a cloudformation template to create vpc and ec2 instance

ec2-sea.yaml

AWSTemplateFormatVersion: '2010-09-09'
Description: 'Create a VPC with public subnet and launch an EC2 instance'

Parameters:
  InstanceType:
    Description: EC2 instance type
    Type: String
    Default: t2.micro
    AllowedValues:
      - t2.micro
      - t2.small
      - t2.medium
    ConstraintDescription: Must be a valid EC2 instance type

  KeyName:
    Description: Name of an existing EC2 KeyPair to enable SSH access
    Type: AWS::EC2::KeyPair::KeyName
    ConstraintDescription: Must be the name of an existing EC2 KeyPair

  SSHLocation:
    Description: IP address range that can SSH to the EC2 instances
    Type: String
    MinLength: 9
    MaxLength: 18
    Default: 0.0.0.0/0
    AllowedPattern: (\d{1,3})\.(\d{1,3})\.(\d{1,3})\.(\d{1,3})/(\d{1,2})
    ConstraintDescription: Must be a valid IP CIDR range of the form x.x.x.x/x

Mappings:
  AWSInstanceType2Arch:
    t2.micro:
      Arch: HVM64
    t2.small:
      Arch: HVM64
    t2.medium:
      Arch: HVM64

  AWSRegionArch2AMI:
    ap-southeast-1:
      HVM64: ami-05fd46f12b86c4a6c

Resources:
  # VPC
  MyVPC:
    Type: AWS::EC2::VPC
    Properties:
      CidrBlock: 10.10.0.0/16
      EnableDnsHostnames: true
      EnableDnsSupport: true
      Tags:
        - Key: Name
          Value: MyVPC

  # Internet Gateway
  MyInternetGateway:
    Type: AWS::EC2::InternetGateway
    Properties:
      Tags:
        - Key: Name
          Value: MyInternetGateway

  # Attach Internet Gateway to VPC
  AttachGateway:
    Type: AWS::EC2::VPCGatewayAttachment
    Properties:
      VpcId: !Ref MyVPC
      InternetGatewayId: !Ref MyInternetGateway

  # Public Subnet
  PublicSubnet:
    Type: AWS::EC2::Subnet
    Properties:
      VpcId: !Ref MyVPC
      CidrBlock: 10.10.1.0/24
      AvailabilityZone: !Select [0, !GetAZs '']
      MapPublicIpOnLaunch: true
      Tags:
        - Key: Name
          Value: Public Subnet

  # Route Table for Public Subnet
  PublicRouteTable:
    Type: AWS::EC2::RouteTable
    Properties:
      VpcId: !Ref MyVPC
      Tags:
        - Key: Name
          Value: Public Route Table

  # Route to Internet Gateway
  PublicRoute:
    Type: AWS::EC2::Route
    DependsOn: AttachGateway
    Properties:
      RouteTableId: !Ref PublicRouteTable
      DestinationCidrBlock: 0.0.0.0/0
      GatewayId: !Ref MyInternetGateway

  # Associate Route Table with Public Subnet
  PublicSubnetRouteTableAssociation:
    Type: AWS::EC2::SubnetRouteTableAssociation
    Properties:
      SubnetId: !Ref PublicSubnet
      RouteTableId: !Ref PublicRouteTable

  # Security Group
  InstanceSecurityGroup:
    Type: AWS::EC2::SecurityGroup
    Properties:
      GroupName: MyInstanceSecurityGroup
      GroupDescription: Enable SSH access via port 22
      VpcId: !Ref MyVPC
      SecurityGroupIngress:
        - IpProtocol: tcp
          FromPort: 22
          ToPort: 22
          CidrIp: !Ref SSHLocation
        - IpProtocol: tcp
          FromPort: 80
          ToPort: 80
          CidrIp: 0.0.0.0/0
      Tags:
        - Key: Name
          Value: MyInstanceSecurityGroup

  # EC2 Instance
  MyEC2Instance:
    Type: AWS::EC2::Instance
    Properties:
      ImageId: !FindInMap [AWSRegionArch2AMI, !Ref 'AWS::Region', !FindInMap [AWSInstanceType2Arch, !Ref InstanceType, Arch]]
      InstanceType: !Ref InstanceType
      KeyName: !Ref KeyName
      SubnetId: !Ref PublicSubnet
      SecurityGroupIds:
        - !Ref InstanceSecurityGroup
      UserData:
        Fn::Base64: !Sub |
          #!/bin/bash
          yum update -y
          yum install -y httpd
          systemctl start httpd
          systemctl enable httpd
          echo "<h1>Hello from CloudFormation!</h1>" > /var/www/html/index.html
      Tags:
        - Key: Name
          Value: MyEC2Instance

Outputs:
  VPCId:
    Description: VPC ID
    Value: !Ref MyVPC
    Export:
      Name: !Sub ${AWS::StackName}-VPC-ID

  PublicSubnetId:
    Description: Public Subnet ID
    Value: !Ref PublicSubnet
    Export:
      Name: !Sub ${AWS::StackName}-PublicSubnet-ID

  InstanceId:
    Description: EC2 Instance ID
    Value: !Ref MyEC2Instance

  InstancePublicIP:
    Description: Public IP address of the EC2 instance
    Value: !GetAtt MyEC2Instance.PublicIp

  WebsiteURL:
    Description: URL for the website
    Value: !Sub 'http://${MyEC2Instance.PublicIp}'