## Summary Roll out [the feature](https://gitlab.com/gitlab-org/gitlab/-/work_items/631600) currently behind the `auto_merge_process_pipeline_guard` feature flag. - DRI: @marc_shaw - Team Slack channel: `#g_code_review` > [!note] > Process and guidance live in the docs - this issue is just the commands and a place to track the rollout. > "Rolling out" means incrementally enabling the flag on GitLab.com to validate stability - it is not the same as releasing the feature, which happens when the flag is removed. > [Feature flag controls](https://docs.gitlab.com/development/feature_flags/controls/) · [Feature flag lifecycle](https://handbook.gitlab.com/handbook/product-development/how-we-work/product-development-flow/feature-flag-lifecycle/#feature-flag-lifecycle) ## What could go wrong? With the flag on, a completed pipeline enqueues `AutoMergeProcessWorker` only when an open merge request for it has auto-merge enabled. The check is one indexed query on the main primary per completed pipeline (about 40/s, 7 buffers per query, plans in the MR). The flag only removes enqueues, so nothing can merge early. The risk is the other way: if the check misses a merge request that does have auto-merge enabled, that merge request stays in auto-merge after its pipeline passes, until something else triggers a run (a push, an approval, opening the merge request page). Watch: - `AutoMergeProcessWorker` job rate (Mimir `sidekiq_jobs_completion_count{worker="AutoMergeProcessWorker"}`) and Sidekiq log lines with `json.meta.caller_id: PipelineProcessWorker`: should drop. - `MergeWorker` job rate: should stay flat. A drop means merges are being missed. - Reports of merge requests stuck in auto-merge with a passed pipeline. Implemented in https://gitlab.com/gitlab-org/gitlab/-/merge_requests/260718. ## Events - [Exceptions with auto_merge_process_pipeline_guard:1](https://log.gprd.gitlab.net/app/discover#/?_g=(time:(from:now-1d,to:now))&_a=(index:'7092c4e2-4eb5-46f2-8305-a7da2edad090',query:(language:kuery,query:'json.exception.feature_flag_states.keyword:%22auto_merge_process_pipeline_guard:1%22'),columns:!(json.exception.class,json.exception.message,json.extra.workflow_id,json.meta.caller_id),sort:!(!(json.time,desc)))) - [Events with auto_merge_process_pipeline_guard:1](https://log.gprd.gitlab.net/app/discover#/?_g=(time:(from:now-1d,to:now))&_a=(index:'7092c4e2-4eb5-46f2-8305-a7da2edad090',query:(language:kuery,query:'json.feature_flag_states:%22auto_merge_process_pipeline_guard:1%22'),columns:!(json.meta.caller_id,json.feature_flag_states),sort:!(!(json.time,desc)))) - [Error rate and other graphs by modifying the examples in the Visualization Library](https://log.gprd.gitlab.net/app/visualize#/?_g=h@358d019&s=FF%20Observability) Feature Flag events are only logged by default for feature flags marked for the current or future milestones. To enable while the feature flag is active, see https://docs.gitlab.com/development/feature_flags/#logging ## Rollout Run all production `/chatops` in [`#production`](https://gitlab.slack.com/archives/C101F3796) and cross-post the results to `#g_code_review`. Background: [incremental rollout process](https://docs.gitlab.com/development/feature_flags/controls/#process), [feature actors](https://docs.gitlab.com/development/feature_flags/#feature-actors). **Non-production** ``` /chatops gitlab run feature set auto_merge_process_pipeline_guard 50 --actors --dev --pre --staging --staging-ref /chatops gitlab run feature set auto_merge_process_pipeline_guard true --dev --pre --staging --staging-ref ``` **Production** - percentage rollout (wait ≥15 min between steps, watch dashboards): ``` /chatops gitlab run feature set auto_merge_process_pipeline_guard <percentage> --actors ``` Or target specific projects instead (the actor is the pipeline's project): ``` /chatops gitlab run feature set --project=gitlab-org/gitlab,gitlab-org/gitlab-foss auto_merge_process_pipeline_guard true ``` ## Before global rollout Confirm the relevant gotchas before going to 100% - see [enabling a feature for GitLab.com](https://docs.gitlab.com/development/feature_flags/controls/#enabling-a-feature-for-gitlabcom): - [Docs + version history](https://docs.gitlab.com/development/documentation/feature_flags/) updated - [Breaking changes](https://docs.gitlab.com/development/documentation/release_notes/#deprecations-removals-and-breaking-changes) announced, if any - [Change management issue](https://handbook.gitlab.com/handbook/engineering/infrastructure-platforms/change-management/#feature-flags-and-the-change-management-process) opened, if required - [External API consumers](https://docs.gitlab.com/development/feature_flags/#do-not-use-feature-flags-in-external-api-consumers) handled with a fail-open mechanism, if applicable ## Cleanup Remove the flag once [deemed stable](https://handbook.gitlab.com/handbook/product-development/how-we-work/product-development-flow/feature-flag-lifecycle/#feature-flag-lifecycle) - see [cleaning up](https://docs.gitlab.com/development/feature_flags/controls/#cleaning-up). Track it here, or open a follow-up [Feature Flag Cleanup issue](https://gitlab.com/gitlab-org/gitlab/-/work_items/new?description_template=Feature%20Flag%20Cleanup). Remove the flag and its YAML definition from the codebase, then: ``` /chatops gitlab run release check <merge-request-url> <milestone> /chatops gitlab run feature delete auto_merge_process_pipeline_guard --dev --pre --staging --staging-ref --production ``` ## Rollback ``` /chatops gitlab run feature set auto_merge_process_pipeline_guard false # production /chatops gitlab run feature set auto_merge_process_pipeline_guard false --dev --pre --staging --staging-ref # non-production /chatops gitlab run feature delete auto_merge_process_pipeline_guard --dev --pre --staging --staging-ref --production # remove entirely ```