[Freeipa-devel] idempotent installer [from LinuxAlt 2013]

[Jan Pazdziora]

On Fri, Nov 15, 2013 at 08:38:11AM +0100, Petr Spacek wrote:
> 
> The point is that you have a chance to fix the problem (reconfigure
> firewall, DNS etc.), run the installer again and it will finish the
> installation or fail later on some other problem. It means that you
> don't need to start from scratch. (This is exactly what was

However, there's still risk that the previous run make some partial
configuration based on wrong DNS, and the "finishing" run will fixup
the rest but those parts will not match.

> Also, it allows you to reproduce the failure again and again

Guaranting reliability of failures is pretty hard. ;-)

> I think you have much better position with declarative installer,

Declarative installers work when they work. Their handling of failures
is not that great. When installer written in bash or python fails,
you can immediatelly start the rollback. The declarative installer
will continue marching towards the goal you gave it, possibly
increasing the number of (wrong) changes which will need to be
restored.

-- 
Jan Pazdziora
Principal Software Engineer, Identity Management Engineering, Red Hat