Re: Bug#814240: systemd triggers break upgrades within unstable

[Zack Weinberg <zackw@panix.com>]

On Mon, Feb 29, 2016 at 12:18 PM, Manuel A. Fernandez Montecelo wrote:
>
>> DPkg::NoTriggers "true";
>> DPkg::ConfigurePending "true";
>> DPkg::TriggersPending "true";
>
>
> After talking about this bug a few days ago with APT Deities (David
> Kalnischkies, in this case), he told me that apt doesn't use "dpkg
> --triggers-only" by default.
>
> He believes that apt /could/ issue that command when
> "DPkg::TriggersPending" or "DPkg::ConfigurePending" are enabled, and
> possibly other similar ones (he didn't mention the specifics).
>
> Such options as marked as experimental and dangerous (man apt.conf) so
> maybe they are better left disabled unless there's a specific need to
> use them.

On the system with the problem, that setting comes from a file named
/etc/apt/apt.conf.d/triggers, whose entire contents are

# cat /etc/apt/apt.conf.d/triggers
DPkg::NoTriggers "true";
PackageManager::Configure "smart";
DPkg::ConfigurePending "true";
DPkg::TriggersPending "true";

It was last modified in 2011.  I have no memory of having created this
file, but it doesn't belong to any package either.  Searching the 'net
for that combination of options brings me to
https://raphaelhertzog.com/2011/05/30/trying-to-make-dpkg-triggers-more-useful-and-less-painful/
and bug #626599.  It is probable that I saw Raphael's blog post go by
and decided to try it out.

I have another computer that runs unstable, and which had not yet
received the systemd 229-2 update; I verified that it does *not* have
any of these settings and then ran the update.  It went through with
no problems.

So that's a pretty strong indicator that this non-default mode is the
cause of the problem.  And it's corroborated by the dpkg/apt logs on
the computer that didn't have these settings, which show no sign of
the problem in the past, as far as I can tell.  But just to make sure,
I would like to leave this bug open until another systemd update comes
along and I can confirm that disabling these settings addresses the
problem on the computer that definitely did have it.

zw