What would it take to make Software Collections work in Fedora?

[Stephen John Smoogen]

On 5 December 2012 15:35, Simo Sorce <simo at redhat.com> wrote:
> On Wed, 2012-12-05 at 15:14 -0700, Stephen John Smoogen wrote:
>> On 5 December 2012 15:07, Simo Sorce <simo at redhat.com> wrote:
>> > On Wed, 2012-12-05 at 16:10 -0500, Matthew Miller wrote:
>> >> On Wed, Dec 05, 2012 at 04:06:38PM -0500, Bill Nottingham wrote:
>> >> > > 1) Fedora is big enough that we have concrete situations where one size
>> >> > >    doesn't fit all. Puppet being broken on F17 (and probably F18 as well)
>> >> > >    is a fine example of something within the distro itself. And, as a
>> >> > >    platform for development, offering more version choices to our users
>> >> > >    would be a strength.
>> >> > <heretical>
>> >> > Well, then maybe Fedora's too big, and we should move to a model where
>> >> > Fedora is much smaller, and the grand Fedora universe contains things that
>> >> > are packaged *for* one or multiple Fedoras.
>> >> > </heretical>
>> >>
>> >> I have a cautious leaning in favor of this heresy. (*Looks around for angry
>> >> villagers with torches*.) It seems like (eventually) the Software
>> >> Collections mechanism might provide part of the infrastructure for doing
>> >> that cleanly.
>> >
>> > Isn't the risk that things will get more broken in collections, due to
>> > dependencies not being anymore strictly checked in a single repository
>> > and general disconnection between the 'main' repo and the specific
>> > collection ?
>>
>> I would expect any sort of Software Collections would be a large
>> Installer Beware item where Fedora does not guarantee anything (it
>> works, it will have security fixes, it doesn't break other stuff) and
>> it is between the Installer and the SC group that made the "bundle" to
>> deal with those issues.
>
> You still need to keep multiple versions of RPMs in the core repo.

Would that not cause a combinatoric nightmare with having to make sure
you had a libX11 compiled against say X number of glibc's or other
libraries that changed in the past so that you had the correct path so
that SC KDE-4.9 had the correct combination it wants of core stuff and
SC GNOME-3.9 had the correct combination for it?

What I have seen with similar commercial software collections you just
replicate everything you need to make your stack work all the way down
to libc if needed. It is stupid in that case but it will trend towards
that as more versions are required to be supported. In the end the OS
is mainly meant to be a firstboot to get the software collections
installed and working.

> Otherwise Collections may simply not be installable from scratch at all
> if any of their package depends strictly on a slightly older version
> than the bleeding edge.
>
> Incidentally keeping multiple version would also allow more graceful
> downgrades when needed, instead of forcing people to go to koji to
> download the older version because it disappeared from repos.

> Simo.
>
> --
> Simo Sorce * Red Hat, Inc * New York
>
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-- 
Stephen J Smoogen.
"Don't derail a useful feature for the 99% because you're not in it."
Linus Torvalds
"Years ago my mother used to say to me,... Elwood, you must be oh
so smart or oh so pleasant. Well, for years I was smart. I
recommend pleasant. You may quote me."  —James Stewart as Elwood P. Dowd