KubeVirt — An Initial Look

Kubernetes is a great solution when you want to run container workloads. The options and flexibility it affords you let you run your applications within containers with ease. This is great when you have applications that are easily containerized. But what if you have applications that aren’t easily containerized (legacy applications, enterprise software) but you’d still like to leverage the features that Kubernetes gives you?

These kinds of workloads are usually able to be run as VMs. Wouldn’t it be great if we were able to schedule VM based workloads with Kubernetes? Well you can, with the KubeVirt add-on for Kubernetes. KubeVirt aims to be a virtual machine management add-on for Kubernetes and it allows administrators to run VMs alongside containers within their Kubernetes clusters. KubeVirt leverages the Custom Resource Definitions API to extend the Kubernetes API and add resource types for virtual machines and sets of virtual machines.

KubeVirt allows the VMs to run within regular Kubernetes Pods, this allows them to have access to standard items that all Pods have access to like storage and networking along with allowing them to be controlled and administered with standard Kubernetes tools like kubectl.

Custom Resource Definitions (CRDs)

Before diving in the KubeVirt architecture let’s quickly touch on what CRDs are?
The Kubernetes API defines resources (endpoints) and actions on those endpoints. Custom Resource Definitions (CRDs) is a feature that allows users to extend the Kubernetes API with additional custom resources with their own names and schemas. Once applied to the API server in your cluster, the Kubernetes API will handle the serving and storage of your newly defined resources.

Now let’s have a look at the high-level architecture of the KubeVirt add-on and the CRDs that extend the functionality of the base Kubernetes API to enable these features.

KubeVirt Components

The primary CRD for KubeVirt is the VirtualMachine (VM) resource. This resource defines all the properties of the VM like the CPU, RAM, number, and…read more