Microservices Architecture with Spring Boot & Kubernetes

Introduction to Microservices Architecture

Modern applications demand scalability, resilience, and maintainability. Microservices architecture, combined with Spring Boot and Kubernetes, provides a robust foundation for building distributed systems. This guide walks through the complete process of designing, implementing, and deploying microservices in a production environment.

Microservice Design Patterns

1. Service Architecture

Essential patterns for microservice design:

• • API Gateway Pattern
• • Circuit Breaker Pattern
• • Event Sourcing
• • CQRS (Command Query Responsibility Segregation)

2. Spring Boot Implementation

@SpringBootApplication
@EnableDiscoveryClient
public class OrderService {
    @Bean
    @LoadBalanced
    public RestTemplate restTemplate() {
        return new RestTemplate();
    }

    @Bean
    public CircuitBreakerFactory circuitBreakerFactory() {
        Resilience4JCircuitBreakerFactory factory = 
            new Resilience4JCircuitBreakerFactory();
        factory.configureDefault(id -> new Resilience4JConfigBuilder(id)
            .timeLimiterConfig(TimeLimiterConfig.custom()
                .timeoutDuration(Duration.ofSeconds(4))
                .build())
            .circuitBreakerConfig(CircuitBreakerConfig.ofDefaults())
            .build());
        return factory;
    }
}

Implementation Details

1. Service Communication

@Service
public class OrderProcessor {
    @Autowired
    private RestTemplate restTemplate;
    
    @CircuitBreaker(name = "payment-service")
    public OrderResponse processOrder(Order order) {
        PaymentRequest paymentRequest = new PaymentRequest(order);
        return restTemplate.postForObject(
            "http://payment-service/api/v1/process",
            paymentRequest,
            OrderResponse.class
        );
    }
}

2. API Gateway Configuration

spring:
  cloud:
    gateway:
      routes:
        - id: order-service
          uri: lb://order-service
          predicates:
            - Path=/api/orders/**
          filters:
            - name: CircuitBreaker
              args:
                name: orderService
                fallbackUri: forward:/fallback

Containerization with Docker

1. Dockerfile Example

FROM openjdk:17-jdk-slim
WORKDIR /app
COPY target/*.jar app.jar
EXPOSE 8080
ENTRYPOINT ["java", "-jar", "app.jar"]

2. Docker Compose Setup

version: '3.8'
services:
  order-service:
    build: ./order-service
    ports:
      - "8081:8080"
    environment:
      - SPRING_PROFILES_ACTIVE=docker
      - EUREKA_CLIENT_SERVICEURL_DEFAULTZONE=http://eureka:8761/eureka/
    depends_on:
      - eureka

Kubernetes Orchestration

1. Deployment Configuration

apiVersion: apps/v1
kind: Deployment
metadata:
  name: order-service
spec:
  replicas: 3
  selector:
    matchLabels:
      app: order-service
  template:
    metadata:
      labels:
        app: order-service
    spec:
      containers:
      - name: order-service
        image: order-service:latest
        ports:
        - containerPort: 8080
        resources:
          requests:
            memory: "256Mi"
            cpu: "200m"
          limits:
            memory: "512Mi"
            cpu: "500m"

2. Service Configuration

apiVersion: v1
kind: Service
metadata:
  name: order-service
spec:
  selector:
    app: order-service
  ports:
    - port: 80
      targetPort: 8080
  type: LoadBalancer

Monitoring and Scaling

Essential monitoring and scaling strategies:

• • Prometheus and Grafana integration
• • Horizontal Pod Autoscaling (HPA)
• • Distributed tracing with Jaeger
• • Log aggregation with ELK stack

Conclusion

Building microservices with Spring Boot and Kubernetes provides a powerful foundation for scalable, resilient applications. By following these patterns and practices, teams can successfully implement and maintain distributed systems while ensuring high availability and performance.