Check the completed rollback target before relying on an ECS circuit breaker

Automatic rollback requires an eligible prior deployment.

Source facts

The ECS deployment circuit breaker evaluates whether a rolling deployment reaches steady state. With rollback enabled, it selects the most recent deployment in COMPLETED state. If no eligible completed deployment exists, the deployment stalls without launching new tasks. AWS exposes rollout state, reasons and deployment events for investigation.

Source: AWS Documentation.

Applicability

This applies to the supported ECS rolling-update deployment controller rather than every deployment strategy.

DSE recommendation

DSE recommends identifying the known-good deployment and its artifact dependencies before a release. Review container and load-balancer health checks so the circuit breaker evaluates meaningful readiness. Assign an owner to deployment-failure alerts and record the manual recovery route for a first deployment or missing rollback target. Preserve the expected task definition and rollback evidence. Do not describe the feature as unconditional recovery; include the completed-target requirement in the release checklist. Keep the rollback artifact and task definition identifiable in the release record, with a named person responsible for first-deployment recovery. Ask that person to explain the manual response when no completed target exists before accepting the automated rollback option.

Verification

Proposed verification: use a disposable service with a completed deployment, introduce a controlled failing revision and observe rollout state and rollback events. Review behavior for an initial deployment separately. Confirm the expected healthy task definition returns before reporting a successful recovery test.

Official reference

AWS Documentation. Reviewed October 20, 2026.