infra-manual/doc/source/drivers.rst

title

Project Driver's Guide

Project Driver's Guide

Feature Branches

There are times when prolonged development on specific features is easier on a feature branch rather than on master. In particular it organizes work to a location that interested parties can follow. Feature branches also move merge points to specific points in time rather than at every proposed change. Learn more about feature branches in the project team guide.

To get started with a feature branch you will need to create the new branch in Gerrit with the 'feature/' prefix. Note that Gerrit ACLs do not allow for pushing of new branches via git, but specific groups of Gerrit users can create new branches. For official OpenStack projects the Release Manager creates feature branches. Unofficial projects may update their Gerrit ACLs to allow their release teams to create these branches. For similar Gerrit ACL reasons branch deletion is typically limited to the Infra team. Keep this in mind before creating many branches that will need cleanup.

If more than one project is involved in a feature development effort, the same feature branch name should be used across all involved projects. This will cause integration testing with Zuul to use the respective feature branch from any project that carries it. Projects without an equivalently named feature branch will use master instead. Use care not to create a feature branch with the same name as a feature branch for an unrelated effort in another project.

One additional thing to keep in mind is that feature branches should be treated like master in most cases. They are specifically not for sustained long term development like stable branches.

Merge Commits

An important activity when using feature branches is syncing to and from the project's master branch. During development on a feature branch a project will want to merge master into the feature branch periodically to keep up to date with changes over time. Then when development on the feature branch is complete, it will need to be merged into master.

Before this can happen the project team's release group will need to have access to push merge commits in Gerrit:

[access "refs/for/refs/*"]
pushMerge = group <projectname>-release

Should be added to the project's ACL file in the project-config repo.

Merge Master into Feature Branch

git remote update
git checkout feature-branch
git pull --ff-only origin feature-branch
git checkout -b merge-branch
git merge origin/master
# Amend the merge commit to automatically add a Change-ID to the commit message
GIT_EDITOR=/bin/true git commit --amend
git review -R feature-branch
git checkout master
git branch -D merge-branch

Merge Feature Branch into Master

git remote update
git checkout master
git pull --ff-only origin master
git checkout -b merge-branch
# Force a merge commit by not fast-forwarding, in case master hasn't updated:
git merge --no-ff origin/feature-branch
# Amend the merge commit to automatically add a Change-ID to the commit message:
GIT_EDITOR=/bin/true git commit --amend
git review -R
git checkout master
git branch -D merge-branch

How To Avoid Merging Specific Files

Sometimes you may have files on one branch you don't want merged to or from another. An easy workaround for this is to checkout the file in question from the target branch and amend your merge commit before pushing it for review. For example, as in the last section you've just merged from origin/feature-branch into your local merge-branch but want to keep the .gitreview file from master because you don't want defaultbranch=feature-branch added to it. Immediately before you git commit --amend do:

git checkout origin/master -- .gitreview

Release Management

This section describes topics related to release management.

Release and stable branches

Projects following the release:cycle-with-milestones model generate release candidates before the final release to encourage 3rd-party testing. The first release candidate (RC1) is cut from the master branch. You can learn more about release management in the project team guide.

Between RC1 and the final release, there needs to be a separate branch in Gerrit for release-critical changes destined for the final release. Meanwhile, development on the master branch should continue as normal (with the addition that changes proposed for the final release should also be proposed for master, and some changes for master may need to be applied to the release branch).

In order to avoid tracking different branches pre- and post-release, this process directly creates a stable/<series> (for example, stable/mitaka) branch that will be reused as the stable maintenance branch post-release. Specific ACLs apply to the branch pre-release, and when the final release is tagged the generic stable branch ACLs are applied instead.

Create stable/* Branch

For OpenStack projects this should be performed by the OpenStack Release Management Team at the Release Branch Point. If you are managing branches for your project you may have permission to do this yourself.

• Go to https://review.openstack.org/ and sign in
• Select 'Admin', 'Projects', then the project
• Select 'Branches'
• Enter stable/<series> in the 'Branch Name' field, and HEAD as the 'Initial Revision', then press 'Create Branch'. Alternatively, you may run git branch stable/<series> <sha> && git push gerrit stable/<series>

Once this is done, you should push a change updating the defaultbranch in .gitreview to match the new name of the branch, so that "git review" automatically pushes to the right branch:

defaultbranch=stable/<series>

To check out the new branch in your local checkout, you can use:

git checkout master
git pull
git checkout stable/<series>

Authoring Changes for stable/*

Create topic branches as normal, but branch them from stable/* rather than master:

git checkout stable/<series>
git pull
git checkout -b <topic branch>

Generally the defaultbranch in .gitreview is adjusted on the new branch so that you can directly use git review. If not, changes for stable/* should be submitted with:

git review stable/<series>

Submit Changes in master to stable/*

If a change to master should also be included in stable/*, use this procedure to cherry-pick that change and submit it for review:

git checkout stable/<series>
git pull
git checkout -b master-to-mp
git cherry-pick -x <SHA1 or "master">
git review stable/<series>
git checkout master
git branch -D master-to-mp

git cherry-pick master will pick the most recent commit from master to apply, if you want a different patch, use the SHA1 of the commit instead.

