Merge Duty#

All code changes to Firefox land in the mozilla-central repository

  • The nightly releases are built from that repo twice a day.

  • DevEdition and Beta releases are built from the beta repository

  • Extended Support Releases follow-up from the relevant ESR repo, such as mozilla-esr102

  • Release and Release Candidates are built from mozilla-release repository

How are those repositories kept in sync? That’s MergeDuty and is part of the releaseduty responsibility.

Overview of Procedure#

MergeDuty consists of multiple separate days of work. Each day you must perform several sequential tasks. The days are spread out over nearly three weeks, with three major days of activity:

Historical context of this procedure:

Originally, the m-c -> m-b was done a week after m-b -> m-r. Starting at Firefox 57, Release Management wanted to ship DevEdition b1 week before the planned mozilla-beta merge day. This meant Releng had to merge both repos at the same time. With 71.0, we’re back to the initial workflow with merging m-b -> m-r in the first week and then m-c -> m-b in the follow-up week.

Do the prep work a week before the merge#

Assign to yourself the migration bug#

A tracking migration bug should’ve already been filed - please assign that to yourself. If there isn’t one (e.g. bug 1694412), please contact the last releaseduty owner and file one. You can find more of this in Release owners.

Do migration no-op trial runs#

Doing a no-op trial run of each migration has one major benefit these days: you ensure that the migrations themselves work prior to Merge day.

General steps#

  1. Go to Treeherder.

  2. Select the repo depending on the merge you want to perform (central, beta or the ESR one).

  3. On the latest push, click on the down arrow at the top right corner.

  4. Select “Custom push action…”

  5. Choose merge-automation

  6. In Treeherder, you’ll see a new push show up in Treeherder in the repo you will be merging to. It can take a few minutes for the push and task to appear.

  7. Click on the merge or bump tasks (not the Gecko decision task). A job details panel will pop up and from there you’ll find a link to the diff file in the artifacts tab. Note: There will be a cron job that kicks off another bump task with same th name, only one of them will contain the diff.

mozilla-beta->mozilla-release migration no-op trial run#

  1. Follow the general steps hopping on beta

  2. Insert the following payload and click submit.

force-dry-run: true
behavior: beta-to-release
push: true

mozilla-central->mozilla-beta migration no-op trial run#

  1. Follow the general steps hopping on central

  2. Insert the following payload and click submit.

force-dry-run: true
behavior: central-to-beta
push: true

mozilla-esr bump no-op trial run#

mozilla-esr branches evolve over time: Today (September 2022), mozilla-esr102 is the current esr, and that is used in the discussion below; in the future, you may need to substitute a different esr version number.

  1. Follow the general steps hopping on esr102

  2. Insert the following payload and click submit.

force-dry-run: true
behavior: bump-esr102
push: true

Diff should be similar to this esr102 one.

Sanity check no blocking migration bugs#

Make sure the bug that tracks the migration has no blocking items.

Release Merge Day - part I#

When: Wait for go from relman to release-drivers@mozilla.org. Relman might want to do the migration in two steps. Read the email to understand which migration you are suppose to do, and then wait for second email. For date, see Release Scheduling calendar or check with relman

Merge beta to release#

  1. Close mozilla-beta. Check “Remember this change to undo later”. Please enter a good message as the reason for the closure, such as “Mergeduty - closing beta for $VERSION RC week”.

  2. Run the m-b -> m-r no-op trial run one more time, and show the diff to another person on releaseduty.

  3. The diff for release should be fairly similar to this, with updated the version change.

  4. Submit a new task with force-dry-run set to false:

force-dry-run: false
behavior: beta-to-release
push: true
warning

It’s not unlikely for the push to take between 10-20 minutes to complete.

warning

If an issue comes up during this phase, you may not be able to run this command (or the no-op one) correctly. You may need to publicly backout some tags/changesets to get back in a known state.

  1. Upon successful run, mozilla-release should get a version bump and branding changes consisting of a commit like this and a tag like this

  2. In the same time mozilla-beta should get a tag like this

  3. Verify changesets are visible on hg pushlog and Treeherder. It may take a couple of minutes to appear.

warning

The decision task of the resulting pushlog in the mozilla-release might fail in the first place with a timeout. A rerun might solve the problem which can be caused by an unlucky slow instance.

Reply to relman migrations are complete#

Reply to the migration request with the template:

This is now complete:
* mozilla-beta is merged to mozilla-release, new version is XX.Y
* beta will stay closed until next week

Release Merge Day - part II - a week after Merge day#

When: Wait for go from relman to release-drivers@mozilla.org. For date, see Release Scheduling calendar or check with relman

Merge central to beta#

  1. Run the m-c -> m-b no-op trial run one more time, and show the diff to another person on releaseduty.

  2. The diff generated by the task should be fairly similar to this.

  3. Submit a new task with force-dry-run set to false:

force-dry-run: false
behavior: central-to-beta
push: true
warning

It’s not unlikely for the push to take between 10-20 minutes to complete.

  1. Upon a successful run, mozilla-beta should get a version bump and branding changes consisting of a commit like this and a tag like this. Click the first HG revision link (left side under date and timestamp) for the merge push to verify this.

