Containers are wonderful and Docker is a really awesome and lifesaving technology, even if you don't host sites and services with millions of users that need to auto-scale etc. Docker can already simplify a simple hosting setup just with a couple of small webpages and a Git server.
Some months ago I switched my whole setup to use only Docker. I used Ubuntu server because that was the best option at my hosting provider. But recently I found RancherOS and that let me rethink...
RancherOS is basically a linux distribution just for Docker and based on Docker, everything is Docker. There's a System-Docker for all the system containers (all system services are containers too) and a User-Docker for all your own containers. You can update everything with just pulling a newer image.
Using a system optimized for Docker has many advantages. It now only makes managing updates etc. a lot easier (because there is less to update), but it also makes everything more secure. It's security by minimalism. Less running services, less system components, less things able to compromise. And also storage is used less. Instead of like 2 GB for a basic Ubuntu Server setup, RancherOS just uses like 1 GB. 1 GB less, which might be a good thing, if your storage is quite limited (my server for example has just 20 GB).
If that caught your curiosity, go ahead to the project's website.
PS: You don't need to install or use Rancher with RancherOS.