What is Service Discovery in Spring Boot Microservices?

Service Discovery (such as Netflix Eureka) allows microservices to dynamically locate each other on a network without hardcoding IP addresses.

Why use an API Gateway in Microservices?

An API Gateway acts as a single entry point for client requests, handling routing, security, rate limiting, and load balancing across all underlying microservices.

Spring Boot Microservices Architecture Tutorial (2026 Guide)

1. What is Monolithic vs Microservices Architecture?

In traditional Monolithic Applications, all business logic, database connections, user interfaces, and background tasks reside within a single codebase. While simple for small projects, monoliths become difficult to scale and maintain as teams grow.

Microservices Architecture decomposes a large system into autonomous, loosely coupled services (e.g., User Service, Order Service, Payment Service). Each microservice has its own dedicated database schema, communicates via lightweight REST/gRPC protocols, and can be deployed independently.

2. Core Components of Spring Cloud Microservices

A. Service Discovery (Spring Cloud Netflix Eureka)

Instead of hardcoding microservice IP addresses, services register themselves with Eureka Naming Server. Other services query Eureka to dynamically discover target instances.

// Eureka Server Application Annotation
@SpringBootApplication
@EnableEurekaServer
public class ServiceRegistryApplication {
    public static void main(String[] args) {
        SpringApplication.run(ServiceRegistryApplication.class, args);
    }
}
      

B. API Gateway (Spring Cloud Gateway)

Acts as the central entry point for external mobile and web clients. It handles authentication tokens (JWT), routing, rate limiting, and CORS headers across all backend microservices.

# application.yml Configuration for API Gateway
spring:
  cloud:
    gateway:
      routes:
        - id: user-service
          uri: lb://USER-SERVICE
          predicates:
            - Path=/api/users/**
        - id: order-service
          uri: lb://ORDER-SERVICE
          predicates:
            - Path=/api/orders/**
      

C. Inter-Service Communication (OpenFeign)

Declarative REST client for Java Spring Boot. Feign allows microservices to invoke endpoints of other microservices using simple interface definitions.

@FeignClient(name = "PAYMENT-SERVICE")
public interface PaymentClient {
    @PostMapping("/api/payments/process")
    PaymentResponse processPayment(@RequestBody PaymentRequest request);
}
      

Microservices FAQ

Q1. How do microservices handle database transactions across multiple services?

Microservices use the Saga Pattern (Choreography or Orchestration) or Event-Driven Architecture (Apache Kafka) to ensure eventual consistency without two-phase commit locks.

Q2. How to implement Fault Tolerance in Spring Boot?

Use Resilience4j Circuit Breaker to prevent cascading failures when a downstream microservice experiences downtime.

Spring Boot Microservices Architecture Guide