Docker is an open platform for developers and sysadmins to build, ship, and run distributed applications. Consisting of Docker Engine, a portable, lightweight runtime and packaging tool, and Docker Hub, a cloud service for sharing applications and automating workflows, Docker enables apps to be quickly assembled from components and eliminates the friction between development, QA, and production environments. As a result, IT can ship faster and run the same app, unchanged, on laptops, data center VMs, and any cloud.
The main features of Docker are:
Lightweight, portable
Build once, run anywhere
VM - without the overhead of a VM
Each virtualised application includes not only the application and the necessary binaries and libraries, but also an entire guest operating system
The Docker Engine container comprises just the application and its dependencies. It runs as an isolated process in userspace on the host operating system, sharing the kernel with other containers.
Containers are isolated
It can be automated and scripted
Pablo Lalloni on 10 Apr 13"The motivation for adding security to Apache Hadoop actually had little to do with traditional notions of security in defending against hackers since all large Hadoop clusters are behind corporate firewalls that only allow employees access. Instead, the motivation was simply that security would allow us to use Hadoop more effectively to pool resources between disjointed groups. Larger clusters are much cheaper to operate and require fewer copies of duplicated data."
