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 - wikipedia
For simple ad-hoc farms of diverse infrastructure, Docker is a simple deployment platform.
YOUTUBE BF9YJSPQUcY Weave creates a virtual network that connects Docker containers deployed across multiple hosts and enables their automatic discovery - github
Docker uses resource isolation features of the Linux kernel such as cgroups and kernel namespaces to allow independent "containers" to run within a single Linux instance, avoiding the overhead of starting and maintaining virtual machines.
YOUTUBE AuvK4GVPuj0 A demo of docker experimental plugins with flocker, weave, swarm and compose all working together.