[Feature flag] Rollout `pipeline_editor_branch_switcher`

What

This issue is for enabling the :pipeline_editor_branch_switcher feature flag on production. This feature flag was introduced by !57562 (merged).

This allows users to switch branches in the pipeline editor.

Relevant Links

• Add the branch switcher to the pipeline editor
• Add branch switcher to empty state of the pipeline editor
• Pipeline editor - Retain the same branch on refresh

Search Behavior

Searching Branches

Pagination Behavior

Infinite Scroll

Owners

• Team: grouppipeline authoring
• Most appropriate slack channel to reach out to: #g_pipeline-authoring
• Best individual to reach out to: @mgandres

Expectations

What are we expecting to happen?

Once enabled, users can use the pipeline editor to edit their CI files on other branches besides the default branch.

What might happen if this goes wrong?

What can we monitor to detect problems with this?

Beta groups/projects

If applicable, any groups/projects that are happy to have this feature turned on early. Some organizations may wish to test big changes they are interested in with a small subset of users ahead of time for example.

• gitlab-org/gitlab project
• gitlab-org/gitlab-com groups
• mgandres1/test-ci-project

Roll Out Steps

• Enable on staging (/chatops run feature set pipeline_editor_branch_switcher true --staging)
• Test on staging
• Ensure that documentation has been updated
• Enable on GitLab.com for individual groups/projects listed above and verify behaviour (/chatops run feature set --project=gitlab-org/gitlab pipeline_editor_branch_switcher true)
• [-] If it is possible to perform an incremental rollout, this should be preferred. Proposed increments are: 10%, 50%, 100%. Proposed minimum time between increments is 15 minutes.
• Coordinate a time to enable the flag with the SRE oncall and release managers
  • In #production mention @sre-oncall and @release-managers. Once an SRE on call and Release Manager on call confirm, you can proceed with the rollout
• Announce on the issue an estimated time this will be enabled on GitLab.com. Note: Once a feature rollout has started, it is not necessary to inform @sre-oncall/@release-managers at each stage of the gradual rollout.
• Enable on GitLab.com by running chatops command in #production (/chatops run feature set pipeline_editor_branch_switcher true)
• Cross post chatops Slack command to #support_gitlab-com (more guidance when this is necessary in the dev docs) and in your team channel
• Announce on the issue that the flag has been enabled
• Remove feature flag and add changelog entry. Ensure that the feature flag definition YAML file has been removed in the same MR that is removing the feature flag from the code
• After the flag removal is deployed, clean up the feature flag by running chatops command in #production channel

Rollback Steps

• This feature can be disabled by running the following Chatops command:

/chatops run feature set --project=gitlab-org/gitlab pipeline_editor_branch_switcher false