Two interesting and opposing takes on the single-process-per-container model of Docker deployment. The first contains some good general practices (especially concerning package updates), the second provides a more in-depth look at and mitigation of Docker's process management and exectution:
Much has changed since my first Dockerfile best practices post. I'll leave the original post up for posterity and this post will include what has change and what you should do now.
You just built a container which contains a minimal operating system, and which only runs your app. But the operating system inside the container is not configured correctly. A proper Unix system should run all kinds of important system services. You're not running them, you're only running your app.