The open-source Docker Linux container project is continuing its march toward broader deployment this week with the release of Docker 0.9 on March 10 and the announcement of a Linux container certification effort from Red Hat today.

Docker leverages a container approach to virtualization, which is fundamentally different from the traditional hypervisor virtual machine model used by VMware's ESX, Microsoft's Hyper-V, and the open-source Xen and Kernel-based Virtual Machine (KVM) projects. Instead of requiring an entire operating system to be virtualized, as is the case in the hypervisor model, Docker virtualizes applications in containers that sit on top of a host operating system.

Docker 0.9 follows the 0.8 release by only a month and is the second release since the open-source project adopted a new rapid release cycle. The open-source Docker project is backed by Docker Inc., which is the lead commercial sponsor of the project.

The new features in the 0.9 release include a focus on expanding the deployment options for Docker users, Scott Johnston, senior vice president of Product at Docker, told eWEEK. The new execution driver API is largely about simplifying deployment and expanding the potential range of supported operating system platforms by removing hard-coded dependencies, Johnston said. Docker currently relies on the LXC (Linux Containers) project to achieve isolation; however, with Docker 0.9 and the execution driver API, that will now change.

"In the first release of this API, if an operating system does not support LXC, there is now an option for either Docker or the community to provide an execution driver for that operating system," Johnston said.

Certification

Linux vendor Red Hat is also a strong supporter of Docker and today announced a new certification effort for containerized apps.

"Red Hat Enterprise Linux 6 currently supports running applications in containers, and we will be enhancing this capability in the upcoming Red Hat Enterprise Linux 7 release as well as adding the capability to OpenShift," Marty Wesley, senior product marketing manager at Red Hat, told eWEEK. "What we have done with this announcement is add a certification that allows software providers [ISVs] to package and distribute their application in a containerized format."

Wesley noted that initially Red Hat's certification only applies to containerized applications in the Docker format. That said, there might be other container formats that gain traction in the future that Red Hat might want to support as well, he added.

Red Hat's ISV partners already certify their applications against Red Hat Enterprise Linux (RHEL), which in a Docker application deployment would still be the underlying operating system. In fact, Wesley said, the ISV application running in a Docker container doesn't need to be certified against RHEL again.

"The container certification is validating that the application is packaged appropriately," he said. "For instance, we want to make sure that the ISV does not do anything that would prevent Red Hat from delivering security or maintenance updates to the Red Hat Enterprise Linux operating system components in the container."

As such, Wesley noted that the new containerized application certification is more about the packaging and the delivery of the application and less about if the application runs on Red Hat Enterprise Linux.

Red Hat customers already run applications in virtualized hypervisors, which present a different certification challenge than Docker container virtualized applications.

"Containerized application certification ensures that the application will run properly with the underlying operating system, while virtualization certification is more about ensuring that the operating system works with the virtual hardware that the hypervisor presents," Wesley said.

Sean Michael Kerner is a senior editor at eWEEK and InternetNews.com. Follow him on Twitter @TechJournalist.