Cloud Formation Yaml to Create Simple Infraestructure

poc.yaml

Description: 
   Goal
   -> create a VPC with
      -> 1 public subnet
      -> 1 private subnet
   -> create an Internet Gateway
   -> create a Nat Gateway
   -> create public instance as bastion
   -> create private instance 

Parameters:
   VpcCidr:
      Type: String
      Default: 10.0.0.0/16
   
   PublicSubnetACidr:
      Type: String
      Default: 10.0.1.0/24
   
   PrivateSubnetACidr:
      Type: String
      Default: 10.0.2.0/24

   BastionKeyPairName:
      Type: AWS::EC2::KeyPair::KeyName
      Default: poc-cf-keypair

Resources:
   VPC:
      Type: AWS::EC2::VPC
      Properties:
         CidrBlock: !Ref VpcCidr
         EnableDnsSupport: true
         EnableDnsHostnames: true
         Tags:
            -  Key: Name
               Value: poc-cf-vpc

   PublicSubnetA:
      Type: AWS::EC2::Subnet
      Properties:
         VpcId: !Ref VPC
         AvailabilityZone: us-west-1a
         CidrBlock: !Ref PublicSubnetACidr
         MapPublicIpOnLaunch: True
         Tags:
            -  Key: Name
               Value: poc-cf-public-subnet-a
   
   PrivateSubnetA:
      Type: AWS::EC2::Subnet
      Properties:
         VpcId: !Ref VPC
         AvailabilityZone: us-west-1b
         CidrBlock: !Ref PrivateSubnetACidr
         Tags:
            -  Key: Name
               Value: poc-cf-private-subnet-a
   
   # Connecting VPC to internet
   
   InternetGateway:
      Type: AWS::EC2::InternetGateway
      Properties:
         Tags:
            -  Key: Name
               Value: ig-vpc
   
   InternetGatewayAttachement:
      Type: AWS::EC2::VPCGatewayAttachment
      Properties:
         InternetGatewayId: !Ref InternetGateway
         VpcId: !Ref VPC
   
   # Creating VPC route table with an entry to route Internet traffic to the Internet Gateway

   PublicRouteTable:
      Type: AWS::EC2::RouteTable
      Properties:
         VpcId: !Ref VPC
         Tags:
            -  Key: Name
               Value: Public routes

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


   # Creating public subnet A route table association

   PublicSubnetARouteTableAssociation:
      Type: AWS::EC2::SubnetRouteTableAssociation
      Properties:
         RouteTableId: !Ref PublicRouteTable
         SubnetId: !Ref PublicSubnetA

   # Now we neer Nat Gateway Associations to our private subnet
   
   NatGatewayAIP:
      Type: AWS::EC2::EIP
      DependsOn: InternetGatewayAttachement
      Properties:
         Domain: vpc

   NatGatewayA:
      Type: AWS::EC2::NatGateway
      Properties:
         AllocationId: !GetAtt NatGatewayAIP.AllocationId
         SubnetId: !Ref PublicSubnetA
   

   # Creating a private subnet A route table association, to this we need a Nat Gateway
   
   PrivateRouteTableA:
      Type: AWS::EC2::RouteTable
      Properties:
         VpcId: !Ref VPC
         Tags:
            -  Key: Name
               Value: Private routes

   DefaultPrivateRoute:
      Type: AWS::EC2::Route
      Properties:
         RouteTableId: !Ref PrivateRouteTableA
         DestinationCidrBlock: 0.0.0.0/0
         NatGatewayId: !Ref NatGatewayA

   PrivateSubnetARouteTableAssociation:
      Type: AWS::EC2::SubnetRouteTableAssociation
      Properties:
         RouteTableId: !Ref PrivateRouteTableA
         SubnetId: !Ref PrivateSubnetA

   # Creating a EC2 instance and SG as Bastion in public subnet

   BastionSG:
      Type: AWS::EC2::SecurityGroup
      Properties:
         VpcId: !Ref VPC
         GroupDescription: we use this instance as ssh bastion
         SecurityGroupIngress:
            -  IpProtocol: tcp
               FromPort: 22
               ToPort: 22
               CidrIp: 0.0.0.0/0
         Tags:
            -  Key: Name
               Value: poc-cf-bastion-sg

   BastionInstance:
      Type: AWS::EC2::Instance
      Properties:
         ImageId: ami-0d382e80be7ffdae5
         InstanceType: t2.micro
         KeyName: !Ref BastionKeyPairName
         SubnetId: !Ref PublicSubnetA
         SecurityGroupIds:
            -  !Ref BastionSG
         Tags:
            -  Key: Name
               Value: poc-cf-bastion-instance

# Note: At this point i had to create a New Key Pair on AWS Console! named poc-cf-keypair

   # Creating a EC2 instance and DG as Private

   PrivateSG:
      Type: AWS::EC2::SecurityGroup
      Properties:
         VpcId: !Ref VPC
         GroupDescription: this is our private instance 
         SecurityGroupIngress:
            -  IpProtocol: tcp
               FromPort: 22
               ToPort: 22
               SourceSecurityGroupId: !Ref BastionSG
         Tags:
            -  Key: Name
               Value: poc-cf-private-dg
   
   PrivateInstance:
      Type: AWS::EC2::Instance
      Properties:
         ImageId: ami-0d382e80be7ffdae5
         InstanceType: t2.micro
         KeyName: !Ref BastionKeyPairName
         SubnetId: !Ref PrivateSubnetA
         SecurityGroupIds:
            -  !Ref PrivateSG
         Tags:
            -  Key: Name
               Value: poc-cf-private-instance

Thanks!, I just updated the NatGateway parameter to receive Bastion NatGateway Id! and it's working 😄