c88582a674
* doc/guix.texi (Scheduled Job Execution): Document it. * gnu/services/mcron.scm (mcron-configuration)[log-file, date-format]: New field. (mcron-shepherd-services): Add log-file and date-format support. Use file-append instead of string-append. Signed-off-by: Maxim Cournoyer <maxim.cournoyer@gmail.com>
224 lines
8.6 KiB
Scheme
224 lines
8.6 KiB
Scheme
;;; GNU Guix --- Functional package management for GNU
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;;; Copyright © 2016, 2017, 2018, 2019, 2020 Ludovic Courtès <ludo@gnu.org>
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;;; Copyright © 2022 Maxim Cournoyer <maxim.cournoyer@gmail.com>
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;;; Copyright © 2023 Bruno Victal <mirai@makinata.eu>
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;;;
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;;; This file is part of GNU Guix.
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;;;
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;;; GNU Guix is free software; you can redistribute it and/or modify it
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;;; under the terms of the GNU General Public License as published by
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;;; the Free Software Foundation; either version 3 of the License, or (at
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;;; your option) any later version.
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;;;
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;;; GNU Guix is distributed in the hope that it will be useful, but
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;;; WITHOUT ANY WARRANTY; without even the implied warranty of
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;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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;;; GNU General Public License for more details.
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;;;
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;;; You should have received a copy of the GNU General Public License
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;;; along with GNU Guix. If not, see <http://www.gnu.org/licenses/>.
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(define-module (gnu services mcron)
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#:use-module (gnu services)
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#:use-module (gnu services configuration)
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#:use-module (gnu services shepherd)
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#:use-module (gnu packages guile-xyz)
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#:use-module (guix deprecation)
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#:use-module (guix records)
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#:use-module (guix gexp)
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#:use-module (srfi srfi-1)
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#:use-module (ice-9 match)
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#:use-module (ice-9 vlist)
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#:export (mcron-configuration
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mcron-configuration?
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mcron-configuration-mcron
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mcron-configuration-jobs
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mcron-configuration-log?
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mcron-configuration-log-file
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mcron-configuration-log-format
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mcron-configuration-date-format
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mcron-service-type))
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;;; Commentary:
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;;;
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;;; This module implements a service that to run instances of GNU mcron, a
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;;; periodic job execution daemon. Example of a service:
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;;
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;; (service mcron-service-type
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;; (mcron-configuration
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;; (jobs (list #~(job next-second-from
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;; (lambda ()
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;; (call-with-output-file "/dev/console"
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;; (lambda (port)
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;; (display "hello!\n" port)))))))))
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;;;
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;;; Code:
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(define list-of-gexps?
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(list-of gexp?))
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(define-maybe/no-serialization string)
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(define-configuration/no-serialization mcron-configuration
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(mcron
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(file-like mcron)
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"The mcron package to use.")
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(jobs
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(list-of-gexps '())
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"This is a list of gexps (@pxref{G-Expressions}), where each gexp
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corresponds to an mcron job specification (@pxref{Syntax, mcron job
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specifications,, mcron, GNU@tie{}mcron}).")
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(log?
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(boolean #t)
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"Log messages to standard output.")
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(log-file
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(string "/var/log/mcron.log")
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"Log file location.")
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(log-format
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(string "~1@*~a ~a: ~a~%")
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"@code{(ice-9 format)} format string for log messages. The default value
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produces messages like @samp{@var{pid} @var{name}: @var{message}}
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(@pxref{Invoking mcron, Invoking,, mcron, GNU@tie{}mcron}).
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Each message is also prefixed by a timestamp by GNU Shepherd.")
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(date-format
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maybe-string
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"@code{(srfi srfi-19)} format string for date."))
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(define (job-files mcron jobs)
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"Return a list of file-like object for JOBS, a list of gexps."
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(define (validated-file job)
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;; This procedure behaves like 'scheme-file' but it runs 'mcron
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;; --schedule' to detect any error in JOB.
