How do you deploy Spring Boot applications on Kubernetes? Kubernetes पर Spring Boot applications कैसे deploy करते हैं?

Create Kubernetes manifests (Deployment, Service, ConfigMap) to run containerized Spring Boot apps. Use kubectl for deployment, manage scaling, and enable service discovery in cluster.

// deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: app
  labels:
    app: app
spec:
  replicas: 3
  strategy:
    type: RollingUpdate
    rollingUpdate:
      maxSurge: 1
      maxUnavailable: 0
  selector:
    matchLabels:
      app: app
  template:
    metadata:
      labels:
        app: app
    spec:
      containers:
      - name: app
        image: app:1.0
        imagePullPolicy: IfNotPresent
        ports:
        - containerPort: 8080
        env:
        - name: SPRING_PROFILES_ACTIVE
          value: 'kubernetes'
        - name: SPRING_DATASOURCE_URL
          valueFrom:
            configMapKeyRef:
              name: app-config
              key: db-url
        resources:
          requests:
            memory: '512Mi'
            cpu: '250m'
          limits:
            memory: '1024Mi'
            cpu: '500m'
        livenessProbe:
          httpGet:
            path: /actuator/health/liveness
            port: 8080
          initialDelaySeconds: 30
          periodSeconds: 10
        readinessProbe:
          httpGet:
            path: /actuator/health/readiness
            port: 8080
          initialDelaySeconds: 10
          periodSeconds: 5

// service.yaml
apiVersion: v1
kind: Service
metadata:
  name: app-service
spec:
  type: LoadBalancer
  selector:
    app: app
  ports:
  - protocol: TCP
    port: 80
    targetPort: 8080

// configmap.yaml
apiVersion: v1
kind: ConfigMap
metadata:
  name: app-config
data:
  db-url: 'jdbc:mysql://mysql-service:3306/appdb'
  log-level: 'INFO'

// Deployment Commands
# Apply manifests
kubectl apply -f deployment.yaml
kubectl apply -f service.yaml
kubectl apply -f configmap.yaml

# Check deployment status
kubectl get deployments
kubectl get pods
kubectl logs -f pod-name

# Scale application
kubectl scale deployment app --replicas=5

// Liveness vs Readiness Probes
// Liveness: Is app alive? (restart if false)
// Readiness: Can app handle traffic? (remove from LB if false)

// Production Checklist:
// 1. Resource limits (CPU, memory)
// 2. Health checks (liveness, readiness)
// 3. Rolling updates
// 4. Service discovery
// 5. ConfigMap for config
// 6. Secrets for credentials
// 7. Persistent volumes for data
// 8. Horizontal Pod Autoscaler (HPA)