Code review comment for lp:~jjo/charms/precise/postgresql/support-no-explicit-version_and_trusty-pg93

> I don't think allowing an unspecified PostgreSQL version is a good idea. It
> means charm deployment is not repeatable, as which version is deployed depends
> on the state of the archive. I don't want 9.4 (or worse, 9.4 beta) being
> installed when my apps are tested with 9.3 just because a newer version is
> available in the archive. This would also break replication, as a unit does
> not know what version the other units in the service are using until after the
> install hook is run and the unit attempt's to join the service's peer
> relation. Archives will not always be under user control, in particular
> apt.postgresql.org for official Debian and Ubuntu backports.
>
> If we really need this so the default version under trusty is 9.3, and the
> default version under precise is 9.1, I think we just want to check
> 'lsb_release -sc' and hard code the default version to the codename. This may
> still cause surprises, but would be repeatable.

I'm fine with hardcoding it, as far as we have a single charm that can be
deployed to either precise,trusty without requiring the user to overload
the config with a version that's already well-known/mapped for this distro
release.

>
> If we keep the 'apt' import, do we need to add python-apt to the default list
> of packages to install?

Good point, fwiw afaicT both precise,trusty it was already installed there.