[FF] update_init_iid_to_read_from_ci_pipeline_iids -- Update the Pipeline internal id init function to read max iid from p_ci_pipeline_iids

Summary

This issue is to roll out the feature on production, that is currently behind the update_init_iid_to_read_from_ci_pipeline_iids feature flag.

This feature flag was introduced in Update pipeline iid init value logic to read fr... (!213992)

Owners

• Most appropriate Slack channel to reach out to: #g_ci-platform
• Best individual to reach out to: @lma-git

Expectations

What are we expecting to happen?

• The Ci::Pipeline model's init function checks the max iid value in the new table p_ci_pipeline_iids instead of p_ci_pipelies. This init function is called by InternalId#initial_value to recalculate last_value when the record doesn't already exist (which can happen when we run InternalId.flush_records! or when a new project is created.)

What can go wrong and how would we detect it?

• Though extremely unlikely, it's possible for the maximum IID value to be "wrong", in which case the new generated iid could be one that is a duplicate instead of new unique value. For example, this could happen if p_ci_pipelines.iid is out of sync with p_ci_pipeline_iids. In such case, the pipeline creation could be stuck because it would keep throwing ActiveRecord::RecordNotUnique errors, which bubbles up in the UI as an error that instructs the user to retry creating the pipeline. That being said, it shouldn't happen because the iids between the tables should be kept totally in sync via database trigger (following the BBM that backfills existing iids in !213722).

Rollout Steps

Note: Please make sure to run the chatops commands in the Slack channel that gets impacted by the command.

Rollout on non-production environments

• Verify the MR with the feature flag is merged to master and has been deployed to non-production environments with /chatops run auto_deploy status <merge-commit-of-your-feature>

• Deploy the feature flag at a percentage (recommended percentage: 50%) with /chatops run feature set update_init_iid_to_read_from_ci_pipeline_iids <rollout-percentage> --actors --dev --pre --staging --staging-ref
• Monitor that the error rates did not increase (repeat with a different percentage as necessary).

• Enable the feature globally on non-production environments with /chatops run feature set update_init_iid_to_read_from_ci_pipeline_iids true --dev --pre --staging --staging-ref
• Verify that the feature works as expected. The best environment to validate the feature in is staging-canary as this is the first environment deployed to. Make sure you are configured to use canary.
• If the feature flag causes end-to-end tests to fail, disable the feature flag on staging to avoid blocking deployments.
  • See #e2e-run-staging Slack channel and look for the following messages:
    • test kicked off: Feature flag update_init_iid_to_read_from_ci_pipeline_iids has been set to true on **gstg**
    • test result: This pipeline was triggered due to toggling of update_init_iid_to_read_from_ci_pipeline_iids feature flag

If you encounter end-to-end test failures and are unable to diagnose them, you may reach out to the #s_developer_experience Slack channel for assistance. Note that end-to-end test failures on staging-ref don't block deployments.

Before production rollout

• If the change is significant and you wanted to announce in #whats-happening-at-gitlab, it best to do it before rollout to gitlab-org/gitlab-com.

Specific rollout on production

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

• Ensure that the feature MRs have been deployed to both production and canary with /chatops run auto_deploy status <merge-commit-of-your-feature>
• Depending on the type of actor you are using, pick one of these options:
  • For project-actor: /chatops run feature set --project=gitlab-org/gitlab,gitlab-org/gitlab-foss,gitlab-com/www-gitlab-com update_init_iid_to_read_from_ci_pipeline_iids true
  • For group-actor: /chatops run feature set --group=gitlab-org,gitlab-com update_init_iid_to_read_from_ci_pipeline_iids true
  • For user-actor: /chatops run feature set --user=lma-git update_init_iid_to_read_from_ci_pipeline_iids true
  • For all internal users: /chatops run feature set --feature-group=gitlab_team_members update_init_iid_to_read_from_ci_pipeline_iids true
• Verify that the feature works for the specific actors.

Preparation before global rollout

• Set a milestone to this rollout issue to signal for enabling and removing the feature flag when it is stable.
• 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 exists for the feature, and the version history text has been updated.
• Ensure that any breaking changes have been announced following the release post process to ensure GitLab customers are aware.
• Notify the #support_gitlab-com Slack channel 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 must be executed in the #production Slack channel and cross-posted (with the command results) to the responsible team's Slack channel.

• Incrementally roll out the feature on production.
  • Example: /chatops run feature set update_init_iid_to_read_from_ci_pipeline_iids <rollout-percentage> --actors.
  • Between every step wait for at least 15 minutes and monitor the appropriate graphs on https://dashboards.gitlab.net.
• After the feature has been 100% enabled, wait for at least one day before releasing the feature.

(Optional) Release the feature with the feature flag

WARNING: This approach has the downside that it makes it difficult for us to clean 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.

See instructions if you're sure about enabling the feature globally through the feature flag definition

If you're still unsure whether the feature is deemed stable but 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.
  • If feature was enabled for various actors, ensure the feature has been enabled globally on production /chatops run feature get update_init_iid_to_read_from_ci_pipeline_iids. If the feature has not been globally enabled then enable the feature globally using: /chatops run feature set update_init_iid_to_read_from_ci_pipeline_iids true
  • Set the default_enabled attribute in the feature flag definition to true.
  • Decide which changelog entry is needed.
• Ensure that the default-enabling 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 https://gitlab.com/gitlab-org/gitlab/-/merge_requests/213992 18.7
• After the default-enabling MR has been deployed, clean up the feature flag from all environments by running these chatops command in the #production channel: /chatops run feature delete update_init_iid_to_read_from_ci_pipeline_iids --dev --pre --staging --staging-ref --production
• 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 "[FF] update_init_iid_to_read_from_ci_pipeline_iids - Cleanup".
  • 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.

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 the update_init_iid_to_read_from_ci_pipeline_iids feature flag. Ask for review/approval/merge as usual. The MR should include the following changes:
  • Remove all references to the feature flag from the codebase.
  • Remove the YAML definitions for the feature from the repository.
• 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 https://gitlab.com/gitlab-org/gitlab/-/merge_requests/213992 18.7
• Close the feature issue to indicate the feature will be released in the current milestone.
• Once the cleanup MR has been deployed to production, clean up the feature flag from all environments by running these chatops command in #production channel: /chatops run feature delete update_init_iid_to_read_from_ci_pipeline_iids --dev --pre --staging --staging-ref --production
• Close this rollout issue.

Rollback Steps

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

/chatops run feature set update_init_iid_to_read_from_ci_pipeline_iids false

• Disable the feature flag on non-production environments:

/chatops run feature set update_init_iid_to_read_from_ci_pipeline_iids false --dev --pre --staging --staging-ref

• Delete feature flag from all environments:

/chatops run feature delete update_init_iid_to_read_from_ci_pipeline_iids --dev --pre --staging --staging-ref --production