Release procedure

This page gives an overview of how sasquatch-backpack releases are made. This information is only useful for maintainers.

sasquatch-backpack’s releases are largely automated through GitHub Actions (see the ci.yaml workflow file for details). When a semantic version tag is pushed to GitHub, sasquatch-backpack is released to PyPI with that version. Similarly, documentation is built and pushed for each version (see https://sasquatch-backpack.lsst.io/v).

Regular releases

Regular releases happen from the main branch after changes have been merged. From the main branch you can release a new major version (X.0.0), a new minor version of the current major version (X.Y.0), or a new patch of the current major-minor version (X.Y.Z). See Backport releases to patch an earlier major-minor version.

Release tags are semantic version identifiers following the PEP 440 specification.

1. Change log and documentation

Change log messages for each release are accumulated using scriv. See Updating the change log in the Developer guide for more details.

When it comes time to make the release, there should be a collection of change log fragments in changelog.d. Those fragments will make up the change log for the new release.

Review those fragments to determine the version number of the next release. Safir follows semver, so follow its rules to pick the next version:

  • If there are any backward-incompatible changes, incremeent the major version number and set the other numbers to 0.

  • If there are any new features, increment the minor version number and set the patch version to 0.

  • Otherwise, increment the patch version number.

Then, run scriv collect --version <version> specifying the version number you decided on. This will delete the fragment files and collect them into CHANGELOG.md under an entry for the new release. Review that entry and edit it as needed (proofread, change the order to put more important things first, etc.). scriv will put blank lines between entries from different files. You may wish to remove those blank lines to ensure consistent formatting by various Markdown parsers.

Finally, create a PR from those changes and merge it before continuing with the release process.

2. GitHub release and tag

Use GitHub’s Release feature to create releases and their corresponding Git tags.

  1. Specify a tag from the appropriate branch (typically main). This tag’s name is PEP 440 and is usually formatted at X.Y.Z (without a v prefix).

  2. For the release name, repeat the version string.

  3. Fill in the release notes, copied from the release notes. You can use GitHub’s change log feature to additionally generate a list of PRs included in the release.

The tag must follow the PEP 440 specification since sasquatch-backpack uses setuptools_scm to set version metadata based on Git tags. In particular, don’t prefix the tag with v.

The ci.yaml GitHub Actions workflow uploads the new release to PyPI and documentation to https://sasquatch-backpack.lsst.io.

Backport releases

The regular release procedure works from the main line of development on the master Git branch. To create a release that patches an earlier major or minor version, you need to release from a release branch.

Creating a release branch

Release branches are named after the major and minor components of the version string: X.Y. If the release branch doesn’t already exist, check out the latest patch for that major-minor version:

git checkout X.Y.Z
git checkout -b X.Y
git push -u

Developing on a release branch

Once a release branch exists, it becomes the “main” branch for patches of that major-minor version. Pull requests should be based on, and merged into, the release branch.

If the development on the release branch is a backport of commits on the main branch, use git cherry-pick to copy those commits into a new pull request against the release branch.

Releasing from a release branch

Releases from a release branch are equivalent to regular releases, except that the release branch takes the role of the main branch.