The -x flag will ensure the commit message records the SHA1 hash of the original commit in master.

If there are conflicts when cherry-picking, do not delete the 'Conflicts' lines git adds to the commit message. These are valuable to reviewers to identify files which need extra attention.

You can learn more about stable branches in the project team guide.

Tagging a Release

This step should be performed by the OpenStack Release Management Team when the release is made. If you are managing your own releases, you may have permission to do this yourself.

Tag the tip of the appropriate branch (stable/<series> for server projects using release candidates, master for the others) with a release tag and push that tag to Gerrit by running the following commands:

git checkout <branch name>
git pull --ff-only
git tag -s <version number>
git push gerrit <version number>

Note

• Git won't have a remote named gerrit until the first time git-review runs. You may need to run git review -s before the push.
• The -s option to git tag signs the tag using GnuPG, so it's important to ensure that the person making the release has a suitable OpenPGP key.
• Make sure you're only adding a single tag when pushing to gerrit, like in the example above.
• After a tag is created the release build will generate a source code tarball and may publish it to a repository such as PyPI.

Gerrit IRC Notifications

The intent of this section is to detail how to set up notifications about all the projects that are hosted on OpenStack Gerrit in the appropriate IRC channels.

GerritBot is an IRC bot that listens to the OpenStack Gerrit server for events and notifies those on Freenode's OpenStack channels.

GerritBot is able to notify the channel for events like creation of patchsets, changes merged, comments added to patchsets and updates to refs. These event notifications can be configured per project, so the channel can have multiple notifications per project.

Before you can configure GerritBot, you need to give channel permissions with an accessbot configuration specific to the channel where you want notifications posted. The configuration file is hosted in openstack-infra/project-config. Edit accessbot/channels.yaml to add your IRC channel if it is not already listed.

In order for GerritBot to post notifications on the IRC channel of the project you are configuring, you need to add your GerritBot configuration into gerritbot/channels.yaml. This file is hosted in openstack-infra/project-config.

The syntax for configuring the notifications is:

<IRC channel>:
      events:
        - patchset-created
        - change-merged
        - comment-added
        - ref-updated
      projects:
        - <project name>
      branches:
        - <branch name>

Please note that the text between the angle brackets are placeholder values. Multiple projects and branches can be listed in the YAML file.

Running Jobs with Zuul

There are two major components in getting jobs running under Zuul. First you must ensure that the job you want to run is defined in the JJB config. The JJB documentation is extensive as are the examples in our JJB config so we will not cover that here.

The second thing you need to do is update Zuul's layout file instructing Zuul to run your job when appropriate. This file is organized into several sections.

1. Zuul python includes. You can largely ignore this section as it declares arbitrary python functions loaded into Zuul and is managed by the Infra team.
2. Pipelines. You should not need to add or modify any of these pipelines but they provide information on why each pipeline exists and when it is triggered. This section is good as a reference.
3. Project templates. Useful if you want to collect several jobs under a single name that can be reused across projects.
4. Job specific overrides. This section is where you specify that a specific job should not vote or run only against a specific set of branches.
5. Projects. This is the section where you will likely spend most of your time. Note it is organized into alphabetical subsections based on git repo name prefix.

To add a job to a project you will need to edit your project in the projects list or add your project to the list if it does not exist. You should end up with something like:

- name: openstack/<projectname>
  template:
    - name: merge-check
  check:
    - gate-new-<projectname>-job
  gate:
    - gate-new-<projectname>-job

The template section applies the common merge-check jobs to the project (every project should use this template). Then we have gate-new-<projectname>-job listed in the check and gate pipelines. This says if an event comes in for openstack/<projectname> that matches the check or gate pipeline triggers run the gate-new-<projectname>-job job against openstack/<projectname> in the matching pipeline.

Integration Tests

One of Zuul's most powerful features is the ability to perform complex integration testing across interrelated repositories. Projects that share one or more jobs are combined into a shared change queue. That means that as changes are approved, they are sequenced in order and can be tested together. It also means that if a change specifies that it depends on another change with a "Depends-On:" header, those changes can be tested together and merged in rapid succession.

