Restart openqa-worker-auto-restart@.service on pkg upgrade without interrupting jobs

[Martchus]

• Only affects openqa-worker-auto-restart@.service units but not other
  worker units
• Does nothing if no such units are running
• The shell code is adapted from the %service_del_postun macro (from
  /usr/lib/rpm/macros.d/macros.systemd as provided by the
  systemd-rpm-macros package)
• See https://progress.opensuse.org/issues/80908#note-8

[okurz]

+1

[Martchus]

Seems like it worked:

Feb 01 10:38:28 linux-9lzf worker[15778]: [info] Registering with openQA localhost
Feb 01 10:38:28 linux-9lzf worker[15778]: [warn] Failed to register at localhost - connection error: Connection refused - trying again in 10 seconds
Feb 01 10:38:30 linux-9lzf systemd[1]: openqa-worker-auto-restart@1.service: Sent signal SIGHUP to main process 15778 (worker) on client request.
Feb 01 10:38:30 linux-9lzf worker[15778]: [info] Received signal HUP
Feb 01 10:38:30 linux-9lzf systemd[1]: openqa-worker-auto-restart@1.service: Succeeded.
Feb 01 10:38:30 linux-9lzf systemd[1]: openqa-worker-auto-restart@1.service: Scheduled restart job, restart counter is at 1.
Feb 01 10:38:30 linux-9lzf systemd[1]: Stopped openQA Worker #1.
Feb 01 10:38:30 linux-9lzf systemd[1]: Starting openQA Worker #1...
Feb 01 10:38:30 linux-9lzf systemd[1]: Started openQA Worker #1.
Feb 01 10:38:31 linux-9lzf worker[17232]: [info] worker 1:

And also other active worker slots are affected, e.g.:

Feb 01 10:38:28 linux-9lzf worker[15987]: [warn] Failed to register at localhost - connection error: Connection refused - trying again in 10 seconds
Feb 01 10:38:30 linux-9lzf systemd[1]: openqa-worker-auto-restart@3.service: Sent signal SIGHUP to main process 15987 (worker) on client request.
Feb 01 10:38:30 linux-9lzf worker[15987]: [info] Received signal HUP
Feb 01 10:38:30 linux-9lzf systemd[1]: openqa-worker-auto-restart@3.service: Succeeded.
Feb 01 10:38:30 linux-9lzf systemd[1]: openqa-worker-auto-restart@3.service: Scheduled restart job, restart counter is at 1.
Feb 01 10:38:30 linux-9lzf systemd[1]: Stopped openQA Worker #3.
Feb 01 10:38:30 linux-9lzf systemd[1]: Starting openQA Worker #3...
Feb 01 10:38:30 linux-9lzf systemd[1]: Started openQA Worker #3.
Feb 01 10:38:31 linux-9lzf worker[17233]: [info] worker 3:

Apparently the postrun script of the already installed package is invoked on updates (and not the postrun script of the new package). Hence it does not work already on the first upgrade and still takes effect one last time when downgrading to a previous package version without this.