## Summary Roll out [the feature](https://gitlab.com/gitlab-org/gitlab/-/work_items/606716) currently behind the `merge_requests_rebase_rate_limit` feature flag. - DRI: @egrieff - 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 for a user, that user's merge request rebases are limited to `merge_requests_rebase_limit` per minute (default 30), shared by the REST API (`PUT /projects/:id/merge_requests/:merge_request_iid/rebase`), the **Rebase** button, and the `/rebase` quick action. Over the limit, nothing is scheduled: the API returns 429, the button shows "Failed to rebase: Too many rebases have been requested. Try again later.", and the quick action shows the same message. The risk is automation that rebases many merge requests in a burst getting a 429. Setting the application setting to `0` turns the limit off without touching the flag. Watch: - Auth log entries with `json.message: "Application_Rate_Limiter_Request"` and `json.env: "merge_requests_rebase_request_limit"`, by user, to confirm they land on automated clients far above human rates. - 429s for the API rebase endpoint and `Projects::MergeRequestsController#rebase`. - `RebaseWorker` volume, which should drop for the heaviest users. - Reports of users or integrations being rate limited when rebasing. Implemented in https://gitlab.com/gitlab-org/gitlab/-/merge_requests/267972. ## Events - [Exceptions with merge_requests_rebase_rate_limit: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:%22merge_requests_rebase_rate_limit:1%22'),columns:!(json.exception.class,json.exception.message,json.extra.workflow_id,json.meta.caller_id),sort:!(!(json.time,desc)))) - [Events with merge_requests_rebase_rate_limit: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:%22merge_requests_rebase_rate_limit: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 merge_requests_rebase_rate_limit 50 --actors --dev --pre --staging --staging-ref /chatops gitlab run feature set merge_requests_rebase_rate_limit true --dev --pre --staging --staging-ref ``` **Production** — percentage rollout (wait ≥15 min between steps, watch dashboards): ``` /chatops gitlab run feature set merge_requests_rebase_rate_limit <percentage> --actors ``` Or target specific actors instead (the flag actor is the user): ``` /chatops gitlab run feature set --user=egrieff merge_requests_rebase_rate_limit true ``` ## Before global rollout Before the production percentage rollout: - [ ] Customer impact check through https://gitlab.com/gitlab-org/gitlab/-/work_items/634694, as required for any new limit. Evidence for the default limit from a week of production traffic: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/267972#note_4168788537 After the flag is enabled: - [ ] Review `merge_requests_rebase_request_limit` entries in `auth.log` and the per-user rebase rates, and lower `merge_requests_rebase_limit` if real callers sit well below the default. Throttled `/rebase` quick actions aren't logged (see the internal note below), so the auth log undercounts what the limit blocks. 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 merge_requests_rebase_rate_limit --dev --pre --staging --staging-ref --production ``` ## Rollback ``` /chatops gitlab run feature set merge_requests_rebase_rate_limit false # production /chatops gitlab run feature set merge_requests_rebase_rate_limit false --dev --pre --staging --staging-ref # non-production /chatops gitlab run feature delete merge_requests_rebase_rate_limit --dev --pre --staging --staging-ref --production # remove entirely ```