Subject: Re: [bug#50504] [PATCH] home-services: Add Mcron.

From: Andrew Tropin <[email-masked]>
Date: Mon, 13 Sep 2021 09:44:18 +0300

On 2021-09-10 20:22, Xinglu Chen wrote:

> On Fri, Sep 10 2021, Andrew Tropin wrote:
>
>> * gnu/home-services/mcron.scm: New file.
>> * gnu/local.mk: Add this.
>> * doc/guix.texi: Add documentation about Mcron Home Service.
>> ---
>>
>> This is the last of home services I consider "must-have" for wip-guix-home.
>>
>> It reuses two functions from (gnu services mcron) via @@, which can be
>> considered as a hack, the alternative solution is to expose those functions
>> via #:export, I can do it if it's a preffered way or suggest other ideas,
>> please.  The discussion on this topic: https://issues.guix.gnu.org/47238
>> Included Ludovic and Xinglu in CC.
>
> An alternative would be put it the (gnu service mcron) to share more
> code between system service and home service.  This was discussed
> briefly on rde-devel[1].  It might be worth discussing this issue on
> guix-devel before we add too many home service.
>

I'll make a thread on possible modules naming for home services later
this week and will discuss this thing too.

>
>> I took a brief look at the testing approach, seems the most relevant is
>> guix-system.sh and it is just a shell script, which runs a few guix system
>> subcommand and check if they fail or succeed.  Please let me know, what is a
>> preferred way for writing tests and I'll try to provide some tests for Guix
>> Home in the separate patch.
>
> The ‘guix-system.sh’ script seems to only test the ‘guix system’
> command, which doesn’t seem that related to the home services.  I guess
> we could check the contents of the generated config files.  There is
> (gnu build marionette) which creates a VM; we could then check that the
> relevant process is running.  Maybe there is a better approach, though.
>

It was a general question about tests for Guix Home, not Mcron home
service, sorry for the confusion.

> 
> [1]:
> <https://lists.sr.ht/~abcdw/rde-devel/%3C87y2cqifpx.fsf%40yoctocell.xyz%3E>
>
>>  doc/guix.texi               |  31 +++++++++-
>>  gnu/home-services/mcron.scm | 115 ++++++++++++++++++++++++++++++++++++
>>  gnu/local.mk                |   1 +
>>  3 files changed, 146 insertions(+), 1 deletion(-)
>>  create mode 100644 gnu/home-services/mcron.scm
>>
>> diff --git a/doc/guix.texi b/doc/guix.texi
>> index e546fcc0d2..a7eacad762 100644
   >> --- a/doc/guix.texi
>> +++ b/doc/guix.texi
>> @@ -35685,7 +35685,36 @@ for example).
>>  @cindex mcron
>>  @cindex scheduling jobs
>>  
>> -mcron info here
>> +The @code{(gnu home-services mcron)} module provides an interface to
>> +GNU@tie{}mcron, a daemon to run jobs at scheduled times (@pxref{Top,,,
>> +mcron, GNU@tie{}mcron}).  The information about system's mcron is
>> +applicable here (@pxref{Scheduled Job Execution}), the only difference
>> +for home services is that they have to be declared in
>> +@code{home-envirnoment} record instead of @code{operating-system}.
>
> “declared in a @code{home-environemnt} record instead of a
> @code{operating-system} record.”
>
>> +@defvr {Scheme Variable} home-mcron-service-type
>> +This is the type of the @code{mcron} home service, whose value is an
>
> Why @code{mcron}?  I would use “Mcron” instead.
>

Good idea, but I sticked with the way it's done in a description of
system mcron service.

