[php-maint] Bug#774559: Bug#774559: php5: dpkg trigger cycle between libapache2-mod-php5{, filter} and php5-common

[Ondřej Surý]

Hi Niels,

using noawait fixes the issue:

root at lettie:/tmp# dpkg --unpack php5-common_5.6.4+dfsg-3_amd64.deb       
(Reading database ... 15181 files and directories currently installed.)
Preparing to unpack php5-common_5.6.4+dfsg-3_amd64.deb ...
Unpacking php5-common (5.6.4+dfsg-3) over (5.6.4+dfsg-3) ...
root at lettie:/tmp# dpkg --configure --pending
Setting up php5-common (5.6.4+dfsg-3) ...
Processing triggers for libapache2-mod-php5 (5.6.4+dfsg-3) ...

Thanks for catching that.

Cheers,
Ondrej

On Sun, Jan 4, 2015, at 13:17, Niels Thykier wrote:
> Package: src:php5
> Version: 5.6.4+dfsg-1
> Severity: serious
> 
> Hi,
> 
> The libapache2-mod-php5 and libapache2-mod-php5filter packages have a
> trigger cycle via the php5-common package.  This was detected by a
> script on jenkins.debian.net[1].
> 
> Steps to reproduce the cycle (in a Jessie/sid chroot):
> 
> """
> apt-get install libapache2-mod-php5 php5-common
> dpkg --unpack
> /var/cache/apt/archives/php5-common_${PHP5-COMMON_VERSION}_*.deb
> dpkg --configure --pending
> """
> (Similar for libapache2-mod-php5filter)
> 
> This simulates an upgrade scenario, where php5-common might be
> temporarily deconfigured while libapache2-mod-php5 (or
> libapache2-mod-php5filter) remains configured.  If this happens, dpkg
> is unable to recover as the cycle requires php5-common to be
> configured for it to run the trigger because the libapache2-mod-php5
> (and libapache2-mod-php5filter) depends on php5-common.
> 
> Known solutions:
> 
>  * Use no-await triggers.  *CAVEAT*: not always applicable.  Known
>  suitable
>    use cases includes "cache" handling, where the cache is allowed to be
>    out of date tempoarily.
>  * Reduce the dependency to Recommends.  *CAVEAT*: Rarely applicable.
>  * Rewrite the solution to avoid triggers entirely. *CAVEAT*: May be
>    non-trivial and likely to involve updates to at least
>    libapache2-mod-php5
>    and libapache2-mod-php5filter.
> 
> ~Niels
> 
> [1]
> https://jenkins.debian.net/view/Warnings/job/dpkg_sid_find_trigger_cycles/24/console
> 
> _______________________________________________
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> pkg-php-maint at lists.alioth.debian.org
> http://lists.alioth.debian.org/cgi-bin/mailman/listinfo/pkg-php-maint


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Ondřej Surý <ondrej at sury.org>
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