Bug#1068439: systemd-cron: cron-update causes re-run of some past timers

[Maximilian Stein]

Thanks for your quick reply.

Am 06.04.24 um 06:37 schrieb Alexandre Detiste:
>
> Can you please try to reproduce the problem without systemd-cron involved;
> by copying the .timer / .service / .sh triplet from /run/systemd/generator
> into /etc/systemd/system and see what happens when
> you do manually what cron-update.service would do.
>
> It does:
>   - systemctl daemon-reload
>   - systemctl restart <your_job>.timer  (via cron.target)
>   - systemctl reset-failed <your_job>.timer
> (hint: systemctl cat cron-update.service)
>
> If the same problem persists; then the bug is definitively in systemd itself.
Yes, indeed, on restart of the .timer unit, the service is executed 
immediately!

So, my mwe looks like this:

$ cat /etc/systemd/system/timerconfusion.timer

[Timer]
Unit=timerconfusion.service
OnCalendar=*-*-* *:0/5

$ cat /etc/systemd/system/timerconfusion.service
[Service]
Type=oneshot
ExecStart=/bin/bash -c 'date --iso-8601=seconds >> 
/var/log/timerconfusion.log'

$ systemctl daemon-reload

$ systemctl starttimerconfusion.timer

$ # wait until timer is executed for the first time

$ cat /var/log/timerconfusion.log

2024-04-06T12:55:07+02:00

$ systemctl restart timerconfusion.timer

$ cat /var/log/timerconfusion.log

2024-04-06T12:55:07+02:00
2024-04-06T12:55:24+02:00


In my test, only the very first restart of the timer after a regular 
scheduled timer execution caused an extraneous service start.

Thanks.

Best,
Maximilian