CoreOS has announced that its rkt (pronounced: rocket) container technology will be integrated with Google’s Kubernetes container management framework. The integration of CoreOS rocket technology with Kubernetes means that the Kubernetes framework need not leverage Docker containers, but can instead rely solely on CoreOS Linux container technology. CoreOS’s rkt technology consists of container runtime software that implements appc, the App container specification designed to provide a standard for containers based around requirements related to composability, security, image distribution and openness. CoreOS launched rocket on the premise that Docker containers had strayed from its original manifesto of developing “a simple component, a composable unit, that could be used in a variety of systems” as noted by CoreOS CEO Alex Polvi in a December 2014 blog post:
Unfortunately, a simple re-usable component is not how things are playing out. Docker now is building tools for launching cloud servers, systems for clustering, and a wide range of functions: building images, running images, uploading, downloading, and eventually even overlay networking, all compiled into one monolithic binary running primarily as root on your server. The standard container manifesto was removed. We should stop talking about Docker containers, and start talking about the Docker Platform. It is not becoming the simple composable building block we had envisioned.
Here, Polvi notes how Docker has transitioned from an initiative focused around creating reusable components to a platform whose mission has deviated from its original manifesto. Today’s announcement of the integration of CoreOS with Kubernetes represents a deepening of the relationship between CoreOS and Google that recently included a $12M funding round led by Google Ventures. While CoreOS previously supported Kubernetes, today’s announcement of its integration into Google’s container management framework represents a clear sign that the battle for container supremacy is now likely to begin in earnest, particularly given that CoreOS brands itself as enabling other technology companies to build Google-like infrastructures. With Google’s wind behind its sails, and executives from Google, Red Hat and Twitter having joined the App container specification community management team, Docker now confronts a real challenger to its supremacy within the container space. Moreover, Google, VMware, Red Hat and Apcera have all pledged support for appc in ways that suggest an alternative standard that defines “how applications can be packaged, distributed, and executed in a portable and self-contained way” may well be emerging.