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

AWSTemplateFormatVersion: 2010-09-09
Description: >
  This template deploys the service alarms.
Metadata:
  version: 1.0.0
Parameters:
  pApp:
    Description: Name of the Application to which the resource belongs
    Type: String
  pCloudWatchAlarmFlag:
    Description: This parameter defines if we need a cloudwatch alaram.
    Type: String
  pClusterName:
    Description: The short name or full Amazon Resource Name (ARN) of the cluster on which to run your service.
    Type: String
  pFargateServiceName:
    Description: Fargate Service Name
    Type: String
  pIteration:
    Description: An integer used to distinguish between instances of the same resource in support ofeither horizontally scaled groups of resources or partitioned resources
    Type: String
    Default: '01'
  pMonitoringTopicArn:
    Description: Monitoring Topic Arn
    Type: String
  pTargetGroupFullName:
    Description: The TargetGroup Arn
    Type: String

Conditions:
  EnableCloudWatchAlarm: !Equals [ !Ref pCloudWatchAlarmFlag, 'true' ]
Resources:
  #See AWS Resource Naming Standards - https://exampleent.atlassian.net/wiki/spaces/CLOUDDOC/pages/149718262/ELZ+AWS+Resource+Naming+Standards#ELZAWSResourceNamingStandards-CloudWatch
  
  #Create a cloudwatch alarm for http5xxx status codes generated by the target group
  #when the number generated exceeds 1 in a 300 second period. 
  #See https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-properties-cw-alarm.html
  rEcsFargateHTTPCodeTarget5XXTooHighAlarm:
    Type: 'AWS::CloudWatch::Alarm'
    Properties:
      AlarmDescription: 'Application load balancer receives 5XX HTTP status codes from EcsFargate'
      AlarmName: !Sub '${pApp}-HTTPCodeTarget5XXTooHighAlarm'
      Namespace: 'AWS/ApplicationELB'
      MetricName: HTTPCode_Target_5XX_Count
      Statistic: Sum
      Period: 300
      EvaluationPeriods: 1
      ComparisonOperator: GreaterThanThreshold
      Threshold: 1
      AlarmActions:
        !If
          - EnableCloudWatchAlarm
          -
            - Ref: pMonitoringTopicArn
            # - Ref: pServiceNowTopicArn
          - !Ref AWS::NoValue
      Dimensions:
        - Name: TargetGroup
          Value: !Ref pTargetGroupFullName

  #Create alarm when number of unhealthy hosts exceeds one in a 300 second period. 
  #See https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-properties-cw-alarm.html
  rEcsFargateTargetConnectionErrorCountTooHighAlarm:
    Type: 'AWS::CloudWatch::Alarm'
    Properties:
      AlarmDescription: 'Application load balancer receives 5XX HTTP status codes from EcsFargate'
      Namespace: 'AWS/ApplicationELB'
      MetricName: UnHealthyHostCount
      AlarmName: !Sub '${pApp}-EcsFargateTargetConnectionErrorCountTooHighAlarm'
      Statistic: Sum
      Period: 300
      EvaluationPeriods: 1
      ComparisonOperator: GreaterThanThreshold
      Threshold: 1
      AlarmActions:
        !If
          - EnableCloudWatchAlarm
          -
            - Ref: pMonitoringTopicArn
            # - Ref: pServiceNowTopicArn
          - !Ref AWS::NoValue
      Dimensions:
        - Name: TargetGroup
          Value: !Ref pTargetGroupFullName

  #Create a cloudwatch alarm if CPU Utilization is greater than 80% in a 300 second period. 
  #See https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-properties-cw-alarm.html
  rEcsFargateCPUUtlizationTooHighAlarm:
    Type: 'AWS::CloudWatch::Alarm'
    Properties:
      AlarmDescription: 'This is alarm triggered when more than 80% of CPU is utilized - EcsFargate'
      Namespace: 'AWS/ECS'
      MetricName: CPUUtilization
      AlarmName: !Sub '${pApp}-EcsFargateCPUUtlizationTooHighAlarm'
      Statistic: Sum
      Period: 300
      EvaluationPeriods: 1
      ComparisonOperator: GreaterThanThreshold
      Threshold: 80
      Dimensions:
        - Name: ClusterName
          Value: !Ref pClusterName
        - Name: ServiceName
          Value:  !Ref pFargateServiceName
      AlarmActions:
        !If
          - EnableCloudWatchAlarm
          -
            - Ref: pMonitoringTopicArn
            # - Ref: pServiceNowTopicArn
          - !Ref AWS::NoValue

  #Create a cloudwatch alarm if Memory Utilization is greater than 80% in a 300 second period. 
  #See https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-properties-cw-alarm.html
  rEcsFargateMemoryUtlizationTooHighAlarm:
    Type: 'AWS::CloudWatch::Alarm'
    Properties:
      AlarmDescription: 'This is alarm triggered when more than 80% of Memory is utilized - EcsFargate'
      Namespace: 'AWS/ECS'
      MetricName: MemoryUtilization
      AlarmName: !Sub '${pApp}-EcsFargateMemoryUtlizationTooHighAlarm'
      Statistic: Sum
      Period: 300
      EvaluationPeriods: 1
      ComparisonOperator: GreaterThanThreshold
      Threshold: 80
      Dimensions:
        - Name: ClusterName
          Value: !Ref pClusterName
        - Name: ServiceName
          Value:  !Ref pFargateServiceName
      AlarmActions:
        !If
          - EnableCloudWatchAlarm
          -
            - Ref: pMonitoringTopicArn
            # - Ref: pServiceNowTopicArn
          - !Ref AWS::NoValue