What is Worker Node in Kubernetes: Explained Simply

A worker node in Kubernetes is a machine (physical or virtual) that runs application containers. It hosts the pods where your apps actually run and communicates with the control plane to receive instructions.

How It Works

Think of Kubernetes like a busy restaurant kitchen. The control plane is the chef who decides what dishes to prepare and when. The worker nodes are the cooks who actually make the dishes. Each worker node runs the containers that hold your applications, just like cooks prepare meals.

Each worker node has a few key parts: the kubelet which listens to the control plane and manages containers, the container runtime like Docker that runs the containers, and the kube-proxy which helps network traffic reach the right containers. The control plane sends instructions to worker nodes, and they carry out the work of running your apps.

Example

This example shows how to list worker nodes in a Kubernetes cluster using the command line.

bash

kubectl get nodes --selector='!node-role.kubernetes.io/control-plane' -o wide

Output

NAME           STATUS   ROLES    AGE   VERSION   INTERNAL-IP    EXTERNAL-IP   OS-IMAGE             KERNEL-VERSION      CONTAINER-RUNTIME
worker-node1   Ready    <none>   10d   v1.27.3   192.168.1.10   <none>        Ubuntu 22.04.2 LTS   5.15.0-76-generic   docker://24.0.5
worker-node2   Ready    <none>   10d   v1.27.3   192.168.1.11   <none>        Ubuntu 22.04.2 LTS   5.15.0-76-generic   docker://24.0.5

When to Use

You use worker nodes whenever you want to run containerized applications in Kubernetes. They are essential for hosting your app's workload. For example, if you deploy a web app, the worker nodes run the containers that serve your website.

In real-world setups, you might have multiple worker nodes to spread your app's load and keep it running even if one node fails. This makes your app reliable and scalable.

Key Points

• Worker nodes run the actual application containers in Kubernetes.
• They communicate with the control plane to get instructions.
• Each node runs components like kubelet, container runtime, and kube-proxy.
• Multiple worker nodes improve app reliability and scalability.

Key Takeaways

Worker nodes are machines that run your app containers in Kubernetes.

They receive instructions from the control plane to manage workloads.

Each node runs essential components like kubelet and container runtime.

Using multiple worker nodes helps your app stay reliable and scalable.