ECS cloud deployment ai_generated true

Deregistered ECS task definition but old tasks are still running with old image

ID: cloud/aws-ecs-task-def-deregister-running

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85%Fix Rate
88%Confidence
3Evidence
2023-01-01First Seen

Version Compatibility

VersionStatusIntroducedDeprecatedNotes
any active — — —

Root Cause

Deregistering an ECS task definition does NOT stop running tasks using it. It only prevents new tasks from using that revision. You must force a new deployment to replace running tasks.

generic

Workarounds

  1. 95% success Force new deployment after updating task definition 
    aws ecs update-service --cluster my-cluster --service my-service --force-new-deployment
  2. 92% success Update the service to use the new task definition revision 
    aws ecs update-service --cluster my-cluster --service my-service --task-definition my-task:NEW_REVISION
  3. 85% success Use deployment circuit breaker to auto-rollback failed deployments 
    --deployment-configuration 'deploymentCircuitBreaker={enable=true,rollback=true}'

Dead Ends

Common approaches that don't work:

  1. Deregister old task definition expecting running tasks to stop 92% fail

    Deregistering only marks the revision as INACTIVE. Running tasks continue indefinitely with the old config.

  2. Update the task definition and wait for ECS to auto-deploy 88% fail

    ECS services don't auto-deploy new task definitions. You must explicitly update the service or force a new deployment.