< ReleaseEngineering


What is a disposable project branch?

These are project branches that can be cloned fresh from any mozilla-central based repo with the full gamut of tests enabled. No l10n or nightlies for now. Similar to TryServer but for longer, and just for you. Unlike Try, the commit level on these branches is level_2 (and above) contributors only so please bear that in mind.

Do you need a disposable branch?

Ask yourself the following:

Does your project have an end date?

If your answer is No then you should follow the process at Project Branch Planning

If your project is a temporary feature sprint that needs its own rapid test coverage but will eventually be merged into mozilla-central and no longer be on its own by all means, please go ahead and

Book one of our fabulous "disposable" project branches

NOTE: The number of disposable branches is limited by CI capacity. If there are no available branches, contact the owners of existing branches to see if you can "sub let".

  • Sign up below in the BOOKING SCHEDULE
  • Make a request (example: bug 1518167) to VCS to reset the repo for you. You can specify the source repository and target revision to use, or default to mozilla-central:tip. Ask that they run the `hgmo-reset-twig.yml` Ansible playbook found in version-control-tools to accomplish this.
  • NOTE: Your repository will have no hooks enabled after a reset. You'll need to specify in the request if you need any configured.
  • After Developer Services runs the reset, they will also notify the teams who operate the automation, so they can adjust their schedulers to recognize the reset. If you don't see the expected builds, check with the automation teams to ensure their reset occurred.
  • Sit back and watch your builds and test results roll in (eg Birch, Cedar, Larch, Maple).

When you're done with one of our fabulous "disposable" project branches

Simply clear your data (bug, contact, dates) from the BOOKING SCHEDULE below. If someone is listed in the "Next in Line" column, please let them know you are done.

That's all there is to it!

Using a custom mozconfig

The mozconfigs used for builds live in the same source tree as the main code, eg

  • Firefox: browser/config/mozconfigs/<platform>
  • Mobile Native: mobile/android/config/mozconfigs/android
  • Mobile XUL: mobile/xul/config/mozconfigs/android-xul

The 'nightly' file is used for optimised builds, 'debug' for debug. If you are unsure which file you need consult a build log to see which is used. You can adjust these as needed on your branch, and they will be carried over to mozilla-central when you merge back. Please take care with any mozconfig changes you merge back (eg exclude local conveniences).

Enabling/Disabling of platforms, tests, nightly updates

If the specific builds/tests you want are not enabled, or if there are builds/tests which you do not need on your branch, ask RelEng to enable/disable them by filing a bug here.

Nightly builds and updates are disabled by default but can be enabled on request.


Project Branch Regist. bug email address of borrower User/Dev Team contact Booking Dates Next in Line
Ash bug 1786042 aleca, darktrojan 2022-08-19 - 2023-08-31
Cypress bug 1171698 2024-01-09 - 2024-12-31
Elm bug 1728404 libwebrtc update 2H2020 2021-07-31 - 2024-12-31
Cedar bug 1820001 iOS prototyping, csadilek 2023-03-02 - 2024-03-31
Fig retired retired retired retired retired
Gum retired retired retired retired retired
Holly bug 1599905, <- 2019-12-02 - 2020-04-02 -
Larch bug 1874491 desktop sidebar Mardak, tarek 2024-01-16 - 2025-01-16
Oak bug 1819778 Android Monorepo project: Prototyping move to M-C., jlorenzo, gl 2023-03-02 - 2024-06-30 -

Be sure to keep a copy of anything you need from the repo prior to unbooking it.

Indefinite booking

See also ReleaseEngineering/SpecialBranches for more info on these branches.

Project Branch Regist. bug email address of borrower User/Dev Team contact Booking Dates
Date disabled disabled disabled DO NOT USE -
Jamun bug 1666242 comm-central as a branch 2020-10-21 - ?
Birch bug 1426132 - Unused 2023-07-20 - indefinite
Maple bug 1397773 MacOS Signing Changes 2023-07-28 - indefinite
Pine bug 1845368 Desktop Integrations Team 2023-07-27 - indefinite -