Introduction
Kubernetes has become the standard platform for deploying and managing containerized applications. It provides powerful capabilities such as automated scaling, self-healing, service discovery, and declarative infrastructure management.
However, not every workload can be easily containerized. Many organizations still rely on traditional virtual machines (VMs) for legacy applications, specialized software, licensing requirements, or operating system dependencies.
As businesses modernize their infrastructure, they often face a challenge: how can they manage both containers and virtual machines using a unified platform?
This is where KubeVirt comes in. KubeVirt extends Kubernetes by enabling virtual machines to run alongside containers within the same cluster. This allows organizations to modernize infrastructure gradually without abandoning existing VM-based workloads.
In this tutorial, you'll learn what KubeVirt is, how it works, its architecture, deployment model, practical use cases, and best practices for managing virtual machines in Kubernetes.
What Is KubeVirt?
KubeVirt is an open-source project that adds virtual machine management capabilities to Kubernetes.
It allows users to:
Create virtual machines
Run VM workloads inside Kubernetes
Manage VMs using Kubernetes APIs
Automate VM operations
Migrate workloads gradually to containers
Instead of maintaining separate virtualization and container platforms, KubeVirt enables both workload types to coexist.
Example:
Kubernetes Cluster
|
+--> Containers
|
+--> Virtual Machines
This unified approach simplifies infrastructure management.
Why Organizations Still Use Virtual Machines
Although containers are popular, virtual machines remain important for many workloads.
Common examples include:
Legacy enterprise applications
Windows workloads
Commercial software requiring VM deployment
Database systems
Applications with OS-specific dependencies
Traditional environments often look like this:
Virtualization Platform
|
+--> VM 1
+--> VM 2
+--> VM 3
Meanwhile, containerized applications run separately:
Kubernetes Cluster
|
+--> Container A
+--> Container B
Managing both platforms independently increases operational complexity.
KubeVirt helps consolidate these environments.
How KubeVirt Works
KubeVirt extends Kubernetes using custom resources and controllers.
Architecture:
Kubernetes API
|
v
KubeVirt
|
+--> Virtual Machines
|
+--> Containers
KubeVirt uses Kubernetes primitives while leveraging virtualization technologies such as:
This allows virtual machines to run as Kubernetes-managed workloads.
KubeVirt Architecture
Several components work together inside KubeVirt.
VirtualMachine Resource
Defines a virtual machine.
Example:
VirtualMachine
This resource describes:
CPU allocation
Memory allocation
Storage
Network settings
VirtualMachineInstance
Represents a running VM.
Example:
VirtualMachineInstance
Similar to how a Pod represents a running container.
Controllers
Controllers monitor and manage VM state.
Responsibilities include:
Starting VMs
Stopping VMs
Scheduling workloads
Handling failures
Virt Launcher
A specialized pod responsible for hosting virtual machine processes.
Example:
Pod
|
v
Virt Launcher
|
v
Virtual Machine
This integrates virtualization directly into Kubernetes workflows.
Installing KubeVirt
KubeVirt can be installed into an existing Kubernetes cluster.
Typical installation steps:
kubectl apply -f kubevirt-operator.yaml
Install the custom resources:
kubectl apply -f kubevirt-cr.yaml
Verify installation:
kubectl get pods -n kubevirt
After installation, Kubernetes can manage virtual machine workloads.
Creating Your First Virtual Machine
A basic VM definition might look like this:
apiVersion: kubevirt.io/v1
kind: VirtualMachine
metadata:
name: demo-vm
spec:
running: true
Apply the configuration:
kubectl apply -f vm.yaml
View the VM:
kubectl get vm
KubeVirt creates and manages the virtual machine automatically.
Virtual Machine Lifecycle
Virtual machines follow a lifecycle similar to containers.
Example:
Created
|
Running
|
Stopped
|
Deleted
Common operations include:
Start VM:
virtctl start demo-vm
Stop VM:
virtctl stop demo-vm
Restart VM:
virtctl restart demo-vm
These operations integrate seamlessly with Kubernetes workflows.
Storage Management
Virtual machines require persistent storage.
Example:
VM
|
v
Persistent Volume
KubeVirt supports:
Persistent Volumes
Storage Classes
Network storage
Cloud storage backends
This allows VMs to retain data across restarts.
