Build system details for Firefox desktop

• Overview
• Timeline and deadlines
  • Updating release

Overview

Thanks to using a single source for localization, we ship all versions of Firefox from a single localization repository.

A job, called l10n-bumper, runs on Taskcluster every hour, and stores information on which changeset (defined by the revision SHA of firefox-l10n) to use for each build in a file called l10n-changesets.json within each revision branch of mozilla-firefox:

• Nightly (main branch of mozilla-firefox) changeset: l10n-changesets.json. This always uses the latest revision of main of firefox-l10n.
• Beta (beta branch of mozilla-firefox) changeset: l10n-changesets.json. This also uses the the latest revision of main of firefox-l10n, but it’s only updated twice a week.
• Before Release Candidate week, the beta tree is closed. The l10n-bumper will restart at the beginning of the next cycle, when the beta tree is reopened.
• When the Beta code is merged to Release, l10n-changesets.json moves together with the rest of the code to the release branch. That means that Release builds will use the same changesets as the last beta with the same version number, and any further change requires code uplifts.

Timeline and deadlines

This is how Beta looks like in a 4 weeks release cycle, with relevant milestones.

On Monday, 8 days before the release, the l10n-bumper will stop updating l10n-changesets.json on beta.

Once the code merges from Beta to Release, any changeset update would require a manual uplift to release and a new Release Candidate (RC) build.

Updating release

When the code moves from beta to release, l10n-changesets.json is frozen, as l10n-bumper is not configured to run against the release branch.

In case of severe issues affecting one or more locales, it’s still possible to manually update the shipping changesets. A patch needs to be provided for l10n-changesets.json in release branch and approved for uplift by Release Drivers (see for example this bug and associated patch). Note that a dot release is needed in order to ship the updated version to users.

The same process applies to ESR versions, as long as the associated esr repository is included among the supported versions in firefox-l10n-source.