AWSTemplateFormatVersion: '2010-09-09'
Description: Deploy a service into an ECS cluster behind a public load balancer.
Parameters:
  GerritServiceName:
    Type: String
    Default: gerrit-master
  ClusterStackName:
      Description: Stack name of the ECS cluster to deply the serivces
      Type: String
      Default: gerrit-cluster
  EnvironmentName:
      Description: An environment name that will be prefixed to resource names
      Type: String
      Default: test
  DockerImage:
        Description: Gerrit official Docker image
        Type: String
        Default: gerritcodereview/gerrit:latest
  DesiredCount:
        Description: How many instances of this task should we run across our cluster?
        Type: Number
        Default: 1
  HTTPPort:
        Description: Gerrit HTTP port
        Type: Number
        Default: 8080
  SSHPort:
        Description: Gerrit SSH port
        Type: Number
        Default: 29418
  HostedZoneName:
        Description: The route53 HostedZoneName.
        Type: String
  Subdomain:
        Description: The subdomain of the Gerrit cluster
        Type: String
        Default: gerrit-master-demo

Resources:
    Service:
        Type: AWS::ECS::Service
        DependsOn:
          - HTTPListener
          - SSHListener
        Properties:
            Cluster:
              Fn::ImportValue:
                  !Join [':', [!Ref 'ClusterStackName', 'ClusterName']]
            DesiredCount: !Ref DesiredCount
            TaskDefinition: !Ref TaskDefinition
            LoadBalancers:
                - ContainerName: !Ref GerritServiceName
                  ContainerPort: !Ref HTTPPort
                  TargetGroupArn: !Ref HTTPTargetGroup
                - ContainerName: !Ref GerritServiceName
                  ContainerPort: !Ref SSHPort
                  TargetGroupArn: !Ref SSHTargetGroup

    TaskDefinition:
        Type: AWS::ECS::TaskDefinition
        Properties:
            Family: !Join ['', [!Ref GerritServiceName, TaskDefinition]]
            TaskRoleArn: !Ref ECSTaskExecutionRole
            ExecutionRoleArn: !Ref ECSTaskExecutionRole
            NetworkMode: bridge
            ContainerDefinitions:
                - Name: !Ref GerritServiceName
                  Essential: true
                  Image: !Ref DockerImage
                  Environment:
                    - Name: "CANONICAL_WEB_URL"
                      Value: !Join [ '', [ 'http://', !Ref 'Subdomain', '.', !Ref 'HostedZoneName' ] ]
                  Environment:
                    - Name: "region"
                      Value: !Ref AWS::Region
                  Cpu: 1024
                  Memory: 2048
                  PortMappings:
                    - ContainerPort: !Ref HTTPPort
                      HostPort: !Ref HTTPPort
                      Protocol: tcp
                    - ContainerPort: !Ref SSHPort
                      HostPort: !Ref SSHPort
                      Protocol: tcp
                  LogConfiguration:
                    LogDriver: awslogs
                    Options:
                        awslogs-group: !Ref AWS::StackName
                        awslogs-region: !Ref AWS::Region
                        awslogs-stream-prefix: !Ref EnvironmentName

    CloudWatchLogsGroup:
        Type: AWS::Logs::LogGroup
        Properties:
            LogGroupName: !Ref AWS::StackName
            RetentionInDays: 14

    LoadBalancer:
        Type: AWS::ElasticLoadBalancingV2::LoadBalancer
        Properties:
            Type: network
            Scheme: internet-facing
            Subnets:
              - Fn::ImportValue:
                  !Join [':', [!Ref 'ClusterStackName', 'PublicSubnetOne']]
            Tags:
                - Key: Name
                  Value: !Join ['-', [!Ref 'EnvironmentName', !Ref 'GerritServiceName', 'nlb']]

    HTTPTargetGroup:
        Type: AWS::ElasticLoadBalancingV2::TargetGroup
        DependsOn: LoadBalancer
        Properties:
            VpcId:
              Fn::ImportValue:
                  !Join [':', [!Ref 'ClusterStackName', 'VPCId']]
            Port: !Ref HTTPPort
            Protocol: TCP

    HTTPListener:
        Type: AWS::ElasticLoadBalancingV2::Listener
        DependsOn: LoadBalancer
        Properties:
            DefaultActions:
            - Type: forward
              TargetGroupArn: !Ref HTTPTargetGroup
            LoadBalancerArn: !Ref LoadBalancer
            Port: !Ref HTTPPort
            Protocol: TCP

    SSHTargetGroup:
        Type: AWS::ElasticLoadBalancingV2::TargetGroup
        DependsOn: LoadBalancer
        Properties:
            VpcId:
              Fn::ImportValue:
                  !Join [':', [!Ref 'ClusterStackName', 'VPCId']]
            Port: !Ref SSHPort
            Protocol: TCP

    SSHListener:
        Type: AWS::ElasticLoadBalancingV2::Listener
        DependsOn: LoadBalancer
        Properties:
            DefaultActions:
            - Type: forward
              TargetGroupArn: !Ref SSHTargetGroup
            LoadBalancerArn: !Ref LoadBalancer
            Port: !Ref SSHPort
            Protocol: TCP

    # This is a role which is used by the ECS tasks themselves.
    ECSTaskExecutionRole:
      Type: AWS::IAM::Role
      Properties:
        AssumeRolePolicyDocument:
          Statement:
          - Effect: Allow
            Principal:
              Service: [ecs-tasks.amazonaws.com]
            Action: ['sts:AssumeRole']
        Path: /
        Policies:
          - PolicyName: AmazonECSTaskExecutionRolePolicy
            PolicyDocument:
              Statement:
              - Effect: Allow
                Action:
                  # Allow the ECS Tasks to download images from ECR
                  - 'ecr:GetAuthorizationToken'
                  - 'ecr:BatchCheckLayerAvailability'
                  - 'ecr:GetDownloadUrlForLayer'
                  - 'ecr:BatchGetImage'
                  # Allow the ECS tasks to upload logs to CloudWatch
                  - 'logs:CreateLogStream'
                  - 'logs:PutLogEvents'
                Resource: '*'
Outputs:
  PublicLoadBalancerDNSName:
    Description: The DNS name of the external load balancer
    Value: !GetAtt 'LoadBalancer.DNSName'
    Export:
      Name: !Join [ ':', [ !Ref 'AWS::StackName', 'PublicLoadBalancerDNSName' ] ]
  CanonicalHostedZoneID:
    Description: Canonical Hosted Zone ID
    Value: !GetAtt 'LoadBalancer.CanonicalHostedZoneID'
    Export:
      Name: !Join [ ':', [ !Ref 'AWS::StackName', 'CanonicalHostedZoneID' ] ]
  PublicLoadBalancerUrl:
    Description: The url of the external load balancer
    Value: !Join ['', ['http://', !GetAtt 'LoadBalancer.DNSName']]
    Export:
      Name: !Join [ ':', [ !Ref 'AWS::StackName', 'PublicLoadBalancerUrl' ] ]
  HostedZoneName:
    Description: Route53 Hosted Zone name
    Value: !Ref HostedZoneName
    Export:
      Name: !Join [ ':', [ !Ref 'AWS::StackName', 'HostedZoneName' ] ]
  Subdomain:
    Description: Service DNS subdomain
    Value: !Ref Subdomain
    Export:
      Name: !Join [ ':', [ !Ref 'AWS::StackName', 'Subdomain' ] ]