title: Updating docker image with new code
body: <p>I am having trouble understanding this part of docker. I have spent many days doing research over this and came across stuff like <code>docker-compose</code> and <code>docker container commit</code>. If I have an image and I make changes to my codebase, how would I update my docker image with the code changes? I thought the Dockerfile was supposed to take care of this, but it does not work for me. Any help is appreciated.</p>