Table of contents

Main branch is Airflow 3.x

The main branch is for development of Airflow 3.x (next minor release). Airflow 3.1.x releases will be cut from v3-1-stable branch. Airflow 2.11.x releases will be cut from v2-11-stable branch.

Contributors

The following section explains which branches you should target with your PR.

Developing for Providers and the Helm Chart

PRs should target the main branch. Make sure your changes are only related to Providers or the Helm chart. Avoid mixing core changes into the same PR.

Developing for Airflow 3.x, 3.1.x

If the PR is relevant to both Airflow 3.x and 3.1.x, it should target the main branch.

If you want to have a fix backported to 3.1.x please add (or request to add) “backport-to-v3-1-test” label to the PR. CI will automatically attempt to create a backport PR after merge.

When preparing a new 3.1.x release, the release manager will sync the v3-1-test branch to v3-1-stable and cut the release from the stable branch. PRs should never target v3-1-stable directly unless explicitly instructed by the release manager.

Developing for Airflow 3

PRs should target main branch.

Developing for Airflow 2.11.x

If a PR can be cleanly cherry-picked from main to v2-11-test, it should target the main branch and include the backport-to-v2-11-test label to automate the backport. If the PR cannot be cherry-picked without conflicts, you must manually create a PR targeting the v2-11-test branch.

[!IMPORTANT] Airflow 2.11 is intended as a bridge release for Airflow 3. As such, it is not expected to introduce new features beyond those relevant to the transition to Airflow 3. That said, we focus only critical security fixes in the maintenance period until end-of-life.

When preparing a new 2.11.x release, the release manager will sync the v2-11-test branch to v2-11-stable and cut the release from the stable branch. PRs should never target v2-11-stable directly unless explicitly instructed by the release manager.

Committers / PMCs

The following sections explains the protocol for merging PRs.

Merging PRs for providers and Helm chart

Make sure PR targets main branch. Avoid merging PRs that involve (providers + core) or (helm chart + core). Core parts should be extracted to a separate PR. Exclusions should be pre-approved specifically with a comment by release manager. Do not treat PR approval (Green V) as exclusion approval.

Merging PRs targeted for Airflow 3.X

The committer who merges the PR is responsible for backporting the PRs that are 3.1 bug fixes (generally speaking) to v3-1-test (latest active branch we release bugfixes from). See next chapter to see what kind of changes we cherry-pick.

It means that they should create a new PR where the original commit from main is cherry-picked and take care for resolving conflicts. If the cherry-pick is too complex, then ask the PR author / start your own PR against v3-1-test directly with the change. Note: tracking that the PRs merged as expected is the responsibility of committer who merged the PR.

Committer may also request from PR author to raise 2 PRs one against main branch and one against v3-1-test prior to accepting the code change.

Mistakes happen, and such backport PR work might fall through cracks. Therefore, if the committer thinks that certain PRs should be backported, they should set 3.1.x milestone for them.

This way release manager can verify (as usual) if all the “expected” PRs have been backported and cherry-pick remaining PRS.

We are using cherry-picker - a tool that has been developed by Python developers. It allows to easily cherry-pick PRs from one branch to another. It works both - via command line and via GitHub Actions interface.

What do we backport to v3-1-test branch?

The v3-1-test latest branch is generally used to release bugfixes, but what we cherry-pick is a bit more nuanced than bugfixes only. We cherry-pick:

  • Bug-fixes (obviously) - but not all of them - often we might decide to not cherry-pick bug-fixes that are not relevant to the latest release or difficult to cherry-pick
  • CI changes - we cherry-pick most CI changes because our CI has a lot of dependencies on external factors (such as dependencies, Python versions, etc.) and we want to keep it up-to-date in the bugfix branch to keep CI green and to make latest workflows work in the same way as in the main branch
  • Documentation changes - we cherry-pick documentation changes that are relevant to the latest release and that help users to understand how to use the latest release. We do not cherry-pick documentation changes that refer to features that are added in main branch and not in the latest release.
  • Minor refactorings in active areas - sometimes we might decide to cherry-pick minor refactorings that are relevant to the latest release and that help us to keep the codebase clean and maintainable, particularly when they are done in areas that are likely to be cherry-picked. The reason why we are doing it is to make it easier for future cherry-picks to avoid conflicts. Committers should use their judgment whether to cherry-pick such changes (default being no) and they should be always justified by explaining why this change is cherry-picked even if it is not a bug-fix.

How to backport PR with GitHub Actions

When you want to backport commit via GitHub actions (you need to be a committer), you should use “Backport commit” action. You need to know the commit hash of the commit you want to backport. You can pin the workflow from the list of workflows for easy access to it.

[!NOTE] It should be the commit hash of the commit in the main branch, not in the original PR - you can find it via git log or looking up main History.

Backport commit

Use main as source of the workflow and copy the commit hash and enter the target branch name (e.g. v2-11-test, v3-0-test).

The action should create a new PR with the cherry-picked commit and add a comment in the PR when it is successful (or when it fails). If automatic backporting fails because of conflicts, you have to revert to manual backporting using cherry-picker CLI.

How to backport PR with cherry-picker CLI

Backporting via CLI might be more convenient for some users. Also it is necessary if you want to backport PR that has conflicts. It also allows to backport commit to multiple branches in the same command.

To backport PRs to any branch (for example: v2-11-test), you can use the following command:

It's easiest to install it (and keep cherry-picker up-to-date) using uv tool:

uv tool install cherry-picker

And upgrade it with:

uv tool upgrade cherry-picker

Then, in order to backport a commit to a branch, you can use the following command:

cherry_picker COMMIT_SHA BRANCH_NAME1 [BRANCH_NAME2 ...]

This will create a new branch with the cherry-picked commit and open a PR against the target branch in your browser.

If the GH_AUTH environment variable is set in your command line, the cherry-picker automatically creates a new pull request when there are no conflicts. To set GH_AUTH, use the token from your GitHub repository.

To set GH_AUTH run this:

export GH_AUTH={token}

Sometimes it might result with conflict. In such case, you should manually resolve the conflicts. Some IDEs like IntelliJ has a fantastic conflict resolution tool - just follow Git -> Resolve conflicts menu after you get the conflict. But you can also resolve the conflicts manually; see How conflicts are are presented and How to resolve conflicts for more details.

cherry_picker --status  # Should show if all conflicts are resolved
cherry_picker --continue  # Should continue cherry-picking process

[!WARNING] Sometimes, when you stop cherry-picking process in the middle, you might end up with your repo in a bad state and cherry-picker might print this message:

🐍 🍒 ⛏

You're not inside a cpython repo right now! 🙅

You should then run cherry-picker --abort to clean up the mess and start over. If that does not work you might need to run git config --local --remove-section cherry-picker to clean up the configuration stored in .git/config.

Merging PRs for Airflow 3

Make sure PR target main branch.

PRs that involve breaking changes

Our goal is to avoid breaking changes whenever possible. Therefore, we should allow time for community members to review PRs that contain such changes - please avoid rushing to merge them. Also, please make sure that such PRs contain a significant newsfragment that contains **Breaking Change**.

Milestones for PR

Set 3.1.x milestone

Milestone will be added only to the original PR.

  1. PR targeting v3-1-test directly - milestone will be on that PR.
  2. PR targeting main with backport PR targeting v3-1-test. Milestone will be added only on the PR targeting v3-1-main.

Set 3.2 milestone

Set for any feature that targets Airflow 3.x only.