Changes/ReplaceYumWithDNF

Replace Yum With DNF

Summary

Make DNF (Dandified Yum)/Yum4 the new default packaging tool in F22.

Owner

• Name: Jan Šilhan
• Email: jsilhan@redhat.com
• Release notes owner:

Current status

• Targeted release: Fedora 22
• Last updated: 2014-03-10
• Tracker bug: <will be assigned by the Wrangler>

Detailed Description

DNF was forked from Yum in January 2012 and available for experimenting in fedora since release 18. The project is now fully capable of replacing Yum in new Fedora installations. We want DNF to become the new default packaging tool in Fedora 22. This entails:

• letting system administrators (including users who routinely manage their packages using the legacy Yum) perform all common packaging operations using DNF, with no or minimal and documented change to the command syntax, apart from replacing the command name. (done)
• providing implementation of Anaconda backend so system can be bootstrapped completely without using legacy Yum. (done)
• providing alternative to all Yum plugins from yum-utils (ongoing)
• providing alternative to all release engineering tools (repoquery, bodhi etc.) from yum-utils (ongoing)
• being ready/having the capacity to help out users with migration of their custom legacy plugins and extensions to DNF. The solid API documentation we provide is of great advantage here. (ongoing)

In practice, the change implies:

• Anaconda installs the system using the DNF backend (with no special switches)
• package 'dnf' is installed by default (referenced by the base comps groups)
• package 'dnf-yum' is installed by default. It obsoletes Yum and provides its own /usr/bin/yum, a short script that redirects to /usr/bin/dnf with an appropriate warning message that DNF is the preferred package manager now. Notice that upgrading F21 to F22 will not cause the compat package to be installed so will not disturb any upgrading users.

Benefit to Fedora

• A CLI package manager tool built on modern depsolving technology allowing for faster and less memory-intensive operation.
• Documented, solid Python API.
• C bindings for lower level libraries:
  • hawkey for package querying and depsolving. PackageKit is already making use of hawkey.
  • librepo for repo operations. PackageKit is already making use of librepo.
  • libcomps for comps operations).
• Unlike Yum, DNF runs in both Python 2 and Python 3.

Scope

This change will be completely transparent for users that use only the graphical package management tools. For anybody using the command line directly there will be some differences, but all the important operations are available with DNF, using the same CLI syntax.

• Proposal owners: The majority of tasks on this change are completed. Some plugins and API calls still need to be added. The Anaconda payload implementation needs more testing, Fedora Test Day for this is pending.

• Other developers: We provide the paylaod implementation for Anaconda developers. Developers of other extensions and developers of plugins that are not part of yum-utils will have to update their code.

• Release engineering: Release engineering tools that are internal to the releng teams and not part of yum-utils will need modifications to migrate to the DNF API.

• Policies and guidelines: None at the moment.

Upgrade/compatibility impact

In F22 we will release DNF as dnf-1.0.0. Yum will still be installable alongside DNF.

Users will have the possibility to manually remove DNF only use the (legacy) yum package.

For the set of incompatible CLI calls see DNF documentation.

How To Test

Install dnf and carry out your usual packaging operations using the dnf command, for instance:

 dnf upgrade

User Experience

See above.

Dependencies

• The main depending package is Anaconda and we've ported it to use DNF as a backend.
• Plugins. Core plugins are/will be ported, we will provide help with porting users' custom legacy plugins.
• Release engineering tools. Work on porting the tools is ongoing.

Contingency Plan

• contingency plan: stay with Yum, release DNF 1.0 but keep Anaconda installing through Yum and do not make announcement/recommendation to users to switch to DNF.
• contingency deadline: beta freeze.
• as long as Anaconda installation through DNF, all CLI operations and the most critical plugins work, this change can ship.

Documentation

DNF Documentation Site, the package ships manual pages of course.