We want to stop systemd from being added to docker images, because of rpm requiring systemctl.

[Chuck Anderson]

On Wed, Apr 30, 2014 at 10:28:56AM -0400, Adam Jackson wrote:
> On Wed, 2014-04-30 at 16:05 +0200, Kalev Lember wrote:
> 
> > I suspect just dropping the deps would break initial installations, e.g.
> > anaconda / livecd-creator. RPM uses the deps to order the transaction so
> > that systemd gets installed first, and the packages that ship service
> > files get installed later. Without the deps, rpm wouldn't know the order
> > in which it has to run the transaction.
> > 
> > For example, when a package bar has a postinstall script that does:
> > 
> >     systemctl enable bar.service >/dev/null 2>&1 || :
> > 
> > ... but if systemctl gets installed _after_ foo in the same transaction,
> > then the systemctl command never runs and service stays disabled.
> 
> If you are right, this is an argument for rpm collections, which we've
> had for ages now and should really start using.

What are "rpm collections" and how do they relate to "software
collections"?  How does this solve the package installation order
without dependencies?  It is hard to find anything useful by searching
for "rpm collections".