[Feature flag] Enable merge_request_refs_cleanup feature flag (#336070) · Issues · GitLab.org / GitLab · GitLab (original) (raw)

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[Feature flag] Enable merge_request_refs_cleanup feature flag

Summary

The merge_request_refs_cleanup was added to disable MergeRequestCleanupRefsWorker because it's causing issues on production.

In #296874 (closed), we implemented a more efficient way to schedule them. We need to roll it out slowly and see how it behaves on production before enabling it by default.

Owners

• Team: groupcode review
• Most appropriate slack channel to reach out to: #g_create_code-review
• Best individual to reach out to: @patrickbajao
• PM: @phikai

The Rollout Plan

Rollout on GitLab.com for a day since the feature flag doesn't have a target as it's instance wide.

Expectations

What are we expecting to happen?

MergeRequestCleanupRefsWorker gets scheduled and no slowdown will occur on production.

What might happen if this goes wrong?

Apdex of worker will be lower. We should disable the flag again.

What can we monitor to detect problems with this?

• Redis Sidekiq dashboard
• Queue detail dashboard

Rollout Steps

Rollout on non-production environments

• Ensure that the feature MRs have been deployed to non-production environments.
  • /chatops run auto_deploy status <merge-commit-of-your-feature>
• Enable the feature globally on non-production environments.
  • /chatops run feature set merge_request_refs_cleanup true --dev
  • /chatops run feature set merge_request_refs_cleanup true --staging
• Verify that the feature works as expected. Posting the QA result in this issue is preferable.

Preparation before production rollout

• Ensure that the feature MRs have been deployed to both production and canary.
  • /chatops run auto_deploy status <merge-commit-of-your-feature>
• Check if the feature flag change needs to be accompanied with achange 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.
• Ensure that documentation has been updated (More info).
• Announce on the feature issue an estimated time this will be enabled on GitLab.com.
• If the feature might impact the user experience, notify #support_gitlab-com and your team channel (more guidance when this is necessary in the dev docs).
• Verify that the feature works as expected. Posting the QA result in this issue is preferable.

Global rollout on production

• Enable the feature globally on production environment.
  • /chatops run feature set merge_request_refs_cleanup true
• Announce on the feature issue that the feature has been globally enabled.
• Wait for at least one day for the verification term.

(Optional) Release the feature with the feature flag

If you're still unsure whether the feature is deemed stablebut want to release it in the current milestone, you can change the default state of the feature flag to be enabled. To do so, follow these steps:

• Create a merge request with the following changes. Ask for review and merge it.
  • Set the default_enabled attribute in the feature flag definition to true.
  • Create a changelog entry.
• Ensure that the default-enabling MR has been deployed to both production and canary. If the merge request was deployed before the code cutoff, the feature can be officially announced in a release blog post.
  • /chatops run auto_deploy status <merge-commit-of-default-enabling-mr>
• Close the feature issue to indicate the feature will be released in the current milestone.
• Set the next milestone to this rollout issue for scheduling the flag removal.
• (Optional) You can create a separate issue for scheduling the steps below to Release the feature.
  • Set the title to "[Feature flag] Cleanup <feature-flag-name>".
  • Execute the /copy_metadata <this-rollout-issue-link> quick action to copy the labels from this rollout issue.
  • Link this rollout issue as a related issue.
  • Close this rollout issue.

WARNING: This approach has the downside that it makes it difficult for us toclean up the flag. For example, on-premise users could disable the feature on their GitLab instance. But when you remove the flag at some point, they suddenly see the feature as enabled and they can't roll it back to the previous behavior. To avoid this potential breaking change, use this approach only for urgent matters.

Release the feature

After the feature has been deemed stable, the clean upshould be done as soon as possible to permanently enable the feature and reduce complexity in the codebase.

• Create a merge request to remove <feature-flag-name> feature flag. Ask for review and merge it.
  • Remove all references to the feature flag from the codebase.
  • Remove the YAML definitions for the feature from the repository.
  • Create a changelog entry.
• Ensure that the cleanup MR has been deployed to both production and canary. If the merge request was deployed before the code cutoff, the feature can be officially announced in a release blog post.
  • /chatops run auto_deploy status <merge-commit-of-cleanup-mr>
• Close the feature issue to indicate the feature will be released in the current milestone.
• Clean up the feature flag from all environments by running these chatops command in #production channel:
  • /chatops run feature delete merge_request_refs_cleanup --dev
  • /chatops run feature delete merge_request_refs_cleanup --staging
  • /chatops run feature delete merge_request_refs_cleanup
• Close this rollout issue.

Rollback Steps

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

/chatops run feature set merge_request_refs_cleanup false

Edited Aug 23, 2023 by Kerri Miller