Working with Kubernetes

The basic components of a Kubernetes setup are clear. However, questions about why Kubernetes could be interesting for administrators and what problems you can actually solve using it remain unanswered. One thing is certain: Google wants to position Kubernetes in the cloud frameworks market – that is, in the same environment inhabited by CoreOS, Project Atomic, and many other macro distributions.

Kubernetes, however, clearly requires more overhead to set up a complete installation. It is much easier to get started using CoreOS. Another fact is that Kubernetes can also be used as a CoreOS add-on. Google provides prebuilt images for Kubernetes as part of the Google Computing Environment (GCE), meaning that the application can be tested quickly and easily at the push of a button. Anyone already familiar with working in a Docker-only environment easily will get used to the Kubernetes functionality after a brief learning curve. Google enhances Docker, adding a feature absent from the normal variant in the form of an option for operating containers with pods and labels in the framework of a cluster.

Until now, the development of Kubernetes has taken place in Google's hallowed halls. The project will only become really interesting once Google opens up to other suppliers and manufacturers. With Red Hat and SUSE also onboard, it will probably not be long before a more comfortable installation exists. Additionally, a Kubernetes GUI, which is currently missing, will probably follow some time later. Kubernetes is therefore, sooner or later, likely to catch the fancy of anyone using container virtualization in a setup with many hypervisor nodes.

Kubernetes, OpenStack, or Both?

When reviewing the solutions available on the market, a different question arises: Is Kubernetes even necessary given that cloud solutions such as OpenStack and CloudStack are available and have a much larger community? Kubernetes and OpenStack share certain similarities in their architecture.

The Server-Agent principle is very similar in both solutions. OpenStack also has central servers and APIs, as well as agents that run on the individual hypervisor hosts and receive their commands there. The function types are also similar in Kubernetes and OpenStack: Both solutions seek to allow the easy use of computing resources on a computer network.

A closer look, however, also shows major differences between OpenStack and Kubernetes. User management is one example: OpenStack is designed to be multiclient capable; Kubernetes does not currently have this capability. In return, Kubernetes is a highly specialized tool, whereas OpenStack seeks to be a universal panacea.

Although Kubernetes is not a small environment, it feels quick and flexible compared with the almost oversized OpenStack. Consequently, it is not surprising that many observers do not regard OpenStack and Kubernetes as competitors but instead as components that complement one another meaningfully.

Mirantis apparently takes a similar view (Figure 3). Mirantis has made a name for itself in the OpenStack community by developing Fuel, an OpenStack setup tool. In February, Mirantis announced an agreement with Google to develop meaningful integration of Kubernetes in OpenStack [5]. The purpose of this action is to offer a viable form of virtualization with containers in OpenStack.

Figure 3: Mirantis does not see OpenStack as a competitor, but rather as a useful supplement. The company is actively working on integrating the two components.

Container support is obviously exactly what has been lacking in OpenStack: The only somewhat useful driver for containers may also be intended for Docker, but it is not part of the official OpenStack distribution and does not lend itself well to production use. If Mirantis succeeds in connecting Kubernetes and OpenStack, a very fruitful joint venture could arise for OpenStack users and those interested in Kubernetes.

Mirantis immediately pinned a short video to the Google announcement to show that the announcement was not just empty words: The photo shows an OpenStack dashboard that lets the user start pods in Kubernetes (Figure 4). Mirantis has not, unfortunately, named a release date for the corresponding components.

Figure 4: Mirantis has already demonstrated that it has integrated Kubernetes into the OpenStack network infrastructure.

Update: At the OpenStack Summit in Vancouver in May, the OpenStack Foundation and Mirantis announced that Kubernetes is now in its Community App Catalog [6].

Conclusions

Kubernetes is an interesting project with powerful backers and is probably not a fluke, seeing that Google has chosen it to be the tool of its own virtualization future and is already committed. However, you should check carefully before committing to Kubernetes, because the software does not offer a universal solution. Instead, Kubernetes focuses on the idea of achieving high virtualization density using fewer resources. Only users who have similar requirements should use Kubernetes. All other users are probably better off with smaller projects, such as CoreOS.