44554e7133
This reverts commit 39e4e00f75, with fixes for
the guix home issues reported and another one found while reconfiguring berlin
in the subsequent commit.
200 lines
7.9 KiB
Scheme
200 lines
7.9 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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;;;
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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-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-configuration/no-serialization mcron-configuration
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(mcron (file-like mcron) "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? (boolean #t) "Log messages to standard output.")
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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}:
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@var{message}\"} (@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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(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
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(match-lambda
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(($ <mcron-configuration> mcron ()) ;nothing to do!
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'())
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(($ <mcron-configuration> mcron jobs log? log-format)
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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 (string-append #$mcron "/bin/mcron")
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#$@(if log?
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#~("--log" "--log-format" #$log-format)
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#~())
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#$@files)
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;; Disable auto-compilation of the job files and set a
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;; 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 "/var/log/mcron.log"))
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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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