Per-Product Config file divergence

[Vít Ondruch]

Dne 11.3.2014 13:25, Stephen Gallagher napsal(a):
> On 03/11/2014 02:46 AM, Vít Ondruch wrote:
> > Dne 10.3.2014 17:10, Toshio Kuratomi napsal(a):
> >> At last week's FESCo meeting, the fact that Products desired to
> >> have divergent configuration was briefly touched on.  On
> >> Thursday, a few FPC members had a brainstorming session about it
> >> and on Friday, sgallagh and that brainstorming continued with
> >> sgallagh, adamw, tflink, notting, and myself.  We came up with a
> >> tentative idea here:
> >>
> >> https://fedoraproject.org/wiki/User:Toshio/Product_Divergence_(config)
> >>
> >>
> >>
> The idea is to allow config file divergence via the alternatives system as
> >> that already provides us with a commandline tool and some
> >> structure to
> > build
> >> on.  We'd still have to write a few pieces to complete the
> >> picture but it seemed to be a better starting point than using
> >> rpm Conflicts between config-packages.
> >>
> >> Anyone have thoughts on this potential path?
> >>
> >> -Toshio
> >>
> >>
>
>
> > With rich dependencies coming to Fedora, wouldn't be better to wait
> > for a bit and benefit from them? We would have product specific
> > configuration in subpackages and installed it such as "Requires:
> > fedora-product-cloud & foo-config-cloud; Requires:
> > fedora-product-server & foo-config-server".
>
>
>
> That unfortunately doesn't address the issue in a realistic way. I
> don't think there's a way that dependency resolution can resolve that
> in a positive way. The closest I can see coming up with would be:
>
> == foo ==
> Requires: foo-config
>
> == foo-config-server ==
> Provides: foo-config = 1.0
> Conflicts: fedora-release-workstation
> Conflicts: fedora-release-cloud
>
> == foo-config-workstation ==
> Provides: foo-config = 1.0
> Conflicts: fedora-release-server
> Conflicts: fedora-release-cloud
>
> == foo-config-cloud ==
> Provides: foo-config = 1.0
> Conflicts: fedora-release-workstation
> Conflicts: fedora-release-server
>
> == foo-config-default ==
> Provides: foo-config = 2.0
> Conflicts: fedora-release-workstation
> Conflicts: fedora-release-server
> Conflicts: fedora-release-cloud
>
> So, if installed on a Product, yum would resolve whichever config
> subpackage doesn't hit any conflicts (which would be the matching
> version or the default, if not on a product).
>
>
> There are a couple down-sides to this approach:
> 1) It eliminates the possibility of having multiple Products installed
> on the same system. Whether we care about this is being debated
> elsewhere, but this approach would make it impossible.
> 2) It might make life a real pain in the neck to deal with adding new
> Products to Fedora, since any package providing custom authentication
> will have to tweak Provides: and Conflicts: to ensure that the new
> Product gets reasonable defaults.

You are speaking about how to achieve that in current Fedora, if I
understand that correctly. I am speaking about F22, where RPM/DNF should
hopefully support rich dependencies.

BTW if each package contains the same file, lets say /etc/foo.cfg, but
the content of this file is different between the packages, they
conflicts without explicit conflict, if I am not mistaken.


Vít

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