Release Lifecycle Proposals
(Moved proposals for release lifecycle to a new page)
(Explain some of the nice properties of the choice proposal)
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back to older releases without causing any update problems.
back to older releases without causing any update problems.
that updates not
a Fedora just updates -testing
Revision as of 23:08, 1 March 2010
Because that comes with some types of disruptive changes which we do not perform in releases and which I do not advocate performing in releases. Rolling releases like Rawhide, Debian unstable, Gentoo etc. have no set points to do disruptive changes. So e.g. you wake up in the morning and your system no longer boots because your kernel upgrade from yesterday enabled libata and you had hd* hardcoded in some place. (Yes, I know that particular change is now a done deal, but there will definitely be similar changes in the future.) As I have explained several times, AIUI, a stable release MUST NOT get upgrades which "break things", e.g.: * require manual adjustment to config files, databases etc., * break support for existing user data (documents, configuration, savegames etc.), * knowingly introduce regressions, * remove features, * radically change the UI (but I don't think minor changes like a menu entry moving to a different place are a serious issue), * bump the soname of a core library on which dozens of packages depend (but I don't personally see a grouped update with a soname change and a rebuild of ALL packages using that library as a problem as long as it's only for a few packages), * change the API of a library in a way that existing applications using it fail to rebuild and cannot easily be fixed (in fact soname bumps MUST be accompanied by rebuilds of everything affected) etc. (and I think we all agree there. But that's why Rawhide is not the answer!), but IMHO (and there opinions differ), it SHOULD get upgrades which: * fix bugs, even if they're not critical or security, * introduce features in a non-disruptive, backwards-compatible way (e.g. there's now a new menu entry which does something cool, at worst that new menu entry might not work perfectly, but it shouldn't affect anything else).
The idea behind this proposal is that when we release a new Fedora, it is a snapshot of rawhide at that time. Throughout its life-cycle, it should stay as close to that snapshot as feasible until it is EOLed. The policy is simple and quick to read. As a user I know what to expect from this policy and as a packager I know what is expected of me.
This will slow down updates on stable releases and allow developers / packagers to focus on the next release.
- Enhancement-only updates would be discouraged.
- Backporting is preferred but understand not everyone has the time/know how to do it.
- We could treat crit path packages with even more scrutiny
- We could create a list of update types that we would not allow. For example: Fixing a br, license change, added doc, etc.
- Bug and security should be examined to determine if they actually impact Fedora and it would be up to the packager to decide if the update was worth the risk to our users or not.
- Provide facilities to sigs and developers to host 'add-on' repos so groups who want additional testing of $PACKAGE, besides just rawhide, could provide a yum repo for people to _manually_ add and test. For example, we could have an LXDE F-12 repo that has the latest versions of LXDE should the LXDE sig choose to do it. (My proposal is certainly not all or nothing, I could see this as causing more harm then good)
Special notes for rawhide updates:
- Anything that does not knowingly break things is fair game
- Things that require manual changes need to get sent / notified to the user (do we need to invent a mechanism for this?
- Such changes should end up in the release notes
- Changes which knowingly break things should be reported to the list/ announced with a timeline and rollback procedure.
Note: I'm not actually on FESCo so if people have a problem with that and ignore my proposal I won't take it personally ;-)
Give the users choice, and do the expected thing by default
The idea behind this proposal is that a Fedora user installing a release N has a lot of choice if they wish to get newer packages:
- They can move to rawhide.
- They can install specific packages from rawhide.
- With NFR, they can now move to a pre-release of N+1.
- They can install specific packages from N+1.
- They can enable updates-testing.
- They can install specific packages from updates-testing.
- If they are on an older Fedora release, they can update to the latest Fedora release.
...but they have almost no options if they are happy to stay with the software that they have. It's also a common user expectation that updates within a release are mainly to fix bugs, and even then very minor bugs might not get fixed (but, if you need it fixed you have lots of choice above).
The way to add choice is to lower the numbers of updates that a user would see by default, and to lower the number of changes that those updates contain. This should be obvious, if you have 500 pending updates there is little choice but to just update everything and hope for the best. In the same way if a package contains 3-6 months of upstream changes then the user just has to hope for the best.
Due to the fact that Fedora cannot reward packagers for doing backports, or employ more developers, the only real option we have is to "punish" the kinds of updates which remove choice from our users. This will likely mean that some updates might not happen, that users would want if they looked at it independtly. But this is exected, as above, and as a known general rule perfect is the enemy of good.
We deal with everything in "days spent in updates-testing" (DSUT). For each package this starts out at 4 days, which is roughly enough for the package to make it into a compose it to get to most of the mirrors and for interested users to easily test it. Each time a package moves from updates-testing => updates the DSUT for that package is doubled. So on the third update for a package the DSUT would be 16 days, however putting an updated package into updates-testing three times would keep the DSUT at 4 days.
For the current stable release we then apply a number of DSUTs to an update, depending on how complicated it is:
- High severity security bugs would get treated mostly as they do now, there would hopefully be more resources to backport fixes instead of rebasing ... but we need to get those out quickly, so they would have 0 DSUT.
- Lower severity security bugs would get 1 DSUT.
- New packages would get 2 DSUT.
- Backport fixes would have 3 DSUT.
- Fixes which include some new features (Eg. a minor upstream rebase, which is mostly fixes) would have 5 DSUT.
- Updates which contain lots of features/improvements (which may, or may not contain bug fixes) would havbe 10 DSUT.
- Any update not containing enough errata information to easily fit into one of the above slots would get 20 DSUT. This would include update information like "updating to upstream version 2.4.8".
Older stable release would be dealt with using a simple rule "all updates must first be in a newer release". This does mean that if you want to update to the version released in the current stable Fedora, it works just as above. This has a number of nice features allowing significantly tested packages that don't change much to easily make it back to older releases without causing any update problems.
While this may seem complicated compared to the other proposals it has a number of good properties and users should find it very simple to understand. Namely that released updates of packages will not update many times and will contain less changes.
- If you are a "normal" part time packager, releasing new versions in new Fedora releases and just doing bug fix updates in stable releases nothing changes. You do a small update once, or maybe twice, a release and wait 1-2 weeks for testing before all users can get it.
- This is easy to implement on the rel-eng side, as no subjective decisions need to be made. All that happens is something takes the two numbers and multiplies them together (how many updates have moved to "updates" with this package name, and the one above given by the changes in the update) and anything can be pushed to stable after that amount of time. This could even be automated.
- Fedora wouldn't be dictating anything extra to packagers, if a packager wanted they could release a huge update at GA without any real explanation and users would still get it, eventually.