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No—Kubernetes did not replace virtual machines. Kubernetes manages containerized workloads, while a virtual machine (VM) runs a guest operating system on virtualized hardware. A Kubernetes cluster can run on VMs, on bare-metal servers, or—when extended with a project such as KubeVirt—manage VMs alongside containers.
What Kubernetes manages—and what it does not
Kubernetes is a platform for deploying, scaling, and operating containerized applications. Its core workload resources describe how Pods should run; Kubernetes is not itself a hypervisor or a general-purpose system for configuring and maintaining guest operating systems. As the Kubernetes overview puts it, “Kubernetes is not a traditional, all-inclusive PaaS (Platform as a Service) system.”
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This distinction is about the layer being managed, not a contest in which one technology makes the other obsolete. A VM provides virtualized hardware and a full guest OS. A container packages an application and its dependencies while sharing the host operating system. Containers are generally lighter, but their isolation model is different and more relaxed than that of a full VM. Which model fits depends on the workload and its operating requirements.
How Kubernetes workload types differ from VMs
Kubernetes’ built-in workload resources manage Pods and their lifecycles. They are not native VM or hypervisor APIs.
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| Resource | Typical purpose |
|---|---|
| Deployment | Runs interchangeable Pods, commonly for stateless applications. |
| StatefulSet | Manages Pods that need stable identities and persistent-storage relationships. |
| DaemonSet | Runs a Pod on selected nodes, often for node-local services. |
| Job | Runs a task to completion. |
| CronJob | Runs Jobs on a schedule. |
These resources let Kubernetes handle application deployment and recovery at the container level. They do not, by themselves, create or maintain a separate guest operating system for each workload.
Two different ways Kubernetes and VMs fit together
Run Kubernetes nodes inside VMs
A Kubernetes cluster can use VMs as its nodes. In this arrangement, the hypervisor remains below the cluster, and Kubernetes schedules container workloads onto the VM-backed nodes. Choosing VM-backed nodes or bare metal is an infrastructure decision separate from choosing whether an application runs in a container.
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Manage VMs through Kubernetes with KubeVirt
KubeVirt adds VM management capabilities to Kubernetes through VM resource types and additional controllers and agents. Its project describes itself as “a virtual machine management add-on for Kubernetes.” This capability comes from KubeVirt, not from Kubernetes core. Bringing VM lifecycle operations into Kubernetes does not automatically make it equivalent to every feature or workflow in an existing virtualization platform.
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See the KubeVirt user guide for the project’s VM-management concepts and documentation.
Should you keep an application in a VM or containerize it?
Containerization is not mandatory. An application may have dependencies on its guest OS, legacy integrations, or established VM-based operating practices that make keeping it virtualized sensible. For a suitable application, a container may improve portability and fit a Kubernetes-based deployment model. Consider the whole operating lifecycle, not just packaging.
- Guest OS and kernel needs: Check whether the application depends on a particular guest OS or system configuration.
- Dependencies and integration: Identify ties to legacy services, host-level components, or VM-specific workflows.
- State and storage: Work out how persistent data is stored, protected, and recovered in the proposed model.
- Security boundary: Compare the isolation requirements of the workload with the container and VM models.
- Team operations: Account for the skills, tooling, and support processes the team can maintain.
A gradual move is possible: teams can containerize suitable components while leaving workloads with VM-specific requirements in VMs. But the change can affect backup, resizing, certification, and lifecycle procedures; these need to be planned rather than assumed to transfer unchanged.
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Should Kubernetes run on VMs or bare metal?
Neither is the universal answer. The CNCF’s comparison of Kubernetes on bare metal and VMs describes tradeoffs involving performance, latency, hardware access, isolation, version flexibility, resource guarantees, and operations. VM-backed clusters may help with isolation and version flexibility; bare metal can remain relevant for specialized or latency-sensitive workloads. Validate these considerations in the actual environment rather than treating them as guarantees.
- Consider VM-backed nodes when isolation between environments or flexibility in cluster versions is important to your design.
- Consider bare metal when specific hardware access or latency needs matter, and the team can operate the infrastructure accordingly.
- For either choice, assess fault domains, resource allocation, lifecycle management, and the skills required to support the setup.
When does KubeVirt make sense?
KubeVirt is worth evaluating when an organization wants to manage VM workloads through Kubernetes APIs and controllers, perhaps alongside container workloads. The fit depends on how well that operating model meets existing requirements; using KubeVirt should not be assumed to preserve every established VM workflow.
- Map current VM lifecycle tasks, including provisioning, resizing, backup, recovery, and migration.
- Check storage and networking needs for the VMs you intend to run.
- Confirm certification and support requirements for the workloads and the platform.
- Compare the required integrations and operational procedures with what the proposed KubeVirt environment supports.
The CNCF’s discussion of migrating VMs to KubeVirt highlights operational differences such as resizing, backup, and workload certification. Those considerations make migration a planning exercise, not a promise that any VM can move unchanged.
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