Document the AMUSE release process

doc/developing/index.rst

@@ -7,4 +7,5 @@ Contents:
    :maxdepth: 2
 
    documenting
+   releasing
    design/index

doc/developing/releasing.rst

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+.. _releasing:
+
+================
+Making a release
+================
+
+Every once in a while, we make a new release of AMUSE, when we feel that enough new
+features have accumulated or when important fixes have been made. AMUSE is quite mature
+by now, and uses a time-based versioning scheme with the `CalVer <https://calver.org/>`_
+pattern vYYYY.MM.MICRO.
+
+Making a release takes three steps: collecting changes, tagging the release, and making
+a release on GitHub.
+
+
+Collecting changes
+==================
+
+Every release should come with a description of changes, so that the users know what to
+expect. GitHub can make these automatically, but it's nice to check by hand to make sure
+nothing and in particular no one (contributor) goes missing.
+
+All the changes are in the git log, so this is a matter of running ``git log`` with your
+favourite options and making a list of changes and contributors.
+
+
+Tagging the release
+===================
+
+Each release needs to be tagged in git to make sure we know exactly which version of the
+software is being released, and so that the build system knows which version it's
+building and installing and can set the metadata correctly.
+
+Git knows two different kinds of tags, annotated tags and lightweight tags. Annotated
+tags are intended for releases, and because of the way our build system is set up, they
+*must* be used. Tagging the current main version of AMUSE is done using:
+
+.. code-block:: bash
+
+    git switch main
+    git pull
+    git tag -a -m 'Release v2025.9.0' v2025.9.0
+
+
+Or whatever the current year and month is. The third number should be used to
+distinguish multiple releases within a single month.
+
+The ``-a`` in the final command makes an annotated tag, ``-m`` adds a (required) message
+to it, and ``v2025.9.0`` is the name of the tag.
+
+Make sure that you follow exactly this pattern (with a ``v`` at the start and periods,
+not underscores or dashes), as the build system relies on it.
+
+If you run
+
+.. code-block:: bash
+
+    git cat-file -t v2025.9.0
+
+
+it should show ``tag``, not ``commit``.
+
+If the tag has been made correctly, then you can push it to GitHub using
+
+.. code-block:: bash
+
+    git push tag v2025.9.0
+
+
+Making a GitHub release
+=======================
+
+Finally, we will make a GitHub release, which adds the release to GitHub's Releases page
+with a nice description, causes GitHub to make a tar.gz archive available for the
+release, and archives the release on Zenodo.
+
+Go to `the AMUSE releases page <https://github.com/amusecode/amuse/releases>`_, and
+click "Draft a new release" at the top. Select the tag you just made, add a title for
+the release (generally just "v2025.9.0" or whatever the version is), and then click
+"Generate release notes".
+
+Check your list of changes and contributors from above against what GitHub generated,
+and edit as needed. Consider whether the release notes make sense from the perspective
+of a user of AMUSE; the developers already know what's going on. In particular, you may
+want to organise the changes a bit, starting with new user-visible features,
+user-visible fixes, then more technical improvements that don't affect the users' every
+day usage.
+
+Once you have something that will help the users quickly see what's new and whether they
+should upgrade, you can set the new release as the latest one, don't make it a
+pre-release (see below), and don't create a discussion, and when all is ready click
+"Publish release" to publish it.
+
+
+Pre-releases
+============
+
+Pre-releases can be a good way of inviting people to test some big changes, giving you a
+chance to fix any issues before making the final release. Pre-releases should be tagged
+as above, with a version of the form v2025.5.0.rc1 (rc stands for release candidate).
+Then a GitHub release can be made and marked as a pre-release.
+
+