Introduction to Kubernetes

What is Kubernetes?

Kubernetes (often written k8s) is an open-source platform that automates deploying, scaling and operating containerized applications. You describe the desired state - how many replicas, which image, which ports - and Kubernetes constantly works to make the actual state match.

Why Not Just Docker?

Docker runs containers on a single machine. Kubernetes runs containers across many machines (a cluster), handles failures, networking, service discovery, upgrades and auto-scaling for you.

Core Building Blocks

• Cluster - a set of machines (nodes) running your containers.
• Pod - the smallest deployable unit; one or more containers sharing network and storage.
• Deployment - manages a set of identical pods, including rolling updates and rollbacks.
• Service - a stable network endpoint in front of a set of pods.
• Namespace - a logical partition of the cluster for organising resources.

Tools You Need

# kubectl - the command line client
kubectl version --client

# a local cluster for learning (alternatives: minikube, kind, k3s)
minikube start --driver=docker
minikube status

Your First Command

kubectl get nodes
kubectl cluster-info

Key Points

• Kubernetes is declarative: you define desired state, not step-by-step instructions.
• Pods are the atomic unit; controllers like Deployment manage them.
• kubectl talks to the cluster API server over HTTPS.