## Summary Roll out [the feature](https://gitlab.com/gitlab-org/embody-team/experimental-observability/documentation/-/work_items/177) currently behind the `ci_traceparent_export_span_id` feature flag. The flag changes the span ID in the `CI_TRACEPARENT` predefined variable from the `:default` span kind to the `:export` kind, so it matches the job span emitted by the CI/CD observability export. Spans that job scripts create from `CI_TRACEPARENT` then nest under the job span in the exported trace instead of being orphaned. The trace ID and `CI_TRACESTATE` are unchanged. Introduced by gitlab-org/gitlab!259435. The flag actor is the project. - DRI: @dakotadux - Team Slack channel: `#embody-team` > [!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? `CI_TRACEPARENT` is built in `Gitlab::Ci::Variables::Builder#predefined_traceparent_variables` for every job, whether or not observability export is enabled. The change only swaps the input to a SHA256-derived span ID and adds one `Feature.enabled?` check per pipeline (memoized per builder), so the performance risk is low. User-visible effect: users who parent their own spans to `CI_TRACEPARENT` will see a different parent span ID. Nothing emits a span with the old `:default` ID, so no existing nesting is lost. Users who also enable EE `ci_job_telemetry` will see their script spans nest under the export job span rather than the runner's `job_execution` span. The flag is a one-switch disable: set it to `false` to restore the `:default` span ID. ### Dependency on `ci_pipeline_otlp_trace_correlation` (child pipelines) `CI_TRACEPARENT` always derives its trace and span IDs from the root pipeline ID (`Gitlab::Ci::Variables::Builder#predefined_traceparent_variables`). The export payload only includes `root_pipeline_id` when `ci_pipeline_otlp_trace_correlation` is enabled (`Gitlab::DataBuilder::Pipeline`). Without it, the exporter falls back to the child pipeline's own ID (`Gitlab::Observability::TracingHelpers#root_pipeline_id`). | Pipeline | `ci_pipeline_otlp_trace_correlation` | `CI_TRACEPARENT` matches exported job span? | |-----------|--------------------------------------|---------------------------------------------| | Top-level | on or off | Yes | | Child | on | Yes | | Child | off | No (trace ID and span ID both differ) | This limitation existed before this flag. Rolling back either flag on its own is still safe. Raised in https://gitlab.com/gitlab-org/gitlab/-/merge_requests/259435#note_3956105550. Spec coverage: !259838. ## Events - [Exceptions with ci_traceparent_export_span_id: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_traceparent_export_span_id:1%22'),columns:!(json.exception.class,json.exception.message,json.extra.workflow_id,json.meta.caller_id),sort:!(!(json.time,desc)))) - [Events with ci_traceparent_export_span_id: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_traceparent_export_span_id: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 `#embody-team`. 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_traceparent_export_span_id 50 --actors --dev --pre --staging --staging-ref /chatops gitlab run feature set ci_traceparent_export_span_id true --dev --pre --staging --staging-ref ``` **Production** — percentage rollout (wait ≥15 min between steps, watch dashboards): ``` /chatops gitlab run feature set ci_traceparent_export_span_id <percentage> --actors ``` Or target specific actors instead: ``` /chatops gitlab run feature set --project=gitlab-org/gitlab,gitlab-org/gitlab-foss ci_traceparent_export_span_id true /chatops gitlab run feature set --group=gitlab-org,gitlab-com ci_traceparent_export_span_id 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): - `ci_pipeline_otlp_trace_correlation` is enabled for the same actors, or the child-pipeline misalignment [above](#dependency-on-ci_pipeline_otlp_trace_correlation-child-pipelines) is accepted - [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_traceparent_export_span_id --dev --pre --staging --staging-ref --production ``` ## Rollback ``` /chatops gitlab run feature set ci_traceparent_export_span_id false # production /chatops gitlab run feature set ci_traceparent_export_span_id false --dev --pre --staging --staging-ref # non-production /chatops gitlab run feature delete ci_traceparent_export_span_id --dev --pre --staging --staging-ref --production # remove entirely ```