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;;; 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) #:hide (mkdir-p)) ;for '%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
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