Re: gitweb: dpkg trigger cycle via apache2
On 2015-01-07 21:29, Jonathan Nieder wrote:
> Hi Niels,
>
> Niels Thykier wrote:
>
>> Debian `dpkg' package management program version 1.17.23 (amd64).
> [...]
>> chain of packages whose triggers are or may be responsible:
>> gitweb -> gitweb
>> packages' pending triggers which are or may be unresolvable:
>> gitweb: /usr/share/apache2/apache2-maintscript-helper
> [...]
>> This simulates an upgrade scenario, where apache2 might be
>> temporarily deconfigured while gitweb remains configured. If this
>> happens, dpkg is unable to recover as the cycle due to "await" trigger
>> AND the dependency requires both packages to be configured.
>
> Puzzling. What prevents the following upgrade path?
>
> 1. deconfigure gitweb
> 2. configure apache2
> 3. configure gitweb
>
Indeed, it seems to solve the issue by doing it manually. I believe a
second call to dpkg --configure --pending will in fact "just work(tm)".
So yes, there is a recovery. That said, it can still cause an
unpleasant upgrade.
> I'm probably missing something obvious, I'm confused at where the
> cycle is here. It seems like gitweb depends on apache2 but not vice
> versa.
>
> Thanks,
> Jonathan
>
It was discussed in length in [1], when Johannes tried to devise a
script for detecting this cycles. I suspect that might be a vastly
better read than what my memory can produce atm. :)
~Niels
[1] https://lists.debian.org/debian-dpkg/2014/12/msg00015.html
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