RancherOS (Documentation, Github, Vagrantfile) is an OS made of containers. In RancherOS, the Docker daemon runs as first process the kernel starts when it boots. We call this instance of Docker "System Docker," as it is responsible for initiating system services, such as udev, DHCP and the console. Each of these system services run as containers. System Docker takes the place of the init system, such as sysvinit or systemd, in other Linux distributions.
How to install and setup Debian 8 minimalist Docker Host
phusion/baseimage-docker is a minimal Ubuntu base image modified for Docker-friendliness