Add target tracking auto scale to your aws ecs service

This cloudformation snippet will add auto scale to your existing cloudformation based ecs service.

To connect it to your service you may need to edit the folowing vars ServiceScalingTarget:

• Service This is the name of the cloudformation block that defines your ecs service
• Ref: ContainerCluster This should pull in the ecs cluster name I define this in a param: ContainerCluster

  ApplicationAutoScalingRole:
    Type: AWS::IAM::Role
    Properties:
      AssumeRolePolicyDocument:
        Statement:
        - Effect: Allow
          Principal:
            Service: [application-autoscaling.amazonaws.com]
          Action: ['sts:AssumeRole']
      Path: /
      Policies:
      -
        PolicyName: ECSBlogScalingRole
        PolicyDocument:
          Statement:
          - Effect: Allow
            Action:
            - ecs:UpdateService
            - ecs:DescribeServices
            - application-autoscaling:*
            - cloudwatch:DescribeAlarms
            - cloudwatch:GetMetricStatistics
            Resource: "*"

  ServiceScalingTarget:
    Type: AWS::ApplicationAutoScaling::ScalableTarget
    Properties:
      MaxCapacity: 20
      MinCapacity: 1
      ResourceId:
        Fn::Join:
        - ''
        - - service/
          - Ref: ContainerCluster
          - "/"
          - Fn::GetAtt:
            - Service
            - Name
      RoleARN:
        Fn::GetAtt:
        - ApplicationAutoScalingRole
        - Arn
      ScalableDimension: ecs:service:DesiredCount
      ServiceNamespace: ecs

  ServiceScalingPolicy:
    Type: AWS::ApplicationAutoScaling::ScalingPolicy
    Properties:
      PolicyName: !Sub ${AWS::StackName}
      PolicyType: TargetTrackingScaling
      ScalingTargetId: !Ref ServiceScalingTarget
      TargetTrackingScalingPolicyConfiguration:
        TargetValue: 50.0
        ScaleInCooldown: 60
        ScaleOutCooldown: 60
        PredefinedMetricSpecification:
          PredefinedMetricType: ECSServiceAverageCPUUtilization