Branched
Branched is the name given to a version of Fedora that has "branched" off of Rawhide and will become the next stable Fedora release. It consists of a package repository named with the Fedora version it will become and contains builds of all Fedora packages updated by maintainers with the goal of stablizing before release and fixing any release features. Nightly live image builds are also available during the later portion of the Fedora Release Life Cycle.
Branched is sometimes referred to by the Fedora release it will become. ie, "Fedora 19 Branched"
Goals
Branched has the following Goals:
- To allow package maintainers to integrate their packages into Fedora for a stable release.
- To allow advanced users access to the newer packages than stable releases typically provide.
- To identify and fix issues with packages before they reach a stable release of Fedora.
Using Branched
This section discusses Branched target users and how to test Branched with Live media, within a virtual installation or on a bare metal installation.
Audience
Branched is targeted at advanced users, testers and package maintainers.
As a branched consumer, you should:
- Be willing to update often. Branched doesn't get as many updates as rawhide (and at times they are frozen), but it still gets a larger amount than a Stable release.
- Be willing and able to troubleshoot problems. From time to time there are problems with Branched packages, and you will need strong troubleshooting skills and the ability to gather information for bug reports. You need a good understanding of yum and how to downgrade packages, as well as boot time troubleshooting.
- Frequent reboots to test new kernel versions and confirm functionality of the boot process. If you can't reboot often, consider using a stable release instead.
- Be willing and able to report bugs as you find them and help maintainers gather information to fix them.
If the above doesn't match you, you may wish to instead follow the Rawhide release (depending on the point in the release cycle) or use regular stable Fedora releases.
Live media
After the Branch event, but before the Fedora stable release, nightly builds will be composed from Branched. You may be able to use these automated Live images to boot and test Branched. These images are automatically composed and not tested by QA
Virtual instances
You may wish to install and run Branched in a virtual machine (VM) instance. This allows you to test when not running Linux, or avoid any impact to your day-to-day workflow.
See the section below on setting up a Branched install.
Getting a Branched install
The Branched tree is directly installable (barring problems).
Install from Live media
If Live media are being composed from Branched (see above), you may be able to download the Live media, copy it to local media, boot and install Branched.
This is the most fragile way to get a Branched install, as Live media is only produced at some points in the cycle, sometimes does not compose, and when it does, may not install correctly.
Point installer to Branched
You can sometimes install Branched by using a stable install media and pointing it to the Rawhide repository for packages to install.
- Download the latest stable or branched install media. (netinstall or DVD install)
- Copy to local media (USB or DVD or CD)
- Boot media and go to the 'Install Source' section and manually enter:
https://dl.fedoraproject.org/pub/fedora/linux/development/rawhide/x86_64/os/
(or i386 for 32bit) - Finish the install as normal.
For this method to work, there should be no major changes in Branched that the installer is not ready for, such as packages it depends on being retired or other similar situations.
Yum from Existing install
You may use yum to upgrade from the most recent Stable or Branched release. You will need to have such an install in place and should likely update to the newest updates before starting.
See Upgrading Fedora using yum Branched info
This method may fail if there are upgrade path issues (newer packages in Stable or Branched than Branched), or broken dependencies.
Latest milestone or test images
At Alpha, Beta and final, a set of install images (DVD and netinstall) and live images for desktops are produced. You can use these to install branched.
Before each of the above milestones, TC and RC images are sometimes available. TC or Test Compose imags are done before milestones when there are known release blocking bugs that need addressing. RC images (Release Candidate) are produced when all known blocker bugs for a release are addressed. If no further blocker bugs are found in an RC image, that RC will become (with no further changes) the release.
TC images may or may not install correctly.
RC images may or may not install correctly, but you can usually find the list of known blockers to see if they affect you.
Alpha and Beta images should install correctly in most cases. This is the preferred way to install if those milestones have been reached.
Communicating
There are a number of ways to communicate with other Branched users:
IRC
Branched discussion is on topic and welcome in both the #fedora-devel and #fedora-qa IRC channels.
Mailing Lists
Branched discussion is on topic and welcome in both the test and devel lists.
Bugzilla
Branched bugs should be reported against the Fedora Product, and version that this branched will become and the affected component. Please do follow best practices when filing. Remember that IRC and mailing lists are useful to help narrow down if some behavior is a bug or where to report it, but are themselves not bug reporting channels. Always file bugs in Bugzilla.
