The Linux kernel has some features that make it possible to isolate a process from all (most) system resources, without actually running it inside a VM. Docker

The Linux kernel has some features that make it possible to isolate a process from all (most) system resources, without actually running it inside a VM. Docker is a tool that makes it easy to launch such isolated processes. You just specify what the filesystem environment should be for the new process, and what process to run in a small file and off it goes. In theory this could make provisioning easier, having each application come in a Docker container that satisfies its own system level dependencies, and does its service level dependencies over connections to other containers/external hosts.