Good introductory read on scaling with Docker from Brandon Okert 

This is the first in a two part post about Scaling with Docker. In Part 1, we’ll focus on getting started with Docker from a scaling perspective. For the most part this will be an intro to Docker, so if you’re already experienced using mutli-container hosts, docker networks, volume containers, monitoring tools, and management scripts, feel free to skim this part. In Part 2, we’ll use the fundamentals from Part 1 to organize scalable multi-host systems, then show where to start to take that to very large scale applications.