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Do we need project-wide support for Debian rolling?

April 29, 2011 by Raphaël Hertzog

The discussion about Debian rolling started sooner than expected on debian-devel (see the thread here). I initially wanted to iron out the biggest problems through discussions on my blog and try to submit a somewhat polished proposal… instead we ended up discussing the same things both on -devel and on my blog.

That said it’s not that bad (except for the time I lost to have similar conversations in both places) because the debian-devel discussions included members of the release team and it looks like they are not fundamentally opposed to the idea.

Despite this, the introduction of a “frozen” suite branched off from “testing/rolling” is not really consensual (yet?). But the idea of officially supporting testing on a best-effort basis appears to have almost no opposition.

While some will undoubtedly believe that this is a useless exercise, I believe it would help if the project stated this in a somewhat official manner. My answer to the question in the title is thus:

YES

I am thus considering to submit a general resolution to that effect. My current draft is below.

Title: Debian endorses usage of testing by end-users, and renames it to rolling

The Debian project recognizes that the Debian testing distribution—initially created to make it easier to prepare and test the next stable release—has become a useful product of its own. It satisfies the needs of users who are looking for the latest stable versions of software and who can cope (or even appreciate) a system that’s constantly evolving.

The Debian project decides to endorse this usage and will strive to provide a good experience to users of “testing”. To better communicate this policy change to our users, “testing” will be renamed “rolling”.

While we believe that this is a good move, we would like to remind our users that Debian is a volunteer project and that our resources are not infinite. Package maintainers are contributing to Debian on a best-effort basis. This means that they might not be able to properly support their package(s) in all distributions. In that case, the project recommends that maintainers apply the following priorities:

Support in stable (security updates, release critical bugs)

Preparation of the next stable release

Support in rolling

Note that this general resolution could have amendments with s/rolling/current/ and that would solve the bikeshedding over the name that started several times already.

I deliberately separated “Preparation of the next stable release” and “Support in rolling” so that priorities are clear even if we decide to not freeze “rolling” and to introduce a “frozen” distribution to finalize the next stable release.

I also did not go into too much details on the implications that it might have, it’s best to leave that up to each contributor/team/etc.

I hesitated to add a paragraph stating that we want to try to gradually improve the usability of testing but in the end I think it would be somewhat redundant. We’re always trying to do our best when we decide to take on something.

All comments welcome (even if you just agree and would be willing to second such a GR).

Update: I will tweak the draft included in this article when I get good suggestions. Thanks to Lucas Nussbaum for the first one.

No freeze of Debian’s development, what does it entail?

April 28, 2011 by Raphaël Hertzog

The main feature of rolling is that it would never freeze. This is not without consequences.

Possible consequences

It can divert developers from working on the release

No freeze means developers are free to continue their work as usual in unstable. Will it be more difficult to release because some people will spend their time working on a new upstream version instead of fixing RC bugs in the version that is frozen? Would we lose the work of the people who do lots of NMU to help with the release?

It makes it more difficult to cherry-pick updates from unstable

No freeze also means that unstable is going to diverge sooner from testing and it will be more difficult to cherry-pick updates from unstable into testing. And the release team likes to cherry-pick updates that have been tested in unstable because updates that comes through testing-proposed-updates have often not been tested and need thus a more careful review.

Frozen earth

My responses to the objections

Those are the two major objections that we’ll have to respond to. Let’s try to analyze them a bit more.

It’s not testing vs rolling

On the first objection I would like to respond that we must not put “testing” and “rolling/unstable” in opposition. The fact that a contributor can’t do its work as usual in unstable does not mean that he will instead choose to work on fixing RC bugs in testing. Probably that some do, but in my experience we simply spend our time differently, either working more on non-Debian stuff or doing mostly hidden work that is then released in big batches at the start of the next cycle (which tends to create problems of its own).

I would also like to argue that by giving more exposure to rolling and encouraging developers to properly support their packages in rolling, it probably means that the overall state of rolling should become gradually better compared to what we’re currently used to with testing.

The objection that rolling would divert resources from getting testing in a releasable shape is difficult to prove and/or disprove. The best way to have some objective data would be to setup a questionnaire and to ask all maintainers. Any volunteer for that?

Unstable as a test-bed for RC bugfixes?

It’s true that unstable will quickly diverge from testing and that it will be more difficult to cherry-pick updates from unstable into testing. This cannot be refuted, it’s a downside given the current workflow of the release team.

But I wonder if the importance of this workflow is not overdone. The reason why they like to cherry-pick from unstable is because it gives them some confidence that the update has not caused other regressions and ensures that testing is improving.

