ESMValCore v2.13.0 release

[jlenh]

Hello hello @ESMValGroup/esmvaltool-developmentteam
Here is a the thread for the the release process of v2.13.0, more updates to come! (Following the steps from here, and see nice diagram here)

Manager	Buddy	Feature Freeze	Feature branch	Milestone
@jlenh	@sloosvel	2025-08-18

Minor Release	Status	Date	RTD	Release	conda-forge	PyPI	Docker
v2.13.0rc1		2025-08-21	Documentation	esmvalcore	conda-forge	esmvalcore --pre	Docker
v2.13.0rc3		2025-09-12	[Documentation]	esmvalcore	conda-forge	esmvalcore --pre	Docker
v2.13.0		TBD

[jlenh]

1. Check that all tests and builds work

• Check that the nightly test run on CircleCI was successful.
• Check that the GitHub Actions test runs were successful.
• Check that the documentation builds successfully on readthedocs.
• Check that the Docker images are building successfully.

All tests should pass before making a release (branch).

Additional Steps

• To access the information required at the Docker link, the user must be signed in and have access to the esmvalgroup organisation.

[jlenh]

2. Create a release branch + 3. Increase the version number

The version number is automatically generated from the information provided by git using setuptools-scm, but a static version number is stored in CITATION.cff.

• Make sure to update the version number and release date in CITATION.cff. (See https://semver.org/ for more information on choosing a version number).
• Make a pull request
• Get it merged into main
• Tag w/ v2.13.0rc1
• Create a release branch v2.13.x off the main branch and push it to GitHub.
• Ask someone with administrative permissions to set up branch protection rules for it so only you and the person helping you with the release can push to it.

Additional Steps

• Check in with assignees for all outstanding PRs and Issues in the current milestone.

4. Add release notes

• Use the script esmvaltool/utils/draft_release_notes.py to create create a draft of the release notes.
• Open a discussion to allow members of the development team to nominate pull requests as highlights. (Discussion)
• Add the most voted pull requests as highlights at the beginning of changelog.
• After the highlights section, list any backward incompatible changes that the release may include.
• The backward compatibility policy. lists the information that should be provided by the developer of any backward incompatible change.
• Make sure to also list any deprecations that the release may include, as well as a brief description on how to upgrade a deprecated feature.
• Review the results, and if anything needs changing, change it on GitHub and re-run the script until the changelog looks acceptable.
• Copy the result to the file doc/changelog.rst.
• Make a pull request
• Get it merged into main

[jlenh]

#2817

[jlenh]

Voting for highlights #2816

[jlenh]

5. Make the (pre-)release on GitHub

• Do a final check that all tests on CircleCI and GitHub Actions completed successfully.
• Then click the releases tab and create the new release from main (see below)
• Create a tag and tick the This is a pre-release box if working with a release candidate.

[jlenh]

https://github.com/ESMValGroup/ESMValCore/releases/tag/v2.13.0rc1

[jlenh]

6. Create and upload the PyPI package

• The package is automatically uploaded to the PyPI by a GitHub action.

[jlenh]

https://pypi.org/project/ESMValCore/2.13.0rc1/

[jlenh]

7. Create the Conda package

• The esmvalcore package is published on the conda-forge conda channel.
• This is done via a pull request on the esmvalcore-feedstock repository.
• To publish a release candidate, you have to open a pull request yourself. An example for this can be found [here]Pre release v2.5.0rc6 conda-forge/esmvalcore-feedstock#35).
• Make sure to use the rc branch as the target branch for your pull request.
• Follow all instructions given by the linter bot.
• The testing of ESMValTool will be performed with the published release candidate.

[jlenh]

conda-forge/esmvalcore-feedstock#87

[jlenh]

https://anaconda.org/conda-forge/esmvalcore/files

[jlenh]

8. Check the Docker images

After making the release, check that the Docker image for that release has been built correctly
by:

• checking that the version tag is available on Dockerhub
• running some recipes with the stable tag Docker container, for example one recipe for Python, NCL, R, and Julia,
• running a recipe with a Singularity container built from the stable tag.

[bouweandela]

I wouldn't expect the stable tag to get updated with a release candidate, but only with the actual release. Does it contain the release candidate now?

[jlenh]

Yes my bad, just copied from Chris' template and didn't check the boxes.
Just the release tag is updated!

[jlenh]

11. Run the recipes - step 2.3/2.4

• Uncomment the release candidate channel item (i.e. conda-forge/label/esmvalcore_rc) in the environment.yml of ESMValTool to add it to the list of channels used.
• Adjust the pin on ESMValCore after each release candidate (e.g. esmvalcore==2.8.0rc1).
• Check that the environment creation of ESMValTool works fine and contains the latest release candidate version.
• Run all the recipes (optionally with a reduced amount of data) to check that they still work with the release candidate.

[jlenh]

See ESMValGroup/ESMValTool#4157