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RFC: Package maintenance and update policy for EPEL -- take 1



Hi everyone,

find below my take for a "Package maintenance and update policy for EPEL". You an find it in the wiki at:
http://fedoraproject.org/wiki/EPEL/GuidelinesAndPolicies/PackageMaintenanceAndUpdates

If you spot typos (there are probably still some...) please fix them in the wiki directly -- that's why the document is there ;-)

Did I miss anything? Do people like the general direction?

CU
thl


= 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 stronger regulated then they are in Fedora now.

[[TableOfContents]]

== Digest ==

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 get maintained in similar ways like the packages get maintained in the Enterprise Linux Distribution they get build 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 it -- so no "hey, there is a new version, it builds, let's ship it" mentality.

== Policy ==

EPEL packages should only enhance and never disturb the Enterprise Linux distributions the packages were build for. Thus packages from EPEL should never replace packages from the base distribution they get build against; kernel-modules further are not allowed, as they can disturb the base kernel easily.

The Packages in the Repository should if possible get maintained in similar ways like the packages get maintained in the Enterprise Linux Distribution they get build 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.

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 build a second time for 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 in parallel with the quarterly update that get released by the Linux Distributor that creates the Enterprise Linux the packages gets build against. There will be a short freeze time period before the quarterly update happens to make sure the repo and its packages are in a good shape. 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.

== 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 (which will be 5.1 later) 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 (which will be 5.1 later) 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 (which will be 5.1 later) 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.

=== Why not a rolling release with up2date packages like 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 bleeding edge 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. BTW, there are already 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/does is not possible for many EPEL packages for another reason, too. New Packages often require new versions of certain core libraries, too. But we we can't provide them in EPEL, as they would replace/disturb stuff from the base distribution.

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 much two years old and way 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.

=== How will the repo actually look like ===

Similar to what [ http://ftp-stud.fht-esslingen.de/pub/Mirrors/centos/ layout] CentOS uses. Rough example:

{{{
* epel/                         # topdir
 * 4/                           # topdir for EPEL4
  * 4 -> 4.5                    # symbolic link to latest version
* 4.1/ # this tree of course will never exists, as this is history, and is here just to show the example .... # 4.2, 4.3, 4.4; those won't ever exists, too * 4.5/ # 4.5, latest version, build target: fedora-epel-4-stable
  * 4.6                         # not yet
  * ....                        # time will come
* testing/ # testing repo, that together with the old packages that didn't get update becomes 4.6 when RHEL 4.6 # releases; build target: fedora-epel-5; gets frozen for a week or two before the quarterly update is # issued; new packages land here for a while, too

 * 5/                           # topdir for EPEL4
  * 5 -> 5.0                    # symbolic link to latest version
* 5.0/ # 5.0, latest version, build target: fedora-epel-5-stable
  * 5.1                         # not yet
  * ....                        # time will come
* testing/ # testing repo, that together with the old packages that didn't get update becomes 4.6 when RHEL 4.6 # releases; build target: fedora-epel-5; gets frozen for a week or two before the quarterly update is # issued; new packages land here for a while, too
}}}

This layout may looks complicated, but has one major benefit: Users can stick to a EPEL repo for a not up2date EL release while a newer EL quarterly update is already out (some users do that on purpose, others have no chance as for example the CentOS update gets normally released up to four weeks after RHEL released a quarterly update). The above layout can makes it possible to prevent that users run into dependency issues that might arise otherwise if packages in the new EPEL release depend on new packages in the new EL release. The EPEL quarterly update further isn't forced on users before they switch to the quarterly update.

Each repo always has all the packages in it; hardlinks will be used to keep the space requirements on the server-side limited, as most packages won't change.


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