[Feature flag] Rollout of cache_home_panel

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Feature

This feature uses the :cache_home_panel feature flag!

• Cache parts of the home_panel partial

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

The Rollout Plan

• Partial Rollout on GitLab.com with beta groups
• Rollout on GitLab.com for a certain period (How long)
• Percentage Rollout on GitLab.com
• Rollout Feature for everyone as soon as it's ready

https://dashboards.gitlab.net/d/web-rails-controller/web-rails-controller?orgId=1

Beta Groups/Projects:

• gitlab-org/gitlab project
• gitlab-org/gitlab-com groups

Expectations

What are we expecting to happen?

• Response time for the project homepage should improve

What might happen if this goes wrong?

• Project homepages could start throwing errors

What can we monitor to detect problems with this?

• Sentry
• https://dashboards.gitlab.net/d/web-rails-controller/web-rails-controller?orgId=1

Rollout Timeline

Initial Rollout

Preparation Phase

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

• Test on staging

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

Partial Rollout Phase

• Enable on GitLab.com for individual groups/projects listed above and verify behaviour (/chatops run feature set --project=gitlab-org/gitlab cache_home_panel 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 cache_home_panel 10 --actors
  • For time-based rollout: /chatops run feature set cache_home_panel 10

• 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

Cleanup

This is an important phase, that should be either done in the next Milestone or as soon as possible. For the cleanup phase, please follow our documentation on how to clean up the feature flag.

• Announce on the issue that the flag has been enabled

• Remove :cache_home_panel feature flag

  • Remove all references to the feature flag from the codebase
  • Remove the YAML definitions for the feature from the repository
  • Create a Changelog Entry

• Clean up the feature flag from all environments by running this chatops command in #production channel /chatops run feature delete cache_home_panel.

Final Step

• Close this rollout issue for the feature flag after the feature flag is removed from the codebase.

Rollback Steps

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

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