ssh-configuration-port config)) (identity (machine-ssh-configuration-identity config)) (host-key (machine-ssh-configuration-host-key config))) (unless host-key (warning (G_ "<machine-ssh-configuration> without a 'host-key' \ is deprecated~%"))) (open-ssh-session host-name #:user user #:port port #:identity identity #:host-key host-key))) (define open-machine-ssh-session* (mlambdaq (config) "Memoizing variant of 'open-machine-ssh-session'." (open-machine-ssh-session config))) (define (machine-ssh-session machine) "Return the SSH session that was given in MACHINE's configuration, or create one from the configuration's parameters if one was not provided." (maybe-raise-unsupported-configuration-error machine) (let ((config (machine-configuration machine))) (or (machine-ssh-configuration-session config) (open-machine-ssh-session config)))) ;;; ;;; Remote evaluation. ;;; (define (machine-become-command machine) "Return as a list of strings the program and arguments necessary to run a shell command with escalated privileges for MACHINE's configuration." (if (string= "root" (machine-ssh-configuration-user (machine-configuration machine))) '() '("/run/setuid-programs/sudo" "-n" "--"))) (define (managed-host-remote-eval machine exp) "Internal implementation of 'machine-remote-eval' for MACHINE instances with an environment type of 'managed-host." (maybe-raise-unsupported-configuration-error machine) (let ((config (machine-configuration machine))) (remote-eval exp (machine-ssh-session machine) #:build-locally? (machine-ssh-configuration-build-locally? config) #:system (machine-ssh-configuration-system config) #:become-command (machine-become-command machine)))) ;;; ;;; Safety checks. ;;; ;; Assertion to be executed remotely. This abstraction exists to allow us to ;; gather a list of expressions to be evaluated and eventually evaluate them ;; all at once instead of one by one. (This is pretty much a monad.) (define-record-type <remote-assertion> (remote-assertion exp proc) remote-assertion? (exp remote-assertion-expression) (proc remote-assertion-procedure)) (define-syntax-rule (remote-let ((var exp)) body ...) "Return a <remote-assertion> that binds VAR to the result of evaluating EXP, a gexp, remotely, and evaluate BODY in that context." (remote-assertion exp (lambda (var) body ...))) (define (machine-check-file-system-availability machine) "Return a list of <remote-assertion> that raise a '&message' error condition if any of the file-systems specified in MACHINE's 'system' declaration do not exist on the machine." (define file-systems (filter (lambda (fs) (and (file-system-mount? fs) (not (member (file-system-type fs) %pseudo-file-system-types)) ;; Don't try to validate network file systems. (not (string-prefix? "nfs" (file-system-type fs))) (not (memq 'bind-mount (file-system-flags fs))))) (operating-system-file-systems (machine-operating-system machine)))) (define (check-literal-file-system fs) (remote-let ((errno #~(catch 'system-error (lambda () (stat #$(file-system-device fs)) #t) (lambda args (system-error-errno args))))) (when (number? errno) (raise (formatted-message (G_ "device '~a' not found: ~a") (file-system-device fs) (strerror errno)))))) (define (check-labeled-file-system fs) (define remote-exp (with-imported-modules (source-module-closure '((gnu build file-systems))) #~(begin (use-modules (gnu build file-systems)) (find-partition-by-label #$(file-system-label->string (file-system-device fs)))))) (remote-let ((result remote-exp)) (unless result (raise (formatted-message (G_ "no file system with label '~a'") (file-system-label->string (file-system-device fs))))))) (define (check-uuid-file-system fs) (define remote-exp (with-imported-modules (source-module-closure '((gnu build file-systems) (gnu system uuid))) #~(begin (use-modules (gnu build file-systems) (gnu system uuid)) (let ((uuid (uuid #$(uuid->string (file-system-device fs)) '#$(uuid-type (file-system-device fs))))) (find-partition-by-uuid uuid))))) (remote-let ((result remote-exp)) (unless result (raise (formatted-message (G_ "no file system with UUID '~a'") (uuid->string (file-system-device fs))))))) (if (machine-ssh-configuration-safety-checks? (machine-configuration machine)) (append (map check-literal-file-system (filter (lambda (fs) (string? (file-system-device fs))) file-systems)) (map check-labeled-file-system (filter (lambda (fs) (file-system-label? (file-system-device fs))) file-systems)) (map check-uuid-file-system (filter (lambda (fs) (uuid? (file-system-device fs))) file-systems))) '())) (define (machine-check-initrd-modules machine) "Return a list of <remote-assertion> that raise a '&message' error condition if any of the modules needed by 'needed-for-boot' file systems in MACHINE are not available in the initrd." (define file-systems (filter (lambda (file-system) (and (file-system-needed-for-boot? file-system) (not (member (file-system-type file-system) %pseudo-file-system-types)))) (operating-system-file-systems (machine-operating-system machine)))) (define (missing-modules fs) (define remote-exp (let ((device (file-system-device fs))) (with-imported-modules (source-module-closure '((gnu build file-systems) (gnu build linux-modules) (gnu system uuid))) #~(begin (use-modules (gnu build