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;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2019 David Thompson <davet@gnu.org>
;;; Copyright © 2019 Jakob L. Kreuze <zerodaysfordays@sdf.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)
  #:use-module (gnu system)
  #:use-module (guix derivations)
  #:use-module (guix monads)
  #:use-module (guix records)
  #:use-module (guix store)
  #:use-module ((guix diagnostics) #:select (source-properties->location))
  #:use-module (srfi srfi-35)
  #:export (environment-type
            environment-type?
            environment-type-name
            environment-type-description
            environment-type-location

            machine
            machine?

            machine-operating-system
            machine-environment
            machine-configuration
            machine-display-name

            deploy-machine
            roll-back-machine
            machine-remote-eval

            &deploy-error
            deploy-error?
            deploy-error-should-roll-back
            deploy-error-captured-args))

;;; Commentary:
;;;
;;; This module provides the types used to declare individual machines in a
;;; heterogeneous Guix deployment. The interface allows users to specify system
;;; configurations and the means by which resources should be provisioned on a
;;; per-host basis.
;;;
;;; Code:


;;;
;;; Declarations for resources that can be provisioned.
;;;

(define-record-type* <environment-type> environment-type
  make-environment-type
  environment-type?

  ;; Interface to the environment type's deployment code. Each procedure
  ;; should take the same arguments as the top-level procedure of this file
  ;; that shares the same name. For example, 'machine-remote-eval' should be
  ;; of the form '(machine-remote-eval machine exp)'.
  (machine-remote-eval environment-type-machine-remote-eval) ; procedure
  (deploy-machine      environment-type-deploy-machine)      ; procedure
  (roll-back-machine   environment-type-roll-back-machine)   ; procedure

  ;; Metadata.
  (name        environment-type-name)       ; symbol
  (description environment-type-description ; string
               (default #f))
  (location    environment-type-location    ; <location>
               (default (and=> (current-source-location)
                               source-properties->location))
               (innate)))


;;;
;;; Declarations for machines in a deployment.
;;;

(define-record-type* <machine> machine make-machine
  machine?
  (operating-system %machine-operating-system); <operating-system>
  (environment      machine-environment)      ; symbol
  (configuration    machine-configuration     ; configuration object
                    (default #f)))            ; specific to environment

(define (machine-operating-system machine)
  "Return the operating system of MACHINE."
  (operating-system-with-provenance
   (%machine-operating-system machine)))

(define (machine-display-name machine)
  "Return the host-name identifying MACHINE."
  (operating-system-host-name (machine-operating-system machine)))

(define (machine-remote-eval machine exp)
  "Evaluate EXP, a gexp, on MACHINE. Ensure that all the elements EXP refers to
are built and deployed to MACHINE beforehand."
  (let ((environment (machine-environment machine)))
    ((environment-type-machine-remote-eval environment) machine exp)))

(define (deploy-machine machine)
  "Monadic procedure transferring the new system's OS closure to the remote
MACHINE, activating it on MACHINE and switching MACHINE to the new generation."
  (let ((environment (machine-environment machine)))
    ((environment-type-deploy-machine environment) machine)))

(define (roll-back-machine machine)
  "Monadic procedure rolling back to the previous system generation on
MACHINE. Return the number of the generation that was current before switching
and the new generation number."
  (let ((environment (machine-environment machine)))
    ((environment-type-roll-back-machine environment) machine)))


;;;
;;; Error types.
;;;

