I know, I'm a little late to this party, but just in case anyone is still around... :) For me, mounting my local app files as a volume is useful during develop

I know, I'm a little late to this party, but just in case anyone is still around... :) For me, mounting my local app files as a volume is useful during development since it keeps the workflow fast. I don't have to rebuild the image every time I want to try the app out, I get to use the new code without delay. If I were deploying as a container, I presume my build process would check the app out of git and build the image based on that fresh checkout. I'm just using Docker as a convenient way of simulating my production environment (dev'ing on Ubuntu 15.04, but deploying to Debian 7), and still be able to iterate rapidly.