My first book was "SaltStack For DevOps" (https://leanpub.com/saltstackfordevops) and it had a success that I didn't expect. That's the main reason why I started my second book.
The second reason is that I saw many people confused by the rapidly growing containers' ecosystem. Docker development is going fast and will probably know many changes in the future. Since I am following these changes and since I am using leanpub for publishing, I had the idea to "continuously publish" this book and keep it up-to-date from a technical pov.
Painless Docker is a practical guide to master Docker and its ecosystem based on real world examples. It tends to be a complete and detailed guide to create, deploy, optimize,secure, trace, debug, log, orchestrate & monitor Docker and Docker clusters.
You can find Painless Docker on: http://painlessdocker.com/ or https://leanpub.com/painless-docker/
Your suggestions are very welcome.