[CentOS-devel] Repository structures for SIG and variants in the future

As part of opening up the possibilities for SIGs and Variants within the
CentOS ecosystem, we need to give some thought to how repositories
should be structured so that different can cooperate with each other.


What we have discussed in the past, and what I'd like to propose to the
-devel community, is that we adopt a page similar to the KDE framework.
The way I envision this working is as follows:

 - Tier 1 repositories: Adds packages only. These repos may not update
or replace anything in the core distribution. (Example: EPEL)

 - Tier 2 repositories: These repositories may provide provide packages
that update or otherwise enhance packages in the base distribution, but
otherwise maintain compatibility.  (Example IUS

 - Tier 3 repositories: These repositories contain packages that
conflict with software inside the core distribution. This would be
Xen4CentOS for example, which replaces the kernel, and adds in xen
functionality.


Each tier may choose to rely on dependencies from repositories in the
tier  above it, but not the other way around. For example, the tier 3
Xen4 repository could choose to rely on packages from a tier1 like EPEL,
or a tier2 like IUS. However a tier1 or tier2 could not rely on a tier3.
A good real-world example of this would be rpmfusion's dependence on the
EPEL repository.


The other aspect of this that needs to be discussed is package
duplication. For example, several of the proposed SIGs have some overlap
in their packages. Would the preference here be that each SIG/Variant
maintain their own version of the package, or should there be a common
package set established? Both methods fit into the model described
above, and both have pros/cons associated.




What does the community think about this?




-- 
Jim Perrin
The CentOS Project | http://www.centos.org
twitter: @BitIntegrity | GPG Key: FA09AD77