;;; GNU Guix --- Functional package management for GNU ;;; Copyright © 2016-2020, 2023 Ludovic Courtès <ludo@gnu.org> ;;; Copyright © 2022 Maxim Cournoyer <maxim.cournoyer@gmail.com> ;;; Copyright © 2023 Bruno Victal <mirai@makinata.eu> ;;; ;;; 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 services mcron) #:use-module (gnu services) #:use-module (gnu services shepherd) #:use-module (gnu packages guile-xyz) #:use-module (guix records) #:use-module (guix gexp) #:use-module (srfi srfi-1) #:use-module (ice-9 match) #:use-module (ice-9 vlist) #:export (mcron-configuration mcron-configuration? mcron-configuration-mcron mcron-configuration-jobs mcron-configuration-log? mcron-configuration-log-file mcron-configuration-log-format mcron-configuration-date-format mcron-configuration-home-service? mcron-service-type)) ;;; Commentary: ;;; ;;; This module implements a service that to run instances of GNU mcron, a ;;; periodic job execution daemon. Example of a service: ;; ;; (service mcron-service-type ;; (mcron-configuration ;; (jobs (list #~(job next-second-from ;; (lambda () ;; (call-with-output-file "/dev/console" ;; (lambda (port) ;; (display "hello!\n" port))))))))) ;;; ;;; Code: ;; Configuration of mcron. ;; XXX: 'define-configuration' cannot be used here due to the need for ;; 'thunked' and 'innate' fields as well as 'this-mcron-configuration'. (define-record-type* <mcron-configuration> mcron-configuration make-mcron-configuration mcron-configuration? this-mcron-configuration (mcron mcron-configuration-mcron ;file-like (default mcron)) (jobs mcron-configuration-jobs ;list of gexps (default '())) (log? mcron-configuration-log? ;Boolean (default #t)) (log-file mcron-configuration-log-file ;string | gexp (thunked) (default (if (mcron-configuration-home-service? this-mcron-configuration) #~(string-append %user-log-dir "/mcron.log") "/var/log/mcron.log"))) (log-format mcron-configuration-log-format ;string (default "~1@*~a ~a: ~a~%")) (date-format mcron-configuration-date-format ;string | #f (default #f)) (home-service? mcron-configuration-home-service? (default for-home?) (innate))) (define (job-files mcron jobs) "Return a list of file-like object for JOBS, a list of gexps." (define (validated-file job) ;; This procedure behaves like 'scheme-file' but it runs 'mcron ;; --schedule' to detect any error in JOB. (computed-file "mcron-job" (with-imported-modules '((guix build utils)) #~(begin (use-modules (guix build utils)) (call-with-output-file "prologue" (lambda (port) ;; This prologue allows 'mcron --schedule' to ;; proceed no matter what #:user option is passed ;; to 'job'. (write '(set! getpw (const (getpwuid (getuid)))) port))) (call-with-output-file "job" (lambda (port) (write '#$job port))) (invoke #+(file-append mcron "/bin/mcron") "--schedule=20" "prologue" "job") (copy-file "job" #$output))) #:options '(#:env-vars (("COLUMNS" . "150"))))) (map validated-file jobs)) (define (shepherd-schedule-action mcron files) "Return a Shepherd action that runs MCRON with '--schedule' for the given files." (shepherd-action (name 'schedule) (documentation "Display jobs that are going to be scheduled.") (procedure #~(lambda* (_ #:optional (n "5")) ;; XXX: This is a global side effect. (setenv "GUILE_AUTO_COMPILE" "0") ;; Run 'mcron' in a pipe so we can explicitly redirect its output to ;; 'current-output-port', which at this stage is bound to the client ;; connection. (let ((pipe (open-pipe* OPEN_READ #$(file-append mcron "/bin/mcron") (string-append "--schedule=" n) #$@files))) (let loop () (match (read-line pipe 'concat) ((? eof-object?) (catch 'system-error (lambda () (zero? (close-pipe pipe))) (lambda args ;; There's a race with the SIGCHLD handler, which ;; could call 'waitpid' before 'close-pipe' above does. If ;; we get ECHILD, that means we lost the race, but that's ;; fine. (or (= ECHILD (system-error-errno args)) (apply throw args))))) (line (display line) (loop))))))))) (define (mcron-shepherd-services config) (match-record config <mcron-configuration> (mcron jobs log? log-file log-format date-format home-service?) (if (eq? jobs '()) '() ;nothing to do (let ((files (job-files mcron jobs))) (list (shepherd-service (provision '(mcron)) (requirement (if home-service? '() '(user-processes))) (modules `((srfi srfi-1) (srfi srfi-26) (ice-9 popen) ;for the 'schedule' action (ice-9 rdelim) (ice-9 match) ((shepherd support) #:select (%user-log-dir)) ,@%default-modules)) (start #~(make-forkexec-constructor (list #$(file-append mcron "/bin/mcron") #$@(if log? `("--log" "--log-format" ,log-format ,@(if date-format (list "--date-format" date-format) '())) '()) #$@files) ;; Disable auto-compilation of the job files and ;; set a sane value for 'PATH'. #:environment-variables (cons* "GUILE_AUTO_COMPILE=0" "PATH=/run/current-system/profile/bin" (remove (cut string-prefix? "PATH=" <>) (environ))) #:log-file #$log-file)) (stop #~(make-kill-destructor)) (actions (list (shepherd-schedule-action mcron files))))))))) (define mcron-service-type (service-type (name 'mcron) (description "Run the mcron job scheduling daemon.") (extensions (list (service-extension shepherd-root-service-type mcron-shepherd-services) (service-extension profile-service-type (compose list mcron-configuration-mcron)))) (compose concatenate) (extend (lambda (config jobs) (mcron-configuration (inherit config) (home-service? (mcron-configuration-home-service? config)) (jobs (append (mcron-configuration-jobs config) jobs))))) (default-value (mcron-configuration)))) ;empty job list ;;; mcron.scm ends here