## Summary This issue is to roll out [the feature](https://gitlab.com/gitlab-org/gitlab/-/issues/589484) on production, that is currently behind the `precompute_pending_build_args` feature flag. Introduced in: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/225133 ## Owners - Most appropriate Slack channel to reach out to: `#g_pipeline-execution` - Best individual to reach out to: @hfyngvason ## Expectations ### What are we expecting to happen? When enabled, the feature pre-computes `Ci::PendingBuild` arguments (tag lookups, CI minutes checks, plan lookups) outside the state machine database transaction by overriding `save`/`save!` on `Ci::Build`. The state machine gem sets `status_event_transition` on the object before calling save, so the override can detect a pending transition and pre-compute the expensive args before `super` enters the transaction. Additionally, `AssignResourceFromResourceGroupService` switches from `retry_lock_with_transaction` to `retry_lock` (no wrapping transaction) when the flag is enabled. Together, these changes reduce idle-in-transaction time during job enqueueing. ### What can go wrong and how would we detect it? - **Stale data**: Pre-computed values could become stale between computation and use. This is acceptable as the data (tags, minutes, plan) rarely changes within milliseconds. - **Regression in job enqueueing**: Jobs might fail to enqueue properly. Monitor for increased `failed` jobs or jobs stuck in `waiting_for_resource` state. - **Unexpected save override interactions**: The `save`/`save!` override runs for every save on `Ci::Build`, but guards ensure it only pre-computes when transitioning to `pending` with the flag enabled. Relevant dashboards: - [CI Pipeline Execution dashboard](https://dashboards.gitlab.net/d/stage-groups-pipeline_execution/stage-groups-group-dashboard-pipeline-execution) - Monitor `Ci::ResourceGroups::AssignResourceFromResourceGroupWorker` idle-in-transaction metrics ## 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 precompute_pending_build_args 50 --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 precompute_pending_build_args true --dev --pre --staging --staging-ref` - [ ] Verify that the feature works as expected. The best environment to validate the feature in is [`staging-canary`](https://about.gitlab.com/handbook/engineering/infrastructure/environments/#staging-canary) as this is the first environment deployed to. Make sure you are [configured to use canary](https://next.gitlab.com/). - [ ] If the feature flag causes end-to-end tests to fail, disable the feature flag on staging to avoid blocking [deployments](https://about.gitlab.com/handbook/engineering/deployments-and-releases/deployments/). - See [`#e2e-run-staging` Slack channel](https://gitlab.enterprise.slack.com/archives/CBS3YKMGD) and look for the following messages: - test kicked off: `Feature flag precompute_pending_build_args has been set to true on **gstg**` - test result: `This pipeline was triggered due to toggling of precompute_pending_build_args 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](https://gitlab.enterprise.slack.com/archives/C07TWBRER7H) for assistance. Note that end-to-end test failures on `staging-ref` [don't block deployments](https://about.gitlab.com/handbook/engineering/infrastructure/environments/staging-ref/#how-to-use-staging-ref). ### Before production rollout - [ ] If the change is significant and you wanted to announce in [#whats-happening-at-gitlab](https://gitlab.enterprise.slack.com/archives/C0259241C), 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](https://gitlab.slack.com/archives/C101F3796) 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](https://docs.gitlab.com/development/feature_flags/#feature-actors) 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 precompute_pending_build_args true` - For **group-actor**: `/chatops run feature set --group=gitlab-org,gitlab-com precompute_pending_build_args 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](https://about.gitlab.com/handbook/engineering/infrastructure-platforms/change-management/#feature-flags-and-the-change-management-process). 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](https://docs.gitlab.com/development/documentation/feature_flags/#add-history-text) has been updated. - [ ] Ensure that any breaking changes have been announced following the [release post process](https://about.gitlab.com/handbook/marketing/blog/release-posts/#deprecations-removals-and-breaking-changes) to ensure GitLab customers are aware. - [ ] Notify the [`#support_gitlab-com` Slack channel](https://gitlab.slack.com/archives/C4XFU81LG) and your team channel ([more guidance when this is necessary in the dev docs](https://docs.gitlab.com/development/feature_flags/controls/#communicate-the-change)). ### Global rollout on production For visibility, all `/chatops` commands that target production must be executed in the [`#production` Slack channel](https://gitlab.slack.com/archives/C101F3796) and cross-posted (with the command results) to the responsible team's Slack channel. - [ ] [Incrementally roll out](https://docs.gitlab.com/development/feature_flags/controls/#process) the feature on production. - Example: `/chatops run feature set precompute_pending_build_args <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](#release-the-feature). ### Release the feature After the feature has been [deemed stable](https://about.gitlab.com/handbook/product-development-flow/feature-flag-lifecycle/#including-a-feature-behind-feature-flag-in-the-final-release), the [clean up](https://docs.gitlab.com/development/feature_flags/controls/#cleaning-up) should be done as soon as possible to permanently enable the feature and reduce complexity in the codebase. - [ ] Create a merge request to remove the `precompute_pending_build_args` 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](https://about.gitlab.com/handbook/engineering/releases/#self-managed-releases-1), the feature can be officially announced in a release blog post: `/chatops run release check <merge-request-url> <milestone>` - [ ] Close [the feature issue](https://gitlab.com/gitlab-org/gitlab/-/issues/589484) 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 precompute_pending_build_args --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 precompute_pending_build_args false ``` - [ ] Disable the feature flag on non-production environments: ``` /chatops run feature set precompute_pending_build_args false --dev --pre --staging --staging-ref ``` - [ ] Delete feature flag from all environments: ``` /chatops run feature delete precompute_pending_build_args --dev --pre --staging --staging-ref --production ```