Release Notes

Release notes for a patch should be included in the patch with the associated changes whenever possible. This allow for simpler tracking. It also enables a single cherry pick to be done if the change is backported to a previous release. In some cases, such as a feature that is provided via multiple patches, release notes can be done in a follow-on review.

If the following applies to the patch, a release note is required:

  • The deployer needs to take an action when upgrading

  • A new feature is implemented

  • Function was removed (hopefully it was deprecated)

  • Current behavior is changed

  • A new config option is added that the deployer should consider changing from the default

  • A security bug is fixed


  • A release note is suggested if a long-standing or important bug is fixed. Otherwise, a release note is not required.

  • It is not recommended that individual release notes use prelude section as it is for release highlights.


Avoid modifying an existing release note file even though it is related to your change. If you modify a release note file of a past release, the whole content will be shown in a latest release. The only allowed case is to update a release note in a same release.

If you need to update a release note of a past release, edit a corresponding release note file in a stable branch directly.

Horizon uses reno to generate release notes. Please read the docs for details. In summary, use

$ tox -e venv -- reno new <bug-,bp-,whatever>

Then edit the sample file that was created and push it with your change.

To see the results:

$ git commit  # Commit the change because reno scans git log.

$ tox -e releasenotes

Then look at the generated release notes files in releasenotes/build/html in your favorite browser.