(define-condition-type &deploy-error &error
  deploy-error?
  (should-roll-back deploy-error-should-roll-back)
  (captured-args deploy-error-captured-args))
s? set symbol) (raise (condition (&message (message (format #f (G_ "service '~a' provided more than once") symbol))))))) (for-each assert-unique (shepherd-service-provision service)) (fold set-insert set (shepherd-service-provision service))) (setq 'shepherd) services)) (define (assert-satisfied-requirements service) ;; Bail out if the requirements of SERVICE aren't satisfied. (for-each (lambda (requirement) (unless (set-contains? provisions requirement) (raise (condition (&message (message (format #f (G_ "service '~a' requires '~a', \ which is not provided by any service") (match (shepherd-service-provision service) ((head . _) head) (_ service)) requirement))))))) (shepherd-service-requirement service))) (for-each assert-satisfied-requirements services)) (define %store-characters ;; Valid store characters; see 'checkStoreName' in the daemon. (string->char-set "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz+-._?=")) (define (shepherd-service-file-name service) "Return the file name where the initialization code for SERVICE is to be stored." (let ((provisions (string-join (map symbol->string (shepherd-service-provision service))))) (string-append "shepherd-" (string-map (lambda (chr) (if (char-set-contains? %store-characters chr) chr #\-)) provisions) ".scm"))) (define (shepherd-service-file/regular service) "Return a file defining SERVICE, a service whose 'free-form' field is #f." (scheme-file (shepherd-service-file-name service) (with-imported-modules %default-imported-modules #~(begin (use-modules #$@(shepherd-service-modules service)) (service '#$(shepherd-service-provision service) #:documentation '#$(shepherd-service-documentation service) #:requirement '#$(shepherd-service-requirement service) ;; The 'one-shot?' slot is new in Shepherd 0.6.0. ;; Older versions ignore it. #:one-shot? '#$(shepherd-service-one-shot? service) #:respawn? '#$(shepherd-service-respawn? service) #$@(if (shepherd-service-respawn-limit service) `(#:respawn-limit ,(shepherd-service-respawn-limit service)) '()) #$@(if (shepherd-service-respawn-delay service) `(#:respawn-delay ,(shepherd-service-respawn-delay service)) '()) #:start #$(shepherd-service-start service) #:stop #$(shepherd-service-stop service) #:actions (actions #$@(map (match-lambda (($ <shepherd-action> name proc doc) #~(#$name #$doc #$proc))) (shepherd-service-actions service)))))))) (define (shepherd-service-file/free-form service) "Return a file defining SERVICE, a service whose 'free-form' field is set." (scheme-file (shepherd-service-file-name service) (with-imported-modules %default-imported-modules #~(begin (use-modules #$@(shepherd-service-modules service)) #$(shepherd-service-free-form service))))) (define (shepherd-service-file service) "Return a file defining SERVICE." (if (shepherd-service-free-form service) (shepherd-service-file/free-form service) (shepherd-service-file/regular service))) (define (scm->go file shepherd) "Compile FILE, which contains code to be loaded by shepherd's config file, and return the resulting '.go' file. SHEPHERD is used as shepherd package." (define shepherd&co (cons shepherd (match (lookup-package-input shepherd "guile-fibers") (#f '()) (fibers (list fibers))))) (let-system (system target) (with-extensions shepherd&co (computed-file (string-append (basename (scheme-file-name file) ".scm") ".go") #~(begin (use-modules (system base compile) (system base target)) ;; Do the same as the Shepherd's 'load-in-user-module'. (let ((env (make-fresh-user-module))) (module-use! env (resolve-interface '(shepherd service))) (with-target #$(or target #~%host-type) (lambda _ (compile-file #$file #:output-file #$output #:env env))))) ;; It's faster to build locally than to download. #:options '(#:local-build? #t #:substitutable? #f))))) (define (shepherd-configuration-action file) "Return a 'configuration' action to display FILE, which should be the name of the service's configuration file." (shepherd-action (name 'configuration) (documentation "Display the name of this service's configuration file.") (procedure #~(lambda (_) (format #t "~a~%" #$file) #$file)))) (define (shepherd-configuration-file services shepherd) "Return the shepherd configuration file for SERVICES. SHEPHERD is used as shepherd package." (assert-valid-graph services) (let ((files (map shepherd-service-file services)) (scm->go (cute scm->go <> shepherd))) (define config #~(begin (use-modules (srfi srfi-1)) (define (make-user-module) ;; Copied from (shepherd support), where it's private. (let ((m (make-fresh-user-module))) (module-use! m (resolve-interface '(shepherd service))) m)) ;; Specify the default environment visible to all the services. ;; Without this statement, all the environment variables of PID 1 ;; are inherited by child services. (default-environment-variables '("PATH=/run/current-system/profile/bin")) ;; Booting off a DVD, especially on a slow machine, can make ;; everything slow. Thus, increase the timeout compared to the ;; default 5s in the Shepherd 0.7.0. See ;; <https://bugs.gnu.org/40572>. (default-pid-file-timeout 30) ;; Load service files one by one; filter out those that could not be ;; loaded--e.g., due to an unbound variable--such that an error in ;; one service definition does not prevent the system from booting. (register-services (parameterize ((current-warning-port (%make-void-port "w"))) (filter-map (lambda (file) (with-exception-handler (lambda (exception) (format #t "Exception caught \ while loading '~a': ~s~%" file exception) #f) (lambda () (save-module-excursion (lambda () (set-current-module (make-user-module)) (load-compiled file)))) #:unwind? #t)) '#$(map scm->go files)))) (format #t "starting services...