CoreOS Cites Progress on Docker Alternative 

CoreOS Inc., the hyperscale Linux operating system upstart, announced a pair of incremental steps in the development of its software container alternative dubbed Rocket. It also highlighted progress on running CoreOS components on the vSphere 5.5 hypervisor.

Since launching its alternative to Docker containers in December, San Francisco-based CoreOS said it has added new features to Rocket version 0.2.0 such as default cryptographic signing and upgrades designed, for instance, to check the status of a container and the application within.

The automatic signature validation feature allows Rocket users to verify a signature by default when retrieving an image, CoreOS engineer Jonathan Boulle explained in a blog post. He said the signature verification feature is backed by a system for storing public keys. CoreOS calls the new feature an "important step towards our goal of Rocket being as secure as possible by default."

The feature also could help CoreOS differentiate Rocket from the much larger ecosystem growing up around Docker containers. CoreOS executives argue that the breadth of that ecosystem makes Docker more of a "platform" than a simple application delivery mechanism.

Along with the Rocket release, CoreOS also signed off on an App Container spec, including a Jetpack implementation of the spec for FreeBSD (Berkeley Software Distribution), designed to power servers and embedded platforms. Boulle called Jetpack "a great test of the cross platform portability" of the App Container spec.

The App Container defines the image format along with the image discovery mechanism and the execution environment using different implementations. CoreOS said last week the application container image for Rocket was "pretty complete."

Meanwhile, VMware announced support for CoreOS container components on vSphere 5.5 as part of an effort to streamline application delivery via containers in virtualized infrastructure. VMware said the technical previews of CoreOS on vSphere 5.5 stemmed from recent collaboration between VMware and CoreOS aimed at running the new OS on the vSphere platform. The collaboration includes integrating VMware's open-vm tools.

VMware also said it expects to continue working with CoreOS to further integrate the OS with vSphere as well as vCloud Air environments.

While working with CoreOS on distributed application delivery, VMware also continues to integrate Docker Machine (which provides a single interface to provision the Docker Engine) along with big data extensions for Mesos and Kubernetes into its cloud applications platform.

Docker APIs also are open, so not only does it have hooks for Kubernetes management tools, but will also support the Mesos cluster and application management tool from Mesosphere. That would eventually allow for VMware’s virtualization management tools to orchestrate Docker containers.

CoreOS was an early supporter of Docker when it launched in 2013. In December 2014, CoreOS CEO Alexi Polvi announced the formation of the Rocket project along with its App Container runtime and software image definition. Polvi argued that Rocket adheres more closely to the original Docker vision of a simple, reusable application container.

Since it's introduction in 2013, Polvi asserted, "The standard container manifesto [has been] removed. We should stop talking about a Docker containers and start talking about a Docker Platform."

"It is not becoming the simple composable build block we had envisioned," Polvi concluded.

Hence, the momentum grows to flesh out the details of what CoreOS hopes will be a "simple composable building block" for application containers.