AWS ECS fargate 自动扩展 - 它如何扩展选择要终止的任务？

Question

I am running java process inside ecs fargate containers and have set-up auto scaling to scale-out when memory utilization is above 60% and scale-in accordingly. This setup is working fine but i am not able to figure out the criteria based upon which ecs determines which tasks it should shutdown as part of the scale-in events ie how does it distinguishes between different tasks and picks one to shutdown? Does it check if there any active requests on the tasks or not and then if there are multiple such tasks then picks randomly?

Answer 1

There is a years long open issue about that on github:

• Control which containers are terminated on scale in

From the issue and its comments you can infer the following:

Does it check if there any active requests on the tasks

No.

if there are multiple such tasks then picks randomly ?

Its random.

Answer 2

There is actually an update of this, now you can make your running task to be protected. Check this one for more details

https://aws.amazon.com/premiumsupport/knowledge-center/ecs-fargate-service-auto-scaling/