Releasing

Start from a clean checkout at main.

Before running through the release it's good to run the build and the tests locally, and make sure CI is passing. You can also test-drive the commit in an existing Bazel workspace to sanity check functionality.

Releasing from HEAD

These are the steps for a regularly scheduled release from HEAD.

Steps

1. Determine the next semantic version number.
2. Update CHANGELOG.md: replace the v0-0-0 and 0.0.0 with X.Y.0.

   awk -v version=X.Y.0 'BEGIN { hv=version; gsub(/\./, "-", hv) } /END_UNRELEASED_TEMPLATE/ { found_marker = 1 } found_marker { gsub(/v0-0-0/, hv, $0); gsub(/Unreleased/, "[" version "] - " strftime("%Y-%m-%d"), $0); gsub(/0.0.0/, version, $0); } { print } ' CHANGELOG.md > /tmp/changelog && cp /tmp/changelog CHANGELOG.md
   

3. Replace VERSION_NEXT_* strings with X.Y.0.

   grep -l --exclude=CONTRIBUTING.md --exclude=RELEASING.md --exclude-dir=.* VERSION_NEXT_ -r \
     | xargs sed -i -e 's/VERSION_NEXT_FEATURE/X.Y.0/' -e 's/VERSION_NEXT_PATCH/X.Y.0/'
   

4. Send these changes for review and get them merged.
5. Create a branch for the new release, named release/X.Y

   git branch --no-track release/X.Y upstream/main && git push upstream release/X.Y
   

The next step is to create tags to trigger release workflow, however we start by using release candidate tags (X.Y.Z-rcN) before tagging the final release (X.Y.Z).

1. Create release candidate tag and push. Increment N for each rc.

   git tag X.Y.0-rcN upstream/release/X.Y && git push upstream --tags
   

2. Announce the RC release: see [Announcing Releases]
3. Wait a week for feedback.
   • Follow [Patch release with cherry picks] to pull bug fixes into the release branch.
   • Repeat the RC tagging step, incrementing N.
4. Finally, tag the final release tag:

   git tag X.Y.0 upstream/release/X.Y && git push upstream --tags
   

Release automation will create a GitHub release and BCR pull request.

Determining Semantic Version

rules_python uses semantic version, so releases with API changes and new features bump the minor, and those with only bug fixes and other minor changes bump the patch digit.

To find if there were any features added or incompatible changes made, review CHANGELOG.md and the commit history. This can be done using github by going to the url: https://github.com/bazel-contrib/rules_python/compare/<VERSION>...main.

Patch release with cherry picks

If a patch release from head would contain changes that aren't appropriate for a patch release, then the patch release needs to be based on the original release tag and the patch changes cherry-picked into it.

In this example, release 0.37.0 is being patched to create release 0.37.1. The fix being included is commit deadbeef.

1. git checkout release/0.37
2. git cherry-pick -x deadbeef
3. Fix merge conflicts, if any.
4. git cherry-pick --continue (if applicable)
5. git push upstream

If multiple commits need to be applied, repeat the git cherry-pick step for each.

Once the release branch is in the desired state, use git tag to tag it, as done with a release from head. Release automation will do the rest.

Announcing releases

We announce releases in the #python channel in the Bazel slack (bazelbuild.slack.com). Here's a template:

Greetings Pythonistas,

rules_python X.Y.Z-rcN is now available
Changelog: https://rules-python.readthedocs.io/en/X.Y.Z-rcN/changelog.html#vX-Y-Z

It will be promoted to stable next week, pending feedback.

It's traditional to include notable changes from the changelog, but not required.

Re-releasing a version

Re-releasing a version (i.e. changing the commit a tag points to) is sometimes possible, but it depends on how far into the release process it got.

The two points of no return are:

• If the PyPI package has been published: PyPI disallows using the same filename/version twice. Once published, it cannot be replaced.
• If the BCR package has been published: Once it's been committed to the BCR registry, it cannot be replaced.

If release steps fail prior to those steps, then its OK to change the tag. You may need to manually delete the GitHub release.

Secrets

PyPI user rules-python

Part of the release process uploads packages to PyPI as the user rules-python. This account is managed by Google; contact rules-python-pyi@google.com if something needs to be done with the PyPI account.