Kubernetes Basics: From Zero to Your First Deployment

Kubernetes (K8s) is the industry-standard container orchestration platform. It's intimidating at first, but the core concepts are straightforward once you see them in action.

Core Concepts

Concept	What It Does
Pod	The smallest deployable unit — wraps one or more containers
Deployment	Manages replicas of a Pod and handles rolling updates
Service	Stable network endpoint to reach your Pods
Namespace	Virtual cluster for isolating resources

Your First Pod

apiVersion: v1
kind: Pod
metadata:
  name: my-app
  labels:
    app: my-app
spec:
  containers:
    - name: app
      image: node:20-alpine
      ports:
        - containerPort: 3000

Apply it:

kubectl apply -f pod.yaml
kubectl get pods

Using a Deployment (Recommended)

Never run bare Pods in production. Use a Deployment:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: my-app
spec:
  replicas: 3
  selector:
    matchLabels:
      app: my-app
  template:
    metadata:
      labels:
        app: my-app
    spec:
      containers:
        - name: app
          image: myrepo/my-app:latest
          ports:
            - containerPort: 3000
          env:
            - name: NODE_ENV
              value: "production"

Exposing with a Service

apiVersion: v1
kind: Service
metadata:
  name: my-app-service
spec:
  selector:
    app: my-app
  ports:
    - port: 80
      targetPort: 3000
  type: LoadBalancer

Essential kubectl Commands

# Apply any manifest
kubectl apply -f deployment.yaml

# Watch pods start up
kubectl get pods -w

# Check logs
kubectl logs deployment/my-app

# Exec into a container
kubectl exec -it <pod-name> -- /bin/sh

# Delete everything
kubectl delete -f deployment.yaml

Next Steps

• Learn Helm for packaging Kubernetes apps
• Set up Horizontal Pod Autoscaler for automatic scaling
• Explore Ingress controllers for routing external traffic

Kubernetes has a steep learning curve but understanding Deployments and Services alone gets you 80% of the way there for most applications.