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(computed-file "mcron-job"
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(with-imported-modules '((guix build utils))
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#~(begin
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(use-modules (guix build utils))
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(call-with-output-file "prologue"
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(lambda (port)
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;; This prologue allows 'mcron --schedule' to
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;; proceed no matter what #:user option is passed
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;; to 'job'.
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(write '(set! getpw
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(const (getpwuid (getuid))))
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port)))
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(call-with-output-file "job"
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(lambda (port)
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(write '#$job port)))
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(invoke #+(file-append mcron "/bin/mcron")
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"--schedule=20" "prologue" "job")
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(copy-file "job" #$output)))
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#:options '(#:env-vars (("COLUMNS" . "150")))))
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(map validated-file jobs))
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(define (shepherd-schedule-action mcron files)
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"Return a Shepherd action that runs MCRON with '--schedule' for the given
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files."
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(shepherd-action
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(name 'schedule)
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(documentation
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"Display jobs that are going to be scheduled.")
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(procedure
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#~(lambda* (_ #:optional (n "5"))
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;; XXX: This is a global side effect.
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(setenv "GUILE_AUTO_COMPILE" "0")
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;; Run 'mcron' in a pipe so we can explicitly redirect its output to
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;; 'current-output-port', which at this stage is bound to the client
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;; connection.
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(let ((pipe (open-pipe* OPEN_READ
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#$(file-append mcron "/bin/mcron")
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(string-append "--schedule=" n)
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#$@files)))
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(let loop ()
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(match (read-line pipe 'concat)
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((? eof-object?)
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(catch 'system-error
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(lambda ()
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(zero? (close-pipe pipe)))
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(lambda args
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;; There's a race with the SIGCHLD handler, which
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;; could call 'waitpid' before 'close-pipe' above does. If
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;; we get ECHILD, that means we lost the race, but that's
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;; fine.
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(or (= ECHILD (system-error-errno args))
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(apply throw args)))))
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(line
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(display line)
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(loop)))))))))
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(define (mcron-shepherd-services config)
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(match-record config <mcron-configuration>
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(mcron jobs log? log-file log-format date-format)
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(if (eq? jobs '())
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'() ;nothing to do
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(let ((files (job-files mcron jobs)))
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(list (shepherd-service
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(provision '(mcron))
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(requirement '(user-processes))
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(modules `((srfi srfi-1)
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(srfi srfi-26)
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(ice-9 popen) ;for the 'schedule' action
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(ice-9 rdelim)
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(ice-9 match)
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,@%default-modules))
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(start #~(make-forkexec-constructor
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(list #$(file-append mcron "/bin/mcron")
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#$@(if log?
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`("--log" "--log-format" ,log-format
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,@(if (maybe-value-set? date-format)
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(list "--date-format"
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date-format)
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'()))
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'())
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#$@files)
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;; Disable auto-compilation of the job files and
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;; set a sane value for 'PATH'.
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#:environment-variables
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(cons* "GUILE_AUTO_COMPILE=0"
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"PATH=/run/current-system/profile/bin"
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(remove (cut string-prefix? "PATH=" <>)
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(environ)))
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#:log-file #$log-file))
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(stop #~(make-kill-destructor))
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(actions
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(list (shepherd-schedule-action mcron files)))))))))
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(define mcron-service-type
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(service-type (name 'mcron)
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(description
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"Run the mcron job scheduling daemon.")
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(extensions
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(list (service-extension shepherd-root-service-type
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mcron-shepherd-services)
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(service-extension profile-service-type
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(compose list
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mcron-configuration-mcron))))
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(compose concatenate)
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(extend (lambda (config jobs)
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(mcron-configuration
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(inherit config)
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(jobs (append (mcron-configuration-jobs config)
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jobs)))))
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(default-value (mcron-configuration)))) ;empty job list
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;;;
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;;; Generate documentation.
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;;;
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(define (generate-doc)
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(configuration->documentation 'mcron-configuration))
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;;; mcron.scm ends here
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