How can I connect my autoscaling group to my ecs cluster?

Question

In all tutorials for ECS you need to create a cluster and after that an autoscaling group, that will spawn instances. Somehow in all these tutorials the instances magically show up in the cluster, but noone gives a hint what's connecting the autoscaling group and the cluster.

my autoscaling group spawns instances as expected, but they just dont show up on my ecs cluster, who holds my docker definitions.

Where is the connection I'm missing?

Answer 1

I was struggling with this for a while. The key to getting the instances in the autoscaling group associated with your ECS cluster is in the user data. When you are creating your launch config when you get to step 3 "Configure Details" hit the advanced tab and enter a simple bash script like the following for your user data.

#!/usr/bin/env bash echo ECS_CLUSTER=your_cluster_name >> /etc/ecs/ecs.config 

All the available parameters for agent configuration can be found here http://docs.aws.amazon.com/AmazonECS/latest/developerguide/ecs-agent-config.html

Answer 2

An autoscaling group is not strictly associated to a cluster. However, an autoscaling group can be configured such that each instance launched registers itself into a particular cluster.

Registering an instance into a cluster is the responsibility of the ECS Agent running on the instance. If you're using the Amazon ECS-optimized AMI, the ECS Agent will launch when the instance boots and register itself into the configured cluster. However, you can also use the ECS Agent on other Linux AMIs by following the installation instructions.