## Summary Roll out [the chat history cache](https://gitlab.com/gitlab-org/gitlab/-/work_items/631643) behind the `duo_workflow_cache_chat_history` feature flag. With the flag on, a `duoMessages` read of a workflow's latest checkpoint reuses a cached chat history and folds only the blobs written since the last read. The actor is the root namespace of the workflow's project or namespace. MR: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/258940 - DRI: @eduardobonet - Team Slack channel: `#g_ai_core_infra` > [!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? - The chat panel shows wrong messages (missing, duplicated, or stale) for a workflow whose history came from the cache. Disable the flag: with the flag off, the cache is not read, and entries expire after 1 hour. - Redis cache memory grows. There is one entry per workflow that a user reads, up to about 0.5 MB compressed for the longest chats seen, with a 1-hour TTL. Watch the `redis-cluster-cache` memory on https://dashboards.gitlab.net. - A cache miss runs one extra blob id query (about 4 ms warm for a 723-blob workflow). To measure the effect, compare the apdex of the `api` `rails_request` SLI for `endpoint_id="GraphqlController#execute:getWorkflowLatestCheckpoint"`, and `json.cpu_s` in Kibana for `json.meta.caller_id: "GraphqlController#execute:getWorkflowLatestCheckpoint"`, before and after each step. ## Events - [Exceptions with duo_workflow_cache_chat_history: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:%22duo_workflow_cache_chat_history:1%22'),columns:!(json.exception.class,json.exception.message,json.extra.workflow_id,json.meta.caller_id),sort:!(!(json.time,desc)))) - [Events with duo_workflow_cache_chat_history: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:%22duo_workflow_cache_chat_history: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_ai_core_infra`. 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 duo_workflow_cache_chat_history 50 --actors --dev --pre --staging --staging-ref /chatops gitlab run feature set duo_workflow_cache_chat_history true --dev --pre --staging --staging-ref ``` **Production** — percentage rollout (wait ≥15 min between steps, watch dashboards): ``` /chatops gitlab run feature set duo_workflow_cache_chat_history <percentage> --actors ``` Or target specific actors instead: ``` /chatops gitlab run feature set --project=gitlab-org/gitlab,gitlab-org/gitlab-foss duo_workflow_cache_chat_history true /chatops gitlab run feature set --group=gitlab-org,gitlab-com duo_workflow_cache_chat_history true /chatops gitlab run feature set --user=eduardobonet duo_workflow_cache_chat_history 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 duo_workflow_cache_chat_history --dev --pre --staging --staging-ref --production ``` ## Rollback ``` /chatops gitlab run feature set duo_workflow_cache_chat_history false # production /chatops gitlab run feature set duo_workflow_cache_chat_history false --dev --pre --staging --staging-ref # non-production /chatops gitlab run feature delete duo_workflow_cache_chat_history --dev --pre --staging --staging-ref --production # remove entirely ```