How can the application be deployed on new EC2 instances?

Explanations:

Launching a script that downloads and installs the application using Amazon EC2 user data is an effective method for automatically deploying the application on new EC2 instances at launch time. User data scripts can run commands, download files, and install software, allowing for a streamlined setup process during instance initialization.

Creating a custom API using Amazon API Gateway to call an installation executable from an AWS CloudFormation Template is not a direct approach to automatically deploy the application on new EC2 instances. This method adds unnecessary complexity and does not leverage EC2 user data for automation during instance launch.

Using AWS Systems Manager to inject the application into an AMI could be an option, but it requires additional steps to create and manage the AMI. The solution does not directly apply to newly launched EC2 instances without pre-creating an AMI with the application installed, making it less efficient for frequent updates.

Configuring AWS CodePipeline to deploy code changes and updates is suited for continuous deployment and updating applications but does not address the need for automatic installation during the initial launch of EC2 instances. This method is more focused on application updates rather than initial deployment on new instances.