In recent years, Kubernetes has become the de facto standard for container orchestration. It’s powerful, flexible, and backed by a vibrant open source community. But we keep seeing the same issue in large enterprises and public sector projects: the assumption that Kubernetes alone is enough to manage a secure, scalable, multi-tenant cloud environment.
The reality is quite different.
Kubernetes Is Not a Complete Cloud Platform
Kubernetes is great for managing containers—but it’s not designed to provide full Infrastructure-as-a-Service (IaaS). You still need to manage the underlying virtual machines, network isolation, storage provisioning, image lifecycle, user and project segmentation, and policy enforcement. That’s where most DIY Kubernetes setups start to fall apart.
Multi-Tenancy Requires More Than Namespaces
Many believe that Kubernetes namespaces are enough to isolate workloads between tenants. But at scale, this quickly becomes a security and operational nightmare.
True multi-tenancy requires resource quotas, user roles, isolated networks, and strict policy enforcement across users, groups, and projects—ideally backed by strong IAM and VDC-level isolation. Kubernetes alone doesn’t offer this out of the box.
OpenNebula Bridges the Gap
This is where OpenNebula comes in. It complements Kubernetes by providing:
- Full VM and container orchestration, including support for VMs, LXC, and Kubernetes clusters.
- Enterprise-grade multi-tenancy with Virtual Data Centers (VDCs), Role-Based Access Control (RBAC), and integrated quotas.
- Dynamic resource provisioning at the edge and core, across hybrid and federated infrastructures.
- Unified management of virtual networks, storage, and applications from a single control plane.
With OpenNebula, Kubernetes becomes just one of the orchestrated components within a broader, fully managed cloud environment. Unlike Kubernetes-only approaches, OpenNebula provides the flexibility to support a wide range of workloads—not just containers, but also virtual machines, LXC containers, and other platforms that many enterprises still rely on. This is essential, as many organizations are looking to run more than just Kubernetes in their private or hybrid clouds, including legacy systems, AI workloads, and specialized applications that don’t fit into a containerized model.
A Cloud Platform, Not Just a Container Engine
Companies that rely on Kubernetes alone often end up building and maintaining a complex ecosystem of tools to fill in the gaps—each one adding new costs, security risks, and integration challenges. OpenNebula offers a unified, open source platform designed to handle the full spectrum of cloud and edge operations, reducing complexity and total cost of ownership.
Kubernetes Virtualization with Minimal Performance Impact
Virtualizing Kubernetes is generally the preferred approach at scale, particularly in multi-tenant, enterprise, and telecom environments. While Kubernetes can run on bare metal, virtualization offers several key advantages that become increasingly critical as infrastructure size and complexity grow. For instance, virtualization allows the deployment of different Kubernetes distributions in isolated environments, tailored to the specific needs of each tenant or use case.
The recommended architecture for ensuring simplified lifecycle management, flexibility, security, isolation, multi-tenancy, and automation is to run and manage Kubernetes clusters on virtual machines. This allows cloud operators to provide dedicated Kubernetes environments to different development teams or tenants, while maintaining strong isolation and clear resource boundaries. By introducing multiple layers of abstraction, this model enhances control, governance, and operational efficiency.
This is also the standard architecture adopted by major cloud providers like AWS, Azure, and Google Cloud. Even those that use Kubernetes on bare metal for limited or specialized workloads still rely on virtualized environments to handle large-scale, production-grade deployments—ensuring isolation, scalability, and operational resilience.
Importantly, the performance overhead of virtualization today is minimal. In fact, with technologies like PCI passthrough and SR-IOV, containers and virtual machines can access hardware resources directly—achieving near-native performance with virtually no overhead.
Kubernetes is a key building block, but it’s not a cloud platform by itself. If you’re building or operating a large-scale, multi-tenant environment—don’t stop at Kubernetes. Start with OpenNebula, and let Kubernetes run where it fits best: as a workload on top of a secure, scalable, and sovereign cloud infrastructure.
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