Description: >
  This template deploys an Application Load Balancer that exposes our various ECS services.
  We create them in a seperate nested template, so it can be referenced by all of the other nested templates.

Parameters:
  EnvironmentName:
    Description: An environment name that will be prefixed to resource names
    Type: String

  VPC:
    Type: AWS::EC2::VPC::Id
    Description: Choose which VPC the Application Load Balancer should be deployed to

  Subnets:
    Description: Choose which subnets the Application Load Balancer should be deployed to
    Type: List<AWS::EC2::Subnet::Id>

  SecurityGroup:
    Description: Select the Security Group to apply to the Application Load Balancer
    Type: AWS::EC2::SecurityGroup::Id

Resources:
  LoadBalancer:
    Type: AWS::ElasticLoadBalancingV2::LoadBalancer
    Properties:
      Name: !Ref EnvironmentName
      Subnets: !Ref Subnets
      SecurityGroups:
        - !Ref SecurityGroup
      Tags:
        - Key: Name
          Value: !Ref EnvironmentName

  LoadBalancerListener:
    Type: AWS::ElasticLoadBalancingV2::Listener
    Properties:
      LoadBalancerArn: !Ref LoadBalancer
      Port: 80
      Protocol: HTTP
      DefaultActions:
        - Type: forward
          TargetGroupArn: !Ref DefaultTargetGroup

  # We define a default target group here, as this is a mandatory Parameters
  # when creating an Application Load Balancer Listener. This is not used, instead
  # a target group is created per-service in each service template (../services/*)
  DefaultTargetGroup:
    Type: AWS::ElasticLoadBalancingV2::TargetGroup
    Properties:
      Name: !Sub ${EnvironmentName}-default
      VpcId: !Ref VPC
      Port: 80
      Protocol: HTTP

Outputs:
  LoadBalancer:
    Description: A reference to the Application Load Balancer
    Value: !Ref LoadBalancer

  LoadBalancerUrl:
    Description: The URL of the ALB
    Value: !GetAtt LoadBalancer.DNSName

  Listener:
    Description: A reference to a port 80 listener
    Value: !Ref LoadBalancerListener