What is Kubernetes Control Plane?

Control planes are based on the Control Theory, a field of engineering and applied mathematics that deals with the control of dynamic systems. The objective of the Control Plane is driving the system to a desired state while minimizing any delay, overshot, or steady-state error and ensuring a level of control stability.

In Kubernetes, the control plane is responsible for managing the state of a Kubernetes cluster. It does this by receiving requests from users or other components of the cluster and processing them to ensure that the desired state of the cluster is achieved. The Control Plane is made up of several components: the API server, the datastore, the scheduler, and the controller manager.

Challenges of Managing Multiple Control Planes

While managing a few Kubernetes clusters can be easy for an experienced platform team, managing multiple control planes for multiple clusters can be complex and resource-intensive. Each control plane requires dedicated machines to be allocated, components to be monitored, versions to be upgraded, policies to be enforced, and more. This can lead to increased operational overhead, longer upgrade times, and increased errors and security risks. Additionally, managing different versions of Kubernetes across multiple clusters can add to the complexity, as different versions may require different configurations, and teams with varying skill sets may be responsible for different clusters.

Simplifying Control Plane Management with Kamaji

Kamaji is a solution that simplifies the management of the control plane in Kubernetes. It is inspired by Network Function Virtualization (NFV) and Network Function Containerization (NFC) principles, which are relatively recent trends in the telco industry. These principles are aimed at replacing physical network components with their virtual or containerized counterparts, enabling software-based implementation of functions like firewalls, load balancers, routers, and switches, with a multi-tenant architecture for optimized resource utilization and service consumption.

With the same approach, Kamaji works by "virtualizing" the Kubernetes Control Plane and offering it as a service to all the Kubernetes workloads. Multiple Control Planes can be hosted on the same multi-tenant infrastructure, enabling high density and allowing a single system to serve hundreds or thousands of Kubernetes Clusters. By consuming the Control Plane as a network service, worker nodes can access it just via its IP address and port without requiring it to be on the same location.

Benefits of Kamaji

Kamaji simplifies the management of the Control Plane in several ways, including:

• Reduced operational overhead: Kamaji eliminates the need for dedicated machines to host control planes, reducing the operational overhead and the associated costs.

• Faster upgrades: Kamaji makes upgrades faster by allowing upgrades to be performed on multiple control planes simultaneously.

• Consistent configurations: Kamaji ensures consistent configurations across multiple clusters, reducing the risk of errors and improving security.

• Enhanced scalability: Kamaji enables the creation of multiple control planes on the same infrastructure, enabling high density and improved scalability.

• Distributed architectures: decoupling the Control Plane from the workloads,  Kamaji enables strong separation between the control plane and the workloads for improved isolation.​ Run Kubernetes workloads everywhere: cloud, edge, and data center.​

With Kamaji, organizations can operate Kubernetes at scale in the simplest and most automated way. All the clusters built with Kamaji are fully compliant CNCF Kubernetes clusters and are compatible with the standard toolchains everybody knows and loves.

How Kamaji works

Kamaji implements the idea to use Kubernetes to manage other Kubernetes clusters by leveraging the automation and reconciliation loop provided by the operator pattern. Kamaji turns any conformant Kubernetes cluster into a management cluster to orchestrate multiple “Tenant Control Planes”. What Kamaji does is to deploy multiple Kuberntes control planes as lightweight pods running in the management cluster instead of dedicated virtual machines. Control Plane pods are deployed by a controller and exposed as a balanced service to the tenant worker nodes. Scalability, automation, and self-healing of the Control Planes are provided out-of-the-box, thanks to Kubernetes and the operator pattern. Management of Tenant Control Planes are fully automated and any drift is detected by Kamaji and immediately reconciled.

Hard Multi-tenancy

And what about the tenant worker nodes? They are just worker nodes: regular instances, e.g. virtual or bare metal, connecting to the Tenant Control Plane. Tenant worker nodes are kept isolated by the infrastructure while the control planes run in different namespaces of the management cluster. A tenant sees no difference between a Kamaji built cluster and a dedicated cluster. At the end, Kamaji implements a full hard multi-tenant environment where each tenant acts as admin of his clusters and shares nothing with other tenants. 

Wrapping out

In conclusion, managing the control plane in Kubernetes can be challenging, especially when running multiple clusters on different infrastructure. However, Kamaji simplifies the management of the control plane by virtualizing it and offering it as a service to Kubernetes workloads. Kamaji reduces the operational overhead, enables faster upgrades, ensures consistent configurations, and enhances scalability, making it a future-ready solution for managing the control plane in Kubernetes. Check the project's documentation and give it a try!