The open-source CoreOS operating system project issued its first beta release today, providing users with a Linux operating system that is built specifically for Docker container delivery.
Docker is an open-source container technology for application virtualization and currently runs on multiple Linux distributions, including Red Hat and Ubuntu. What CoreOS is aiming to provide is a purpose-built Linux operating system, optimized for Docker containers. CoreOS is backed by venture capitalist firms Andreessen Horowitz and Sequoia Capital. Alex Polvi, CEO of CoreOS, told eWEEK that so far he has raised a seed round of financing in an amount that has not yet been publicly disclosed. CoreOS has been in alpha since August 2013.
CoreOS has a number of differentiated features that make it ideal for high availability container use, Polvi claimed. A Docker container is a form of virtualization that relies on the underlying host operating system. In contrast, a traditional virtualization hypervisor requires an operating system for each virtual machine.
"We're a very slimmed-down, lightweight operating system with Docker containers," Polvi said. "CoreOS has features for built-in clustering that allow organizations to build out fault-tolerant distributed server environments."
The way that CoreOS provides high availability is by including two root file systems as part of a default installation. When a system update is required, the update is first applied to the root file system that is not currently running, Polvi explained. It's a system that he refers to as a "double-buffer" approach.
"With the double-buffer approach, we can download a system update and apply it without making any modification to the running system," Polvi said. "You do need to reboot to get the new version, but the old root file system is still there in case anything goes wrong with the update."
CoreOS has been designed to be clustered and, as such, rebooting of the file system is also not an issue for availability. In a clustered deployment, multiple nodes of the same host operating system are run simultaneously. One of the host nodes can be taken down to reboot, while the running applications continue to operate on another node in the cluster.
"We're taking the approach that you would find at big server deployments like Google, where they let software manage where applications run," Polvi said. "That's the approach we're taking with CoreOS."
CoreOS uses the latest stable Linux kernel: release 3.14.1. Greg Kroah-Hartman, who is the stable Linux kernel maintainer for the Linux Foundation, is part of the CoreOS community, according to Polvi.
A Linux kernel is only part of a full Linux distribution, which is why CoreOS also leverages tools from the Google Chrome OS community. Chrome OS is the Linux operating system that powers Google Chromebook notebook computers.
"The actual tools that we use originated with the Google Chrome OS project," Polvi said. "We're not a derivative of Chrome OS; we're using the same tools to build our operating system."
The idea of having a stripped-down Linux operating system for Docker is one that Red Hat is also pursuing with the Project Atomic effort that was launched on April 15. One of Red Hat's key promises with Project Atomic is that since it runs on Red Hat Enterprise Linux, users can rely on vendors' certifications that are already in place.
"Our customers are buying commodity hardware, and everything they are running is supported in the upstream Linux kernel," Polvi said. "For application certification and support, that's something we're working on. We're still just an early-stage startup."
In terms of general availability and a stable release, Polvi said that it's coming in the near term. The CoreOS development cycle is loosely tracking the Docker development cycle, and Polvi expects to have a stable release at the same point this year that Docker 1.0 is released later this year.
Sean Michael Kerner is a senior editor at eWEEK and InternetNews.com. Follow him on Twitter @TechJournalist.