What is KubeVirt

The revolutionary force in software is containerizing applications and using Kubernetes to manage them. This is 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 non-Kubernetes platforms can get complicated. This is where KubeVirt comes in. KubeVirt addresses the demands of development teams that want to use Kubernetes but have running VM workloads that are challenging to containerize. This blog will discuss all you need to know 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. With KubeVirt, you get a bridge connecting containerization’s agility, effectiveness, and the world of traditional virtual machines. This technology allows Kubernetes to manage, deploy, and schedule virtual machines using the same tools as containerized workloads. This 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 overwhelmed by the thought of handling it all.

KubeVirt gives developers a unified platform to modify and build VM-based and container 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. This 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. This ensures that your 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. This will help isolate your virtualized workloads and secure communication within the cluster.
• Centralized Management: 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 get to save money on utilities and software as you migrate more VMs to Kubernetes.
• Zero Hypervisor Tax: KuberVirt protects you from hypervisor tax. You get to 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 the purpose and functionality of each component, you’ll be better equipped to leverage KubeVirt effectively within your Kubernetes environment. Let’s dive into the core components of KubeVirt:

• Virt-controller

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. Once the pod is automatically scheduled to a particular node,  the virt-controller changes the VM object with the node name. Then it hands off further responsibilities to the virt-handler node running on each node within the cluster.

• Virt-handler

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. Once a VM object is removed., the virt-handler will monitor the deletion and turn off the domain.

• Virt-launcher

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 libvirtd.

• Networking and Storage

Disks backed by volumes may configure KubeVirt VMs. Some of these volumes include;

– Persistent Volume Claim: This is similar to a pod and is how a user requests storage. Volumes enable Kubernetes persistent volumes to be directly attached to KubeVirt VMs as disks. Currently, a limitation exists where the persistent volumes must be Internet Small Computer Systems Interface (ISCSI) block devices. However, efforts are underway to support file-based persistent volume disks, providing more flexibility in storage options for KubeVirt VMs.

– Ephemeral Volumes: KubeVirt utilizes Ephemeral Volumes, which are local copy-on-write images that rely on a read-only network volume as a backing store. These ephemeral images are generated and supported by KubeVirt when a VM starts and then discarded when the VM stops. Currently, PVC volumes must back ephemeral volumes. 

Features of KubeVirt

KubeVirt is an open-source project that enables virtual machines (VMs) and containerized workloads to coexist within Kubernetes clusters. Several features of KubeVirt make it suitable for modern businesses. One of the features of KubeVirt is its ability to integrate with existing Kubernetes deployments seamlessly. Doing this provides a convenient option for organizations already utilizing container orchestration. Another noteworthy feature is its unified management interface, which enables IT professionals to manage VMs and containers using familiar Kubernetes APIs and tools.

One of KubeVirt’s standout features is its ability to enable virtualization within nested containers. Nested container virtualization refers to running containers within a VM and then running additional containers within those containers. This approach allows for advanced use cases such as running containerized applications within legacy VM-based environments or deploying complex multi-tier applications with different isolation levels.

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

KubeVirt supports unlimited VMs, allowing you to store persistent data. Due to this, there are a number of use cases for KubeVirt.

Management of Traditional Workloads

KuberVirt is an efficient application orchestration engine that reduces the complexity of distributed computing. You don’t need to keep separate environments, personnel, or skill sets for either application when you combine VM Based and Containerized workloads. 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. Instead of building separate DevOps pipelines for your containerized and VM-based workloads, you can combine and manage them from one place.

Working with Legacy Applications

You can’t simply relocate some applications to cloud-native environments. 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. This means 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. These applications can communicate more easily with containerized applications when you manage them in Kubernetes. In a containerized VM, not all legacy applications are easy to run. In KubeVirt, running mainframe software or applications requiring hardware connections with sensors or additional infrastructure may become more complex. But any hardware that connects over the network should work with a KubeVirt VM because KubeVirt is leveraging the pod’s network connectivity. This means that by using the container environment to connect current VMs with legacy hardware and software, KubeVirt can integrate legacy applications in today’s architectures and development pipelines.

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