file-systems) (gnu build linux-modules) (gnu system uuid)) (define dev #$(cond ((string? device) device) ((uuid? device) #~(find-partition-by-uuid (string->uuid #$(uuid->string device)))) ((file-system-label? device) #~(find-partition-by-label #$(file-system-label->string device))))) (missing-modules dev '#$(operating-system-initrd-modules (machine-operating-system machine))))))) (remote-let ((missing remote-exp)) (unless (null? missing) (raise (formatted-message (G_ "missing modules for ~a:~{ ~a~}~%") (file-system-device fs) missing))))) (if (machine-ssh-configuration-safety-checks? (machine-configuration machine)) (map missing-modules file-systems) '())) (define* (machine-check-forward-update machine) "Check whether we are making a forward update for MACHINE. Depending on its 'allow-upgrades?' field, raise an error or display a warning if we are potentially downgrading it." (define config (machine-configuration machine)) (define validate-reconfigure (if (machine-ssh-configuration-allow-downgrades? config) warn-about-backward-reconfigure ensure-forward-reconfigure)) (remote-let ((provenance #~(call-with-input-file "/run/current-system/provenance" read))) (define channels (sexp->system-provenance provenance)) (check-forward-update validate-reconfigure #:current-channels channels))) (define (machine-check-building-for-appropriate-system machine) "Raise a '&message' error condition if MACHINE is configured to be built locally and the 'system' field does not match the '%current-system' reported by MACHINE." (let ((config (machine-configuration machine)) (system (remote-system (machine-ssh-session machine)))) (when (and (machine-ssh-configuration-build-locally? config) (not (string= system (machine-ssh-configuration-system config)))) (raise (formatted-message (G_ "incorrect target system\ ('~a' was given, while the system reports that it is '~a')~%") (machine-ssh-configuration-system config) system))))) (define (check-deployment-sanity machine) "Raise a '&message' error condition if it is clear that deploying MACHINE's 'system' declaration would fail." (define assertions (parameterize ((%current-system (machine-ssh-configuration-system (machine-configuration machine))) (%current-target-system #f)) (append (machine-check-file-system-availability machine) (machine-check-initrd-modules machine) (list (machine-check-forward-update machine))))) (define aggregate-exp ;; Gather all the expressions so that a single round-trip is enough to ;; evaluate all the ASSERTIONS remotely. #~(map (lambda (file) (false-if-exception (primitive-load file))) '#$(map (lambda (assertion) (scheme-file "remote-assertion.scm" (remote-assertion-expression assertion))) assertions))) ;; First check MACHINE's system type--an incorrect value for 'system' would ;; cause subsequent invocations of 'remote-eval' to fail. (machine-check-building-for-appropriate-system machine) (mlet %store-monad ((values (machine-remote-eval machine aggregate-exp))) (for-each (lambda (proc value) (proc value)) (map remote-assertion-procedure assertions) values) (return #t))) ;;; ;;; System deployment. ;;; (define not-config? ;; Select (guix …) and (gnu …) modules, except (guix config). (match-lambda (('guix 'config) #f) (('guix _ ...) #t) (('gnu _ ...) #t) (_ #f))) (define (machine-boot-parameters machine) "Monadic procedure returning a list of 'boot-parameters' for the generations of MACHINE's system profile, ordered from most recent to oldest." (define bootable-kernel-arguments (@@ (gnu system) bootable-kernel-arguments)) (define remote-exp (with-extensions (list guile-gcrypt) (with-imported-modules `(((guix config) => ,(make-config.scm)) ,@(source-module-closure '((guix profiles)) #:select? not-config?)) #~(begin (use-modules (guix config) (guix profiles) (ice-9 textual-ports)) (define %system-profile (string-append %state-directory "/profiles/system")) (define (read-file path) (call-with-input-file path (lambda (port) (get-string-all port)))) (map (lambda (generation) (let* ((system-path (generation-file-name %system-profile generation)) (boot-parameters-path (string-append system-path "/parameters")) (time (stat:mtime (lstat system-path)))) (list generation system-path time (read-file boot-parameters-path)))) (reverse (generation-numbers %system-profile))))))) (mlet* %store-monad ((generations (machine-remote-eval machine remote-exp))) (return (map (lambda (generation) (match generation ((generation system-path time serialized-params) (let* ((params (call-with-input-string serialized-params read-boot-parameters)) (root (boot-parameters-root-device params)) (label (boot-parameters-label params)) (version (boot-parameters-version params))) (boot-parameters (inherit params) (label (string-append label " (#" (number->string generation) ", " (let ((time (make-time time-utc 0 time))) (date->string (time-utc->date time) "~Y-~m-~d ~H:~M")) ")")) (kernel-arguments (append (bootable-kernel-arguments system-path root version) (boot-parameters-kernel-arguments params)))))))) generations)))) (define-syntax-rule (with-roll-back should-roll-back? mbody ...) "Catch exceptions that arise when binding MBODY, a monadic expression in %STORE-MONAD, and collect their arguments in a &deploy-error condition, with the 'should-roll-back' field