What is it?

Release build promotion (or "build promotion" for short), is the latest release pipeline for Firefox being developed by ReleaseEngineering at Mozilla.

Release build promotion starts with the builds produced and tested by CI (e.g. on mozilla-beta or mozilla-release). We take these builds, and use them as the basis to generate all our l10n repacks, partial updates, etc. that are required to release Firefox. We "promote" the CI builds to the release channel.

How is this different?

The previous release pipeline also started with builds produced and tested by CI. However, when it came time to do a release, we would create an entirely new set of builds with slightly different build configuration. These builds would not get the regular CI testing.

Release build promotion improves the process by removing the second set of builds. This drastically improves the total time to do a release, and also increases our confidence in our products since we now are shipping exactly what's been tested. We also improve visibility of the release process; all the tasks that make up the release are now reported to Treeherder along with the corresponding CI builds.

Current status

Release build promotion is in use for Firefox desktop starting with the 46 beta cycle. ESR and release branches have not yet been switched over.

Firefox for Android is also not yet handled. We plan to have this ready for Firefox 47.

What's next?

• Support Firefox for Android
• Support release and ESR branches
• Extend this process back to nightly channels

More information

For more information, please refer to these other resources about build promotion:

• March 7th, 2016 Mozilla Project Meeting - Jordan Lund (:jlund) presentation about release build promotion (starts at ~3:20 and ends at about ~10:15)