Amazon Elastic Container Service (ECS) supports Automated Spot Instance Draining, a new capability that reduces service interruptions due to Spot termination for ECS workloads. This feature will enable ECS customers to safely manage any interruptions of ECS tasks running on Spot instances due to termination of the underlying EC2 Spot instance.

from Recent Announcements https://aws.amazon.com/about-aws/whats-new/2019/09/amazon-ecs-supports-automated-draining-for-spot-instances-running-ecs-services/