Re: deb/rpm package purge

["Laszlo Boszormenyi (GCS)" <gcs@debian.hu>]

On Wed, 2013-03-20 at 05:48 -0700, Sage Weil wrote:
> On Wed, 20 Mar 2013, Laszlo Boszormenyi (GCS) wrote:
> > On Tue, 2013-03-19 at 15:59 -0700, Sage Weil wrote:
> > > As a point of comparison, mysql removes the config files but not 
> > > /var/lib/mysql.
> > > The question is, is that okay/typical/desireable/recommended/a bad idea?
 I should have asked this sooner. Do you know _any_ program that removes
your favorite music collection, your family photos or your business
emails when you do uninstall it?
I suspect that your question was theoretical instead.

On Wed, 2013-03-20 at 09:48 -0500, Mark Nelson wrote:
On 03/20/2013 07:48 AM, Sage Weil wrote:
> It's not as important given that it won't outright destroy the cluster, 
> but perhaps we should also leave /etc/ceph untouched on purge if a 
> ceph.conf file has been placed in it (since that also was not installed 
> by the package, but rather by a user?).  I figure we should probably try 
> to get it right now.  The message about the directory not being empty 
> sounds good.
 Sure, personal user data must be kept. If it's a big amount of data and
left under a non-standard location (ie, not under his/her $HOME) then
s/he should be informed where those files are located on purge.

> My thought here is:
> - remove anything created by the packages in /var/lib/ceph that has been 
> untouched since package installation.
> - remove /var/lib/ceph if it has been untouched
 Please note that you have to store some kind of checksum for the files
then. Probably md5sum is enough.

> - remove /etc/ceph if it has been untouched
 This is an other case. dpkg itself handle package files here, called
conffiles. I should check the method (md5sum and/or sha1 variants) used
for the checksum on these files. On upgrade it's used not to overwrite
local changes by the user. It may worth to read a bit more about it[1]
from Raphaël Hertzog. He is the co-author of Debian Administrator's
handbook[2] BTW.
 On purge dpkg will remove the package conffiles no matter what. It
won't check if those were changed or not. You may not mark the files
under /etc as conffiles, but then you'll lose the mentioned
merge logic on upgrades; dpkg will just overwrite those.
 In short, files under /var/lib/ceph are the only candidates for
in-package checksumming. How many files under there that essential for
the packages?

Laszlo/GCS
[1] http://raphaelhertzog.com/2010/09/21/debian-conffile-configuration-file-managed-by-dpkg/
[2] http://debian-handbook.info/

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