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Run Containers and VMs Together with KubeVirt

Although many enterprises have deployed Kubernetes and containers, most also operate virtual machines. The two environments will likely co-exist for years, creating operational complexity, adding cost in terms of time and infrastructure.

Without going into the pros and cons of one versus the other, it’s useful to remember that each virtual machine or VM contains its own instance of a full operating system and is intended to operate as if it were a standalone server—hence the name. In a containerized environment, by contrast, multiple containers share one instance of an operating system, almost always some flavor of Linux.

Not all application services run well in containers, resulting in a need to run both.

For example, a VM is better than a container for LDAP/Active Directory applications, tokenization applications, and applications with intensive GPU requirements. You may also have a legacy application that for some reason (no source code, licensing, deprecated language, etc.) can’t be modernized and therefore has to run in a VM, possibly against a specific OS like Windows.

Whatever the reason your application requires VMs or containers, running and managing multiple environments increases the complexity of your operations, requiring separate control planes and possibly separate infrastructure stacks. That may not seem like a big deal if you just need to run one or a small set of VMs to support a single instance of an otherwise containerized application. But what if you have many such applications? And what if you need to run multiple instances of those apps across different cloud environments? Your operations can become very complicated very quickly. 

Wouldn’t it be great if you could run VMs as part of your Kubernetes environment?

This is exactly what KubeVirt enables you to do. In this blog, I’ll dig into what KubeVirt is, the benefits of using it, and how Rafay integrates this technology so that you can get started using it right away.

What is KubeVirt?

KubeVirt is a Kubernetes add-on that enables Kubernetes to provision, manage, and control VMs on the same infrastructure as containers. An open source project under the auspices of the Cloud Native Computing Foundation (CNCF), KubeVirt currently is in the incubation phase

This technology enables Kubernetes to schedule, deploy, and manage VMs using the same tools as containerized workloads, eliminating the need for a separate environment with different monitoring and management tools. This gives you the best of both worlds, VMs and Kubernetes working together.

WIth KubeVirt, you can declaratively:

  • Create a VM
  • Schedule a VM on a Kubernetes cluster
  • Launch a VM
  • Stop a VM
  • Delete a VM

Your VMs run inside Kubernetes pods and utilize standard Kubernetes networking and storage.


For a deeper discussion of how KubeVirt works and the components involved, take a look at the blog Getting to Know KubeVirt on

What are the benefits of KubeVirt?

KubeVirt integrates with existing Kubernetes tools and practices such as monitoring, logging, alerting, and auditing, providing significant benefits including:

  • Centralized management: Manage VMs and containers using a single set of tools.
  • No hypervisor tax: Eliminate the need to license and run a hypervisor to run the VMs associated with your application.
  • Predictable performance: For workloads that require predictable latency and performance, KubeVirt uses the Kubernetes CPU manager to pin vCPUs and RAM to a VM.
  • CI/CD for VMs: Develop application services that run in VMs and integrate and deliver them using the same CI/CD tools that you use for containers.
  • Authorization: KubeVirt comes with a set of predefined RBAC ClusterRoles that can be used to grant users permissions to access KubeVirt Resources.

Centralizing management of VMs and containers simplifies your infrastructure stack and offers a variety of less obvious benefits as well. For instance, adopting KubeVirt reduces the load on your DevOps teams by eliminating the need for separate VM and container pipelines, speeding daily operations. As you migrate more VMs to Kubernetes, you can see savings in software and utility costs, not to mention the hypervisor tax. In the long term you can decrease your infrastructure footprint just by leveraging Kubernetes’ ability to package and schedule your virtual applications.

Kubernetes with KubeVirt provides faster time to market, reduced cost, and simplified management. Automating the lifecycle management of VMs using Kubernetes helps consolidate the CI/CD pipeline of your virtualized and containerized applications. With Kubernetes as an orchestrator, changes in either type of application can be similarly tested, and safely deployed, reducing the risk of manual errors and enabling faster iteration. 

KubeVirt: Challenges and Best Practices

There are a few things to keep in mind if you’re deploying KubeVirt. As I mentioned above, one of the reasons you may want to run a VM instead of a container is for specialized hardware like GPUs. If this applies to your workload, you’ll need to make sure that at least one node in your cluster contains the necessary hardware and then pin the pod containing the VM to the node(s) with that hardware.

As with any Kubernetes add-on, managing KubeVirt when you have a fleet of clusters—possibly running in multiple, different environments—becomes more challenging. It’s important to ensure technology is deployed the same way in each cluster, and possibly tailored to the hardware available.

Finally, Kubernetes skills are in short supply. Running a VM on KubeVirt generally requires the ability to understand and edit YAML configuration files. You’ll need to make sure that everyone who needs to deploy VMs on KubeVirt has the skills and tools to do so from developers to operators.

KubeVirt at Rafay

Rafay’s Kubernetes Operations Platform (KOP) is the ideal solution for companies that want to deploy and manage KubeVirt across a fleet of Kubernetes clusters. With Rafay, you are able to deploy KubeVirt with the right configuration everywhere you need it, with tools to make your team productive right away.

Rafay’s support for VMs includes:

  • Streamlined Admin Experience: Add the VM Operator to a cluster blueprint and apply it to a fleet of clusters. Rafay automatically deploys the necessary virtualization components on the target clusters.
  • Standardization and Consistency: Using the VM Operator as part of a cluster blueprint enables you to achieve standardization and consistency across a fleet of clusters.
  • VM Wizard: There is no Kubernetes learning curve. Simply provide the ISO image for your VMs and use the Rafay-provided VM Wizard to configure, deploy, and operate VMs on Kubernetes.
  • Multi-Cluster Deployments: Use Rafay’s sophisticated, multi-cluster placement policies to deploy and operate VMs across a fleet of remote Kubernetes clusters in a single operation.
  • Integrated Monitoring and Secure Remote Diagnostics: Centrally monitor the status and health of VMs deployed across your environment. Receive alerts and notifications if there are operational issues. Remotely diagnose and repair operational issues, even on remote clusters behind firewalls.

The market demand for operating VMs and containers on a single unified operations platform is growing rapidly. With Rafay KOP, you are able to run legacy applications with the same underlying orchestration as cloud-native applications across a fleet of clusters distributed across cloud, data center, and remote/edge environments, eliminating the complexity of separate VM and container environments. Rigorous QA and certification testing processes ensure that Rafay’s KubeVirt implementation is stable and performs as expected, even as the underlying code evolves.

To get started deploying VMs on Kubernetes with Rafay, all you have to do is create a custom blueprint and select the VM Operator from the Managed System Add-Ons drop-down. KubeVirt components are then automatically deployed on any cluster this blueprint is applied to.

Ready to find out why so many enterprises and platform teams have partnered with Rafay to streamline Kubernetes operations?  Sign up for a free trial today and learn more about running virtualized workloads on Rafay.


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