Yogesh Upadhyay created a recipe-style description for deploying sharable instances of AEM using Docker.
The first mention I know of using Docker with AEM or Apache Sling was a presentation from Bertrand Delacrétaz at AdaptTo. He created a project to explore using Docker to deploy dynamic Apache Sling servers. See Continous Deployment with Apache Sling.
Once again, the definition of docker is:
Apache Docker is an open-source project that automates the deployment of applications inside software containers, by providing an additional layer of abstraction and automation of operating system–level virtualization on Linux.Docker uses resource isolation features of the Linux kernel such as groups and kernel namespaces to allow independent “containers” to run within a single Linux instance, avoiding the overhead of starting virtual machines [Wikipedia]
Even though he does not provide much information about the concept behind the process, he gives a very detailed, step-by-step, set of instructions to get AEM running in Docker. If there are ever any gaps in instructions from his blog, he is very good at replying to comments to his posts. Wemblog | How to Set Up Shareable Docker Image for Adobe CQ/AEM