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The cloud-native ecosystem is constantly evolving, with developers increasingly expected to manage both containerized applications and legacy virtual machine (VM) workloads within the same infrastructure. Kubernetes, as the de facto standard for container orchestration, has transformed how we deploy and scale microservices. However, many mission-critical applications still run on virtual machines, which don't easily transition to containers due to deep operating system dependencies, licensing constraints, or legacy design patterns.
This is where KubeVirt enters the picture. KubeVirt provides a powerful, developer-centric solution that bridges the gap between virtual machines and Kubernetes workloads, enabling VMs to run as first-class citizens alongside containers. By integrating VM management into the Kubernetes control plane, KubeVirt unlocks hybrid workload orchestration, where both VMs and containers share the same networking, storage, CI/CD pipelines, and security policies.
In this comprehensive, highly descriptive blog, we’ll explore everything developers need to know about KubeVirt: its architecture, core concepts, benefits, use cases, and how it redefines how modern infrastructure handles hybrid workloads.
Modernization is not always a clean break from the past. Enterprises and organizations across industries often have legacy workloads running on VMs, applications that cannot be containerized easily. These applications might rely on specific kernel modules, system-level privileges, or complex networking configurations not suitable for a container environment.
Despite the explosive growth of Kubernetes, the reality is that VMs still dominate many production environments. Organizations face a significant challenge: How do they transition to cloud-native operations without entirely abandoning their existing VM-based investments?
KubeVirt addresses this challenge head-on by extending Kubernetes with virtualization capabilities. It allows you to run, manage, and scale virtual machines within Kubernetes, enabling containerized microservices and virtual machines to co-exist, interact, and be orchestrated using a single platform.
Instead of choosing between containerization and virtualization, KubeVirt lets developers operate both together. You gain the flexibility of containers for stateless applications and the reliability of VMs for stateful or legacy services, without fragmenting your infrastructure.
KubeVirt introduces virtualization into Kubernetes through Custom Resource Definitions (CRDs) and a set of custom controllers that extend the Kubernetes API. By doing this, VMs can be treated like native Kubernetes objects, just like Pods, Deployments, and Services.
Key components include:
This architecture makes virtualization declarative, version-controlled, and aligned with Kubernetes-native practices.
The virt-operator plays a critical role in maintaining consistency across your Kubernetes cluster. It watches for changes in the KubeVirt deployment and applies upgrades and patches when necessary. This reduces administrative overhead, particularly in large-scale environments, by automating the reconciliation of component states.
The virt-controller ensures that VM definitions in Kubernetes are reflected in real-time instances. If a developer defines a VM and specifies that it should be running, the virt-controller takes the necessary actions to spin up the appropriate resources, monitor the VM’s health, and take corrective action when needed.
The virt-handler runs as a DaemonSet across all cluster nodes. It interfaces directly with the host’s virtualization layer (KVM, libvirt), ensuring that VM operations are properly executed on the physical node. It’s responsible for creating and destroying VM instances and maintaining isolation between workloads.
Each virtual machine is wrapped inside a virt-launcher pod. This pod serves as a wrapper that spawns a QEMU process to run the actual VM. This isolation model allows VMs to leverage Kubernetes’ security boundaries while maintaining compatibility with the VM’s OS and runtime dependencies.
With KubeVirt, you can define a VM using YAML and manage it with kubectl, just like any other Kubernetes resource. This empowers developers to:
This makes it possible to seamlessly integrate legacy workloads into your CI/CD pipelines, ensuring they benefit from automated deployments, scaling strategies, and modern DevOps practices.
VMs can be paused, resumed, migrated, or deleted with declarative commands. For example, a VM can be paused during off-hours to save resources and resumed when needed, all managed through GitOps-style workflows.
One of the biggest advantages KubeVirt brings is the ability to unify your DevOps pipelines. Rather than maintaining two separate systems for VMs and containers, KubeVirt consolidates everything under Kubernetes:
By enabling VMs to run on Kubernetes, teams get:
This operational consistency is particularly important in regulated industries like finance or healthcare where VM-based workloads are still prevalent.
Instead of provisioning separate infrastructure for virtual machines, developers can consolidate workloads on a single Kubernetes cluster. This leads to:
Additionally, idle VM instances can be paused, freeing resources for containers or other workloads.
Developers can now build hybrid applications that mix container-based microservices and virtualized components. For example, a legacy backend service running in a VM can communicate with a containerized frontend or API gateway, all managed through Kubernetes.
KubeVirt integrates with Kubernetes CNI and CSI interfaces. This means:
KubeVirt supports live migration of VM workloads with minimal downtime. Developers can:
Telecommunications providers often deal with latency-sensitive workloads that can’t be containerized. KubeVirt allows VMs to run with SR-IOV support and guaranteed resources, making it a perfect match for 5G and edge computing deployments.
Organizations can lift-and-shift existing VMs into Kubernetes while simultaneously developing container-native microservices. This hybrid strategy enables gradual modernization, reducing the risk of big-bang migrations.
Teams working with embedded systems or operating system kernels can use VMs for isolated testing environments. KubeVirt VMs can be programmatically created, tested, and destroyed during CI cycles, improving test repeatability and speed.
With KubeVirt, developers no longer need to treat VMs as second-class citizens in a DevOps environment, they gain all the automation, consistency, and agility of containers.
Running VMs on Kubernetes introduces new complexities. Developers and platform teams must:
Not all Kubernetes clusters are ready out of the box for virtualization. Nodes must support KVM, and additional security configurations (e.g., SELinux, AppArmor) may need tuning. Monitoring resource pressure becomes critical when mixing VMs and containers.
To start using KubeVirt:
Many community examples and tutorials are available to help get up and running quickly.
KubeVirt is not just a tool, it’s a strategic enabler for organizations navigating the complexities of modernizing legacy applications while building cloud-native systems. By running VMs as Kubernetes resources, KubeVirt transforms your Kubernetes cluster into a universal compute platform capable of handling almost any workload.
It empowers developers with:
For any developer, DevOps engineer, or platform architect, KubeVirt represents the future of hybrid infrastructure orchestration.
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