Amazon ECS Availability Zone service rebalancing service event messages - Amazon Elastic Container Service
service (service-name) is not AZ balanced with number-tasks tasks in Availability Zone 1, number-tasks in Availability Zone 2, and number-tasks in Availability Zone 3. AZ Rebalancing in progress.service (service-name) is AZ balanced with number-tasks tasks in Availability Zone 1, number-tasks tasks in Availability Zone 2, and number-tasks tasks in Availability Zone 3.service-name has started number-tasks tasks in Availability Zone to AZ Rebalance: task-ids.service-name has stopped number-tasks running tasks in Availability Zone due to AZ rebalancing: task-id.service (service-name) is unable to place a task in Availability Zone because no container instance met all of its requirements.service (service-name) is unable to place a task in Availability Zone.service (service-name) was unable to AZ Rebalance because task-set-name was unable to scale in due to reason.service (service-name) stopped AZ Rebalancing.
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Amazon ECS Availability Zone service rebalancing service event messages

The following are examples of service event messages you might see.

service (service-name) is not AZ balanced with number-tasks tasks in Availability Zone 1, number-tasks in Availability Zone 2, and number-tasks in Availability Zone 3. AZ Rebalancing in progress.

The service scheduler sends a service (service-name) is not AZ balanced service event when the number of tasks is not evenly spread across Availability Zones. There is no action to take. This is an information event.

service (service-name) is AZ balanced with number-tasks tasks in Availability Zone 1, number-tasks tasks in Availability Zone 2, and number-tasks tasks in Availability Zone 3.

The service scheduler sends a service (service-name) is AZ balanced service event when Availability Zone service rebalancing completes. There is no action to take. This is an information event.

service-name has started number-tasks tasks in Availability Zone to AZ Rebalance: task-ids.

The service scheduler sends a service-name/task-set-name has started number tasks in Availability Zone service event when it starts tasks in an Availability Zone because of service rebalancing. There is no action to take. This is an information event.

service-name has stopped number-tasks running tasks in Availability Zone due to AZ rebalancing: task-id.

The service scheduler sends a service-name/task-set-name has started number tasks in Availability Zone service event when it stops tasks in an Availability Zone because of service rebalancing. There is no action to take. This is an information event.

service (service-name) is unable to place a task in Availability Zone because no container instance met all of its requirements.

The service scheduler sends a service-name is unable to place a task in Availability Zone service event because no container instance met all of its requirements. To address the issue, launch instances in the Availability Zone.

service (service-name) is unable to place a task in Availability Zone.

The service scheduler sends a service-name is unable to place a task in Availability Zone service event when you use the Fargate launch type and there is no available capacity.

You can add additional subnets in the Availability Zone in the error message, or contact Amazon Web Services Support to get additional capacity.

service (service-name) was unable to AZ Rebalance because task-set-name was unable to scale in due to reason.

The service scheduler sends a service-name was unable to AZ Rebalance because task-set-name was unable to scale in due to reason service event when you use task scale-in protection.

You can do one the following:

  • Wait until the protection on the current tasks expire, enabling them to be terminated.

  • Determine which tasks can be stopped and use the UpdateTaskProtection API with the protectionEnabled option set to false to unset protection for these tasks.

  • Increase the desired task count of the service to more than the number of protected tasks.

service (service-name) stopped AZ Rebalancing.

The service scheduler sends a service-name stopped AZ Rebalancing service event when the Availability Zone rebalancing operation stopped. This is an information event. Amazon ECS sends additional events which provide more information.