WebApp-Network.yml

Description:
    This a cloud formation template for deploying two public subnets
    and two private subnets, along with the NAT gateway and Internet Gateway.
    These subnets are complimented by their routing tables, in this template.
Parameters:

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

    VpcCIDR: 
        Description: Please enter the IP range (CIDR notation) for this VPC
        Type: String
        Default: 10.0.0.0/16

    PublicSubnet1CIDR:
        Description: Please enter the IP range (CIDR notation) for the public subnet in the first Availability Zone
        Type: String
        Default: 10.0.0.0/24

    PublicSubnet2CIDR:
        Description: Please enter the IP range (CIDR notation) for the public subnet in the second Availability Zone
        Type: String
        Default: 10.0.1.0/24

    PrivateSubnet1CIDR:
        Description: Please enter the IP range (CIDR notation) for the private subnet in the first Availability Zone
        Type: String
        Default: 10.0.2.0/24

    PrivateSubnet2CIDR:
        Description: Please enter the IP range (CIDR notation) for the private subnet in the second Availability Zone
        Type: String
        Default: 10.0.3.0/24

Resources:

    VPC: 
        Type: AWS::EC2::VPC
        Properties:
            CidrBlock: !Ref VpcCIDR
            EnableDnsHostnames: true
            Tags: 
                - Key: Name 
                  Value: !Ref EnvironmentName
            
    InternetGateway:
        Type: AWS::EC2::InternetGateway
        Properties:
            Tags:
                - Key: Name
                  Value: !Ref EnvironmentName
            
    InternetGatewayAttachment:
        Type: AWS::EC2::VPCGatewayAttachment
        Properties:
            InternetGatewayId: !Ref InternetGateway
            VpcId: !Ref VPC

    PublicSubnet1: 
        Type: AWS::EC2::Subnet
        Properties:
            VpcId: !Ref VPC
            AvailabilityZone: !Select [ 0, !GetAZs '' ]
            CidrBlock: !Ref PublicSubnet1CIDR
            MapPublicIpOnLaunch: true
            Tags: 
                - Key: Name 
                  Value: !Sub ${EnvironmentName} Public Subnet (AZ1)

    PublicSubnet2: 
        Type: AWS::EC2::Subnet
        Properties:
            VpcId: !Ref VPC
            AvailabilityZone: !Select [ 1, !GetAZs '' ]
            CidrBlock: !Ref PublicSubnet2CIDR
            MapPublicIpOnLaunch: true
            Tags: 
                - Key: Name 
                  Value: !Sub ${EnvironmentName} Public Subnet (AZ2)

    PrivateSubnet1: 
        Type: AWS::EC2::Subnet
        Properties:
            VpcId: !Ref VPC
            AvailabilityZone: !Select [ 0, !GetAZs '' ]
            CidrBlock: !Ref PrivateSubnet1CIDR
            MapPublicIpOnLaunch: false
            Tags: 
                - Key: Name 
                  Value: !Sub ${EnvironmentName} Private Subnet (AZ1)

    PrivateSubnet2: 
        Type: AWS::EC2::Subnet
        Properties:
            VpcId: !Ref VPC
            AvailabilityZone: !Select [ 1, !GetAZs '' ]
            CidrBlock: !Ref PrivateSubnet2CIDR
            MapPublicIpOnLaunch: false
            Tags: 
                - Key: Name 
                  Value: !Sub ${EnvironmentName} Private Subnet (AZ2)

    NatGateway1EIP:
        Type: AWS::EC2::EIP
        DependsOn: InternetGatewayAttachment
        Properties: 
            Domain: vpc

    NatGateway2EIP:
        Type: AWS::EC2::EIP
        DependsOn: InternetGatewayAttachment
        Properties:
            Domain: vpc

    NatGateway1: 
        Type: AWS::EC2::NatGateway
        Properties: 
            AllocationId: !GetAtt NatGateway1EIP.AllocationId
            SubnetId: !Ref PublicSubnet1

    NatGateway2: 
        Type: AWS::EC2::NatGateway
        Properties:
            AllocationId: !GetAtt NatGateway2EIP.AllocationId
            SubnetId: !Ref PublicSubnet2

    PublicRouteTable:
        Type: AWS::EC2::RouteTable
        Properties: 
            VpcId: !Ref VPC
            Tags: 
                - Key: Name 
                  Value: !Sub ${EnvironmentName} Public Routes

