Kubernetes in Kubernetes: How to Build Your Own Cloud!

In this exciting continuation of our series on Kubernetes, we explore how you can run Kubernetes in Kubernetes (K8s in K8s). Technologies like Kamaji and Cluster API take center stage, along with their integration with KubeVirt. After covering how to prepare Kubernetes on bare metal and transform it into a management system for virtual machines in previous articles, here’s the final touch: With these technologies, you can build a fully managed Kubernetes environment and operate virtual Kubernetes clusters with just one click.

Cluster API

The Cluster API is an extension for Kubernetes that allows managing Kubernetes clusters as custom resources within another Kubernetes cluster.

The main goal of the Cluster API is to provide a unified interface for describing the fundamental entities of a Kubernetes cluster and managing their lifecycle. This enables the automation of processes for creating, updating, and deleting clusters, simplifying scaling and infrastructure management.

In the context of the Cluster API, there are two terms: Management Cluster and Tenant Cluster.

• Management Cluster: This is a Kubernetes cluster used to provision and manage other clusters. It contains all necessary Cluster API components and is responsible for describing, creating, and updating tenant clusters. It is often used solely for this purpose.
• Tenant Cluster: These are the user clusters or clusters provisioned using the Cluster API. They are created by describing the relevant resources in the management cluster. These clusters are then used by end-users to deploy applications and services.

It’s important to understand that tenant clusters don’t necessarily run on the same infrastructure as the management cluster; they are often hosted elsewhere.

For its operation, the Cluster API utilizes the concept of providers, which are separate controllers responsible for specific components of the cluster to be created. Within the Cluster API, there are several types of providers. The main ones are:

• Infrastructure Provider: Responsible for provisioning the computing infrastructure, e.g., virtual machines or physical servers.
• Control Plane Provider: Provides the Kubernetes control plane, namely the components kube-apiserver, kube-scheduler, and kube-controller-manager.
• Bootstrap Provider: Used to generate the cloud-init configuration for the virtual machines and servers to be created.

To get started, you need to install the Cluster API itself and a provider of each type. A complete list of supported providers can be found in the documentation.

For installation, you can use the clusterctl utility or the Cluster API Operator as the more declarative method.

Choosing the Providers

Infrastructure Provider

To operate Kubernetes clusters using KubeVirt, the KubeVirt Infrastructure Provider must be installed. This enables the provisioning of virtual machines for worker nodes in the same management cluster where the Cluster API is operated.

With these tools and technologies, you are well-equipped to build your own cloud solution with Kubernetes. ayedo is your partner in the Kubernetes world and supports you in implementing these powerful technologies.

Source: Kubernetes Blog