# 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:

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

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 1. Ensure your main branch is synced to upstream:
     ```sh
     git switch main
     git pull upstream main
     ```
 2. Add a list of contributors with:
    ```sh
    git log "$(git tag --sort=v:refname | tail -1).." --format=%aN | sort -u | perl -pe 's/\n/$1, /'
    ```
    This will return the number of contributors:
    ```sh
    git log "$(git tag --sort=v:refname | tail -1).." --format=%aN | sort -u | wc -l
    ```
 3. Write a release summary: ~50 words describing the high level features. This
    will be used in the release emails, tweets, GitHub release notes, etc.
 4. 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{YYYY.MM.X-1} whats-new.rst` where {YYYY.MM.X-1} is the previous
      release.
 5. 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.
 6. After merging, again ensure your main branch is synced to upstream:
     ```sh
     git pull upstream main
     ```
 7. If you have any doubts, run the full test suite one final time!
      ```sh
      pytest
      ```
 8. Check that the ReadTheDocs build is passing on the `main` branch.
 9. 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.
 10. This should automatically trigger an upload of the new build to PyPI via GitHub Actions.
    Check this has run [here](https://github.com/pydata/xarray/actions/workflows/pypi-release.yaml),
    and that the version number you expect is displayed [on PyPI](https://pypi.org/project/xarray/)
11. Add a section for the next release {YYYY.MM.X+1} to doc/whats-new.rst:
     ```rst
     .. _whats-new.YYYY.MM.X+1:

     vYYYY.MM.X+1 (unreleased)
     ---------------------

     New Features
     ~~~~~~~~~~~~


     Breaking changes
     ~~~~~~~~~~~~~~~~


     Deprecations
     ~~~~~~~~~~~~


     Bug fixes
     ~~~~~~~~~


     Documentation
     ~~~~~~~~~~~~~


     Internal Changes
     ~~~~~~~~~~~~~~~~

     ```
12. Commit your changes and push to main again:
      ```sh
      git commit -am 'New whatsnew section'
      git push upstream main
      ```
    You're done pushing to main!

13. 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.

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## Note on version numbering

As of 2022.03.0, we utilize the [CALVER](https://calver.org/) version system.
Specifically, we have adopted the pattern `YYYY.MM.X`, where `YYYY` is a 4-digit
year (e.g. `2022`), `0M` is a 2-digit zero-padded month (e.g. `01` for January), and `X` is the release number (starting at zero at the start of each month and incremented once for each additional release).
