AutoScaling.yml

 ECSCluster:
    Type: AWS::ECS::Cluster
    Properties:
      ClusterName: !Sub ${AWS::StackName}

  ECSAutoScalingGroup:
    Type: AWS::AutoScaling::AutoScalingGroup
    Properties:
      VPCZoneIdentifier:
        - Fn::ImportValue: !Sub '${VPCStackName}-${SubnetType}SubnetList'
      LaunchConfigurationName: !Ref ECSLaunchConfiguration
      MetricsCollection:
      -
        Granularity: "1Minute"
        Metrics:
          - "GroupMinSize"
          - "GroupMaxSize"
      MinSize: !Ref MinSize
      MaxSize: !Ref MaxSize
      DesiredCapacity: !Ref Desired
      TerminationPolicies:
        - Default
      Tags:
        - Key: Name
          Value: !Sub ${AWS::StackName} ECS host
          PropagateAtLaunch: true
    CreationPolicy:
      ResourceSignal:
        Timeout: PT5M
    UpdatePolicy:
      AutoScalingRollingUpdate:
        MinInstancesInService: 1
        MaxBatchSize: 1
        PauseTime: PT5M
        WaitOnResourceSignals: true

  ScaleUpPolicy:
    Type: AWS::AutoScaling::ScalingPolicy
    Properties:
      AdjustmentType: ChangeInCapacity
      AutoScalingGroupName: !Ref ECSAutoScalingGroup
      EstimatedInstanceWarmup: 300
      MetricAggregationType: Average
      PolicyType: StepScaling
      StepAdjustments:
      # The X bound is the difference between the breach threshold and the
      # aggregated CloudWatch metric value
         - MetricIntervalLowerBound: "0"
           MetricIntervalUpperBound: "15"
           ScalingAdjustment: "1"
         - MetricIntervalLowerBound: "15"
           ScalingAdjustment: "2"

  ScaleDownPolicy:
    Type: AWS::AutoScaling::ScalingPolicy
    Properties:
      AdjustmentType: ChangeInCapacity
      AutoScalingGroupName: !Ref ECSAutoScalingGroup
      EstimatedInstanceWarmup: 300
      MetricAggregationType: Average
      PolicyType: StepScaling
      StepAdjustments:
      # The X bound is the difference between the breach threshold and the
      # aggregated CloudWatch metric value
          - MetricIntervalUpperBound: "0"
            ScalingAdjustment: "-1"