## Summary Roll out [the feature](https://gitlab.com/gitlab-org/gitlab/-/issues/621543) currently behind the `ci_redundant_pipeline_cancel_from_cache` feature flag. - DRI: @mbobin - Team Slack channel: `#g_ci-platform` > [!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? When the flag is on, `Ci::CancelRedundantPipelinesWorker` cancels older pipelines from the redis cache instead of searching `p_ci_pipelines`. - **Prerequisite:** enable `ci_redundant_pipeline_candidates_cache` for the same actors first, and wait a couple of days. Before that wait, the cache does not hold the older pipelines or the protection of pipelines that started earlier, so this flag could cancel a pipeline that it must leave alone. - **Wrong pipeline canceled:** a pipeline with a started non-interruptible job is canceled. Look for reports of auto-canceled pipelines that ran non-interruptible jobs. - **Redundant pipeline not canceled:** expected when the cache is lost. Cancellation is best-effort, and the cache path does not go back to the search. - **Rollback:** disable the flag. The worker goes back to the `p_ci_pipelines` search, and the cache stays full. ## Events - [Exceptions with ci_redundant_pipeline_cancel_from_cache: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:%22ci_redundant_pipeline_cancel_from_cache:1%22'),columns:!(json.exception.class,json.exception.message,json.extra.workflow_id,json.meta.caller_id),sort:!(!(json.time,desc)))) - [Events with ci_redundant_pipeline_cancel_from_cache: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:%22ci_redundant_pipeline_cancel_from_cache: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 ## Before enabling `ci_redundant_pipeline_cancel_from_cache` The comparison MR (https://gitlab.com/gitlab-org/gitlab/-/merge_requests/260274) adds fields to the `"Canceling redundant pipelines"` log line. These fields show how the search decisions differ from the redis cache. Use them to check the cache before cancellation reads from it. 1. Enable `ci_redundant_pipeline_candidates_cache` for the same actors. For example: ```plaintext /chatops gitlab run feature set --project=gitlab-org/gitlab ci_redundant_pipeline_candidates_cache true ``` 1. Wait 24 hours or more, so the cache holds the pipelines that run. 1. For a few days, watch the comparison fields on the `"Canceling redundant pipelines"` log line in Kibana. Use this query: ```plaintext json.message:"Canceling redundant pipelines" and (json.cache_missed_count > 0 or json.cache_would_cancel_count > 0) ``` 1. Continue only if both of these are true: - `cache_would_cancel_count` stays at 0. - `cache_missed_count` stays at about 0. Misses for pipelines older than 24 hours are expected, because the cache TTL is 24 hours. If you see an id in `cache_would_cancel_ids`, find the cause before you continue. 1. A `cache_would_keep_count` above 0 is expected when a non-interruptible job finishes without running. Make a note of it, but do not stop the rollout for it. ## Rollout Run all production `/chatops` in [`#production`](https://gitlab.slack.com/archives/C101F3796) and cross-post the results to `#g_ci-platform`. 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 ci_redundant_pipeline_cancel_from_cache 50 --actors --dev --pre --staging --staging-ref /chatops gitlab run feature set ci_redundant_pipeline_cancel_from_cache true --dev --pre --staging --staging-ref ``` **Production** — percentage rollout (wait ≥15 min between steps, watch dashboards): ``` /chatops gitlab run feature set ci_redundant_pipeline_cancel_from_cache <percentage> --actors ``` Or target specific actors instead: ``` /chatops gitlab run feature set --project=gitlab-org/gitlab,gitlab-org/gitlab-foss ci_redundant_pipeline_cancel_from_cache true /chatops gitlab run feature set --group=gitlab-org,gitlab-com ci_redundant_pipeline_cancel_from_cache true /chatops gitlab run feature set --user=mbobin ci_redundant_pipeline_cancel_from_cache 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 ci_redundant_pipeline_cancel_from_cache --dev --pre --staging --staging-ref --production ``` ## Rollback ``` /chatops gitlab run feature set ci_redundant_pipeline_cancel_from_cache false # production /chatops gitlab run feature set ci_redundant_pipeline_cancel_from_cache false --dev --pre --staging --staging-ref # non-production /chatops gitlab run feature delete ci_redundant_pipeline_cancel_from_cache --dev --pre --staging --staging-ref --production # remove entirely ```