The AWS ECS Autoscaler keeps track of the cpu and memory requirements of the services running in an ECS cluster, and adjusts the desired capacity of the underlying AWS autoscaling group to minimize wastage. It can be run as a task in the ECS cluster itself, or on a separate management server.
In a cloudformation template, on the ECS cluster:
Service:
Properties:
Cluster: my-cluster-name
DesiredCount: 2
TaskDefinition: !Ref AutoscalingTaskDefinition
Type: AWS::ECS::Service
AutoscalingTaskDefinition:
Properties:
ContainerDefinitions:
- Environment:
- Name: AS_GROUP_NAME
Value: MY_AUSTOSCALING_GROUP_NAME
- Name: CLUSTER_NAME
Value: MY_CLUSTER_NAME
Essential: true
Image: !Sub trinitymirror/aws-ecs-autoscaler:${AutoscalingVersion}
Memory: 200
Cpu: 100
Name: Autoscaler
Type: AWS::ECS::TaskDefinition
And it would require the following permissions attached to the Austoscaling group's launch configuration iam role to run:
- Action:
- autoscaling:DescribeAutoScalingGroups
- autoscaling:SetDesiredCapacity
- autoscaling:TerminateInstanceInAutoScalingGroup
Effect: Allow
Resource: '*'
- Action:
- ecs:DescribeContainerInstances
- ecs:DescribeServices
- ecs:DescribeTaskDefinition
- ecs:DescribeTasks
- ecs:ListContainerInstances
- ecs:ListServices
- ecs:ListTasks
Effect: Allow
Resource: '*'
- Action:
- ec2:DescribeInstances
Effect: Allow
Resource: '*'
Note that the autoscaling actions do require access to all resources, and cannot be limited to just your autoscaling group - this is a limitation of AWS autoscaling groups
DRY_RUN=true
- Causes the container to not actually run any changes, just print to stdout what it would do.