Packaging Guidelines and Policies for EPEL
The packages in EPEL follow the Fedora Packaging and Maintenance Guidelines -- that includes, but is not limited to the packaging guidelines , the package naming guidelines , the package review guidelines and the packaging policies that are designed and maintained by the FESCo and Packaging Committee . There are however some EPEL-specific exceptions, which you can find below.
Please note that the sections "Guidelines" and "Policies" use their names on purpose. Consider the guidelines as something that should be followed normally, but doesn't have to if there are good reasons not to -- please ask the EPEL SIG members in case you are in doubt if your reasons are good. The word policies has a stronger meaning, and what is written in that section should be considered rules that must always be followed.
Package maintenance and update policy
EPEL wants to provide a common "look and feel" to the users of our repository. Thus the EPEL SIG wrote this policy that describes the regulations for package maintenance and updates in EPEL, that are a bit more strictly regulated then they are in Fedora now.
The goal is to have packages in EPEL that enhances the Enterprise Linux distributions the packages were build against without disturbing or replacing packages from that distribution. The packages in the repository should, if possible, be maintained in similar ways to the Enterprise Packages they were built against. In other words: have a mostly stable set of packages that normally to not change at all and only changes if there are good reasons for it -- so no "hey, there is a new version, it builds, let's ship it" mentality.
EPEL packages should only enhance and never disturb the Enterprise Linux distributions they were build for. Thus packages from EPEL should never replace packages from the target base distribution - including those on the base distribution as well as layered products; kernel-modules further are not allowed, as they can disturb the base kernel easily.
The packages in the repository should, if possible, be maintained in similar ways to the Enterprise Packages they were built against. In other words: have a mostly stable set of packages that normally does not change at all and only changes if there are good reasons for changes. This is the spirit of a stable enterprise environment.
The changes that cant be avoided get routed into different release trees. Only updates that fix important bugs (say: data-corruption, security problems, really annoying bugs) go to a testing branch for a short time period and then are pushed to the stable branch; those people that sign and push the EPEL packages to the public repo will skim over the list of updated packages for the stable repo to make sure that sure the goal "only important updates for the stable branch" is fulfilled.
Other updates get queued up in a testing repository over time. That repository becomes the new stable branch after one month of testing. There will be a short freeze time period before the monthly update happens to make sure the repository and its packages are in a good shape -- packages in this phase still can be removed if thats is needed. But even this updates should be limited to fixes only as far as possible and should be tested in Fedora beforehand if possible. Updated Packages that change the ABI or require config file adjustments must be avoided if somehow possible. Compat- Packages that provide the old ABI need to be provided in the repo if there is no way around a package update that changes the ABI. Packages in the testing repo that contain dependency issues or where the maintainer doesn't feel they are stable will be held back from the stable push.
When a new quarterly update is released, EPEL will wait until the CentOS version of that update is available. At that time, a stable push will be done to pull in tested packages from testing, and the stable repository will be linked to the current quarterly release version.
Guidelines and Backgrounds for this policy
Some examples of what package updates that are fine or not
Examples hopefully help to outline how to actually apply above policy in practise.
Minor version updates
Let's assume package foo is shipped in EPEL 5.0 as version 1.0.1; upstream developers now ship 1.0.2
- build for the stable branch only if it fixes serious bugs
- build for the testing branch is acceptable if the upstream release is mostly a bugfix release without new features and the package got run-time testing
A little bit bigger minor version updates
Let's assume package foo is shipped in EPEL 5.0 as version 1.0.1; upstream developers now ship 1.2.0; the ABI is compatible to 1.0.1 and the existing config files continue to work
- build for the stable branch only if it fixes a really serious bug
- build for the testing branch is acceptable if it fixes serious bugs
A yet again little bit bigger minor version updates
Let's assume package foo is shipped in EPEL 5.0 as version 1.0.1; upstream developers now ship 1.4.0; the ABI is compatible to 1.0.1, but the config files need manual adjustments
- build for the stable branch is normally not acceptable; a backport should be strongly considered if there are any serious bugs that must be fixed
- build for the testing branch is also disliked; but it is acceptable if there is no other easy way out to solve serious bugs; but the update and the config file adjustments need to be announced to the users properly -- say in form of release notes that get published together with the quarterly announcement.
A major version update
Let's assume package foo is shipped in EPEL 5.0 as version 1.0.1; upstream developers now ship 2.0.0; the ABI changes or the config files need manual adjustments
- this update should be avoided if possible at all. If there really is no other way out to fix a serious bug then it rare cases it might be acceptable to build the new version for the testing branch and mention the update and the needed adjustments in the release notes for the next update. An additional compat- packages with the old libs is necessary if the ABI changed.
Add more examples as they show up
If to many show up put them into a separate document.
Still unsure if a package is fine for EPEL?
Just ask on EPEL developers mailing list or #epel on freenode.org for opinions from EPEL SIG members.
Why not a rolling release with latest packages like what was in Fedora Extras?
Why should we? That would be what Fedora Extras did and worked and works well for it -- but that's mainly because Fedora (Core) has lots of updates and a nearly rolling-release scheme/quick release cycle, too. But the Enterprise Linux we build against is much more careful with updates and has longer life-cycle; thus we should do the same for EPEL, as most users will properly prefer it that way, as they chose a stable distro for some reasons -- if they want the latest packages they might have chosen Fedora.
Sure, there are lots of areas where having a mix of a stable base and a set of quite new packages on top of it is wanted. *Maybe* the EPEL project will provide a solution (in parallel to the carefully updated repository!) for those cases in the long term, but not for the start. There are already third party repositories out there that provide something in this direction, so users might be served by them already.
Further: A rolling release scheme like Fedora Extras did is not possible for many EPEL packages for another reason, new packages often require new versions of certain core libraries. This will cause problems in EPEL because we won't be able to provide updated libs as it would replace libraries in the core OS.
Example: This document was written round about when RHEL5 got released; many packages that get build for RHEL5 can't be build for RHEL4 at this point of time already, as the RHEL4-gtk2-Package is two years old and is to old for many current applications, as they depend on a newer gtk2. So if even if we would try to have a rolling scheme with with quite new package we'd fail, as we can't build a bunch of package due to this dependencies on libs; in the end we would have a repo with some quite new packages while others are still quite old. That mix wouldn't make either of the "latest versions" or "careful updates only" sides happy; so we try to target the "careful updates only" sides. Remember, EPEL's support and updates cycle is much longer then Fedora's.
Getting a Fedora package in EPEL
Distribution specific guidelines
- EPEL4 Python packages should manually depend on the proper python version that it was build for. Most old FC-3 python packages should still use this trick.