1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
|
;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2016, 2017, 2018, 2019, 2020 Ludovic Courtès <ludo@gnu.org>
;;; Copyright © 2022 Maxim Cournoyer <maxim.cournoyer@gmail.com>
;;;
;;; 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 configuration)
#:use-module (gnu services shepherd)
#:use-module (gnu packages guile-xyz)
#:use-module (guix deprecation)
#: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-format
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:
(define list-of-gexps?
(list-of gexp?))
(define-configuration/no-serialization mcron-configuration
(mcron
(file-like mcron)
"The mcron package to use.")
(jobs
(list-of-gexps '())
"This is a list of gexps (@pxref{G-Expressions}), where each gexp
corresponds to an mcron job specification (@pxref{Syntax, mcron job
specifications,, mcron, GNU@tie{}mcron}).")
(log?
(boolean #t)
"Log messages to standard output.")
(log-format
(string "~1@*~a ~a: ~a~%")
"@code{(ice-9 format)} format string for log messages. The default value
produces messages like @samp{@var{pid} @var{name}: @var{message}}
(@pxref{Invoking mcron, Invoking,, mcron, GNU@tie{}mcron}).
Each message is also prefixed by a timestamp by GNU Shepherd."))
(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
(match-lambda
(($ <mcron-configuration> mcron ()) ;nothing to do!
'())
(($ <mcron-configuration> mcron jobs log? log-format)
(let ((files (job-files mcron jobs)))
(list (shepherd-service
(provision '(mcron))
(requirement '(user-processes))
(modules `((srfi srfi-1)
(srfi srfi-26)
(ice-9 popen) ;for the 'schedule' action
(ice-9 rdelim)
(ice-9 match)
,@%default-modules))
(start #~(make-forkexec-constructor
(list (string-append #$mcron "/bin/mcron")
#$@(if log?
#~("--log" "--log-format" #$log-format)
#~())
#$@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 "/var/log/mcron.log"))
(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)
(jobs (append (mcron-configuration-jobs config)
jobs)))))
(default-value (mcron-configuration)))) ;empty job list
;;;
;;; Generate documentation.
;;;
(define (generate-doc)
(configuration->documentation 'mcron-configuration))
;;; mcron.scm ends here
|