Over the past year or so, Docker, the operating system (OS)-level container technology, has created quite an industry stir. Docker promises faster application delivery cycles and reduced production infrastructure costs — and major vendors like Amazon, Google, IBM, and even Microsoft are falling over themselves to get on board. This report clarifies for app developers the most significant things that are known about Docker and the critical questions that remain so they can plan their approach to investigating, adopting, and managing risks around Docker.