AWSTemplateFormatVersion: '2010-09-09'
Description: Deploy a backend service on AWS Fargate, hosted in a private subnet, and accessible via Service Discovery.
Mappings:
  EnvironmentNameConfig:
    Environment:
      Name: '{{ environment.name}}'
  TaskSize:
    x-small:
      cpu: 256
      memory: 512
    small:
      cpu: 512
      memory: 1024
    medium:
      cpu: 1024
      memory: 2048
    large:
      cpu: 2048
      memory: 4096
    x-large:
      cpu: 4096
      memory: 8192
Resources:
  # Register service in ServiceDiscovery Service
  DiscoveryService:
    Type: AWS::ServiceDiscovery::Service
    Properties:
      Description: Discovery Service for the Demo Application
      DnsConfig:
        RoutingPolicy: MULTIVALUE
        DnsRecords:
          - TTL: 60
            Type: A
      HealthCheckCustomConfig:
        FailureThreshold: 1
      Name: '{{service_instance.inputs.service_discovery_name}}'
      NamespaceId: '{{environment.outputs.PrivateNamespace}}'
  # A log group for storing the stdout logs from this service's containers
  LogGroup:
    Type: AWS::Logs::LogGroup
    Properties:
      LogGroupName: '{{service.name}}/{{service_instance.name}}'

  # The task definition. This is a simple metadata description of what
  # container to run, and what resource requirements it has.
  TaskDefinition:
    Type: AWS::ECS::TaskDefinition
    Properties:
      Family: '{{service.name}}_{{service_instance.name}}'
      Cpu: !FindInMap [TaskSize, {{service_instance.inputs.task_size}}, cpu]
      Memory: !FindInMap [TaskSize, {{service_instance.inputs.task_size}}, memory]
      NetworkMode: awsvpc
      RequiresCompatibilities:
        - FARGATE
      ExecutionRoleArn: '{{environment.outputs.ECSTaskExecutionRole}}'
      TaskRoleArn: !Ref "AWS::NoValue"
      ContainerDefinitions:
        - Name: '{{service_instance.name}}'
          Cpu: !FindInMap [TaskSize, {{service_instance.inputs.task_size}}, cpu]
          Memory: !FindInMap [TaskSize, {{service_instance.inputs.task_size}}, memory]
          Image: '{{service_instance.inputs.image}}'
          PortMappings:
            - ContainerPort: '{{service_instance.inputs.port}}'
          LogConfiguration:
            LogDriver: 'awslogs'
            Options:
              awslogs-group: '{{service.name}}/{{service_instance.name}}'
              awslogs-region: !Ref 'AWS::Region'
              awslogs-stream-prefix: '{{service.name}}/{{service_instance.name}}'
      Tags:
        - Key: Name
          Value: !FindInMap ['EnvironmentNameConfig', 'Environment', 'Name']

  # The service_instance.inputs. The service is a resource which allows you to run multiple
  # copies of a type of task, and gather up their logs and metrics, as well
  # as monitor the number of running tasks and replace any that have crashed
  Service:
    Type: AWS::ECS::Service
    Properties:
      ServiceName: '{{service.name}}_{{service_instance.name}}'
      Cluster: '{{environment.outputs.ClusterName}}'
      LaunchType: FARGATE
      DesiredCount: '{{service_instance.inputs.desired_count}}'
      NetworkConfiguration:
        AwsvpcConfiguration:
          AssignPublicIp: DISABLED
          SecurityGroups:
            - '{{environment.outputs.ContainerSecurityGroup}}'
          Subnets:
            - '{{environment.outputs.PrivateSubnetOne}}'
            - '{{environment.outputs.PrivateSubnetTwo}}'
      TaskDefinition: !Ref 'TaskDefinition'
      ServiceRegistries:
      - RegistryArn: !GetAtt DiscoveryService.Arn
      Tags:
        - Key: Name
          Value: !FindInMap ['EnvironmentNameConfig', 'Environment', 'Name']

Outputs:
  ServiceDiscovery:
    Description: The registered service discovery Service Id
    Value: !Ref DiscoveryService