set to SHOULD-ROLL-BACK?" (catch #t (lambda () mbody ...) (lambda args (raise (condition (&deploy-error (should-roll-back should-roll-back?) (captured-args args))))))) (define (deploy-managed-host machine) "Internal implementation of 'deploy-machine' for MACHINE instances with an environment type of 'managed-host." (define config (machine-configuration machine)) (define host (machine-ssh-configuration-host-name config)) (define system (machine-ssh-configuration-system config)) (maybe-raise-unsupported-configuration-error machine) (when (machine-ssh-configuration-authorize? (machine-configuration machine)) (unless (file-exists? %public-key-file) (raise (formatted-message (G_ "no signing key '~a'. \ Have you run 'guix archive --generate-key'?") %public-key-file))) (remote-authorize-signing-key (call-with-input-file %public-key-file (lambda (port) (string->canonical-sexp (get-string-all port)))) (machine-ssh-session machine) (machine-become-command machine))) (mlet %store-monad ((_ (check-deployment-sanity machine)) (boot-parameters (machine-boot-parameters machine))) ;; Make sure code that check %CURRENT-SYSTEM, such as ;; %BASE-INITRD-MODULES, gets to see the right value. (parameterize ((%current-system system) (%current-target-system #f)) (let* ((os (machine-operating-system machine)) (eval (cut machine-remote-eval machine <>)) (menu-entries (map boot-parameters->menu-entry boot-parameters)) (bootloader-configuration (operating-system-bootloader os)) (bootcfg (operating-system-bootcfg os menu-entries))) (define-syntax-rule (eval/error-handling condition handler ...) ;; Return a wrapper around EVAL such that HANDLER is evaluated if an ;; exception is raised. (lambda (exp) (lambda (store) (guard (condition ((inferior-exception? condition) (values (begin handler ...) store))) (values (run-with-store store (eval exp) #:system system) store))))) (mbegin %store-monad (with-roll-back #f (switch-to-system (eval/error-handling c (raise (formatted-message (G_ "\ failed to switch systems while deploying '~a':~%~{~s ~}") host (inferior-exception-arguments c)))) os)) (with-roll-back #t (mbegin %store-monad (upgrade-shepherd-services (eval/error-handling c (warning (G_ "\ an error occurred while upgrading services on '~a':~%~{~s ~}~%") host (inferior-exception-arguments c))) os) (install-bootloader (eval/error-handling c (raise (formatted-message (G_ "\ failed to install bootloader on '~a':~%~{~s ~}~%") host (inferior-exception-arguments c)))) bootloader-configuration bootcfg)))))))) ;;; ;;; Roll-back. ;;; (define (roll-back-managed-host machine) "Internal implementation of 'roll-back-machine' for MACHINE instances with an environment type of 'managed-host." (define remote-exp (with-extensions (list guile-gcrypt) (with-imported-modules (source-module-closure '((guix config) (guix profiles))) #~(begin (use-modules (guix config) (guix profiles)) (define %system-profile (string-append %state-directory "/profiles/system")) (define target-generation (relative-generation %system-profile -1)) (if target-generation (switch-to-generation %system-profile target-generation) 'error))))) (define roll-back-failure (condition (&message (message (G_ "could not roll-back machine"))))) (mlet* %store-monad ((boot-parameters (machine-boot-parameters machine)) (_ -> (if (< (length boot-parameters) 2) (raise roll-back-failure))) (entries -> (map boot-parameters->menu-entry (list (second boot-parameters)))) (locale -> (boot-parameters-locale (second boot-parameters))) (crypto-dev -> (boot-parameters-store-crypto-devices (second boot-parameters))) (store-dir -> (boot-parameters-store-directory-prefix (second boot-parameters))) (old-entries -> (map boot-parameters->menu-entry (drop boot-parameters 2))) (bootloader -> (operating-system-bootloader (machine-operating-system machine))) (bootcfg (lower-object ((bootloader-configuration-file-generator (bootloader-configuration-bootloader bootloader)) bootloader entries #:locale locale #:store-crypto-devices crypto-dev #:store-directory-prefix store-dir #:old-entries old-entries))) (remote-result (machine-remote-eval machine remote-exp))) (when (eqv? 'error remote-result) (raise roll-back-failure)))) ;;; ;;; Environment type. ;;; (define managed-host-environment-type (environment-type (machine-remote-eval managed-host-remote-eval) (deploy-machine deploy-managed-host) (roll-back-machine roll-back-managed-host) (name 'managed-host-environment-type) (description "Provisioning for machines that are accessible over SSH and have a known host-name. This entails little more than maintaining an SSH connection to the host."))) (define (maybe-raise-unsupported-configuration-error machine) "Raise an error if MACHINE's configuration is not an instance of <machine-ssh-configuration>." (let ((config (machine-configuration machine)) (environment (environment-type-name (machine-environment machine)))) (unless (and config (machine-ssh-configuration? config)) (raise (formatted-message (G_ "unsupported machine configuration '~a' for environment of type '~a'") config environment))))) ;; Local Variables: ;; eval: (put 'remote-let 'scheme-indent-function 1) ;; eval: (put 'with-roll-back 'scheme-indent-function 1) ;; eval: (put 'eval/error-handling 'scheme-indent-function 1) ;; End: