Deregister a Container Instance
When you are finished with a container instance, you can deregister it from your cluster.
Following deregistration, the container instance is no longer able to accept new tasks. If you have tasks running on the container instance when you deregister it, these tasks remain running until you terminate the instance or the tasks stop through some other means. However, these tasks are orphaned (no longer monitored or accounted for by Amazon ECS). If an orphaned task on your container instance is part of an Amazon ECS service, then the service scheduler starts another copy of that task, on a different container instance, if possible. Any containers in orphaned service tasks that are registered with a Classic Load Balancer or an Application Load Balancer target group are deregistered. They begin connection draining according to the settings on the load balancer or target group.
If you intend to use the container instance for some other purpose after deregistration, you should stop all of the tasks running on the container instance before deregistration. This stops any orphaned tasks from consuming resources.
Because each container instance has unique state information, they should not be deregistered from one cluster and re-registered into another. To relocate container instance resources, we recommend that you terminate container instances from one cluster and launch new container instances with the latest Amazon ECS-optimized AMI in the new cluster. For more information, see Terminate Your Instance in the Amazon EC2 User Guide for Linux Instances and Launching an Amazon ECS Container Instance.
Deregistering a container instance removes the instance from a cluster, but it does not terminate the EC2 instance. If you are finished using the instance, be sure to terminate it in the Amazon EC2 console to stop billing. For more information, see Terminate Your Instance in the Amazon EC2 User Guide for Linux Instances.
If you terminate a running container instance with a connected Amazon ECS container agent, the agent automatically deregisters the instance from your cluster. Stopped container instances or instances with disconnected agents are not automatically deregistered when terminated.
To deregister a container instance
Open the Amazon ECS console at https://console.aws.amazon.com/ecs/.
From the navigation bar, choose the region that your container instance is registered in.
In the navigation pane, choose Clusters and select the cluster that hosts your container instance.
On the Cluster :
namepage, choose ECS Instances.
Choose the container instance ID that to deregister.
On the Container Instance :
idpage, choose Deregister.
Review the deregistration message, and choose Yes, Deregister.
If you are finished with the container instance, terminate the underlying Amazon EC2 instance. For more information, see Terminate Your Instance in the Amazon EC2 User Guide for Linux Instances.
If your instance is maintained by an Auto Scaling group or AWS CloudFormation stack, terminate the instance by updating the Auto Scaling group or AWS CloudFormation stack. Otherwise, the Auto Scaling group re-creates the instance after you terminate it.