How to make a Gammapy release#

This page contains step-by-step instructions for how to make a Gammapy release. The procedure shown here is inspired by the astropy release scheme. The general procedure can be broken down into three major steps:

Feature freeze: freeze the core package features and create a new branch for the release. This is typically done two weeks before the release.
Release candidate: proposed feature release which should be tested. This is typically done one week before the final release.
Final release.

Feature Freeze and Branching#

A few days before the feature freeze:

Update the author list manually in the CITATION.cff.
- You can use the helper script dev/authors.py for this.
On the main branch, build the changelog for the version you are about to release. This is done through the use of towncrier with the following line:
```
towncrier build --version <version>
```
- The changelog will be saved as docs/release-notes/CHANGELOG.rst, you should update the name to be the correct one for your version, in addition to adapting the required lines in the docs/release-notes/index.rst to ensure it is included in the docs.
- To generate the list of pull requests and issues, and list of authors run python dev/github_summary.py create_pull_request_table. Note that you will need to use your github token here.
Open two separate PRs for each of these changes and mark each with the backport-v<version>.x label. Gather feedback from the Gammapy user and dev community. These PRs will be merged and backport to the v<version>.x branch at the release candidate stage.

On the day of the feature freeze:

Add a new milestone to the GitHub issue tracker for the version v<version>.x (this will also be used for the next bugfix release). Also create a backport-v<version>.x label, which has the description on merge: backport to v<version.x to allow for automatic backport triggering.

Update your local main branch to the latest from remote:

git fetch upstream --tags --prune
git checkout -B main upstream/main

From the github online interface, create a new branch v<version>.x
Update the entry for the feature freeze in the Gammapy release calendar.

Releasing the first major release candidate#

First, make sure you have a gpg key generated for your GitHub account.
In the gammapy-webpage repo:
- Add an entry for the release candidate like v1.0rc1 or v1.1rc1 in the download/index.json file, by copying the entry for dev tag. As we do not handle release candidates nor bug fix releases for data, this still allows to fix bugs in the data during the release candidate testing.
- In the download/install folder, copy a previous environment file as gammapy-1.0rc1-environment.yml.
- Adapt the dependency conda env name and versions as required in this file. Normally, it should be the latest versions of the packages. Note that for the release candidates, gammapy must be included under pip.
Switch to the correct branch and update the CITATION.cff date and version by running the dev/prepare-release.py script:
```
git checkout v1.0.x
python ./dev/prepare-release.py --release v1.0rc1
```
Commit and push the branch back to GitHub:
```
git push upstream v1.0.x
```
Now merge the PR for the changelog, if this has not already been done.
Locally create a new release candidate tag on the v1.0.x, like v1.0rc1 for Gammapy and push:
```
git tag -s v1.0rc1 -m "Tagging v1.0rc1"
git push upstream v1.0rc1
```
Once the tag is pushed, the release action in charge of packaging and uploading to PyPi should be triggered automatically. Once complete, it will trigger the docs build on the gammapy-docs repository.
Check the Actions on gammapy repo and gammapy-docs to check that the necessary actions have started.
Once the docs build is successful find the tutorials_jupyter.zip file for the release candidate in the gammapy-docs repo and adapt the download/index.json to point to it.
Edit docs/stable/index.html so that the URL points to the last stable version, e.g.: url=../1.3 instead of url=../${release}.
Update the entry for the release candidate in the Gammapy release calendar.
Create a testing page like Gammapy v1.0rc testing.
Advertise the release candidate and motivate developers and users to report test fails and bugs and list them on the page created before.

Releasing the final version of the major release#

Create a new tag in the gammapy-data repo, like v1.0 or v1.1.
Create a new tag in the gammapy-benchmarks repo, like v1.0 or v1.1.
In the gammapy-webpage repo:
- In the download/install folder, copy a previous environment file as gammapy-1.0-environment.yml.
- Adapt the dependency conda env name and versions as required in this file. Make sure to move gammapy=1.0 into the dependencies list.
- Update the datasets entry in the download/index.json to point to this new release tag. Also update the notebook entry, typically the link extensions are the same between versions.
In the gammapy repo, switch to the correct branch and update the CITATION.cff date and version by running the dev/prepare-release.py script:
```
git checkout v1.0.x
python ./dev/prepare-release.py --release v1.0rc1
git push
```
Locally create a new release tag like v1.0 for Gammapy and push the tag to upstream:
```
git tag -s v1.0 -m "Tagging v1.0"
git push upstream v1.0.x
```
In the gammapy-docs repo:
- Kill the possible dev-docs build actions as they might interfere with the release docs build.
- Wait for the triggered release docs build to finish.
- Edit docs/stable/switcher.json to add the new version.
- Edit docs/stable/index.html so that the url points to the new version.
In the gammapy-webpage repo:
- Find the tutorials_jupyter.zip file for the new release in the gammapy-docs repo and confirm the link in download/index.json is correct.
- Mention the release on the front page and on the news page. Both the news.html and index.html should be edited at this step to include the correct version numbers.
Update the entry for the actual release in the Gammapy release calendar.
Finally:
- The Gammapy conda-forge package at conda-forge/gammapy-feedstock should be automatically updated within hours and a PR opened. Check that this is the case and if not, perform the manual update of the recipe meta.yaml on your gammapy-feedstock fork and open the PR. Finally, when all tests for all distributions successfully ran, merge the PR.
- Encourage the Gammapy developers to try out the new stable version (update and run tests) via the GitHub issue for the release and wait a day or two for feedback.

Post release#

Steps for the day to announce the release:

Send release announcement to the Gammapy mailing list and on Gammapy Slack.
If it’s a big release with important new features or fixes, also send the release announcement to the following mailing lists (decide on a case by case basis, if it’s relevant to the group of people):
- https://groups.google.com/forum/#!forum/astropy-dev
- CTAO AS WG list (cta-wg-as@cta-observatory.org)
- hess-forum list (hess-forum@lsw.uni-heidelberg.de)
Make sure the release milestone and issue is closed on GitHub.
Update these release notes with any useful infos / steps that you learned while making the release (ideally try to script / automate the task or check, e.g. as a make release-check-xyz target).
Update the version numbers in gammapy-webpage repo master branch to allow the Binder Dockerfile to be updated:
- In gammapy-webpage repo update the master branch:
```
git checkout master
git pull
```
- Update the four files: postBuild, requirements.txt, runtime.txt, and start in the master branch:
```
git add postBuild requirements.txt runtime.txt start
git commit -s -m "Update binder configuration for new release"
git push origin master
```
- Tag the new version and push to the upstream repository:
```
git tag -s v1.3 -m "Tagging v1.3"
git push --tags
```
Open a milestone and issue for the next release (and possibly also a milestone for the release after, so that low-priority issues can already be moved there). Find a release manager for the next release, assign the release issue to them, and ideally put a tentative date (to help developers plan their time for the coming weeks and months).
Start working on the next release.

Make a Bugfix release#

Add an entry for the bug-fix release like v1.0.1 or v1.1.2 in the download/index.json file in the gammapy-webpage repo. The datasets entry should point to the last stable version, like v1.0 or v1.1. We do not provide bug-fix release for data.
Follow the Astropy bug fix release instructions.
To create the changelog, towncrier is utilised:
```
towncrier build --version=<version> --keep
```
- As we will create the changelog again for the major release, we should utilise the keep keyword, as to not delete the fragments.
Follow the instructions for a major release for the updates of CITATION.cff, the modifications in the gammapy-docs and gammapy-webpage repos as well as the conda builds.