fai-debconf and softupdate

[Gebhardt Thomas]

Hi,

just got the same problem as

Date: Mon, 12 May 2008 16:56:31 +0200
From: Eymen Alyaz <alyaz at ins.uni-bonn.de>
Subject: exim4-config with debconf fails

and found that this is due to an unexpected behaviour of fai-debconf while 
performing a "fai softupdate" .

I use to keep the vanilla fai config just as it is and tie local modifications
to local classes which superseed the default fai configuration. This policy
helps me to keep in sync with fai upstream updates.

But this does not work with fai-debconf, let's see why:

FAIBASE has the debconf config:
exim4-config exim4/dc_eximconfig_configtype select local delivery only; ...

which is superseeded by MYCLASS:
exim4-config    exim4/dc_eximconfig_configtype  select  mail sent by ... 

because MYCLASS follows FAIBASE in the class hierarchy.

So the debconf database of my host has
exim4-config    exim4/dc_eximconfig_configtype  select  mail sent by ...

Now comes fai-debconf and softupdate:
fai-debconfig doesn't bother about class hierarchy but only looks for changed
debconf entries. Therefore the MYCLASS debconf line is discarded during the
diff and the debconf database (and the host config) gets reverted to the 
default FAIBASE entry, a behaviour that conflicts with the principle of least 
surprise.

fai-debconf should process conflicting entries in $LOGDIR/debconf.data
(later entries overwrite earlier entries) before performing a diff to the 
current debconf values.

SY, Th. Gebhardt