Kubernetes: Orchestration Basics

Kubernetes orchestrates containerized applications at scale. This article covers Kubernetes fundamentals.

Introduction

Kubernetes provides:

Container orchestration
Auto-scaling
Self-healing
Rolling updates
Service discovery

Kubernetes Manifests

Deployment

apiVersion: apps/v1
kind: Deployment
metadata:
  name: app-deployment
spec:
  replicas: 3
  selector:
    matchLabels:
      app: myapp
  template:
    metadata:
      labels:
        app: myapp
    spec:
      containers:
      - name: app
        image: myapp:1.0.0
        ports:
        - containerPort: 3000
        env:
        - name: NODE_ENV
          value: "production"
        resources:
          requests:
            memory: "256Mi"
            cpu: "250m"
          limits:
            memory: "512Mi"
            cpu: "500m"
        livenessProbe:
          httpGet:
            path: /health
            port: 3000
          initialDelaySeconds: 30
          periodSeconds: 10

Service

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

Commands

Kubectl Commands

# ✅ Good: Deploy application
kubectl apply -f deployment.yaml
kubectl apply -f service.yaml

# ✅ Good: Check status
kubectl get deployments
kubectl get pods
kubectl get services

# ✅ Good: View logs
kubectl logs deployment/app-deployment
kubectl logs pod-name

# ✅ Good: Scale deployment
kubectl scale deployment app-deployment --replicas=5

# ✅ Good: Update image
kubectl set image deployment/app-deployment app=myapp:2.0.0

# ✅ Good: Rollback
kubectl rollout undo deployment/app-deployment

# ✅ Good: Delete resources
kubectl delete deployment app-deployment
kubectl delete service app-service

Best Practices

Use resource limits:

# ✅ Good: Resource limits
resources:
  requests:
    memory: "256Mi"
    cpu: "250m"
  limits:
    memory: "512Mi"
    cpu: "500m"

# ❌ Bad: No limits

Use health checks:

# ✅ Good: Health checks
livenessProbe:
  httpGet:
    path: /health
    port: 3000
  initialDelaySeconds: 30

# ❌ Bad: No health checks

Use namespaces:

# ✅ Good: Use namespaces
kubectl create namespace production
kubectl apply -f deployment.yaml -n production

# ❌ Bad: Use default namespace
kubectl apply -f deployment.yaml

Summary

Kubernetes is essential. Key takeaways:

Create deployments
Define services
Set resource limits
Use health checks
Scale applications
Update images
Rollback deployments
Use namespaces

Next Steps

Learn about Infrastructure
Explore CI/CD
Study Monitoring
Practice Kubernetes
Deploy applications