webapp-cloudformation

To launch the infrastructure for executing a web application using AWS CloudFormation, you'll need a CloudFormation template that automates the process of setting up a VPC, EC2 instances, a Load Balancer, and other resources. Below are the steps and an example CloudFormation template.

Steps to Launch Infrastructure Using CloudFormation:

1. Go to the AWS Management Console:

   • Navigate to the CloudFormation service in the AWS Management Console.

2. Create a New Stack:

   • Click on Create Stack and choose "With new resources (standard)".
   • You can either upload your template as a .yaml file or paste it directly into the editor.

3. Configure Stack Details:

   • Enter a Stack Name (e.g., WebAppInfrastructure).
   • Provide any parameters required by the template (e.g., instance type, key pair name).

4. Review and Create:

   • Review the stack configuration, ensure the permissions are appropriate, and click Create Stack.
   • Wait for CloudFormation to provision all the resources. You can monitor the process in the Events tab.

5. Access and Test Your Web Application:

   • Once the stack is created, access your web application using the Load Balancer's DNS or Elastic IP.
   • CloudFormation will automatically create and link all required resources like EC2, Security Groups, VPC, and Load Balancer.

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CloudFormation Template for a Simple Web Application

Here’s a basic CloudFormation template that launches a VPC, an EC2 instance in a public subnet, and an Application Load Balancer.

AWSTemplateFormatVersion: "2010-09-09"
Description: "CloudFormation Template to launch infrastructure for a web application."

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

Resources:
  MyVPC:
    Type: AWS::EC2::VPC
    Properties:
      CidrBlock: 10.0.0.0/16
      EnableDnsSupport: true
      EnableDnsHostnames: true
      Tags:
        - Key: Name
          Value: MyVPC

  MyInternetGateway:
    Type: AWS::EC2::InternetGateway

  AttachGateway:
    Type: AWS::EC2::VPCGatewayAttachment
    Properties:
      VpcId: !Ref MyVPC
      InternetGatewayId: !Ref MyInternetGateway

  PublicSubnet:
    Type: AWS::EC2::Subnet
    Properties:
      VpcId: !Ref MyVPC
      CidrBlock: 10.0.1.0/24
      MapPublicIpOnLaunch: true

  MyRouteTable:
    Type: AWS::EC2::RouteTable
    Properties:
      VpcId: !Ref MyVPC

  PublicRoute:
    Type: AWS::EC2::Route
    Properties:
      RouteTableId: !Ref MyRouteTable
      DestinationCidrBlock: 0.0.0.0/0
      GatewayId: !Ref MyInternetGateway

  AssociateRouteTable:
    Type: AWS::EC2::SubnetRouteTableAssociation
    Properties:
      SubnetId: !Ref PublicSubnet
      RouteTableId: !Ref MyRouteTable

  WebServerSecurityGroup:
    Type: AWS::EC2::SecurityGroup
    Properties:
      GroupDescription: "Allow HTTP and SSH traffic"
      VpcId: !Ref MyVPC
      SecurityGroupIngress:
        - IpProtocol: tcp
          FromPort: 22
          ToPort: 22
          CidrIp: 0.0.0.0/0
        - IpProtocol: tcp
          FromPort: 80
          ToPort: 80
          CidrIp: 0.0.0.0/0

  EC2Instance:
    Type: AWS::EC2::Instance
    Properties:
      InstanceType: !Ref InstanceType
      KeyName: !Ref KeyName
      SecurityGroupIds:
        - !Ref WebServerSecurityGroup
      SubnetId: !Ref PublicSubnet
      ImageId: ami-0ebfd941bbafe70c6  # Amazon Linux 2023 AMI
      UserData:
        Fn::Base64: |
          #!/bin/bash
          yum update -y
          yum install -y httpd
          systemctl start httpd
          systemctl enable httpd
          echo "Hello World from $(hostname -f)" > /var/www/html/index.html

  ApplicationLoadBalancer:
    Type: AWS::ElasticLoadBalancingV2::LoadBalancer
    Properties:
      Name: WebAppLoadBalancer
      Subnets:
        - !Ref PublicSubnet
      SecurityGroups:
        - !Ref WebServerSecurityGroup

  LoadBalancerListener:
    Type: AWS::ElasticLoadBalancingV2::Listener
    Properties:
      LoadBalancerArn: !Ref ApplicationLoadBalancer
      Protocol: HTTP
      Port: 80
      DefaultActions:
        - Type: forward
          TargetGroupArn: !Ref WebAppTargetGroup

  WebAppTargetGroup:
    Type: AWS::ElasticLoadBalancingV2::TargetGroup
    Properties:
      VpcId: !Ref MyVPC
      Port: 80
      Protocol: HTTP
      TargetType: instance
      HealthCheckProtocol: HTTP
      HealthCheckPath: /
      Matcher:
        HttpCode: 200

Explanation of Key Sections:

1. VPC and Networking:

   • VPC is created with a CIDR block of 10.0.0.0/16.
   • A Public Subnet with CIDR block 10.0.1.0/24 is provisioned.
   • Internet Gateway and Route Table are set up to allow internet traffic.

2. Security Groups:

   • The WebServerSecurityGroup opens port 22 (SSH) and port 80 (HTTP) to the internet.

3. EC2 Instance:

   • Amazon Linux 2023 AMI is used to launch an instance.
   • UserData is used to install and start Apache HTTP Server (httpd), making the instance a simple web server.

4. Application Load Balancer:

   • An Application Load Balancer (ALB) is created to distribute traffic across EC2 instances.
   • A Listener is set up for port 80 to forward traffic to the web server.

5. Auto Scaling Group (Optional):

   • You can add an Auto Scaling Group with rules to automatically scale EC2 instances based on traffic or resource usage.

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This template sets up a basic web application infrastructure on AWS. Let me know if you need further customization or additional services like databases or Auto Scaling.