Re: Restart rsyslog only once after few packages are upgraded

[Michael Biebl <biebl@debian.org>]

Am 26.10.22 um 11:49 schrieb Jędrzej Dudkiewicz:
> I'm sorry if it was answered earlier, but I *really* couldn't find
> anything about it.
>
> I have few packages that are installed as part of a larger system on
> Debian running on BeagleBone. These packages frequently (for some
> strange reason - I'm not the only developer) modify files that go to
> the /etc/rsyslog.d/ directory. These files are not part of
> configuration, they are copied there by hand in postinstall script
> from known source, reason being that which file is copied depends on
> external configuration. This works without major problems. What is
> problematic is that when these packages are upgraded, they are
> upgraded few at a time, sometimes two are upgraded, sometimes four,
> sometimes all of them. Because of this each package contains the
> following:
>
> systemctl restart rsyslog
>
> in its postinstall script. As this causes rsyslog to be restarted a
> few times in a row it sometimes results in rsyslog not functioning.

This shouldn't be a problem in theory.
That said, rsyslog could be part of the upgrade process, so maybe is in 
an inconsistent state when you trigger the restart.
Would be interested to know more about the specific failures you 
encountered.

> Thus, my question:
>
> Is there a way to restart rsyslog only once, after all packages are
> installed? I hope for something similar to "dh $@ --with-systemd" in
> "rules" file (but "dh -l" does not show anything that looks like it
> should work). My guess is that it should possible to somehow combine
> "dh $@ --with-systemd" to achieve what I want, but I don't even know
> where should I start.

The rsyslog package already offers a dpkg trigger which does
`invoke-rc.d rsyslog try-restart || true`

This trigger is activated by packages installing files into /etc/rsyslog.d

But you can activate that trigger explicitly as well via
dpkg-trigger --now-await rsyslog


So, if your package ships a file in /etc/rsyslog.d/ everything should 
work ootb. If you create the file dynamically via maintscripts, you need 
to add an explicit dpkg trigger in your maintscripts.

Michael

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