[Feature flag] Enable improved merge diff highlighting

What

Remove the :improved_merge_diff_highlighting feature flag

Introduced in !52499 (diffs)

Owners

  • Team: groupsource code
  • Most appropriate slack channel to reach out to: #g_create_source-code-be
  • Best individual to reach out to: @vyaklushin

Expectations

What are we expecting to happen?

This feature flag changes the diff highlighting algorithm. It should lead to more precise highlighting.

Before After
Screenshot_2021-01-26_at_16.44.27 Screenshot_2021-01-26_at_16.46.36

What might happen if this goes wrong?

The merge request diff highlighting can be incorrect.

What can we monitor to detect problems with this?

Related slack channels

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.

Roll Out Steps

  • Enable on staging (/chatops run feature set improved_merge_diff_highlighting 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 improved_merge_diff_highlighting true)
  • 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
  • Enable on GitLab.com by running chatops command in #production (/chatops run feature set improved_merge_diff_highlighting 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
  • 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 improved_merge_diff_highlighting false
Edited by Vasilii Iakliushin