Skip to main content

App Container spec gains new support as a community-led effort

Today is the inaugural CoreOS Fest, the community event for distributed systems and application containers. We at CoreOS are here to celebrate you – those who want to join us on a journey to secure the backend of the Internet and build distributed systems technologies to bring web scale architecture to any organization. We've come a long way since releasing our first namesake project, CoreOS Linux, in 2013, and as a company we now foster dozens of open source projects as we work together with the community to create the components necessary for this new paradigm in production infrastructure.

An important part of working with this community has been the development of the App Container spec (appc), which provides a definition on how to build and run containerized applications. Announced in December, the appc spec emphasizes application container security execution, portability and modularity. rkt, a container runtime developed by CoreOS, is the first implementation of appc.

As security and portability between stacks becomes central to the successful adoption of application containers, today appc has gained support from various companies in the community:

  • Google has furthered its support of appc by implementing rkt into Kubernetes and joining as a maintainer of appc
  • Apcera has announced an additional appc implementation called Kurma
  • Red Hat has assigned an engineer to participate as a maintainer of appc
  • VMware recently announced how they will contribute to appc and shipped rkt in Project Photon

In order to ensure the specification remains a community-led effort, the appc project has established a governance policy and elected several new community maintainers unaffiliated with CoreOS: initially, Vincent Batts of Red Hat, Tim Hockin of Google and Charles Aylward of Twitter. This new set of maintainers brings each of their own unique points of view and allows appc to be a true collaborative effort. Two of the initial developers of the spec from CoreOS, Brandon Philips and Jonathan Boulle, remain as maintainers, but now are proud to have the collective help of others to make the spec what it is intended to be: open, well-specified and developed by a community.

In the months after the launch of appc, we have seen the adoption and support behind a common application container specification grow quickly. These companies and individuals are coming together to ensure there is a well defined specification for application containers, providing guidelines to ensure security, openness and modularity between stacks.

Google furthers its support of appc by integrating rkt into Kubernetes

Today also marks support for appc arriving in the Kubernetes project, via the integration of rkt as a configurable container runtime for Kubernetes clusters.

"The first implementation of the appc specification into Kubernetes, through the support of CoreOS rkt, is an important milestone for the Kubernetes project," said Craig McLuckie, product manager and Kubernetes co-founder at Google. "Designed with cluster first management in mind, appc support enables developers to use their preferred container image through the same Google infrastructure inspired orchestration framework."

Kubernetes is an open source project introduced by Google to help organizations run their infrastructure in a similar manner to the internal infrastructure that runs Google Search, Gmail and other Google services. Today's announcement of rkt being integrated directly into Kubernetes means that users will have the ability to run ACIs, the image format defined in the App Container spec, and take advantage of rkt’s first-class support for pods. rkt’s native support for running Docker images means they can also continue to use their existing images.

Apcera’s new implementation of appc, Kurma

Also announced today is Kurma, a new implementation of appc by Apcera. Kurma is an execution environment for running applications in containers. Kurma provides a framework that allows containers to be managed and orchestrated beyond itself. Kurma joins a variety of implementations of the appc spec that have emerged in the last six months, such as Jetpack, an App Container runtime for FreeBSD, and libappc, a C++ library for working with containerized applications.

"Apcera has long been invested in secure container technology to power our core platform," said Derek Collison, founder and CEO of Apcera. "We are excited to bring our technology to the open source community and to partner with CoreOS on the future of appc."

Red Hat involvement as a maintainer of appc

Red Hat recently assigned an engineer to participate as a maintainer of appc. Bringing years of experience in container development and leadership in Docker, Kubernetes and the Linux community as a whole, they bring a unique skillset to the effort.

“The adoption of container technology is an exciting trend and one that we believe can have significant customer benefit,” said Matt Hicks, senior director, engineering, Red Hat. “But at the same time, fragmentation of approaches and formats runs the risk of undercutting the momentum. We are excited to be included as maintainers and will work to not only innovate, but also to help create stability for our customers that adopt containers.”

VMware’s continued support of appc

In April, VMware announced support for appc and shipped rkt in Project Photon™, making rkt available to VMware vSphere® and VMware vCloud® Air™ customers. VMware has been an early proponent of appc and is working closely with the community to push forward the spec.

Today VMware reaffirmed their commitment to appc, showing its importance as a community-wide specification.

“VMware supports appc today offering rkt to our customers as a container runtime engine,” said Kit Colbert, vice president and CTO, Cloud-Native Apps, VMware. “We will work with the appc community to address portability and security across platforms – topics that are top of mind for enterprises seeking to support application containers in their IT environments.”

Join the appc community effort

We welcome these new companies into the community and invite others to join the movement to bring forward a secure and portable container standard. Get involved by joining the appc mailing list and discussion on GitHub. We welcome the continued independent implementations of tools to be able to run the same container consistently.

Thank you to all who are coming out to CoreOS Fest. Please follow along with the event on Twitter @CoreOSFest and #CoreOSFest. For those who aren't able to make it in person, the talks will be recorded and available at a later date.