In order to use this to its full advantage, your job should allow Zuul to perform all of the git operations for all of the projects related to the integration test. If you install the software under test from the git checkouts supplied by Zuul, the test run will include all of the changes that will be merged ahead of the change under test.

To do this, use the zuul-cloner command as follows:

sudo -E /usr/zuul-env/bin/zuul-cloner --cache-dir /opt/git \
    https://git.openstack.org \
    openstack/project1 \
    openstack/project2 \
    openstack/projectN

Where the final arguments are the names of all of the projects involved in the integration test. They will be checked out into the current directory (e.g., ./openstack/project1). If you need them to be placed in a different location, see the clonemap feature of zuul-cloner which allows for very flexible (including regular expressions) directory layout descriptions.

Use that command in a single Jenkins Job Builder definition that you then invoke from all of the related projects. This way they all run the same job (which tests the entire system) and Zuul knows to combine those projects into a shared change queue.

Zuul comes with extensive documentation too and should be referenced for more information.

Retiring a Project

If you need to retire a project and no longer accept patches, it is important to communicate that to both users and contributors. The following steps will help you wind down a project gracefully.

Announce Retirement

Use mailing lists or other channels to announce to users and contributors that the project is being retired. Be sure to include a date upon which maintenance will end, if that date is in the future.

End Project Gating

Check out a copy of the openstack-infra/project-config repository and edit zuul/layout.yaml. Find the section for your project and change it to look like this:

- name: openstack/<projectname>
  template:
    - name: merge-check
    - name: noop-jobs

Also, remove your project from jenkins/jobs/projects.yaml, and if you have created any other jobs specific for your project in jenkins/jobs/, remove them as well.

Submit that change and make sure to mention in the commit message that you are ending project gating for the purposes of retiring the project. Wait for that change to merge and then proceed.

Remove Project Content

Once Zuul is no longer running tests on your project, prepare a change that removes all of the files from your project except the README. Double check that all dot files are also removed.

Replace the contents of the README with a message such as this:

This project is no longer maintained.

The contents of this repository are still available in the Git
source code management system.  To see the contents of this
repository before it reached its end of life, please check out the
previous commit with "git checkout HEAD^1".

(Optional:)
For an alternative project, please see <alternative project name> at
<alternative project URL>.

For any further questions, please email
openstack-dev@lists.openstack.org or join #openstack-dev on
Freenode.

Merge this commit to your project.

If any users missed the announcement that the project is being retired, removing the content of the repository will cause any users who continuously deploy the software as well as users who track changes to the repository to notice the retirement. While this may be disruptive, it is generally considered better than continuing to deploy unmaintained software. Potential contributors who may not have otherwise read the README will in this case, as it is the only file in the repository.

Remove Project from Infrastructure Systems

Once your repository is in its final state, prepare a second change to the openstack-infra/project-config repository that does the following:

• Remove your project from zuul/layout.yaml.

• Replace the contents of gerrit/acls/openstack/<projectname>.config with:

  [project]
  state = read only

• Remove your project from gerritbot/channels.yaml.

Remove Repository from the Governance Repository

If this was an official OpenStack project, remove it from the reference/projects.yaml file in the openstack/governance repository. Note that if the project was recently active, this may have implications for automatic detection of ATCs.

Package Requirements

The OpenStack CI infrastructure sets up nodes for testing that contain a minimal system and a number of convenience distribution packages.

If you want to add additional packages, you have several options.

If you run Python tests using tox, you can install them using requirements.txt and test-requirements.txt files (see also the global requirements process). If these Python tests need additional distribution packages installed as well and if those are not in the nodes used for testing, they have to be installed explicitly.

If you run devstack based tests, then list missing binary packages below the files directory of devstack.

For non-devstack based tests, add a bindep.txt file containing listing the required distribution packages. It is a cross-platform list of all dependencies needed for running tests. The bindep utility will be used to install the right dependencies per distribution when running in the OpenStack CI infrastructure.

If you use bindep, create a bindep tox environment as well:

[testenv:bindep]
# Do not install any requirements. We want this to be fast and work even if
# system dependencies are missing, since it's used to tell you what system
# dependencies are missing! This also means that bindep must be installed
# separately, outside of the requirements files.
deps = bindep
commands = bindep test

This way a developer can just run bindep to get a list of missing packages for their own system:

$ tox -e bindep

The output of this can then be fed into the distribution package manager like apt-get, dnf, yum, or zypper to install missing binary packages.

The OpenStack CI infrastructure will install packages marked for a profile named "test" along with any packages belonging to the default profile of the bindep.txt file. Add any build time requirements and any requirements specific to the test jobs to the "test" profile, add requirements for both test and runtime to the base profile:

# A runtime dependency
libffi6
# A build time dependency
libffi-devel [test]