    DefaultPublicRoute: 
        Type: AWS::EC2::Route
        DependsOn: InternetGatewayAttachment
        Properties: 
            RouteTableId: !Ref PublicRouteTable
            DestinationCidrBlock: 0.0.0.0/0
            GatewayId: !Ref InternetGateway

    PublicSubnet1RouteTableAssociation:
        Type: AWS::EC2::SubnetRouteTableAssociation
        Properties:
            RouteTableId: !Ref PublicRouteTable
            SubnetId: !Ref PublicSubnet1

    PublicSubnet2RouteTableAssociation:
        Type: AWS::EC2::SubnetRouteTableAssociation
        Properties:
            RouteTableId: !Ref PublicRouteTable
            SubnetId: !Ref PublicSubnet2
    

    PrivateRouteTable1:
        Type: AWS::EC2::RouteTable
        Properties: 
            VpcId: !Ref VPC
            Tags: 
                - Key: Name 
                  Value: !Sub ${EnvironmentName} Private Routes (AZ1)

    DefaultPrivateRoute1:
        Type: AWS::EC2::Route
        Properties:
            RouteTableId: !Ref PrivateRouteTable1
            DestinationCidrBlock: 0.0.0.0/0
            NatGatewayId: !Ref NatGateway1

    PrivateSubnet1RouteTableAssociation:
        Type: AWS::EC2::SubnetRouteTableAssociation
        Properties:
            RouteTableId: !Ref PrivateRouteTable1
            SubnetId: !Ref PrivateSubnet1

    PrivateRouteTable2:
        Type: AWS::EC2::RouteTable
        Properties: 
            VpcId: !Ref VPC
            Tags: 
                - Key: Name 
                  Value: !Sub ${EnvironmentName} Private Routes (AZ2)

    DefaultPrivateRoute2:
        Type: AWS::EC2::Route
        Properties:
            RouteTableId: !Ref PrivateRouteTable2
            DestinationCidrBlock: 0.0.0.0/0
            NatGatewayId: !Ref NatGateway2

    PrivateSubnet2RouteTableAssociation:
        Type: AWS::EC2::SubnetRouteTableAssociation
        Properties:
            RouteTableId: !Ref PrivateRouteTable2
            SubnetId: !Ref PrivateSubnet2

Outputs: 

    VPC: 
        Description: A reference to the created VPC
        Value: !Ref VPC
        Export:
          Name: !Sub ${EnvironmentName}-VPCID

    VPCPublicRouteTable:
        Description: Public Routing
        Value: !Ref PublicRouteTable
        Export:
          Name: !Sub ${EnvironmentName}-PUB-RT

    VPCPrivateRouteTable1:
        Description: Private Routing AZ1
        Value: !Ref PrivateRouteTable1
        Export:
          Name: !Sub ${EnvironmentName}-PRI1-RT

    VPCPrivateRouteTable2:
        Description: Private Routing AZ2
        Value: !Ref PrivateRouteTable2
        Export:
          Name: !Sub ${EnvironmentName}-PRI2-RT

    PublicSubnets:
        Description: A list of the public subnets
        Value: !Join [ ",", [ !Ref PublicSubnet1, !Ref PublicSubnet2 ]]
        Export:
          Name: !Sub ${EnvironmentName}-PUB-NETS

    PrivateSubnets:
        Description: A list of the private subnets
        Value: !Join [ ",", [ !Ref PrivateSubnet1, !Ref PrivateSubnet2 ]]
        Export:
          Name: !Sub ${EnvironmentName}-PRIV-NETS

    PublicSubnet1:
        Description: A reference to the public subnet in the 1st Availability Zone
        Value: !Ref PublicSubnet1
        Export:
          Name: !Sub ${EnvironmentName}-PUB1-SN

    PublicSubnet2: 
        Description: A reference to the public subnet in the 2nd Availability Zone
        Value: !Ref PublicSubnet2
        Export:
          Name: !Sub ${EnvironmentName}-PUB2-SN

    PrivateSubnet1:
        Description: A reference to the private subnet in the 1st Availability Zone
        Value: !Ref PrivateSubnet1
        Export:
          Name: !Sub ${EnvironmentName}-PRI1-SN

    PrivateSubnet2: 
        Description: A reference to the private subnet in the 2nd Availability Zone
        Value: !Ref PrivateSubnet2
        Export:
          Name: !Sub ${EnvironmentName}-PRI2-SN