CloudFormation multi-AZ stack

network.yaml

# This template creates a VPC and a pair public and private subnets spanning the first two AZs of your current region.
# Each instance in the public subnet can accessed the internet and be accessed from the internet
# thanks to a route table routing traffic through the Internet Gateway.
# Private subnets feature a NAT Gateway located in the public subnet of the same AZ, so they can receive traffic 
# from within the VPC.
VPC: 
    Type: AWS::EC2::VPC
    Properties:
        CidrBlock: !Ref VpcCIDR
        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