[Feature flag] Enable Slack App Home

Summary

This issue is to rollout the feature on production, that is currently behind the slack_events_app_home_opened feature flag.

Owners

• Team: ~"group::integrations"
• Most appropriate slack channel to reach out to: #g_ecosystem_integrations
• Best individual to reach out to: @.luke
• PM: @g.hickman

Expectations

What are we expecting to happen?

Unfortunately we can't actually test this on SaaS before enabling, as to test it requires our GitLab Slack App to be republished to the Slack app directory, and once that happens the feature is live for everyone. Instead, we'll need to QA on staging and then enable on production.

When is the feature viable?

Immediately.

What might happen if this goes wrong?

The API endpoint /api/v4/integrations/slack/events might error. This endpoint is only used by the Slack Events API.

The GitLab Slack App's Home tab will not display our intended view, although the customer will not see any errors. Just a place-holder view provided by Slack.

What can we monitor to detect problems with this?

Sentry for errors.

Kibana to see the worker.

What can we check for monitoring production after rollouts?

Sentry for errors.

Kibana to see the worker.

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 slack_events_app_home_opened true --dev --staging --staging-ref
• Verify that the feature works as expected. Posting the QA result in this issue is preferable. The best environment to validate the feature in is staging-canary as this is the first environment deployed to. Note you will need to make sure you are configured to use canary as outlined here when accessing the staging environment in order to make sure you are testing appropriately.

Specific rollout on production

The feature flag does not take an actor so there is no rollout.

Preparation before global rollout

• 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.
• Ensure that documentation has been updated (More info).
• Announce on the feature issue an estimated time this will be enabled on GitLab.com.
• Ensure that any breaking changes have been announced following the release post process to ensure GitLab customers are aware.
• Notify #support_gitlab-com and your team channel (more guidance when this is necessary in the dev docs).

Global rollout on production

For visibility, all /chatops commands that target production should be executed in the #production slack channel and cross-posted (with the command results) to the responsible team's slack channel (#g_TEAM_NAME).

• Incrementally roll out the feature.
  • If the feature flag in code has an actor, perform actor-based rollout.
    • /chatops run feature set slack_events_app_home_opened <rollout-percentage> --actors
  • If the feature flag in code does NOT have an actor, perform time-based rollout (random rollout).
    • /chatops run feature set slack_events_app_home_opened <rollout-percentage> --random
  • Enable the feature globally on production environment.
    • /chatops run feature set slack_events_app_home_opened true
• Announce on the feature issue that the feature has been globally enabled.
• Wait for at least one day for the verification term.

Release the feature

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

You can either create a follow-up issue for Feature Flag Cleanup or use the checklist below in this same issue.

• Create a merge request to remove slack_events_app_home_opened 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 included in the release package. If the merge request was deployed before the monthly release was tagged, the feature can be officially announced in a release blog post.
  • /chatops run release check <merge-request-url> <milestone>
• Close the feature issue to indicate the feature will be released in the current milestone.
• If not already done, clean up the feature flag from all environments by running these chatops command in #production channel:
  • /chatops run feature delete slack_events_app_home_opened --dev --staging --staging-ref --production
• Close this rollout issue.

Rollback Steps

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

/chatops run feature set slack_events_app_home_opened false