Kubernetes Nodes: Components, Types, and Management Guide

What Are Kubernetes Nodes?

A Kubernetes Node is an individual physical or virtual machine where workloads are scheduled. Multiple nodes combine to form a cluster. Nodes can run on physical hardware or virtual machines from cloud providers like AWS, GCP, or Azure.

As per Kubernetes v1.31, a single cluster can support up to 5,000 nodes.

Types of Kubernetes Nodes

1. Control Plane Node

• Houses core Kubernetes components like the API server, etcd, and controller manager.
• Manages cluster state and orchestrates workloads.
• Multiple control plane nodes ensure High Availability.

2. Worker Node

• Hosts application pods.
• Runs Kubelet to manage pod lifecycle.
• Executes workloads scheduled by the control plane.

Kubernetes Node Components

Kubelet

• Communicates with the control plane to run pods.
• Ensures containers are healthy and running.
• Provides a read-only HTTP endpoint for health and spec information.

Kube Proxy

• Handles networking and load balancing for pods.
• Routes traffic to appropriate service endpoints.
• Operates in iptables or ipvs mode for performance.

Container Runtime

• Executes containers inside pods.
• Common runtimes: containerd, Docker, CRI-O.
• Kubelet uses the Container Runtime Interface (CRI) to communicate with the runtime.

Understanding Node Properties

Node Labels

• Used to identify and categorize nodes.
• Example: kubectl label node node01 env=test
• Helps in pod scheduling using selectors and affinities.

Node Annotations

• Non-identifying metadata for nodes.
• Useful for automation and tooling integrations.

kubectl describe node

Node Allocation & Capacity

• Shows CPU, memory, storage, and max pods.
• Determines scheduling decisions.

Node Conditions

• Monitors Ready status, Memory Pressure, Disk Pressure, PID Pressure.
• Critical for troubleshooting node health.

Node Info & Status

• Shows hardware details, OS image, runtime versions, and IP addresses.
• Accessible via: kubectl describe node <node-name>

kubectl get nodes --show-labels

The different Node labels also help with scheduling pods onto the nodes. To learn more about scheduling pods and how labels help in it.

Useful Kubernetes Node Commands

• kubectl get nodes – List all nodes
• kubectl get nodes --show-labels – Show nodes with labels
• kubectl get nodes -o wide – Detailed node info
• kubectl describe node <node-name> – Node details and conditions
• kubectl get node -o yaml – View complete YAML manifest
• kubectl get pods -o wide – View pod-to-node mapping
• kubectl label node <node> key=value – Add a label
• kubectl taint node <node> key=value:NoSchedule – Taint a node

Kubernetes Node Management with Devtron

Devtron provides an intuitive Kubernetes dashboard to simplify node management:

• Visualize node status, IPs, roles, and versions
• Monitor CPU, memory, and pod utilization
• View labels, annotations, and taints in one place
• Integrated terminal to execute node-level commands without SSH

With Devtron, you can quickly troubleshoot node issues and optimize resource allocation without manually switching between CLI and manifests.

Conclusion

Kubernetes Nodes are an essential part of the Cluster. They can either be physical machines or Virtual Machines that are connected to the Kubernetes cluster. Pods are always placed on certain nodes within the cluster. The two main types of nodes are the Control Plane node, which houses the critical Kubernetes components, and the worker node which houses the various application pods. The Kubelet, Kube Proxy, and container runtime are some of the critical components that are present on every node within the cluster.

FAQ

Siddhant Khisty

Siddhant is a Product Executive at Devtron with expertise in Kubernetes, ArgoCD, and DevOps. An organizer for Cloud Native Nashik, he loves open-source tech, automation, and securing deployments.