CoreOS unveils Rocket, a possible competitor to Docker

CoreOS, the Linux operating system specialist that’s been busy this past year making sure its technology powers Docker containers, detailed on Monday a new container technology called Rocket that’s essentially a competitor to Docker.

Rocket is basically a container engine, like [company]Docker[/company], but without all the extras Docker’s been working on to make itself more enterprise friendly. These features include tools for spinning up cloud servers, the ability to have clustered systems and even networking capabilities, wrote [company]CoreOS[/company] CEO Alex Polvi in a blog post.

Because of the way Docker appears to be shifting from its original idea of creating a “standard container” to what now seems like a container-centric application-development hub for enterprises, CoreOS decided that it needed to step in and develop its own standardized version.

“We should stop talking about Docker containers, and start talking about the Docker Platform,” wrote Polvi. “It is not becoming the simple composable building block we had envisioned.”

CoreOS believes that its new container technology can be the industry standard when it comes to running containers in large production environments. CoreOS calls its containers “App Containers,” which are comprised of an app container image, runtime and container-discovery protocol. The App Container Image is similar to a Docker container image, which contains an application’s necessary elements like source code and binary files.

The Rocket runtime was developed with the App Container’s specifications in mind and its purpose is to essentially launch the containers “as a command line tool,” wrote Polvi.

Polvi claims that the way Docker works, especially as it pertains to the Docker daemon, which Docker describes as “the persistent process that manages containers,” is “fundamentally flawed” when it comes to security and composability and the new Rocker container model is built to address these concerns.

From the blog post:
[blockquote person=”CoreOS” attribution=”CoreOS”]At CoreOS we have large, serious users running in enterprise environments. We cannot in good faith continue to support Docker’s broken security model without addressing these issues. Additionally, in the past few weeks Docker has demonstrated that it is on a path to include many facilities beyond basic container management, turning it into a complex platform. Our primary users have existing platforms that they want to integrate containers with. We need to fill the gap for companies that just want a way to securely and portably run a container.

Indeed the last several Docker releases have been focussed on security, but to be fair, that’s to be expected from a relatively new project that’s aiming for large-scale enterprise use.

CoreOS is still planning on contributing to the Docker open-source project (CoreOS co-founder and CTO Brandon Philips sits on the Docker governance board), and that “CoreOS will evaluate contributing this work once App Container matures,” wrote Polvi.

Story Update
Docker’s Ben Golub wrote up a blog post in response to the Rocket news and had this to say:
“While we disagree with some of the arguments and questionable rhetoric and timing of the Rocket announcement, we hope that we can all continue to be guided by what is best for users and developers.”