Docker 101 Workshop
Gravitational CTO, Sasha Klizhentas, gives an introduction of Docker and goes through the basic concepts. You can also go through this workshop online at https://github.com/gravitational/workshop/blob/master/docker.md.
As I noted in a previous article, the build environment is a key area on which organizations should focus their container security efforts. Companies don’t usually think of the build environment when it comes to securing their containers. But it’s critical that they do.