[Feature flag] Rollout of `api_caching_merge_requests`

Feature

Related !61067 (merged)

This feature uses the :api_caching_merge_requests feature flag!

• Issue Name

Owners

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

Stakeholders

The Rollout Plan

• Partial Rollout on GitLab.com with beta groups
• Percentage Rollout on GitLab.com
• Rollout Feature for everyone as soon as it's ready

https://dashboards.gitlab.net/d/api-rails-controller/api-rails-controller?orgId=1&var-PROMETHEUS_DS=Global&var-environment=gprd&var-stage=main&var-controller=Grape&var-action=GET%20%2Fapi%2Fprojects%2F:id%2Fmerge_requests

Beta Groups/Projects:

• gitlab-org/gitlab project

Expectations

What are we expecting to happen?

Response times for the merge requests list API should go down

What might happen if this goes wrong?

• Response times for the merge requests list API could go up

What can we monitor to detect problems with this?

https://dashboards.gitlab.net/d/api-rails-controller/api-rails-controller?orgId=1&var-PROMETHEUS_DS=Global&var-environment=gprd&var-stage=main&var-controller=Grape&var-action=GET%20%2Fapi%2Fprojects%2F:id%2Fmerge_requests

Rollout Timeline

Rollout Steps

Preparation Phase

• Enable on staging (/chatops run feature set feature_name true --staging)

• Test on staging

• Announce on the issue an estimated time this will be enabled on GitLab.com

• Check if the feature flag change needs to be accompanied with a change management issue. Cross link the issue here if it does.

• Ensure that you or a representative in development can be available for at least 2 hours after feature flag updates in production. If a different developer will be covering, or an exception is needed, please inform the oncall SRE by using the @sre-oncall Slack alias.

Partial Rollout Phase

• Enable on GitLab.com for individual groups/projects listed above and verify behaviour (/chatops run feature set --project=gitlab-org/gitlab api_caching_merge_requests true)

• Verify behaviour (See Beta Groups) and add details with screenshots as a comment on this issue

• 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.

  • When setting percentages, make sure that the feature works correctly between feature checks. See #327117 (closed) for more information
  • For actor-based rollout: /chatops run feature set api_caching_merge_requests 10 --actors
  • For time-based rollout: /chatops run feature set api_caching_merge_requests 10

Full Rollout Phase

• Make the feature flag enabled by default i.e. Change default_enabled to 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

• Create a cleanup issue using the "Feature Flag Removal" template

Rollback Steps

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

/chatops run feature set api_caching_merge_requests false