## Summary Roll out [the fix](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/258717) currently behind the `trace_diff_note_line_range` feature flag. - DRI: @slashmanov - 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? When enabled, every push to a merge request re-maps the `line_range` of its active diff notes and saves it to `notes.position`. A wrong mapping would write wrong comment ranges, visible in the "Comment on lines" label, line highlighting and "Compare changes" on outdated threads. Comment positions themselves are not affected. Disabling the flag stops new writes; ranges already written stay until the next push re-maps them. ## Events - [Exceptions with trace_diff_note_line_range: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:%22trace_diff_note_line_range:1%22'),columns:!(json.exception.class,json.exception.message,json.extra.workflow_id,json.meta.caller_id),sort:!(!(json.time,desc)))) - [Events with trace_diff_note_line_range: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:%22trace_diff_note_line_range: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 trace_diff_note_line_range 50 --actors --dev --pre --staging --staging-ref /chatops gitlab run feature set trace_diff_note_line_range true --dev --pre --staging --staging-ref ``` **Production** — percentage rollout (wait ≥15 min between steps, watch dashboards): ``` /chatops gitlab run feature set trace_diff_note_line_range <percentage> --actors ``` Or target specific actors instead: ``` /chatops gitlab run feature set --project=gitlab-org/gitlab,gitlab-org/gitlab-foss trace_diff_note_line_range true /chatops gitlab run feature set --group=gitlab-org,gitlab-com trace_diff_note_line_range true /chatops gitlab run feature set --user=slashmanov trace_diff_note_line_range 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 trace_diff_note_line_range --dev --pre --staging --staging-ref --production ``` ## Rollback ``` /chatops gitlab run feature set trace_diff_note_line_range false # production /chatops gitlab run feature set trace_diff_note_line_range false --dev --pre --staging --staging-ref # non-production /chatops gitlab run feature delete trace_diff_note_line_range --dev --pre --staging --staging-ref --production # remove entirely ```