Kubernetes Deployment YAML for Java Applications

This comprehensive guide covers Kubernetes deployment configurations specifically optimized for Java applications, including best practices, resource management, and production-ready configurations.

Basic Java Application Deployment

1. Simple Spring Boot Deployment

apiVersion: apps/v1 kind: Deployment metadata: name: spring-boot-app namespace: java-apps labels: app: spring-boot-app version: v1 component: backend spec: replicas: 3 selector: matchLabels: app: spring-boot-app template: metadata: labels: app: spring-boot-app version: v1 annotations: prometheus.io/scrape: "true" prometheus.io/port: "8080" prometheus.io/path: "/actuator/prometheus" spec: containers: - name: spring-boot-app image: my-registry/java-app:1.0.0 imagePullPolicy: IfNotPresent ports: - containerPort: 8080 name: http protocol: TCP env: - name: SPRING_PROFILES_ACTIVE value: "production" - name: JAVA_OPTS value: "-Xmx512m -Xms256m -XX:+UseG1GC" resources: requests: memory: "512Mi" cpu: "250m" limits: memory: "1Gi" cpu: "500m" livenessProbe: httpGet: path: /actuator/health/liveness port: 8080 initialDelaySeconds: 90 periodSeconds: 30 timeoutSeconds: 10 failureThreshold: 3 readinessProbe: httpGet: path: /actuator/health/readiness port: 8080 initialDelaySeconds: 30 periodSeconds: 15 timeoutSeconds: 5 failureThreshold: 3 startupProbe: httpGet: path: /actuator/health/readiness port: 8080 initialDelaySeconds: 10 periodSeconds: 10 failureThreshold: 30 volumeMounts: - name: tmp-volume mountPath: /tmp volumes: - name: tmp-volume emptyDir: {} terminationGracePeriodSeconds: 60 --- apiVersion: v1 kind: Service metadata: name: spring-boot-service namespace: java-apps labels: app: spring-boot-app spec: selector: app: spring-boot-app ports: - port: 80 targetPort: 8080 protocol: TCP name: http type: ClusterIP

Advanced Java-Specific Configurations

2. Microservices Deployment with Multiple JVM Options

apiVersion: apps/v1 kind: Deployment metadata: name: user-service namespace: microservices spec: replicas: 2 selector: matchLabels: app: user-service strategy: type: RollingUpdate rollingUpdate: maxSurge: 1 maxUnavailable: 0 template: metadata: labels: app: user-service tier: backend annotations: sidecar.istio.io/inject: "true" spec: containers: - name: user-service image: my-registry/user-service:2.1.0 ports: - containerPort: 8080 env: - name: JAVA_TOOL_OPTIONS value: >- -Xmx1024m -Xms512m -XX:+UseG1GC -XX:MaxGCPauseMillis=200 -XX:+UnlockExperimentalVMOptions -XX:+UseContainerSupport -Djava.security.egd=file:/dev/./urandom -Dspring.profiles.active=kubernetes - name: SPRING_APPLICATION_NAME value: "user-service" - name: MANAGEMENT_ENDPOINTS_WEB_EXPOSURE_INCLUDE value: "health,info,metrics,prometheus" - name: LOGGING_LEVEL_COM_EXAMPLE value: "INFO" resources: requests: memory: "768Mi" cpu: "300m" ephemeral-storage: "1Gi" limits: memory: "1536Mi" cpu: "800m" ephemeral-storage: "2Gi" livenessProbe: httpGet: path: /actuator/health/liveness port: 8080 httpHeaders: - name: Custom-Header value: "Liveness-Check" initialDelaySeconds: 120 periodSeconds: 30 timeoutSeconds: 10 readinessProbe: httpGet: path: /actuator/health/readiness port: 8080 initialDelaySeconds: 45 periodSeconds: 20 timeoutSeconds: 5 startupProbe: httpGet: path: /actuator/health/readiness port: 8080 initialDelaySeconds: 15 periodSeconds: 10 failureThreshold: 30 lifecycle: preStop: exec: command: - /bin/sh - -c - | curl -X POST http://localhost:8080/actuator/shutdown || true sleep 30 volumeMounts: - name: config-volume mountPath: /app/config - name: logs-volume mountPath: /app/logs securityContext: runAsNonRoot: true runAsUser: 1000 allowPrivilegeEscalation: false readOnlyRootFilesystem: true volumes: - name: config-volume configMap: name: user-service-config - name: logs-volume emptyDir: {} imagePullSecrets: - name: registry-credentials nodeSelector: node-type: application tolerations: - key: "app" operator: "Equal" value: "java" effect: "NoSchedule"

