Kubernetes Architecture Guide

Most engineers learn Kubernetes by memorizing commands.

The best engineers understand how the architecture works.

When you understand the architecture, troubleshooting becomes easier.

Imagine managing these tasks manually:

  • Hundreds of servers
  • Thousands of containers
  • Constant deployments
  • Hardware failures
  • Traffic spikes

Kubernetes automates these tasks. A cluster has two main parts: The Control Plane and Worker Nodes.

The Control Plane manages the cluster. The Worker Nodes run your applications.

Core Components:

The API Server: This is the gateway. Every kubectl command goes here first.

ETCD: This is the database. It stores all cluster data like Pods and Secrets. It is the single source of truth.

The Scheduler: This picks the best node for your Pod. It looks at CPU and memory availability.

Controllers: These monitor cluster health. They ensure the actual state matches your desired state.

Cloud Controller: This manages cloud-specific tasks like load balancers in AWS.

Worker Node Components:

Kubelet: This is the agent on each node. It receives instructions and runs containers.

Container Runtime: This runs the containers. Examples include containerd and CRI-O.

Kube Proxy: This handles networking and traffic routing.

The Pod: This is the smallest unit. Your applications run inside Pods.

How a Deployment Works:

  1. API Server receives your request.
  2. ETCD stores the new state.
  3. Scheduler selects a node.
  4. Kubelet starts the Pod.
  5. Container runtime starts the containers.
  6. Kube Proxy enables networking.

Kubernetes uses Desired State Management. If you ask for 3 replicas, Kubernetes ensures 3 replicas exist. If one fails, Kubernetes starts a new one. This is self-healing.

Knowledge of architecture is vital for CKA, DevOps, and SRE roles. Without it, fixing production issues is hard.

Test your knowledge:

The API Server is healthy. The Worker Nodes are healthy. ETCD is unavailable.

Can you schedule new Pods? Why or why not?

Post your answer below.

Source: https://dev.to/arnabadhikar/kubernetes-architecture-the-complete-beginner-to-intermediate-guide-3e4l

Optional learning community: https://t.me/GyaanSetuAi