Networking in KubeVirt
Virtual machines often need network connectivity.
Example:
VM
|
v
Kubernetes Network
|
v
Other Services
Networking options include:
This enables communication between VMs and containerized applications.
Live Migration
One of KubeVirt's most powerful features is live migration.
Traditional migration:
Shutdown VM
|
Move Host
|
Start VM
KubeVirt supports live migration:
Running VM
|
Move Host
|
Continue Running
Benefits include:
This is particularly valuable for production systems.
Running Legacy Applications
Many organizations want to modernize gradually.
Example:
Legacy Billing System
Instead of rewriting immediately:
Run Inside KubeVirt VM
At the same time:
New Services
|
v
Containers
This hybrid approach reduces migration risks.
Practical Example
Consider an enterprise application environment.
Components:
Legacy ERP System
Windows Application
Modern API Service
Frontend Application
Deployment:
Kubernetes Cluster
|
+--> ERP VM
|
+--> Windows VM
|
+--> API Containers
|
+--> Frontend Containers
All workloads are managed through a single platform.
This simplifies operations and governance.
KubeVirt and Hybrid Workloads
Most enterprises operate mixed environments.
Example:
Containers
|
Virtual Machines
|
Storage Services
KubeVirt allows organizations to:
This makes Kubernetes more versatile.
Benefits of KubeVirt
Unified Management
Manage containers and VMs using Kubernetes APIs.
Gradual Modernization
Move legacy workloads without immediate refactoring.
Kubernetes Integration
Leverage existing Kubernetes tooling and workflows.
Automation Support
Use CI/CD pipelines and Infrastructure as Code.
Resource Efficiency
Share infrastructure across different workload types.
Reduced Operational Complexity
Avoid maintaining separate orchestration platforms.
Best Practices
Containerize When Practical
Containers remain the preferred choice for cloud-native workloads.
Use VMs only when necessary.
Monitor Resource Usage
Track:
CPU utilization
Memory consumption
Storage usage
Network performance
Virtual machines typically consume more resources than containers.
Plan Storage Carefully
Use reliable persistent storage solutions for production workloads.
Secure VM Access
Implement:
Security remains critical.
Use Live Migration
Enable live migration where possible to reduce downtime during maintenance.
Automate Deployments
Manage VM definitions using GitOps and Infrastructure as Code practices.
KubeVirt vs Traditional Virtualization
| Feature | Traditional Virtualization | KubeVirt |
|---|
| VM Support | Yes | Yes |
| Container Support | No | Yes |
| Kubernetes Integration | No | Native |
| Unified API | Limited | Yes |
| Automation | Moderate | Strong |
| Cloud-Native Workflows | Limited | Excellent |
| Hybrid Workloads | Limited | Excellent |
KubeVirt combines virtualization capabilities with modern Kubernetes management.
Common Use Cases
KubeVirt is frequently used for:
Legacy Application Migration
Moving traditional workloads into Kubernetes environments.
Hybrid Infrastructure
Managing VMs and containers together.
Development and Testing
Running isolated VM environments.
Enterprise Workloads
Supporting applications that require full operating systems.
Disaster Recovery
Providing flexible workload management and migration.
Gradual Cloud-Native Adoption
Allowing organizations to modernize at their own pace.
When Should You Use KubeVirt?
KubeVirt is a strong choice when:
Legacy applications cannot be containerized.
Virtual machines and containers must coexist.
Kubernetes is already the primary orchestration platform.
Infrastructure consolidation is a goal.
Hybrid modernization strategies are required.
It is particularly valuable for enterprises transitioning toward cloud-native architectures.
Conclusion
KubeVirt bridges the gap between traditional virtualization and modern Kubernetes-based infrastructure. By enabling virtual machines to run alongside containers within the same cluster, it provides organizations with a practical path toward infrastructure modernization without forcing immediate application rewrites.
Whether you're managing legacy enterprise systems, Windows workloads, hybrid environments, or gradual migration projects, KubeVirt allows you to leverage Kubernetes as a unified platform for both virtual machines and containers. As enterprises continue modernizing their infrastructure, KubeVirt is becoming an increasingly important tool for supporting diverse workloads while maintaining operational simplicity.