>
>> +@code{home-mcron-configuration} object.  It allows one to manage tasks
>
> “It allows one to manage scheduled tasks.”
>
>> +This service type can be the target of a service extension that provides
>> +it additional job specifications (@pxref{Service Composition}).  In
>
> s/it//
>
>> +other words, it is possible to define services that provide additional
>> +mcron jobs to run.
>> +@end defvr
>> +
>> +@deftp {Data Type} home-mcron-configuration
>> +Data type representing the configuration of mcron.
>> +
>> +@table @asis
>> +@item @code{mcron} (default: @var{mcron})
>> +The mcron package to use.
>> +
>> +@item @code{jobs}
>> +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}).
>> +@end table
>> +@end deftp
>>  
>>  @node Shepherd Home Service
>>  @subsection Managing User's Daemons
>> diff --git a/gnu/home-services/mcron.scm b/gnu/home-services/mcron.scm
>> new file mode 100644
>> index 0000000000..fdfde179a5
>> --- /dev/null
>> +++ b/gnu/home-services/mcron.scm
>> @@ -0,0 +1,115 @@
>> +;;; GNU Guix --- Functional package management for GNU
>> +;;; Copyright © 2021 Andrew Tropin <[email-masked]>
>> +;;; Copyright © 2021 Xinglu Chen <[email-masked]>
>> +;;;
>> +;;; 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 home-services mcron)
>> +  #:use-module (gnu packages guile-xyz)
>> +  #:use-module (gnu home-services)
>> +  #:use-module (gnu home-services shepherd)
>> +  #:use-module (gnu services shepherd)
>> +  #:use-module (guix records)
>> +  #:use-module (guix gexp)
>> +  #:use-module (srfi srfi-1)
>> +  #:use-module (ice-9 match)
>> +
>> +  #:export (home-mcron-configuration
>> +            home-mcron-service-type))
>> +
>> +;;; Commentary:
>> +;;
>> +;; Service for the GNU mcron cron job manager.
>> +;;
>> +;; Example configuration, the first job runs mbsync once every ten
>> +;; minutes, the second one writes "Mcron service" to ~/mcron-file once
>> +;; every minute.
>> +;;
>> +;; (service home-mcron-service-type
>> +;;            (home-mcron-configuration
>> +;;             (jobs (list #~(job '(next-minute
>> +;;                                  (range 0 60 10))
>> +;;                                (lambda ()
>> +;;                                  (system* "mbsync" "--all")))
>> +;;                         #~(job next-minute-from
>> +;;                                (lambda ()
>> +;;                                  (call-with-output-file (string-append (getenv "HOME")
>> +;;                                                                        "/mcron-file")
>> +;;                                    (lambda (port)
>> +;;                                      (display "Mcron service" port)))))))))
>> +;;
>> +;;; Code:
>> +
>> +(define-record-type* <home-mcron-configuration> home-mcron-configuration
>> +  make-home-mcron-configuration
>> +  home-mcron-configuration?
>> +  (package home-mcron-configuration-package ; package
>> +           (default mcron))
>> +  (jobs home-mcron-configuration-jobs   ; list of jobs
>> +        (default '())))
>> +
>> +(define job-files (@@ (gnu services mcron) job-files))
>> +(define shepherd-schedule-action
>> +  (@@ (gnu services mcron) shepherd-schedule-action))
>> +
>> +(define home-mcron-shepherd-services
>> +  (match-lambda
>> +    (($ <home-mcron-configuration> mcron '()) ; no jobs to run
>> +     '())
>> +    (($ <home-mcron-configuration> mcron jobs)
>> +     (let ((files (job-files mcron jobs)))
>> +       (list (shepherd-service
>> +              (documentation "User cron jobs.")
>> +              (provision '(mcron))
>> +              (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 #$(file-append mcron "/bin/mcron") #$@files)
>> +                        #:log-file (string-append
>> +                                    (or (getenv "XDG_LOG_HOME")
>> +                                        (format #f "~a/.local/var/log"
>> +                                                (getenv "HOME")))
>> +                                    "/mcron.log")))
>> +              (stop #~(make-kill-destructor))
>> +              (actions
>> +               (list (shepherd-schedule-action mcron files)))))))))
>> +
>> +(define home-mcron-profile (compose list home-mcron-configuration-package))
>> +
>> +(define (home-mcron-extend config jobs)
>> +  (home-mcron-configuration
>> +   (inherit config)
>> +   (jobs (append (home-mcron-configuration-jobs config)
>> +                 jobs))))
>> +
>> +(define home-mcron-service-type
>> +  (service-type (name 'home-mcron)
>> +                (extensions
>> +                 (list (service-extension
>> +                        home-shepherd-service-type
>> +                        home-mcron-shepherd-services)
>> +                       (service-extension
>> +                        home-profile-service-type
>> +                        home-mcron-profile)))
>> +                (compose concatenate)
>> +                (extend home-mcron-extend)
>> +                (default-value (home-mcron-configuration))
>> +                (description
>> +                 "Install and configure the GNU mcron cron job manager.")))
>> diff --git a/gnu/local.mk b/gnu/local.mk
>> index 31ad1a43db..8212bc5391 100644
>> --- a/gnu/local.mk
>> +++ b/gnu/local.mk
>> @@ -80,6 +80,7 @@ GNU_SYSTEM_MODULES =				\
>>    %D%/home-services/configuration.scm		\
>>    %D%/home-services/shells.scm			\
>>    %D%/home-services/shepherd.scm		\
>> +  %D%/home-services/mcron.scm			\
>>    %D%/home-services/utils.scm			\
>>    %D%/home-services/xdg.scm			\
>>    %D%/image.scm					\
>> -- 
>> 2.33.0