Welcome to VM-Operator

Overview picture

The goal of this project is to provide an easy to use and flexible solution for running Qemu/KVM based VMs in Kubernetes pods.

The image used for the VM pods combines Qemu and a control program for starting and managing the Qemu process. This application is called “the runner”.

While you can deploy a runner manually (or with the help of some helm templates), the preferred way is to deploy “the manager” application which acts as a Kubernetes operator for runners and thus the VMs.

If you just want to try out things, you can skip the remainder of this page and proceed to “the manager”.

Motivation

The project was triggered by a remark in the discussion about RedHat dropping SPICE support from the RHEL packages. Which means that you have to run Qemu in a container on RHEL and derivatives if you want to continue using Spice. So KubeVirt comes to mind. But one comment mentioned that the KubeVirt project isn’t interested in supporting SPICE either.

Time to have a look at alternatives. Libvirt has become a common tool to configure and run Qemu. But some of its functionality, notably the management of storage for the VMs and networking is already provided by Kubernetes. Therefore this project takes a fresh approach of running Qemu in a pod using a simple, lightweight manager called “runner”. Providing resources to the VM is left to Kubernetes mechanisms as much as possible.

VMs and Pods

VMs are not the typical workload managed by Kubernetes. You can neither have replicas nor can the containers simply be restarted without a major impact on the “application”. So there are many features for managing pods that we cannot make use of. Qemu in its container can only be deployed as a pod or using a stateful set with replica 1, which is rather close to simply deploying the pod (you get the restart and some PVC management “for free”).

A second look, however, reveals that Kubernetes has more to offer.

It has a well defined API for managing resources.
It provides access to different kinds of managed storage for the VMs.
Its managing features are useful for running the component that manages the pods with the VMs.

And if you use Kubernetes anyway, well then the VMs within Kubernetes provide you with a unified view of all (or most of) your workloads, which simplifies the maintenance of your platform.