Offlineimap is not able to run as a shepherd service

[Lars Rustand <rustand.lars@gmail.com>]

Hello, I'm trying to run offlineimap as a shepherd service, but it fails
in a weird way. I'm able to run offlineimap just fine when I start from
the commandline, but inside the service it fails with this error:

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2023-12-07 10:31:13 Traceback:
2023-12-07 10:31:13   File "/gnu/store/g2231vkzbnncyj72085n1ylkh8hq16lm-offlineimap-8.0.0/lib/python3.10/site-packages/offlineimap/accounts.py", line 298, in syncrunner
2023-12-07 10:31:13     self.__sync()
2023-12-07 10:31:13   File "/gnu/store/g2231vkzbnncyj72085n1ylkh8hq16lm-offlineimap-8.0.0/lib/python3.10/site-packages/offlineimap/accounts.py", line 374, in __sync
2023-12-07 10:31:13     remoterepos.getfolders()
2023-12-07 10:31:13   File "/gnu/store/g2231vkzbnncyj72085n1ylkh8hq16lm-offlineimap-8.0.0/lib/python3.10/site-packages/offlineimap/repository/IMAP.py", line 681, in getfolders
2023-12-07 10:31:13     imapobj = self.imapserver.acquireconnection()
2023-12-07 10:31:13   File "/gnu/store/g2231vkzbnncyj72085n1ylkh8hq16lm-offlineimap-8.0.0/lib/python3.10/site-packages/offlineimap/imapserver.py", line 683, in acquireconnection
2023-12-07 10:31:13     e.args[0][:35] == 'IMAP4 protocol error: socket error:':
2023-12-07 10:31:13
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I am using the exact same commandline arguments both in the shepherd
service and when running offlineimap manually, so Shepherd must be doing
something weird that causes offlineimap to fail.

Here is my service definition:

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(define-module (lrustand services offlineimap)
  #:use-module (gnu)
  #:use-module (gnu services)
  #:use-module (gnu packages mail)
  #:use-module (gnu services shepherd)
  #:use-module (gnu services configuration)
  #:use-module (guix gexp)
  #:use-module (guix records)
  #:use-module (ice-9 curried-definitions)
  #:use-module (gnu home services)
  ;; For the 'home-shepherd-service-type' mapping.
  #:use-module (gnu home services shepherd)
  #:export (offlineimap-configuration
            offlineimap-configuration?

            offlineimap-configuration-log-file
            offlineimap-configuration-pid-file

            offlineimap-shepherd-service
            offlineimap-service-type
            home-offlineimap-service-type))

(define-configuration/no-serialization offlineimap-configuration
  (pid-file
   (string "/var/run/offlineimap.pid")
   "Where to store the PID file.")
  (config-file
   (string "/home/lars/.config/offlineimap/config")
   "Configuration file to use.")
  (log-file
   (string "/home/lars/offlineimap.log")
   "File where ‘offlineimap’ writes its log to.")
  (extra-options
   (list-of-strings '())
   "This option provides an “escape hatch” for the user to provide
arbitrary command-line arguments to ‘offlineimap’ as a list of strings.")
  (home-service?
   (boolean for-home?)
   ""))

(define offlineimap-shepherd-service
  (match-record-lambda <offlineimap-configuration>
    (pid-file config-file log-file extra-options home-service?)
    (list (shepherd-service
           (provision '(offlineimap))
           (documentation "")
           (requirement (if home-service? '() '(user-processes)))
           (start #~(make-forkexec-constructor
                      (list (string-append #$offlineimap
                                           "/bin/offlineimap")
                             #$@extra-options
                             "-c" #$config-file
                             "-l" #$log-file)
                     #:log-file #$log-file
                     #:pid-file #$pid-file))
           (stop #~(make-kill-destructor))
           (one-shot? #f)
           (respawn? #t)))))

(define offlineimap-service-type
  (service-type
   (name 'offlineimap)
   (extensions
    (list (service-extension shepherd-root-service-type
                             offlineimap-shepherd-service)))
   (default-value (offlineimap-configuration))
   (description
    "Synchronize remote IMAP mail with local Maildir.")))

(define home-offlineimap-service-type
  (service-type
   (inherit (system->home-service-type offlineimap-service-type))
   (default-value (for-home (offlineimap-configuration)))))
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