Backporting process

Backport Criteria

Committers may nominate PRs that have been merged into master as candidates for backport into stable releases if they affect the stable production usage of community users.

Backport criteria for current minor release

Criteria for inclusion into the next stable release of the current latest minor version of Cilium, for example in a v1.2.z release prior to the release of version v1.3.0:

  • All bugfixes

Backport criteria for X.Y-1.Z and X.Y-2.Z

Criteria for the inclusion into the next stable release of the prior two minor versions of Cilium, for example in a v1.0.z or v1.1.z release prior to the release of version v1.3.0:

  • Security relevant fixes
  • Major bugfixes relevant to the correct operation of Cilium

Backporting guide

Cilium PRs that are marked with the label needs-backport/X.Y need to be backported to the stable branch X.Y. The following steps summarize the process for backporting these PRs:

  • One-time setup
  • Preparing PRs for backport
  • Cherry-picking commits into a backport branch
  • Posting the PR and updating GitHub labels

One-time setup

  1. The scripts referred to below need to be run on Linux, they do not work on macOS. You can use the cilium dev VM for this, but you need to configure git to have your name and email address to be used in the commit messages:

    $ git config --global user.name "John Doe"
$ git config --global user.email johndoe@example.com

  2. Make sure you have a GitHub developer access token with the public_repos scope available. For details, see contrib/backporting/README.md

  3. This guide makes use of several tools to automate the backporting process. The basics require bash and git, but to automate interactions with github, further tools are required.

    Dependency Required? Download Command
    bash Yes N/A (OS-specific)
    git Yes N/A (OS-specific)
    jq Yes N/A (OS-specific)
    python3 No Python Downloads
    PyGithub No pip3 install PyGithub
    Github hub CLI (>= 2.8.3) No N/A (OS-specific)

Preparation

Pull requests that are candidates for backports to the X.Y stable release are tracked through the following links:

Make sure that the Github labels are up-to-date, as this process will deal with all commits from PRs that have the needs-backport/X.Y label set (for a stable release version X.Y). If any PRs contain labels such as backport-pending/X.Y, ensure that the backport for that PR have been merged and if so, change the label to backport-done/X.Y.

Creating the backports branch

  1. Run contrib/backporting/start-backport for the release version that you intend to backport PRs for. This will pull the latest repository commits from the Cilium repository (assumed to be the git remote origin), create a new branch, and runs the contrib/backporting/check-stable script to fetch the full set of PRs to backport.

    $ GITHUB_TOKEN=xxx contrib/backporting/start-backport 1.0

    Note

    This command will leave behind a file in the current directory with a name based upon the release version and the current date in the form vRELEASE-backport-YYYY-MM-DD.txt which contains a prepared backport pull-request description so you don’t need to write one yourself.

  2. Cherry-pick the commits using the master git SHAs listed, starting from the oldest (top), working your way down and fixing any merge conflicts as they appear. Note that for PRs that have multiple commits you will want to check that you are cherry-picking oldest commits first. The cherry-pick script accepts multiple arguments, in which case it will attempt to apply each commit in the order specified on the command line until one cherry pick fails or every commit is cherry-picked.

    $ contrib/backporting/cherry-pick <oldest-commit-sha>
...
$ contrib/backporting/cherry-pick <newest-commit-sha>

  3. (Optional) If there are any commits or pull requests that are tricky or time-consuming to backport, consider reaching out for help on Slack. If the commit does not cherry-pick cleanly, please mention the necessary changes in the pull request description in the next section.

  4. Push your backports branch to cilium repo.

    $ git push -u origin

Creating the backport pull request

The backport pull-request may be created via CLI tools, or alternatively you can use the GitHub web interface to achieve these steps.

Via command-line tools

These steps require all of the tools described in the One-time setup section above. It pushes the git tree, creates the pull request and updates the labels for the PRs that are backported, based on the vRELEASE-backport-YYYY-MM-DD.txt file in the current directory.

# contrib/backporting/submit-backport

The script takes up to three positional arguments:

usage: submit-backport [branch version] [pr-summary] [your remote]
  • The first parameter is the version of the branch against which the PR should be done, and defaults to the version passed to start-backport.
  • The second one is the name of the file containing the text summary to use for the PR, and defaults to the file created by start-backport.
  • The third one is the name of the git remote of your (forked) repository to which your changes will be pushed. It defaults to the git remote which matches github.com/<your github username>/cilium.

Via GitHub Web Interface

  1. Push your backports branch to your fork of the Cilium repo.

    $ git push -u <remote_for_your_fork> HEAD

  2. Create a new PR from your branch towards the feature branch you are backporting to. Note that by default Github creates PRs against the master branch, so you will need to change it. The title and description for the pull request should be based upon the vRELEASE-backport-YYYY-MM-DD.txt file that was generated by the scripts above.

  3. Label the new backport PR with the backport label for the stable branch such as backport/X.Y as well as kind/backports so that it is easy to find backport PRs later.

  4. Mark all PRs you backported with the backport pending label backport-pending/X.Y and clear the needs-backport/vX.Y label.

After the backports are merged

After the backport PR is merged, mark all backported PRs with backport-done/X.Y label and clear the backport-pending/X.Y label(s). If the backport pull request description was generated using the scripts above, then the full command is listed in the pull request description.

# Set PR 1234's v1.0 backporting labels to done
contrib/backporting/set-labels.py 1234 done 1.0.