I forgot to mention, the Phusion guys (who Mitchell mentions in the post and who create the excellent Passenger web server) have created some great assets for Vagrant and Docker:
And regarding role-based containers, Phusion's Hong Lai says:
"Wait, I thought Docker is about running a single process in a container?
Absolutely not true. Docker runs fine with multiple processes in a container. In fact, there is no technical reason why you should limit yourself to one process - it only makes things harder for you and breaks all kinds of essential system functionality, e.g. syslog.
Baseimage-docker encourages multiple processes through the use of runit."
> Docker runs fine with multiple processes in a container.
I think that, while most people realize this, it's important to highlight this fact again. Generally, the examples you see are "look, we can run this would-be-backgrounded-elsewhere daemon in the foreground in its own container!", when IMO this sets the bar a bit low for how people initially approach Docker. Containers have simplified my life significantly, and (again, IMO) their real power becomes evident when you treat them as logical units vs individual components.
https://github.com/phusion/baseimage-docker
https://github.com/phusion/passenger-docker (built on the baseimage above)
http://blog.phusion.nl/2013/11/08/docker-friendly-vagrant-bo...
And regarding role-based containers, Phusion's Hong Lai says:
"Wait, I thought Docker is about running a single process in a container?
Absolutely not true. Docker runs fine with multiple processes in a container. In fact, there is no technical reason why you should limit yourself to one process - it only makes things harder for you and breaks all kinds of essential system functionality, e.g. syslog.
Baseimage-docker encourages multiple processes through the use of runit."