3. Stateful Java Application (e.g., with Database)

apiVersion: apps/v1 kind: StatefulSet metadata: name: order-processing-service namespace: java-apps spec: serviceName: "order-service" replicas: 2 selector: matchLabels: app: order-processing-service template: metadata: labels: app: order-processing-service version: v2 spec: containers: - name: order-service image: my-registry/order-service:3.0.0 ports: - containerPort: 8080 env: - name: JAVA_OPTS value: "-Xmx2g -Xms1g -XX:+UseG1GC -XX:MaxRAMPercentage=75.0" - name: POD_NAME valueFrom: fieldRef: fieldPath: metadata.name - name: NAMESPACE valueFrom: fieldRef: fieldPath: metadata.namespace resources: requests: memory: "2Gi" cpu: "500m" limits: memory: "3Gi" cpu: "1000m" volumeMounts: - name: data-volume mountPath: /app/data - name: temp-volume mountPath: /tmp volumes: - name: data-volume persistentVolumeClaim: claimName: order-data-pvc - name: temp-volume emptyDir: {} volumeClaimTemplates: - metadata: name: order-data-pvc spec: accessModes: [ "ReadWriteOnce" ] storageClassName: "fast-ssd" resources: requests: storage: 10Gi

Complete Microservices Stack

4. Multi-Service Deployment with ConfigMaps and Secrets

--- # ConfigMap for application configuration apiVersion: v1 kind: ConfigMap metadata: name: java-app-config namespace: java-apps data: application.yml: | server: port: 8080 shutdown: graceful spring: datasource: url: jdbc:postgresql://postgres-service:5432/mydb jpa: hibernate: ddl-auto: validate show-sql: false redis: host: redis-service port: 6379 logging: level: com.example: INFO org.hibernate.SQL: WARN management: endpoints: web: exposure: include: health,info,metrics endpoint: health: show-details: always probes: enabled: true --- # Secret for sensitive data apiVersion: v1 kind: Secret metadata: name: app-secrets namespace: java-apps type: Opaque data: database-password: cG9zdGdyZXNfcGFzc3dvcmQ= # base64 encoded api-key: eW91cl9hcGlfa2V5 # base64 encoded --- # Deployment using ConfigMap and Secret apiVersion: apps/v1 kind: Deployment metadata: name: api-gateway namespace: java-apps spec: replicas: 2 selector: matchLabels: app: api-gateway template: metadata: labels: app: api-gateway version: v1.2.0 spec: containers: - name: api-gateway image: my-registry/api-gateway:1.2.0 ports: - containerPort: 8080 env: - name: JAVA_OPTS value: "-Xmx1g -Xms512m -XX:+UseG1GC -Dspring.config.location=file:/app/config/application.yml" - name: DB_PASSWORD valueFrom: secretKeyRef: name: app-secrets key: database-password - name: API_KEY valueFrom: secretKeyRef: name: app-secrets key: api-key volumeMounts: - name: config-volume mountPath: /app/config readOnly: true resources: requests: memory: "768Mi" cpu: "300m" limits: memory: "1536Mi" cpu: "800m" livenessProbe: httpGet: path: /actuator/health/liveness port: 8080 initialDelaySeconds: 60 periodSeconds: 30 readinessProbe: httpGet: path: /actuator/health/readiness port: 8080 initialDelaySeconds: 30 periodSeconds: 15 volumes: - name: config-volume configMap: name: java-app-config items: - key: application.yml path: application.yml --- # Service for API Gateway apiVersion: v1 kind: Service metadata: name: api-gateway-service namespace: java-apps annotations: prometheus.io/scrape: "true" prometheus.io/port: "8080" spec: selector: app: api-gateway ports: - name: http port: 80 targetPort: 8080 protocol: TCP type: LoadBalancer externalTrafficPolicy: Local

Horizontal Pod Autoscaling

5. Auto-scaling Configuration for Java Apps

apiVersion: autoscaling/v2 kind: HorizontalPodAutoscaler metadata: name: java-app-hpa namespace: java-apps spec: scaleTargetRef: apiVersion: apps/v1 kind: Deployment name: spring-boot-app minReplicas: 2 maxReplicas: 10 metrics: - type: Resource resource: name: cpu target: type: Utilization averageUtilization: 70 - type: Resource resource: name: memory target: type: Utilization averageUtilization: 80 - type: Pods pods: metric: name: http_requests_per_second target: type: AverageValue averageValue: "500" behavior: scaleDown: stabilizationWindowSeconds: 300 policies: - type: Percent value: 50 periodSeconds: 60 - type: Pods value: 2 periodSeconds: 60 selectPolicy: Min scaleUp: stabilizationWindowSeconds: 60 policies: - type: Percent value: 100 periodSeconds: 30 - type: Pods value: 4 periodSeconds: 30 selectPolicy: Max