  2. Verify that browser/locales/l10n-changesets.json has revisions, not default, and/or verify that the merge task has l10n-bump in the logs. You’ll need to click on the second HG revision link (commit message will be something like "no bug - Bumping Firefox |10n...") to verify this. The diff should look like this

  3. In the same time mozilla-central should get a tag like this

  4. Verify changesets are visible on hg pushlog and Treeherder. It may take a couple of minutes to appear.

warning

The decision task of the resulting pushlog in the mozilla-beta might fail in the first place with a timeout. A rerun might solve the problem which can be caused by an unlucky slow instance.

warning

The merge day automation may not be idempotent. The merge automation task may fail and auto-retry (because of a worker shutdown, for instance). If the task retries after updating the state of the repo, it will update the state of the repo again, pushing repeated commits.

Re-opening the tree(s)#

Restore mozilla-beta tree to its previous state (approval-required) so that l10n bumper can run.

Tag central and bump versions#

What happens: A new tag is needed to specify the end of the nightly cycle. Then clobber and bump versions in mozilla-central as instructions depict.

  1. Follow the general steps

  2. Insert the following payload and click submit.

force-dry-run: false
push: true
behavior: bump-central

  1. Upon successful run, mozilla-central should get a version bump consisting of a commit like this and a tag like this

  2. Verify changesets are visible on hg pushlog and Treeherder. It may take a couple of minutes to appear.

Trigger ship-geckoview#

Trigger the ship-geckoview hook after the decision task completes so android apps can pick up the new gecko major version.

Bump ESR version#

Note: You could have one ESR to bump, or two. If you are not sure, ask.

Run the bump-esr no-op trial run one more time, and show the diff to another person on releaseduty.

Diff should be similar to this one.

Push your changes generated by the no-op trial run:

  1. Follow the general steps

  2. Insert the following payload and click submit.

force-dry-run: false
push: true
behavior: bump-esr102

Note This is currently set to esr102; the defaults can be overridden in-tree in taskcluster/ci/config.yml or specified here using an action payload such as:

force-dry-run: false
push: true
behavior: bump-esr
to-branch: esr102
to-repo: https://hg.mozilla.org/releases/mozilla-esr102

  1. Upon successful run, mozilla-esr${VERSION} should get a commit like this.

  2. Verify new changesets popped on https://hg.mozilla.org/releases/mozilla-esr102/pushloghtml

Reply to relman central bump completed#

Reply to the migration request with the template:

This is now complete:
* mozilla-central is merged to mozilla-beta, new version is XXX.0b1
* mozilla-central has been tagged and version bumped to YYY.0a1
* mozilla-esr102 has been version bumped to ZZZ.A.0esr
* new geckoview nightly builds have been triggered
* newly triggered nightlies will pick the version change on cron-based schedule

Hint: verify current versions

Update wiki versions#

  1. Edit the new values manually: (ok to update a day early)

Update the releng changelog#

  1. Edit the changelog by adding a new section for the current Nightly release. You can also delete the previous section if it is empty.

Bump Nightly version and release dates in ShipIt#

In ShipIt, the Firefox nightly version and the release dates are hard-coded, and a human must update them when new nightly builds become available. The nightly builds trigger on the schedule defined in .cron.yml (in UTC) and take a few hours to complete. Once the new nightly version appears in firefox/nightly/latest-mozilla-central/, we can update the nightly version and release dates in ShipIt. Bumping the Firefox nightly version and release dates in ShipIt should be done on release day. This way, we can be confident that the first nightly builds with the new version will be available to ShipIt.

WARNING: Do not bump the nightly version or release dates in ShipIt until the new nightly builds are available.

Follow these steps to bump the nightly version and release dates in ShipIt:

  1. git clone git@github.com:mozilla-releng/shipit.git

  2. git checkout -b nightly_version_bump_${version}

  3. Edit FIREFOX_NIGHTLY’s major version in api/src/shipit_api/common/config.py

  4. Edit the LAST and NEXT known dates (all 6 of them) in api/src/shipit_api/common/config.py (the release dates can be found on this Wiki page)

  5. Commit, then submit a pull request

  6. Someone on the Thunderbird team should open a similar PR in ShipIt the same day to bump the Thunderbird version. If there hasn’t been a Thunderbird PR put up for review yet, please ping #tbdrivers

  7. Merge the Firefox and Thunderbird pull requests onto main

  8. Push ShipIt’s main branch to production after a new nightly version has been pushed to firefox/nightly/latest-mozilla-central/

  9. Log into ShipIt, click the gear icon on the top right, then click on “Rebuild product-details”

  10. Monitor the versions info page for firefox and thunderbird to make sure they are up to date

Close migration bug, file one for the next release#

Once release is out of the door on Tuesday, close the existing bug tracking this release, from initial step and clone that bug into a similar one, tracking the next release. Please CC all the RelEng team. One can find the next release date in Release owners.

Historical issues#

The merge day automation may not be idempotent#

The merge automation task may fail and auto-retry (because of a worker shutdown, for instance). If the task retries after updating the state of the repo, it will update the state of the repo again, pushing repeated commits.