Kubernetes (K8s) is the industry-standard platform for orchestrating containerized applications. Once you’ve mastered Docker, Kubernetes is your next step to managing containers at scale.

What is Kubernetes?

Kubernetes automates deployment, scaling, and management of containerized applications. Think of it as an operating system for your cluster of machines.

Core Components:

• Pod: Smallest deployable unit (one or more containers)
• Service: Exposes pods to network traffic
• Deployment: Manages pod replicas and updates
• Namespace: Virtual cluster for resource isolation

Why Use Kubernetes?

Key Benefits:

• Auto-scaling: Automatically adjust resources based on load
• Self-healing: Restart failed containers automatically
• Load balancing: Distribute traffic across pods
• Rolling updates: Deploy new versions with zero downtime

Getting Started

Install kubectl:

# macOS
brew install kubectl

# Linux
curl -LO "https://dl.k8s.io/release/$(curl -L -s https://dl.k8s.io/release/stable.txt)/bin/linux/amd64/kubectl"
chmod +x kubectl
sudo mv kubectl /usr/local/bin/

Verify installation:

kubectl version --client

Your First Pod

Create a simple nginx pod:

# pod.yaml
apiVersion: v1
kind: Pod
metadata:
  name: nginx-pod
spec:
  containers:
  - name: nginx
    image: nginx:latest
    ports:
    - containerPort: 80

Deploy it:

kubectl apply -f pod.yaml
kubectl get pods
kubectl describe pod nginx-pod

Creating a Deployment

Deployments are more robust than raw pods:

# deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: web-app
spec:
  replicas: 3
  selector:
    matchLabels:
      app: web
  template:
    metadata:
      labels:
        app: web
    spec:
      containers:
      - name: nginx
        image: nginx:1.21
        ports:
        - containerPort: 80

Deploy and scale:

kubectl apply -f deployment.yaml
kubectl get deployments
kubectl scale deployment web-app --replicas=5

Exposing Your Application

Create a Service to expose your deployment:

# service.yaml
apiVersion: v1
kind: Service
metadata:
  name: web-service
spec:
  type: LoadBalancer
  selector:
    app: web
  ports:
  - port: 80
    targetPort: 80

Apply and check:

kubectl apply -f service.yaml
kubectl get services

Common Commands

Pod Management:

kubectl get pods                    # List all pods
kubectl logs <pod-name>            # View logs
kubectl exec -it <pod-name> bash   # Shell into pod
kubectl delete pod <pod-name>      # Delete pod

Deployment Management:

kubectl rollout status deployment/web-app
kubectl rollout history deployment/web-app
kubectl rollout undo deployment/web-app

ConfigMaps and Secrets

ConfigMap for configuration:

apiVersion: v1
kind: ConfigMap
metadata:
  name: app-config
data:
  DATABASE_URL: "postgres://db:5432"
  LOG_LEVEL: "info"

Secret for sensitive data:

kubectl create secret generic db-password \
  --from-literal=password='mySecretPassword'

Best Practices

1. Use namespaces for environment separation
2. Set resource limits to prevent resource exhaustion
3. Implement health checks (liveness and readiness probes)
4. Use labels for organization and selection
5. Store configs in ConfigMaps, secrets in Secrets

Development Tools

Minikube - Local Kubernetes cluster:

brew install minikube
minikube start
minikube dashboard

K9s - Terminal-based cluster management:

brew install k9s
k9s

Next Steps

• Learn Helm for package management
• Explore Ingress controllers for routing
• Study persistent volumes for stateful apps
• Implement CI/CD pipelines with K8s
• Investigate service meshes (Istio, Linkerd)

Kubernetes has a steep learning curve, but it’s essential for modern cloud-native development. Start with local clusters, practice basic operations, and gradually move to production deployments.