CoreOS First Stable Release
CoreOS is a new, rearchitected, Linux distribution, providing container management, powered by Docker, service discovery with Etcd, a highly-available key value store, and process management with Fleet, a distributed init system for clusters.
Since the first alpha version was released in August 2013, 191 releases have been tagged. CoreOS 367.1.0 is the first version in the new stable channel, and includes:
- Linux 3.15.2
- Docker 1.0.1
- Cloudinit 0.8.9
- Fleet 0.5.0
- Etcd 0.4.4
- Locksmith 0.1.4
The stable release is not including Etcd and Fleet as stable, this release is only targeted at the base operating system and Docker 1.0. Etcd and Fleet stable support will be in subsequent releases.
CoreOS is designed to be updated automatically with different schedules per channel, and instructions are provided to switch from the alpha or beta channels to the new stable channel.
A feature of CoreOS is that it updates the entire operating system as a single unit, instead of package by package. Initially, the operating system is booted into the root A partition and CoreOS begins talking to the update service to find out about new updates. If there is an update available it is downloaded and installed to root B. To ensure the application is not disrupted, the disk and network I/O this process is allowed to use is rate limited with Linux cgroups.
Using this dual-root scheme is a change on the existing workflow of yum or apt-get, making a system update an atomic operation that can be rolled back. The root partition is not modified and the server is never in an unstable or partially upgraded state. The upgrade is finished by rebooting the machine, and it will start on root B partition with a freshly updated system.
Commercial support is provided via CoreOS Managed Linux, with patches delivered as a continuous stream of updates, and without the need for major migrations. With this offering customers have also access to their own installations of CoreUpdate, a hosted dashboard that allows full control over CoreOS updates. Custom channels, server groups, rate-limiting updates and more can be configured within CoreUpdate.
CoreOS provides support on all major cloud providers, including Rackspace Cloud, Amazon EC2 (including HVM), and Google Compute Engine. Bare metal, OpenStack and Vagrant are also officially supported, while other platforms such as VMware or Libvirt are supported by the community.