deploy-infra.sh:

1. The stack name is the name that CloudFormation will use to refer to the group of resources it will manage.

2. The main.yml file is the CloudFormation template that we will use to define our infrastructure.

3. make our helper script executable : chmod +x deploy-infra.sh

4. AWS Systems manager : https://docs.aws.amazon.com/systems-manager/latest/userguide/what-is-systems-manager.html

5. This is a special parameter type that allows our template to get the latest AMI without having to specify the exact version

We use the AWS SSM provided value that specifies the most up-to-date AMI.

#On line 7: This is a special parameter type that allows our template to get the latest AMI without having to specify the exact version.

!Sub : is a CloudFormation function that performs string interpolation. Here, we interpolate the stack name into the security group description.

Commands:

1. aws ec2 describe-instances