Why Kubernetes?

Docker gets your app into a container. Kubernetes gets that container running reliably at scale. It handles scheduling, self-healing, scaling, and rolling updates automatically — things that would take weeks to build manually.

In this guide, we'll use kind (Kubernetes in Docker) to spin up a local cluster and deploy a simple web app. No cloud account needed.

Prerequisites

  • Docker installed and running
  • kubectl CLI installed
  • kind installed (brew install kind or see kind.sigs.k8s.io)

Step 1: Create a Local Cluster

# Create a cluster named "devops-lab"
kind create cluster --name devops-lab

# Verify it's running
kubectl cluster-info --context kind-devops-lab
kubectl get nodes

You should see one node in Ready status within about 60 seconds.

Step 2: Understand the Core Concepts

Before deploying, know these three objects:

  • Pod — the smallest deployable unit, wraps one or more containers
  • Deployment — manages a set of identical Pods, handles rollouts and rollbacks
  • Service — exposes your Pods to the network (internally or externally)

Step 3: Write Your First Deployment

Create a file called deployment.yaml:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-app
  labels:
    app: nginx
spec:
  replicas: 3
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.25-alpine
        ports:
        - containerPort: 80
        resources:
          requests:
            cpu: "50m"
            memory: "64Mi"
          limits:
            cpu: "100m"
            memory: "128Mi"

Apply it:

kubectl apply -f deployment.yaml
kubectl get pods -w  # watch pods come up

Step 4: Expose it with a Service

Create service.yaml:

apiVersion: v1
kind: Service
metadata:
  name: nginx-service
spec:
  selector:
    app: nginx
  ports:
    - protocol: TCP
      port: 80
      targetPort: 80
  type: NodePort

kubectl apply -f service.yaml
kubectl port-forward service/nginx-service 8080:80

Open http://localhost:8080 — you should see the nginx welcome page. You just deployed your first app on Kubernetes.

Step 5: Scale and Self-Heal

Try killing a pod and watch Kubernetes bring it back:

# Scale to 5 replicas
kubectl scale deployment nginx-app --replicas=5

# Delete a pod — Kubernetes will recreate it automatically
kubectl delete pod $(kubectl get pods -l app=nginx -o jsonpath='{.items[0].metadata.name}')

# Watch the magic
kubectl get pods -w

Key Takeaways

  • Kubernetes separates what you want (desired state) from how it gets there
  • The control loop constantly reconciles actual state with desired state
  • Always set resource requests and limits — without them, a noisy pod can starve your entire cluster
  • Start with Deployments, Services, and ConfigMaps — those three cover 80% of real use cases