# Copyright 2020 Amazon.com, Inc. or its affiliates. All Rights Reserved.
# SPDX-License-Identifier: MIT-0

AWSTemplateFormatVersion: 2010-09-09
Description: >
  This template the auto scaling for the EcsFargate application.
Metadata:
  version: 1.0.0
Parameters:
  pApp:
    Description: Name of the Application to which the resource belongs
    Type: String
  pCpuScaleInCooldown:
    Type: Number
    Default: 60
    MinValue: 0
    MaxValue: 300
    Description: The number of seconds to wait before performing another scale in based on average cpu utilization. Default to 60 - override as needed.
  pCpuScaleOutCooldown:
    Type: Number
    Default: 60
    MinValue: 0
    MaxValue: 300
    Description: The number of seconds to wait before performing another scale out based on average cpu utilization. Default to 60 - override as needed.
  pCpuAutoScalingTargetValue:
    Type: Number
    Default: 75
    MinValue: 0
    MaxValue: 100
    Description: The target average CPU utilization percent before scaling out/in occurs. Default to 70 - override as needed.
  pDesiredCount:
    Description: Provide the desired number of task definition instances to run in cluster
    Type: Number
  pEcsAutoScalingRole:
    Description: The short name or full Amazon Resource Name (ARN) of the auto scaling role
    Type: String
  pECSClusterName:
    Description: The name of the ecs cluster 
    Type: String
  pEcsFargateServiceName:
    Description: The name of the ecs fargate service 
    Type: String
  pMaxContainers:
    Type: Number
    Default: 5
    Description: The maximum number of nodes that can be in the cluster. Default to a max of 5 - override as needed.
  pMemoryAutoScalingTargetValue:
    Type: Number
    Default: 75
    MinValue: 0
    MaxValue: 100
    Description: The target average memory utilization percent before scaling out/in occurs. Default to 75 - override as needed.
  pMemoryScaleInCooldown:
    Type: Number
    Default: 60
    MinValue: 0
    MaxValue: 300
    Description: The number of seconds to wait before performing another scale in based on average cpu utilization. Default to 60 - override as needed. 
  pMemoryScaleOutCooldown:
    Type: Number
    Default: 60
    MinValue: 0
    MaxValue: 300
    Description: The number of seconds to wait before performing another scale out based on average cpu utilization. Default to 60  - override as needed.

Resources:
  #See AWS Resource Naming Standards - https://exampleent.atlassian.net/wiki/spaces/CLOUDDOC/pages/149718262/ELZ+AWS+Resource+Naming+Standards#ELZAWSResourceNamingStandards-ECS
  #See https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-applicationautoscaling-scalabletarget.html#cfn-applicationautoscaling-scalabletarget-resourceid
  #Define how the service will scale.
  AutoScalingTarget:
    Type: AWS::ApplicationAutoScaling::ScalableTarget
    Properties:
      MinCapacity: !Ref pDesiredCount
      MaxCapacity: !Ref pMaxContainers
      ResourceId:
        Fn::Sub:
        - "service/${ecsClusterName}/${ecsServiceName}"
        - ecsClusterName: !Ref pECSClusterName
          ecsServiceName: !Ref pEcsFargateServiceName
      ScalableDimension: ecs:service:DesiredCount
      ServiceNamespace: ecs
      # AWS ARN and IAM role that allow auto scaling
      RoleARN:
        !Ref pEcsAutoScalingRole

            # Fn::ImportValue:
            #   !Sub ${pSystem}-${pIteration}-${pApp}-${pEnvironment}-ecscluster

  #See https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-applicationautoscaling-scalingpolicy.html
  # Auto scaling based on cpu usage for the target specified in the ScalingTargetId.. When CPU utilization is more
  # than the value specified in the TargetValue parameter, ECS will scale out. When CPU utilization is less than the value
  # specified in the TargetValue parameter, ECS will attempt to scale in. ECS will wait the number of seconds
  # specified in the ScaleInCooldown and ScaleOutCooldown before performing subsequent scale downs or ups.
  CPUAutoScalingPolicy:
    Type: AWS::ApplicationAutoScaling::ScalingPolicy
    Properties:
      PolicyName: !Sub ${pApp}-cpuscalepolicy
      PolicyType: TargetTrackingScaling
      ScalingTargetId: !Ref AutoScalingTarget
      TargetTrackingScalingPolicyConfiguration:
        PredefinedMetricSpecification:
          PredefinedMetricType: ECSServiceAverageCPUUtilization
        ScaleInCooldown: !Ref pCpuScaleInCooldown
        ScaleOutCooldown: !Ref pCpuScaleOutCooldown
        # Desired cpu utilization
        TargetValue: !Ref pCpuAutoScalingTargetValue

  #See https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-applicationautoscaling-scalingpolicy.html
  # Auto scaling based on memory usage for the target specified in the ScalingTargetId. When average memory utilization
  # is more than the value specified in the TargetValue parameter, ECS will scale out. When memory utilization is less
  # than the value specified in the TargetValue parameter, ECS will attempt to scale in. ECS will wait the number of seconds
  # specified in the ScaleInCooldown and ScaleOutCooldown before performing subsequent scale downs or ups.
  MemoryAutoScalingPolicy:
    Type: AWS::ApplicationAutoScaling::ScalingPolicy
    Properties:
      PolicyName: !Sub ${pApp}-memoryscalepolicy
      PolicyType: TargetTrackingScaling
      ScalingTargetId: !Ref AutoScalingTarget
      TargetTrackingScalingPolicyConfiguration:
        PredefinedMetricSpecification:
          PredefinedMetricType: ECSServiceAverageMemoryUtilization
        ScaleInCooldown: !Ref pMemoryScaleInCooldown
        ScaleOutCooldown: !Ref pMemoryScaleOutCooldown
        # Desired average memory utilization
        TargetValue: !Ref pMemoryAutoScalingTargetValue