Monday, April 6, 2015

6 operating systems designed just for Docker and other container runtimes

If you’re familiar with Unix-like free software operating systems, I’m sure you’ve probably lost count of the number of Linux distributions in active developments. I know, it’s a very long list, and growing.
But get ready for the same trend on the container technology side, because the conditions that made it possible to have hundreds of Linux distributions – freely available source code, hordes of developers with time to spare and an itch to scratch – are also in play in the field of containerization.
So far, I’ve been able to identify just six of such container-native operating systems, as they are called, but trust me, there will be many more to come.
So here are six container-native operating systems that I’m aware of. If you know of any not in the list, please post a comment.
1. Boot2Docker: “Is a lightweight Linux distribution made specifically to run Docker containers”. Weighing in at just 24 MB, it’s truly lightweight and runs completely from RAM, with a boot time in the 5-second range. The current development version features:
  • Linux kernel 3.18.5 with AUFS
  • Docker v1.5.0 – using libcontainer
  • Container persistence via disk automount on /var/lib/docker
  • SSH keys persistence via disk automount
Boot2Docker has not been certified for use in production, but I don’t think that has stopped some intrepid devops from doing just that. More information is available at the project’s GitHub page here.
2. CoreOS: Is a production-ready Linux distribution “that has been rearchitected to provide features needed to run modern infrastructure stacks.” That’s another way of saying that it’s been designed just for running containers. CoreOS is supported by a company of the same name, with commercial support provided by the company. More information about CoreOS is available at
3. OSv: The official description of OSv says that it:
reduces the memory and cpu overhead imposed by a traditional OS. Scheduling is lightweight, the application and the kernel cooperate, and memory pools are shared. OSv provides unparalleled short latencies and constant predictable performance, which translates directly to capex savings by reducing the size and number of OS instances.
OSv is still in private beta, but you may sign up to gain access. Details at
4. Project Atomic: Is a Red Hat-sponsored project and, like others in this list, aims to provide a container-native operating system. It is specifically designed for deploying and managing Docker containers. Downloads are available for CentOS Atomic Host, Fedora Atomic Host, and Red Hat Atomic Host. Links to those downloads and detailed project information and documentation are available at
Project Atomic
5. RancherOS: From the official description:
In RancherOS, the Docker daemon runs as PID 1, the first process the kernel starts. We call this instance of Docker “System Docker,” as it is responsible for initiating system services, such as udev, DHCP and the console. System Docker takes the place of the init system, such as sysvinit or systemd, in other Linux distributions. System Docker manages all of the system services as Docker containers.
RancherOS Docker containers
6. Ubuntu Core: Is a rendition of Ubuntu described as:
a minimal server image with the same libraries as today’s Ubuntu, but applications are provided through a simpler mechanism. The snappy approach is faster, more reliable, and lets us provide stronger security guarantees for apps and users – that’s why we call them “snappy” applications.
Snappy apps and Ubuntu Core itself can be upgraded atomically and rolled back if needed – a bulletproof approach to systems management that is perfect for container deployments. It’s called “transactional” or “image-based” systems management
Ubuntu Core containers
So there you have it folks – six container-native operating systems you can download and install on your machine or run on your Cloud computing provider’s platform.

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