But if they’re considering to cherry-pick an update, it’s because the current package in testing is plagued by an RC bug. Supposing that the updated package has introduced a regression, is it really better to keep the current RC bug compared to trading it for a new regression? It sure depends on the precise bugs involved so that’s why they prefer to know up-front about the regression instead of making a blind bet.

Given this, I think we should use testing-proposed-updates (tpu) as a test-bed for RC bug fixes. We should ask beta-testers to activate this repository and to file RC bugs for any regression. And instead of requiring a full review by a release manager for all uploads to testing-proposed-updates, uploads should be auto-accepted provided that they do not change the upstream version and that they do not add/remove binary packages. Other uploads would still need manual approval by the release managers.

On top of this, we can also add an infrastructure to encourage peer-reviews of t-p-u uploads so that reviews become more opportunistic instead of systematic. Positive reviews would help reduce the aging required in t-p-u before being accepted into testing.

This changes the balance by giving a bit more freedom to maintainers but still keeps the safety net that release managers need to have. It should also reduce the overall amount of work that the release team has to do.

Comments welcome

Do you see other important objections beside the two that I mentioned?

Do you have other ideas to overcome those objections?

What do you think of my responses? Does your experience infirm or confirm my point of view?

Towards Debian rolling: my own Debian CUT manifesto

April 27, 2011 by Raphaël Hertzog

As you might know, I’m of one the people who promote the idea of having a Constantly Usable Testing (CUT). I will post a set of articles on this topic to help me clarify my ideas and to get some early feedback of other Debian contributors. I plan to use the result of this process to kickstart a broader discussion on debian-devel (where I hope to get the release team involved).

Let’s start by defining my own objectives with Debian CUT. I won’t speak of the part of Debian CUT that plans to make regular snapshots of testing with installable media because that’s not where I will invest my time. I do hope other people will do it though. Instead I will concentrate on changes that would improve Debian testing for end-users. I consider that testing (in its current form) is largely usable already but there are two main obstacles to overcome.

Testing without freezes = rolling

The first one is that testing is no longer testing during freezes. The regular flow of new upstream versions—that makes testing so interesting for many users—is stalled because we’re using testing to finalize the next stable version. That’s why I’d like to introduce a new suite called “rolling” that would work like the current testing except that it never freezes. Testing would no longer be a permanent suite, it would only exist during the freeze and it would be branched off from rolling.

Rolling should be a supported distribution

The second obstacle is not really technical. We must advertise rolling as a distribution that ordinary people can use but we should make it clear that it’s never going to have the same level of polish that a stable release can have. And to back up this assertion, we must empower Debian developers to be able to provide good support of their software in rolling, this probably means using “rolling-proposed-updates” more often to push fixes and security updates when the natural flow of updates is blocked by transitions or other problems. Some maintainers won’t have the time required to provide the same level of support as they currently do for a stable release and that’s okay, it’s not worse than the current testing. The goal is to treat it on a best-effort basis and to try to gradually improve the situation.

My goal for wheezy

This is the the minimal implementation of CUT that I would like to target in the wheezy timeframe. Having testing as a temporary branch of rolling is not a strict requirement, although I’d argue that it’s important to not waste resources towards maintaining two separate yet very similar distributions.

Should Debian embrace those goals?

Ignoring all possible problems that will surface while trying to implement those goals, can we agree that Debian should embrace those goals because it means providing a better service to a class of users that is not satisfied by the current stable release?

I will come back to the expected problems in a subsequent post and we will have the opportunity to discuss them. Here I just want to see whether we can have broad buy-in on the principles behind Debian rolling and CUT.

Journey of a new GNOME 3 Debian packager

April 11, 2011 by Raphaël Hertzog

With all the buzz around GNOME 3, I really wanted to try it out for real on my main laptop. It usually runs Debian Unstable but that’s not enough in this case, GNOME 3 is not fully packaged yet and it’s only in experimental for now.

I asked Josselin Mouette (of the pkg-gnome team) when he expected it to be available and he could not really answer because there’s lots of work left. Instead Roland Mas gently answered me “Sooner if you help”. 🙂

First steps as a GNOME packager

This is pretty common in free software and for once I followed the advice, I spent most of sunday helping out with GNOME 3 packaging. I have no prior experience with GNOME packaging but I’m fairly proficient in Debian packaging in general so when I showed up on #debian-gnome (irc.debian.org) on sunday morning, Josselin quickly added me to the team on alioth.debian.org.

