Docker is an open source Linux containerization technology which lets an admin run multiple apps with all their dependencies in secure sandboxes on the same underlying Linux OS. It makes an attractive alternative to typical virtualization. Hadoop community is working on patches that will bring Docker into the data management system. To know more, go through the article by Jack Clark, World's only Distributed Systems Reporter.

http://www.theregister.co.uk/2014/05/02/docker_hadoop/