AWSTemplateFormatVersion: '2010-09-09'
Description: This template deploys an automatically generated CloudWatch
             dashboard for the referenced ECS service.
Transform:
  - AWS::LanguageExtensions

Parameters:
  ServiceArn:
    Type: String
    Description: The ARN of the service that we want to generate the dashboard from.

Resources:
  # A CloudWatch log group for persisting the deployment events
  ServiceEventLog:
    Type: AWS::Logs::LogGroup

  # Create the EventBridge rule that captures deployment events into the CloudWatch log group
  CaptureServiceDeploymentEvents:
    Type: AWS::Events::Rule
    Properties:
      Description:
        Fn::Sub:
          - 'Capture service deployment events from the ECS service ${ServiceName}'
          # Scary but working way to get service's human name from it's ARN
          - ServiceName: !Select [2, !Split ['/', !Select [5, !Split [':', !Ref ServiceArn]]]]
      EventPattern:
        source:
          - aws.ecs
        detail-type:
          - "ECS Deployment State Change"
          - "ECS Service Action"
        resources:
          - !Ref ServiceArn
      # Where to send the events
      Targets:
        - Arn: !Sub arn:aws:logs:${AWS::Region}:${AWS::AccountId}:log-group:${ServiceEventLog}
          Id: 'CloudWatchLogGroup'

  # Create a log group resource policy that allows EventBridge to put logs into
  # the log group
  LogGroupForEventsPolicy:
    Type: AWS::Logs::ResourcePolicy
    Properties:
      PolicyName: EventBridgeToCWLogsPolicy
      PolicyDocument: !Sub
      - >
        {
          "Version": "2012-10-17",
          "Statement": [
            {
              "Sid": "EventBridgetoCWLogsPolicy",
              "Effect": "Allow",
              "Principal": {
                "Service": [
                  "delivery.logs.amazonaws.com",
                  "events.amazonaws.com"
                ]
              },
              "Action": [
                "logs:CreateLogStream",
                "logs:PutLogEvents"
              ],
              "Resource": [
                "${LogArn}"
              ]
            }
          ]
        }
      - { LogArn: !GetAtt ServiceEventLog.Arn, RuleArn: !GetAtt CaptureServiceDeploymentEvents.Arn}

  # This resource creates the widgets that will live in the CloudWatch
  # dashboard, by pulling stats from Container Insights
  ServiceDashboard:
    Type: AWS::CloudWatch::Dashboard
    Properties:
      DashboardName:
        Fn::Sub:
          - "${ServiceName}-dashboard"
          - ServiceName: !Select [2, !Split ['/', !Select [5, !Split [':', !Ref ServiceArn]]]]
      DashboardBody:
        Fn::ToJsonString:
          widgets:
            # A table that shows recent deployment events
            - type: log
              x: 0
              y: 0
              width: 24
              height: 4
              properties:
                region: !Ref AWS::Region
                title: Service Deployments
                query: !Sub "SOURCE '${ServiceEventLog}' | fields @timestamp, detail.eventName, detail.deploymentId | sort @timestamp desc | limit 500"
                view: table

            # A graph showing the running task count over time
            - type: metric
              x: 0
              y: 13
              width: 24
              height: 6
              properties:
                metrics:
                - - "ECS/ContainerInsights"
                  - "RunningTaskCount"
                  - "ServiceName"
                  # Extract service name from service ARN
                  - !Select [2, !Split ['/', !Select [5, !Split [':', !Ref ServiceArn]]]]
                  - "ClusterName"
                  # Extract cluster name from service ARN
                  - !Select [1, !Split ['/', !Select [5, !Split [':', !Ref ServiceArn]]]]
                - [ ".", "DesiredTaskCount", ".", ".", ".", "." ]
                view: timeSeries
                stacked: false
                region: !Ref AWS::Region
                stat: Sum
                period: 60
                yAxis:
                  left:
                    min: 0
                title: "DesiredTaskCount, RunningTaskCount"

            # A graph showing CPU and Memory utilization over time
            - type: metric
              x: 0
              y: 13
              width: 24
              height: 6
              properties:
                metrics:
                - - "ECS/ContainerInsights"
                  - "CpuUtilized"
                  - "ServiceName"
                  # Extract service name from service ARN
                  - !Select [2, !Split ['/', !Select [5, !Split [':', !Ref ServiceArn]]]]
                  - "ClusterName"
                  # Extract cluster name from service ARN
                  - !Select [1, !Split ['/', !Select [5, !Split [':', !Ref ServiceArn]]]]
                - [ ".", "MemoryUtilized", ".", ".", ".", "." ]
                view: timeSeries
                stacked: false
                region: !Ref AWS::Region
                stat: Sum
                period: 60
                yAxis:
                  left:
                    min: 0
                title: "CPU Utilization, Memory Utilization"