Still being a pkg-gnome rookie, I started by reading the documentation on pkg-gnome.alioth.debian.org. This is enough to know where to find the code in the SVN repository, and how to do releases, but it doesn’t contain much information about what you need to know to be a good GNOME packager. It would have been great to have some words on introspection and what it changes in terms of packaging for instance.

Josselin suggested me to start with one of the modules that was not yet updated at all (most packages have a pre-release version—usually 2.91—in experimental, but some are still at 2.30).

Packages updated and problems encountered

(You can skip this section if you’re not into GNOME packaging)

So I picked up totem. I quickly updated totem-pl-parser as a required build-dependency and made my first mistake by uploading it to unstable (it turns out it’s not a problem for this specific package). Totem itself was more complicated even if some preliminary work was already in the subversion repository. It introduces a new library which required a new package and I spent a long time debugging why the package would not build in a minimalistic build environment.

Indeed while the package was building fine in my experimental chroot, I took care to build my test packages like the auto-builders would do with sbuild (in sid environment + the required build-dependencies from experimental) and there it was failing. In fact it turns out pkg-config was failing because libquvi-dev was missing (and it was required by totem-pl-parser.pc) but this did not leave any error message in config.log.

Next, I decided to take care of gnome-screensaver as it was not working for me (I could not unlock the screen once it was activated). When built in my experimental chroot, it was fine but when built in the minimalistic environment it was failing. Turns out /usr/lib/gnome-screensaver/gnome-screensaver-dialog was loading both libgtk2 and libgtk3 at the same time and was crashing. It’s not linked against libgtk2 but it was linked against the unstable version of libgnomekbdui which is still using libgtk2. Bumping the build-dependency on libgnomekbd-dev fixed the problem.

In the evening, I took care of mutter and gnome-shell, and did some preliminary work on gnome-menus.

Help is still welcome

There’s still lots of work to do, you’re welcome to do like me and join to help. Come on #debian-gnome on irc.debian.org, read the documentation and try to update a package (and ask questions when you don’t know).

Installation of GNOME 3 from Debian experimental

You can also try GNOME 3 on your Debian machine, but at this point I would advise to do it only if you’re ready to invest some time in understanding the remaining problems. It’s difficult to cherry-pick just the required packages from experimental, I tried it and at the start I ended up with a bad user experience (important packages like gnome-themes-standard or gnome-icon-theme not installed/updated and similar issues).

To help you out with this, here’s a file that you can put in /etc/apt/preferences.d/gnome to allow APT to upgrade the most important GNOME 3 packages from experimental:

Package: gnome gnome-desktop-environment gnome-core alacarte brasero cheese ekiga empathy gdm3 gcalctool gconf-editor gnome-backgrounds gnome-bluetooth gnome-media gnome-netstatus-applet gnome-nettool gnome-system-monitor gnome-system-tools gnome-user-share baobab gnome-dictionary gnome-screenshot gnome-search-tool gnome-system-log gstreamer0.10-tools gucharmap gvfs-bin hamster-applet nautilus-sendto seahorse seahorse-plugins sound-juicer totem-plugins remmina vino gksu xdg-user-dirs-gtk gnome-shell gnome-panel dmz-cursor-theme eog epiphany-browser evince evolution evolution-data-server file-roller gedit gnome-about gnome-applets gnome-control-center gnome-disk-utility gnome-icon-theme gnome-keyring gnome-menus gnome-panel gnome-power-manager gnome-screensaver gnome-session gnome-settings-daemon gnome-terminal gnome-themes gnome-user-guide gvfs gvfs-backends metacity mutter nautilus policykit-1-gnome totem yelp gnome-themes-extras gnome-games libpam-gnome-keyring rhythmbox-plugins banshee rhythmbox-plugin-cdrecorder system-config-printer totem-mozilla epiphany-extensions gedit-plugins evolution-plugins evolution-exchange evolution-webcal gnome-codec-install transmission-gtk avahi-daemon tomboy network-manager-gnome gnome-games-extra-data gnome-office update-notifier shotwell liferea epiphany-browser-data empathy-common nautilus-sendto-empathy brasero-common
Pin: release experimental
Pin-Priority: 500

Package: *
Pin: release experimental
Pin-Priority: 150

The list might not be exhaustive and sometimes you will have to give supplementary hints to apt for the upgrade to succeed, but it’s better than nothing.

I hope you find this useful. I’m enjoying my shiny new GNOME 3 desktop and it’s off for a good start. My main complaint is that hamster-applet (time tracker) has not yet been integrated in the shell.