Upgrading the software in an AMI without creating a new one

Question

Is there any way to unpack the AMI, upgrade the application in it and pack it back? This is for testing a temporary fix in the application. I don’t want to create an EC2 instance for the sake of modifying the application in the AMI.

Answer 1

When an EC2 instance is launched, AWS allows us to pass the user data as mentioned in the AWS Documentation here. This can be a script which gets executed when the EC2 instance starts. The script can be used to install or upgrade the application. This is the recommended approach for a temporary fix testing. If a lot of EC2s have to be created with the new application, instead of using the user data approach, it’s always better to create a new AMI with the new application.