HOW_TO_RELEASE.md

How to issue an xarray release in 16 easy steps

Time required: about an hour.

These instructions assume that upstream refers to the main repository:

$ git remote -v
{...}
upstream        https://github.com/pydata/xarray (fetch)
upstream        https://github.com/pydata/xarray (push)

1. Ensure your main branch is synced to upstream:

   git switch main
   git pull upstream main

2. Confirm there are no commits on stable that are not yet merged (ref):

   git merge upstream/stable

3. Add a list of contributors with:

   git log "$(git tag --sort="v:refname" | tail -1).." --format=%aN | sort -u | perl -pe 's/\n/$1, /'

   This will return the number of contributors:

   git log $(git tag --sort="v:refname" | tail -1).. --format=%aN | sort -u | wc -l

4. Write a release summary: ~50 words describing the high level features. This will be used in the release emails, tweets, GitHub release notes, etc.

5. Look over whats-new.rst and the docs. Make sure "What's New" is complete (check the date!) and add the release summary at the top. Things to watch out for:

   • Important new features should be highlighted towards the top.
   • Function/method references should include links to the API docs.
   • Sometimes notes get added in the wrong section of whats-new, typically due to a bad merge. Check for these before a release by using git diff, e.g., git diff v{0.X.Y-1} whats-new.rst where {0.X.Y-1} is the previous release.

6. Open a PR with the release summary and whatsnew changes; in particular the release headline should get feedback from the team on what's important to include.

7. After merging, again ensure your main branch is synced to upstream:

   git pull upstream main

8. If you have any doubts, run the full test suite one final time!

   pytest

9. Check that the ReadTheDocs build is passing.

10. Issue the release on GitHub. Click on "Draft a new release" at https://github.com/pydata/xarray/releases. Type in the version number (with a "v") and paste the release summary in the notes.

11. This should automatically trigger an upload of the new build to PyPI via GitHub Actions. Check this has run here, and that the version number you expect is displayed on PyPI

12. Update the stable branch (used by ReadTheDocs) and switch back to main:

     git switch stable
     git rebase main
     git push --force upstream stable
     git switch main

    You may need to first fetch it with git fetch upstream, and check out a local version with git checkout -b stable upstream/stable.

    It's OK to force push to stable if necessary. (We also update the stable branch with git cherry-pick for documentation only fixes that apply the current released version.)

13. Add a section for the next release {0.X.Y+1} to doc/whats-new.rst:

    .. _whats-new.0.X.Y+1:
    
    v0.X.Y+1 (unreleased)
    ---------------------
    
    New Features
    ~~~~~~~~~~~~
    
    
    Breaking changes
    ~~~~~~~~~~~~~~~~
    
    
    Deprecations
    ~~~~~~~~~~~~
    
    
    Bug fixes
    ~~~~~~~~~
    
    
    Documentation
    ~~~~~~~~~~~~~
    
    
    Internal Changes
    ~~~~~~~~~~~~~~~~
    

14. Commit your changes and push to main again:

    git commit -am 'New whatsnew section'
    git push upstream main

    You're done pushing to main!

15. Update the docs. Login to https://readthedocs.org/projects/xray/versions/ and switch your new release tag (at the bottom) from "Inactive" to "Active". It should now build automatically.

16. Issue the release announcement to mailing lists & Twitter. For bug fix releases, I usually only email xarray@googlegroups.com. For major/feature releases, I will email a broader list (no more than once every 3-6 months):

    • pydata@googlegroups.com
    • xarray@googlegroups.com
    • numpy-discussion@scipy.org
    • scipy-user@scipy.org
    • pyaos@lists.johnny-lin.com

    Google search will turn up examples of prior release announcements (look for "ANN xarray"). Some of these groups require you to be subscribed in order to email them.

Note on version numbering

We follow a rough approximation of semantic version. Only major releases (0.X.0) should include breaking changes. Minor releases (0.X.Y) are for bug fixes and backwards compatible new features, but if a sufficient number of new features have arrived we will issue a major release even if there are no compatibility breaks.

Once the project reaches a sufficient level of maturity for a 1.0.0 release, we intend to follow semantic versioning more strictly.