~%") (let ((services-to-start '#$(append-map shepherd-service-provision (filter shepherd-service-auto-start? services)))) (start-in-the-background services-to-start) ;; Hang up stdin. At this point, we assume that 'start' methods ;; that required user interaction on the console (e.g., ;; 'cryptsetup open' invocations, post-fsck emergency REPL) have ;; completed. User interaction becomes impossible after this ;; call; this avoids situations where services wrongfully lead ;; PID 1 to read from stdin (the console), which users may not ;; have access to (see <https://bugs.gnu.org/23697>). (redirect-port (open "/dev/null" (logior O_RDONLY O_CLOEXEC)) (current-input-port))))) (scheme-file "shepherd.conf" config))) (define* (shepherd-service-lookup-procedure services #:optional (provision shepherd-service-provision)) "Return a procedure that, when passed a symbol, return the item among SERVICES that provides this symbol. PROVISION must be a one-argument procedure that takes a service and returns the list of symbols it provides." (let ((services (fold (lambda (service result) (fold (cut vhash-consq <> service <>) result (provision service))) vlist-null services))) (lambda (name) (match (vhash-assq name services) ((_ . service) service) (#f #f))))) (define* (shepherd-service-back-edges services #:key (provision shepherd-service-provision) (requirement shepherd-service-requirement)) "Return a procedure that, when given a <shepherd-service> from SERVICES, returns the list of <shepherd-service> that depend on it. Use PROVISION and REQUIREMENT as one-argument procedures that return the symbols provided/required by a service." (define provision->service (shepherd-service-lookup-procedure services provision)) (define edges (fold (lambda (service edges) (fold (lambda (requirement edges) (vhash-consq (provision->service requirement) service edges)) edges (requirement service))) vlist-null services)) (lambda (service) (vhash-foldq* cons '() service edges))) (define (shepherd-service-upgrade live target) "Return two values: the subset of LIVE (a list of <live-service>) that needs to be unloaded, and the subset of TARGET (a list of <shepherd-service>) that need to be restarted to complete their upgrade." (define (essential? service) (memq (first (live-service-provision service)) '(root shepherd))) (define lookup-target (shepherd-service-lookup-procedure target shepherd-service-provision)) (define lookup-live (shepherd-service-lookup-procedure live live-service-provision)) (define (running? service) (and=> (lookup-live (shepherd-service-canonical-name service)) live-service-running)) (define live-service-dependents (shepherd-service-back-edges live #:provision live-service-provision #:requirement live-service-requirement)) (define (obsolete? service) (match (lookup-target (first (live-service-provision service))) (#f (every obsolete? (live-service-dependents service))) (_ #f))) (define to-restart ;; Restart services that are currently running. (filter running? target)) (define to-unload ;; Unload services that are no longer required. Essential services must ;; be kept and transient services such as inetd child services should be ;; kept as well--they'll vanish eventually. (remove (lambda (live) (or (essential? live) (live-service-transient? live))) (filter obsolete? live))) (values to-unload to-restart)) ;;; ;;; User processes. ;;; (define %do-not-kill-file ;; Name of the file listing PIDs of processes that must survive when halting ;; the system. Typical example is user-space file systems. "/etc/shepherd/do-not-kill") (define (user-processes-shepherd-service requirements) "Return the 'user-processes' Shepherd service with dependencies on REQUIREMENTS (a list of service names). This is a synchronization point used to make sure user processes and daemons get started only after crucial initial services have been started---file system mounts, etc. This is similar to the 'sysvinit' target in systemd." (define grace-delay ;; Delay after sending SIGTERM and before sending SIGKILL. 4) (list (shepherd-service (documentation "When stopped, terminate all user processes.") (provision '(user-processes)) (requirement requirements) (start #~(const #t)) (stop #~(lambda _ (define (kill-except omit signal) ;; Kill all the processes with SIGNAL except those listed ;; in OMIT and the current process. (let ((omit (cons (getpid) omit))) (for-each (lambda (pid) (unless (memv pid omit) (false-if-exception (kill pid signal)))) (processes)))) (define omitted-pids ;; List of PIDs that must not be killed. (if (file-exists? #$%do-not-kill-file) (map string->number (call-with-input-file #$%do-not-kill-file (compose string-tokenize (@ (ice-9 rdelim) read-string)))) '())) (define (now) (car (gettimeofday))) (define (sleep* n) ;; Really sleep N seconds. ;; Work around <http://bugs.gnu.org/19581>. (define start (now)) (let loop ((elapsed 0)) (when (> n elapsed) (sleep (- n elapsed)) (loop (- (now) start))))) (define lset= (@ (srfi srfi-1) lset=)) (display "sending all processes the TERM signal\n") (if (null? omitted-pids) (begin ;; Easy: terminate all of them. (kill -1 SIGTERM) (sleep* #$grace-delay) (kill -1 SIGKILL)) (begin ;; Kill them all except OMITTED-PIDS. XXX: We would ;; like to (kill -1 SIGSTOP) to get a fixed list of ;; processes, like 'killall5' does, but that seems ;; unreliable. (kill-except omitted-pids SIGTERM) (sleep* #$grace-delay) (kill-except omitted-pids SIGKILL) (delete-file #$%do-not-kill-file))) (let wait () ;; Reap children, if any, so that we don't end up with ;; zombies and enter an infinite loop. (let reap-children () (define result (false-if-exception (waitpid WAIT_ANY (if (null? omitted-pids) 0 WNOHANG)))) (when (and (pair? result) (not (zero? (car result)))) (reap-children))) (let ((pids (processes))) (unless (lset= = pids (cons 1 omitted-pids)) (format #t "waiting for process termination\ (processes left: ~s)~%" pids) (sleep* 2) (wait)))) (display "all processes have been terminated\n") #f)) (respawn? #f)))) (define user-processes-service-type (service-type (name 'user-processes) (extensions (list (service-extension shepherd-root-service-type user-processes-shepherd-service))) (compose concatenate) (extend append) ;; The value is the list of Shepherd services 'user-processes' depends on. ;; Extensions can add new services to this list. (default-value '()) (description "The @code{user-processes} service is responsible for terminating all the processes so that the root file system can be re-mounted read-only, just before rebooting/halting. Processes still running after a few seconds after @code{SIGTERM} has been sent are terminated with @code{SIGKILL}."))) ;;; shepherd.scm ends here