<!-- Title suggestion: [FF] `ci_job_telemetry` -- <short description> --> ## Summary This issue is to roll out [the feature](https://gitlab.com/gitlab-org/gitlab/-/issues/590588) on production, that is currently behind the `ci_job_telemetry` feature flag. ## Owners - Most appropriate Slack channel to reach out to: `#g_ci-platform` - Best individual to reach out to: @pedropombeiro ## Expectations ### What are we expecting to happen? When the `ci_job_telemetry` feature flag is enabled for a project, the `/api/v4/jobs/request` endpoint will include a `tracing` object (containing `trace_id`, `otel_endpoints` as an array of endpoint objects with URL and auth configuration, and for child pipeline jobs, `span_parent_id`) inside the `features` object of the job payload response. The presence of `features.tracing` signals to the GitLab Runner that the pipeline was sampled and it should emit OTLP telemetry data (traces) for CI jobs. The `trace_id` is derived deterministically from the **root** pipeline ID, so all jobs across parent and child pipelines share the same trace. For child pipeline jobs, `span_parent_id` references the trigger (bridge) job's span ID, allowing child pipeline jobs to nest under the trigger job in the trace tree. The initial rollout targets **DevEx Customer0 projects on hosted runners** (i.e. `gitlab-org/gitlab` and related projects). Sampling is handled at the Rails level using a global application setting (`ci_job_telemetry_sampling_rate`, see gitlab-org/gitlab#593834) combined with a deterministic hash of the root pipeline ID — `features.tracing` is only included for sampled pipelines. The OTEL Collector endpoint configuration is provided from Rails via `features.tracing.otel_endpoints` (an array of endpoint objects with `url` and optional `auth`, see gitlab-org/gitlab#591941 and [endpoint auth schema](https://handbook.gitlab.com/handbook/engineering/architecture/design-documents/ci_job_telemetry/#endpoint-auth-schema)), so runners receive the endpoint dynamically without static `config.toml` configuration. This is a prerequisite for the [parent CI Job Telemetry epic](https://gitlab.com/groups/gitlab-org/-/epics/20632), which tracks the full MVC scope including runner instrumentation, ClickHouse materialized views, and the telemetry ingestion pipeline.