AWS Elastic Beanstalk Linux Docker Platform – Extensions Setup/Configuration

How do I setup/configure AWS Elastic Beanstalk’s Docker Platform to run extensions (.ebextensions)? I cannot find any examples of this. There are several examples of the app running WITHOUT Docker but not WITH. Where do I put my extension files? How do they get executed? I’ve tried several different methods…it just doesn’t seem feasible that beanstalk will reach into the docker image to pull out extension files to run and configure the OS. How does this work? Is this a Pre/Post deploy step I need to do to configure the OS?

Source: Docker Questions