An Introduction to the Kubernetes Control Plane - The Brains Behind the Brawn

Tyler Au
6 minutes
January 18th, 2024
Tyler Au
6 minutes
January 18th, 2024

What is the Kubernetes Control Plane? 

Flying, in itself, is an art. The idea that an airplane, weighing hundreds of thousands of pounds, is able to take off and reach thousands of feet in the sky from a seemingly tame takeoff is perplexing. While many marvel at the planes and the pilots, something that’s truly fascinating is the responsibility that air traffic control assumes, carefully guiding thousands of flights a day to their destination without any complications.

The idea of brains vs brawn is heavily overrated, as the two often work in conjunction with each other. Like the air traffic control acting as the brains behind the airplane’s brawn, the Kubernetes control plane is the mastermind behind Kubernetes operations themselves. 

The Kubernetes control plane manages clusters and other crucial Kubernetes resources, mobilizing worker nodes and pods to execute tasks based on incoming information. Making crucial decisions for the cluster, the Kubernetes control plane is able to run on any machine within the cluster. Its primary purpose is to orchestrate the operations of containerized apps, mainly the deployment, management, and maintenance aspects, while moving clusters from their current to desired state for better performance.

One of the most important components of Kubernetes, the Kubernetes control plane (and the operational knowhow for it) are crucial for companies utilizing the defining edge technology. With Kubernetes and associated technology only rising in popularity throughout the years, perfecting your Kubernetes control plane is of the utmost importance.

The Five Instrumental Kubernetes Control Plane Components

The individual Kubernetes control plane components work in harmony to best service the clusters and applications in traditional Kubernetes operations. The components of a Kubernetes control plane include: 

kube apiserver

The kube apiserver is responsible for managing container lifecycles and acts as the front end for the control plane. Kube apiserver operates by receiving client requests and scaling based on traffic, deploying instances based on the amount of resources demanded. Essentially securing the end-to-end operations for containers, kube apiserver ensures that all containers are running to their greatest potential, making sure that resource consumption is allocated optimally.

kube scheduler

As the name suggests, the kube scheduler is responsible for scheduling pods to operate on certain nodes. Specifically watching out for newly created pods, the kube scheduler operates under set restrictions, including:

  • Deadlines
  • Resource requirements
  • Hardware and software restrictions
  • Policy restrictions
  • Data locality
  • Inter-workload interference

And more.

kube controller manager

Kube controller managers are tasked with running and managing controller processes, with a controller being control loops that monitor and adjust cluster states to bring it closer to a desired state. With the help of the kube apiserver, the kube controller manager is able to bring clusters to their desired states based on the resources they’re interacting with. These resource interactions drastically change the type of controller, some types include:

  • Node Controller: Controller responsible for node actions and statuses, including onboarding and responsiveness
  • Job Controller: Monitors the creations of new jobs, typically single tasks, and sends pods to complete said tasks
  • EndpointSlice Controller: Creates and manages EndpointSlice resources, with EndpointSlice being a set of network connections endpoints
  • ServiceAccount Controller: Creates ServiceAccounts for new namespaces, with serviceAccounts being process identities within pods

cloud controller manager

Like the kube controller manager, the cloud controller manager interacts with cloud API’s, enabling you to link clusters with those API and its resources. It's important to note that when working with multiple cloud providers, the cloud controller manager will run controllers only on specific providers, letting you manage multiple managers within a single interface. 

Similar to the kube controller manager, the cloud controller manager has three different types:

  • Node Controller: Checks whether a node inside a certain cloud provider is working and has been deleted if unresponsive
  • Route Controller: Sets up node communication routes in the cloud infrastructure
  • Service Controller: Creates and manages cloud load balancers

etcd

etcd is Kubernetes’ data store for all cluster data. Relevant cluster data includes key determinants in a cluster’s current and desired state- information that apiserver collects and uses to bridge the two states. 

These 5 components work in conjunction and create the control plane. The state of the control plane components is extremely important, as inoperation in one of them can stop valuable processes within a cluster’s lifecycle. 

Kubernetes Control Plane Operations

The Kuberetes control plane operates by mobilizing worker nodes. A worker node would execute certain tasks and perform functions based on the instructions from the control plane and the state of the cluster. 

Like the control plane itself, worker nodes are comprised of different vital parts:

  • Kubelet: A node agent running on each node that ensures that clusters are operating smoothly
  • Container Runtime: Software tasked with running containers smoothly
  • Kube proxy: Network proxy that runs on each node

Worker nodes act upon instructions as a result from communicating with the control plane through their kubelets. In this process, kube proxy mobilizes assets and resources necessary for worker nodes to execute their instructions and ensure that pods are operating under strict restrictions. Lastly, container runtimes run the containers.

The Kubernetes control plane manages these three components in order to ensure that containerized applications are operating smoothly.

Revolutionizing Kubernetes with Lyrid

Kubernetes itself is a complex beast. That point is only exemplified by the nuances of the brains behind it: the Kubernetes control plane. In order to keep your application running, different lines of communication must be established by the plane and its working parts, mobilizing control plane nodes and worker nodes alike to best service your clusters. The tech only gets more mind-bending when operating Kubernetes itself, though it doesn’t have to be hard. 

Supercharge your Kubernetes experience with Lyrid! Our managed Kubernetes enables you to leverage all the best features of Kubernetes (powerful automations, increased scalability and flexibility, resource optimization, etc) without the headache of having to deal with Kubernetes head on. Woilo, a social networking app, was able to drastically reduce the rate of their app crashing by 90%, increase their user engagement and satisfaction, and even open up new revenue streams with Lyrid’s managed Kubernetes!

If you’re looking for a Kubernetes solution, or want to take a product tour with one of our specialists, book a demo with us

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