It's easy to build new images from Dockerfiles. And "cut-n-paste" based "inheritance" works well when combining two or more Dockerfiles into a single one that has everything you want.

But you can't use composition to combine the actual downloaded images themselves.

Using Chef within Docker to build up the services is documented on the Docker site[1], and of course puppet or whatever is essentially the same.

[1] http://docs.docker.com/articles/chef/