Kubevirt – What is virtualization nested in containers 

Kubevirt – What is virtualization nested in containers 

The revolutionary force in software is containerizing applications and using Kubernetes to manage them. It is an efficient application orchestration engine that reduces the complexity of distributed computing. That’s the reason why many companies are switching over to  Kubernetes. However, having some cloud-native applications running on a Kubernetes platform and others running on as a Virtual Machines in other platforms can get complicated. This is where KubeVirt comes in.    

This blog will discuss all you need about KubeVirt, including its benefits, features, and use cases.  


What is KubeVirt?    

KubeVirt is a Kubernetes extension that lets users natively run traditional Virtual Machine (VM) workloads alongside container workloads in their Kubernetes or  OpenShift clusters.   

Agility and scalability are critical in today’s digital landscape. However, traditional virtualization tools can often fall short of meeting the ever-evolving demands of modern business. KubeVirt addresses the demands of development teams that want to use Kubernetes but have workloads running in the virtual machines that are hard to be containerized. It is a kind of a bridge connecting containerization’s agility, effectiveness, and the world of traditional virtual machines.    

Kubernetes allows the management, deployment, and scheduling of virtual machines using the same tools as containerized workloads, which removes the need for a separate environment with management tools and specialized monitoring.   

One cannot overstate the benefits of KubeVirt for companies looking to update their virtual machine workloads but are but they can’t afford to migrate legacy applications to the containers   

KubeVirt gives developers a unified platform to modify and build M and container-based applications immediately. When it begins to make sense, and over time, you can start to containerize virtualized applications by disintegrating them into microservices.  


Benefits of using KubeVirt for virtualization in Kubernetes    

When you maintain multiple infrastructures for your VM workload or containerized workloads, you keep separate layers of networking, scheduling capabilities, metrics, logging, and monitoring.    

With KubeVirt, you can leverage the power of Kubernetes to run container workloads and VM workloads alongside each other and get the same benefits. Some of the following are the reasons why KubeVirt is excellent for running Virtualization in Kubernetes:      

  • Seamless Integration: With KubeVirt, the lines between virtual machines and containers blur as both coexist within the same Kubernetes platform. You no longer need separate management tools or disjointed workflows.   
  • Live Migration: One of KubeVirt’s standout features is live migration, which allows you to move running virtual machines between hosts without service disruption. With KubeVirt, you can seamlessly migrate VMs to optimize performance, balance workloads, or perform maintenance tasks while maintaining business continuity.   
  • High Security: Kubervirt inherits the security features of Kubernetes. Thanks to this solution, VMs have a robust and secure environment. You can also leverage Kubernetes’ RBAC (Role-Based Access Control) and network policies to enforce  granular access control. That action helps to isolate your virtualized workloads and secure communication within the cluster.  
  • Streamlined Infrastructure Orchestration: Centralizing container and VM management streamlines your infrastructure stack while providing several less apparent benefits. By eliminating the need for separate container and VM pipelines, KubeVirt minimizes the stress on your DevOps teams, speeding up daily procedures. You also save money on utilities and software by migrating more VMs to Kubernetes.   
  • Zero Hypervisor Tax: KuberVirt protects you from  hypervisor tax. You eliminate the need to license and use a hypervisor to run the VMs associated with your application. By exploiting Kubernetes’ ability to schedule and package virtual apps, you may reduce your infrastructure footprint in the long run.   

Components of KubeVirt    

When it comes to understanding the inner workings of KubeVirt, it’s crucial to familiarize yourself with its key components. By grasping each element’s purpose and functionality, you’ll better equip yourself to leverage KubeVirt within your Kubernetes environment effectively. Let’s dive into the core components of KubeVirt:   



The  virt-controller is a crucial component that handles the orchestration of virtual machines in KubeVirt. It is also a Kubernetes Operator responsible for cluster-wide virtualization functionality.      

The virt-controller takes notice of new VM objects posted to the API server. Once it does, it creates the pod in which the VM will run. The virt-controller automatically schedules the pod to a particular node. Then, it hands off further responsibilities to the virt-handler node running on each node within the cluster.    


The  virt-handler is also as reactive as the virt-controller. It watches for changes to the VM object and performs all necessary procedures to change a VM to meet the needed state. The virt-handler uses a libvirtd instance in the VM pod to refer to the VM specification and send signals that it has created an appropriate domain. The virt-handler will monitor the deletion of a VM object and turn off the domain once it is removed.         


KubeVirt creates one pod for every VM object. Then, the pod’s primary container runs the virt-launcher KubeVirt component. The main objective of the virt-launcher Pod is to provide the namespaces and cgroups that will host the VM process.    

Virt-handler signals virt-launcher to start a VM by handing the VM’s CRD object to Virt-launcher. Virt-launcher then uses a local libvirtd instance within its container to start the VM. Once this occurs, the virt-launcher monitors the VM process and terminates once the virtual machine has exited.       

There are instances when the Kubernetes runtime could attempt to shut down the virt-launcher pod before the VM process has finished. When this happens, the virt-launcher forwards signals to the VM process and tries to slow the pod’s termination until the virtual machine has shut down successfully.        

Also, every VM pod has an instance of libvirtd. The virt-launcher runs the VM process lifecycle from libvirt.    

For a user to take advantage of technologies like KubeVirt, Kubernetes deployments must run on  bare-metal servers because there is little support for  nested virtualization. Sadly, bare metal servers are costly because individual applications only need some available resources on the node, and bare metal servers have no fundamental provision.       


Use Cases of KubeVirt 

Management of Traditional Workloads    

Combining VM-based and containerized workloads could simplify your daily workflow, yet it still requires a particular set of skills. 

As a result, it is easier to bring VM-based workloads closer to your DevOps workflows, thanks to the fact that you can create VM declaratively and manage them with Kubernetes commands and virtctl.    


Working with Legacy Applications    

With KubeVirt, you can move any app you run on a physical or virtual server to a VM managed using a virt-launcher in a Kubernetes pod.    

You can use Kubernetes in cloud-native environments to manage applications made up of a patchwork of different technologies or older applications you can’t rearchitect.      

Using the  container environment to connect current VMs with  legacy hardware and software, KubeVirt can integrate legacy applications in today’s architectures 


Final Summary    

Two critical technologies drive data center IT: virtualization and containerization. Container-based workloads are beginning to replace virtualization-based workloads because of their portability and scalability.     

The KubeVirt makes it possible to combine advanced virtualization and Kubernetes container orchestration. With KubeVirt, you can have a VM running and controlled by Kubernetes in parallel with containers hosting microservices. You’re getting the best of both worlds! 




08:25 AM, Oct 19


Chief Software Architect

Marcin Kubacki

Chief Software Architect, Member of the Board at Storware, Ph.D. Marcin, sometimes called Mr. V., as a an inventor of Storware vProtect code, joined the company in 2015. In 2016 Marcin earned a Ph.D. at Warsaw University of Technology.