How can I use the AWS launch template to achieve the goal of deploying a fleet of EC2 instances for a web-based application?

In the context of AWS, you can achieve consistent Configuration and easy scalability by using the AWS launch template to deploy EC2 Instance for a particular web-based application by using the several steps which are given below:-

Creating a launch template

You can use the AWS management console to create a launch template. You can specify parameters such as AMI ID, instance type, key pair, security group, etc.

Aws ec2 create-launch-template –launch-template-name my-launch-template

--version-description “Initial version”

--launch-template-data file://launch_template.json

 In the launch _ template.json file you can define the Configuration:-

{
  “ImageId”: “ami-xxxxxxxx”,
  “InstanceType”: “t2.micro”,
  “KeyName”: “my-key-pair”,
  “SecurityGroupIds”: [“sg-xxxxxxxx”],
  “IamInstanceProfile”: {
    “Arn”: “arn:aws:iam::123456789012:instance-profile/my-iam-role”
  },
  “UserData”: “base64-encoded-user-data-script”
}

Include auto scaling Configuration

If you have a concern about scalability then you can try to integrate auto-scaling Configuration into your launch template. You can specify the parameters such as minimum and maximum instance count, desired capacity, etc.

{
  “ImageId”: “ami-xxxxxxxx”,
  “InstanceType”: “t2.micro”,
  “KeyName”: “my-key-pair”,
  “SecurityGroupIds”: [“sg-xxxxxxxx”],
  “IamInstanceProfile”: {
    “Arn”: “arn:aws:iam::123456789012:instance-profile/my-iam-role”
  },  “UserData”: “base64-encoded-user-data-script”,
  “InstanceMarketOptions”: {
    “MarketType”: “spot”
  },
  “TagSpecifications”: [
    {
      “ResourceType”: “instance”,
      “Tags”: [
        {
          “Key”: “Name”,
          “Value”: “MyInstance”
        }
      ]
    }
  ]
}

Utilize parameterized values

You can make use of parameterized values with your launch template to make the Configuration dynamic and reusable across different environments.

{
  “ImageId”: “${imageId}”,
  “InstanceType”: “${instanceType}”,
  “KeyName”: “${keyName}”,
  “SecurityGroupIds”: [“${securityGroupId}”],
  “IamInstanceProfile”: {
    “Arn”: “${iamInstanceProfileArn}”
  },
  “UserData”: “base64-encoded-user-data-script”
}
Optimization of performance
You can include Configuration in the launch template which can optimize the performance.
{
  “InstanceType”: “c5.large”,
  “BlockDeviceMappings”: [
    {
      “DeviceName”: “/dev/sda1”,
      “Ebs”: {
        “VolumeSize”: 50,
        “VolumeType”: “gp2”,
        “DeleteOnTermination”: true
      }
    }
  ],
  “NetworkInterfaces”: [
    {
      “AssociatePublicIpAddress”: true,
      “DeviceIndex”: 0,
      “Groups”: [“sg-xxxxxxxx”],
      “SubnetId”: “subnet-xxxxxxxx”
    } 

  ]}