Job and CronJob for Batch Processing

6. Spring Batch Job Deployment

--- # CronJob for scheduled batch processing apiVersion: batch/v1 kind: CronJob metadata: name: data-processor-job namespace: java-apps spec: schedule: "0 2 * * *" # Run daily at 2 AM concurrencyPolicy: Forbid startingDeadlineSeconds: 600 jobTemplate: spec: template: spec: containers: - name: batch-processor image: my-registry/batch-processor:1.0.0 env: - name: JAVA_OPTS value: "-Xmx2g -Xms1g -XX:+UseG1GC -Dspring.batch.job.names=dataMigrationJob" - name: SPRING_PROFILES_ACTIVE value: "batch,production" resources: requests: memory: "2Gi" cpu: "500m" limits: memory: "3Gi" cpu: "1000m" volumeMounts: - name: input-data mountPath: /app/input - name: output-data mountPath: /app/output volumes: - name: input-data persistentVolumeClaim: claimName: input-data-pvc - name: output-data persistentVolumeClaim: claimName: output-data-pvc restartPolicy: OnFailure activeDeadlineSeconds: 3600 # 1 hour timeout --- # One-time Job apiVersion: batch/v1 kind: Job metadata: name: database-migration-job namespace: java-apps spec: backoffLimit: 3 activeDeadlineSeconds: 1800 template: spec: containers: - name: migration-job image: my-registry/migration-service:2.1.0 env: - name: JAVA_OPTS value: "-Xmx1g -Xms512m -Dspring.datasource.url=jdbc:postgresql://db-host:5432/mydb" command: ["java"] args: - "-jar" - "/app/app.jar" - "--spring.batch.job.name=dataMigrationJob" resources: requests: memory: "1Gi" cpu: "500m" limits: memory: "2Gi" cpu: "1000m" restartPolicy: Never

Advanced Features and Best Practices

7. Pod Disruption Budget

apiVersion: policy/v1 kind: PodDisruptionBudget metadata: name: java-app-pdb namespace: java-apps spec: minAvailable: 2 selector: matchLabels: app: spring-boot-app

8. Network Policies

apiVersion: networking.k8s.io/v1 kind: NetworkPolicy metadata: name: java-app-network-policy namespace: java-apps spec: podSelector: matchLabels: app: spring-boot-app policyTypes: - Ingress - Egress ingress: - from: - namespaceSelector: matchLabels: name: frontend-namespace ports: - protocol: TCP port: 8080 egress: - to: - namespaceSelector: matchLabels: name: database-namespace ports: - protocol: TCP port: 5432 - to: - namespaceSelector: matchLabels: name: redis-namespace ports: - protocol: TCP port: 6379

Monitoring and Observability

9. ServiceMonitor for Prometheus

apiVersion: monitoring.coreos.com/v1 kind: ServiceMonitor metadata: name: spring-boot-monitor namespace: java-apps labels: app: spring-boot-app release: prometheus spec: selector: matchLabels: app: spring-boot-app endpoints: - port: http path: /actuator/prometheus interval: 30s scrapeTimeout: 10s relabelings: - sourceLabels: [__meta_kubernetes_pod_name] targetLabel: pod_name

Best Practices Summary

Resource Management

# Good practices for Java apps resources: requests: memory: "512Mi" # Start with reasonable requests cpu: "250m" limits: memory: "1Gi" # Set limits to prevent runaway processes cpu: "500m"

JVM Optimization

env: - name: JAVA_OPTS value: >- -Xmx512m -Xms256m -XX:+UseG1GC -XX:MaxRAMPercentage=75.0 -XX:+UnlockExperimentalVMOptions -XX:+UseContainerSupport -Djava.security.egd=file:/dev/./urandom

Health Checks

livenessProbe: httpGet: path: /actuator/health/liveness port: 8080 initialDelaySeconds: 90 # Give JVM time to start periodSeconds: 30 readinessProbe: httpGet: path: /actuator/health/readiness port: 8080 initialDelaySeconds: 30 periodSeconds: 15 startupProbe: httpGet: path: /actuator/health/readiness port: 8080 initialDelaySeconds: 10 periodSeconds: 10 failureThreshold: 30 # Allow up to 5 minutes for startup

Graceful Shutdown

terminationGracePeriodSeconds: 60 lifecycle: preStop: exec: command: - /bin/sh - -c - | # Send graceful shutdown signal to Spring Boot curl -X POST http://localhost:8080/actuator/shutdown || true sleep 30

These Kubernetes deployment configurations provide a solid foundation for running Java applications in production environments, with proper resource management, health monitoring, and scalability considerations specific to JVM-based applications.