Note that broken dependencies are mailed to maintainers for each daily Branched compose where a package has such broken dependencies. Therefore, it's usually not worth filing a bug for broken dependencies unless they don't appear in the daily report, or you have a fix or improvement to suggest.
Producing Branched
Branched goes through several phases:
The Branched compose runs every day starting at 09:15UTC. All branched builds at that time that are stable are composed and sycned out. Note that during freezes there will be many days where 0 packages are added to the compose. Branched is under "development/VERSION" on the mirrors. You can find a local "42" mirror on the public mirror list. Compose time varies depending on number of changes but is typically between 5 and 8 hours.
Right after branching off from rawhide, but before alpha change freeze, Branched is much like Rawhide. All packages built the previous day are composed and synced out. Bodhi is not used yet.
At alpha change freeze, Bodhi (the Fedora updates system) is enabled. All builds must now use it. Builds are pushed to updates-testing repository and after meeting critera for stable are added to the base package repository, which is still composed once a day. During the Alpha change freeze, only updates that fix accepted blocker bugs or freeze exceptions are allowed to go stable.
As soon as Alpha is set to "go", the Alpha change freeze is lifted and packages can once again go to the base repository when marked stable.
At the Beta change freeze, again only builds that are accepted blockers or freeze exceptions are allowed to go stable. After Beta is "go" stable builds are again pushed.
At the Final change freeze, things happen much as Alpha and Beta, however, after Final is signed off on, the branched compose is disabled completely, and packages set to go stable are pushed to a new 'updates' repoistory and become 0 day updates.
Composes are done in a rawhide chroot using the 'mash' tool called from a script maintained by Fedora Release engineering: http://git.fedorahosted.org/cgit/releng/tree/scripts/buildrawhide If the base set of packages in rawhide needed to compose rawhide are broken, the daily compose may fail.
A report for each Branched compose is sent to to the test and the devel lists. This report contains output from the 'repodiff' tool from the previous compose as well as a broken dependency report for packages with broken dependencies. Additionally, private email is sent to maintainers with packages containing broken dependencies.
Package maintainers should read and follow the Branched release updates policy for building any packages in Branched.
Branched packages are not 100% signed until the Alpha Change freeze milestone.
Questions and Answers
Q: So Branched is very stable and we can all use it?
A: No. See audience above. There are things that break from time to time, but if you are able to downgrade or troubleshoot such issues aren't too severe, however most users should stick to Stable Fedora releases.
Q: I'm using a Stable Fedora release, but I want the newer package for foo thats only available in Branched. Can I just yum install it?
A: No. Mixing releases like this is a very bad idea. Your better options are:
- Obtain the src.rpm for the package you wish and try and rpmbuild --rebuild it (which may or may not work depending on dependencies)
- Ask the Fedora maintainer in a bug report to update the stable version if permitted by policy.
Q: How can I tell when the branched compose for the day has finished?
A: You can see the reports it sends to the test and the devel lists. You can also watch fedmsg for the messages that rawhide compose has finished.
Hints and Tips
- Your package management system can be of great help in diagnosing and working around issues you find. Do read up and understand: 'yum downgrade' 'yum history' 'yum update --skip-broken' 'koji download-build'.
- You should update frequently (preferably every day). This allows you to more easily narrow down when a problem or issue appeared. If you apply a week of Branched updates at once you have many more packages to examine to narrow down issues.
- Reboot often (preferably whenever new kernels arrive). This allows you to test the boot up process and packages related to it, as well as newer kernels. Read and understand the Dracut troubleshooting steps.
- Follow the test and the devel lists for rawhide issues, try and at least skim them before doing your daily Branched updates. Look for '[rawhide]' subjects or reports of issues. Additionally if you find a problem and are not sure what to file bugs against you can open a discussion there.
- Branched kernels are made with a large amount of debugging enabled. You can often gain a good deal of performance by passing "slub_debug=-" to your kernel boot line in /etc/grub2.cfg. Additionally, you can run kernels in the Rawhide Kernel Nodebug repo that have all debugging disabled.
- If you are using a graphical desktop environment in your Branched install, you may wish to install several of them. This allows you to still login and troubleshoot when your primary desktop environment is not working for some reason.
- Have a rescue media handy of the current stable Fedora release for emergencies.
History
Branched was created as part of the "No frozen Rawhide" proposals:
http://fedoraproject.org/wiki/No_Frozen_Rawhide_Proposal
http://fedoraproject.org/wiki/No_Frozen_Rawhide_Implementation