UbuntuForDebianDevelopers

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This document is intended to provide practical information about Ubuntu specifically for Debian developers.
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 * '''Lack of manpower''' : ~8400 source packages in ''universe'', split amongst [https://launchpad.net/people/motu ~35 MOTUs] and a few outsiders.
 * '''Lack of tools''' : Ubuntu currently lacks most of the tools to take care of the packages in a global way.
 * '''Lack of consensus about how Debian want Ubuntu's patches'''
 * '''Lack of response from some Debian maintainers''' : when Ubuntu changes are integrated by Debian, it makes the life of MOTUs much easier. However, some bugs have been opened months ago in the BTS, but are ignored from the Debian maintainer; these must then be maintained separately.

There are of course plans to change that by improving processes and writing tools, but this takes time.
 * '''It doesn't scale''': Ubuntu developers regularly make changes across a range of packages in the distribution, including transitions which touch hundreds of packages. Individually filing these patches can take more time than the work itself.
 * '''Differences of opinion''': Debian developers have different preferences about how they wish to receive patches, and some object to receiving them at all. By providing subscription mechanisms, Ubuntu allows Debian developers to express their preferences and have them respected automatically.
 * '''Difficult to track''': A great deal of bookkeeping is required in order to keep track of which patches have been merged into Debian, either modified or unmodified. Our long-term strategy is to apply proper revision control tools to this problem, but in the meantime, the bug tracker has too much overhead.
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XXX work in progress

Introduction

This document is intended to provide practical information about Ubuntu specifically for Debian developers.

  • Ubuntu is proud to be [http://www.ubuntulinux.org/ubuntu/relationship based on Debian].

  • Ubuntu wants to maintain a healthy and collaborative relationship with Debian developers.
  • Ubuntu has brought new users and developers to the GNU/Linux community. Some day, those new users might become Free Software developers, advocates or DD's.

How does Ubuntu differ from Debian?

Purpose and Scope

Ubuntu has a narrower focus than Debian in many ways. For example, Ubuntu supports only a subset of the architectures that Debian does, and targets specific users (for example, desktop users and server administrators), while Debian seeks to be more universal.

Community Governance

Ubuntu has its own [http://www.ubuntu.com/community/processes community government structure], in some ways inspired by Debian's but in other ways different. There are different governing bodies, procedures for becoming a developer, upload privileges, and more.

Licensing

Ubuntu has four [http://ubuntulinux.org/ubuntu/components components] (like Debian's main, contrib and non-free), distinguished by [http://www.ubuntu.com/ubuntu/licensing licence policy] and support terms. The following table summarizes the differences:

Source packages in Ubuntu components as of 2006-01-18:

Free software

non-free software

Offically supported

main (2297)

restricted (5)

Unofficial

universe (8363)

multiverse (364)

Officially supported packages receive security updates sponsored by Canonical, and more rigorous QA relative to the release cycle, while unofficial packages are maintained on a "best effort" basis, primarily through incorporating the Debian maintainer's work.

Packages

Most source packages are copied unmodified from Debian, but other sources include [http://www.apt-get.org/ apt-get.org], [http://revu.tauware.de/ REVU], directly from organisations such as Blackdown and WineHQ, and packages which are created by Ubuntu developers specifically for Ubuntu.

Package maintenance

Unlike Debian, Ubuntu packages usually do not have a designated maintainer. In effect, all packages in Ubuntu are maintained by teams. Packages in Ubuntu main and restricted are maintained by the [https://launchpad.net/people/ubuntu-core-dev Ubuntu Core Development Team], while packages in Ubuntu universe and multiverse are maintained by the [https://launchpad.net/people/ubuntu-dev Ubuntu Development Team]. If you need to discuss a specific change, try poking the last person who changed the package (see the changelog at [http://changelogs.ubuntu.com/]).

Bug tracking

Ubuntu tracks bugs in [http://bugs.ubuntu.com Launchpad]. The Launchpad bug tracker makes it possible to keep track of bugs in multiple contexts, for example, if a bug is fixed upstream but not in Debian, or fixed in Debian but not in Ubuntu. It can also store links to bugs filed upstream and in Debian, and notify Ubuntu developers when their status changes. More information about bug tracking in Launchpad can be found at XXX.

Relationship to Canonical

XXX work in progress

What is MOTU?

With the creation of the universe component, volunteers were needed to look after these packages. A team called The Masters of the Universe (["MOTU"]) was formed for this purpose. MOTUs sync (import without modification) or merge (import with Ubuntu-specific changes) packages from Debian. MOTUs handle bugs reported on software inside universe and multiverse.

Why does Ubuntu need to change my packages? What kind of changes are made?

There are many reasons why packages in Ubuntu diverge from Debian, including:

  • Policy differences between Debian and Ubuntu (for example, dependencies, build-time options, etc.)
  • Bug fixes
  • Development of new features
  • Transitions: Ubuntu routinely carries out packaging transitions ahead of Debian, in collaboration with Debian representatives where a consistent policy is needed
  • Newer upstream versions: Ubuntu tracks upstream more closely than Debian in some cases
    • GNOME
    • KDE
    • Linux
    • Toolchain (GCC et al)

How does Ubuntu cooperate with Debian?

For many packages in main, Ubuntu has good working relationships with the Debian maintainer(s) and is involved with the core Debian development. Many volunteer developers are active in both Debian and Ubuntu camps. Canonical employs some Debian developers, which should help changes flow directly back to Debian.

How can I obtain patches from Ubuntu?

  • Patches for Ubuntu packages are generated regularly and forwarded to the [http://packages.qa.debian.org Debian Package Tracking System] (derivatives keyword) and the [http://lists.ubuntu.com/mailman/listinfo/ubuntu-patches ubuntu-patches mailing list]. By using these resources, you can receive timely notification of incremental patches to your Debian packages, or to all packages in Ubuntu.

  • The complete delta between Debian and Ubuntu for a given package is published in Ubuntu's [http://patches.ubuntu.com Debian patches repository]

  • In the future, Ubuntu plans to maintain this delta using distributed revision control tools, providing a convenient way to review and merge changes

Why aren't these patches submitted to the Debian BTS instead?

  • It doesn't scale: Ubuntu developers regularly make changes across a range of packages in the distribution, including transitions which touch hundreds of packages. Individually filing these patches can take more time than the work itself.

  • Differences of opinion: Debian developers have different preferences about how they wish to receive patches, and some object to receiving them at all. By providing subscription mechanisms, Ubuntu allows Debian developers to express their preferences and have them respected automatically.

  • Difficult to track: A great deal of bookkeeping is required in order to keep track of which patches have been merged into Debian, either modified or unmodified. Our long-term strategy is to apply proper revision control tools to this problem, but in the meantime, the bug tracker has too much overhead.

How can I minimize the Ubuntu delta for my packages?

XXX work in progress


For more information about Debian collaboration in Ubuntu, see DebianCollaboration.

UbuntuForDebianDevelopers (last edited 2008-09-22 11:48:26 by 82-69-40-219)