AWSTemplateFormatVersion: '2010-09-09'
Description: Deploy a service into an ECS cluster behind a public load balancer.

Parameters:
  InternetGatewayIdProp:
    Type: String
    Default: ""
    Description: Internet Gateway id. If empty Internet Gateway will be created
  VPCIdProp:
    Type: String
    Default: ""
    Description: VPC id. If empty VPC will be created
  SubnetIdProp:
    Type: String
    Default: ""
    Description: Subnet id. If empty Network Stack will be created
Mappings:
  # Hard values for the subnet masks. These masks define
  # the range of internal IP addresses that can be assigned.
  # The VPC can have all IP's from 10.0.0.0 to 10.0.255.255
  # There is the subnet which cover the ranges:
  #
  # 10.0.0.0 - 10.0.0.255
  SubnetConfig:
    VPC:
      CIDR: '10.0.0.0/16'
    PublicOne:
      CIDR: '10.0.0.0/24'

Conditions:
  CreateVPC: !Equals [!Ref VPCIdProp, ""]
  CreateNetworkStack: !Equals [!Ref SubnetIdProp, ""]
  CreateInternetGateway: !And
     - !Equals [!Ref InternetGatewayIdProp, ""]
     - !Condition CreateNetworkStack
Resources:
  VPC:
    Condition: CreateVPC
    Type: AWS::EC2::VPC
    Properties:
      EnableDnsSupport: true
      EnableDnsHostnames: true
      CidrBlock: !FindInMap ['SubnetConfig', 'VPC', 'CIDR']

  # Public subnets, where containers can have public IP addresses
  PublicSubnetOne:
    Condition: CreateNetworkStack
    Type: AWS::EC2::Subnet
    Properties:
      AvailabilityZone:
         Fn::Select:
         - 0
         - Fn::GetAZs: {Ref: 'AWS::Region'}
      VpcId: !If [CreateVPC, !Ref 'VPC', !Ref 'VPCIdProp' ]
      CidrBlock: !FindInMap ['SubnetConfig', 'PublicOne', 'CIDR']
      MapPublicIpOnLaunch: true

  # Setup networking resources for the public subnets. Containers
  # in the public subnets have public IP addresses and the routing table
  # sends network traffic via the internet gateway.
  InternetGateway:
    Condition: CreateInternetGateway
    Type: AWS::EC2::InternetGateway
  GatewayAttachement:
    Condition: CreateNetworkStack
    Type: AWS::EC2::VPCGatewayAttachment
    Properties:
      VpcId: !If [CreateVPC, !Ref 'VPC', !Ref 'VPCIdProp' ]
      InternetGatewayId: !If [CreateInternetGateway, !Ref 'InternetGateway', !Ref 'InternetGatewayIdProp' ]
  PublicRouteTable:
    Condition: CreateNetworkStack
    Type: AWS::EC2::RouteTable
    Properties:
      VpcId: !If [CreateVPC, !Ref 'VPC', !Ref 'VPCIdProp' ]
  PublicRoute:
    Condition: CreateNetworkStack
    Type: AWS::EC2::Route
    DependsOn: GatewayAttachement
    Properties:
      RouteTableId: !Ref 'PublicRouteTable'
      DestinationCidrBlock: '0.0.0.0/0'
      GatewayId: !If [CreateInternetGateway, !Ref 'InternetGateway', !Ref 'InternetGatewayIdProp' ]
  PublicSubnetOneRouteTableAssociation:
    Condition: CreateNetworkStack
    Type: AWS::EC2::SubnetRouteTableAssociation
    Properties:
      SubnetId: !Ref PublicSubnetOne
      RouteTableId: !Ref PublicRouteTable
Outputs:
  VPCRef:
    Value: !If [CreateVPC, !Ref 'VPC', !Ref 'VPCIdProp' ]
  PublicSubnetOneRef:
    Value: !If [CreateNetworkStack, !Ref 'PublicSubnetOne', !Ref 'SubnetIdProp' ]
  PublicOneCIDR:
    Value: !FindInMap ['SubnetConfig', 'PublicOne', 'CIDR']