Article 06: Service Discovery with Eureka

1. Objective

Learn how services discover each other dynamically using Eureka.

2. Key Concepts

• Service Registry
• Service Discovery
• Eureka Server
• Eureka Client

3. Problem Without Discovery

• Hardcoded hostnames
• Manual configuration
• Poor scalability

4. Eureka Architecture

          [Eureka Server]
           /           \
 [User Service]   [Order Service]

5. Hands-On: Create Eureka Server

Dependencies:

• spring-cloud-starter-netflix-eureka-server

Enable server:

@EnableEurekaServer
@SpringBootApplication
public class DiscoveryServerApplication {
}

application.yml:

server:
  port: 8761

6. Register Services as Eureka Clients

Add dependency:

• spring-cloud-starter-netflix-eureka-client

application.yml:

eureka:
  client:
    service-url:
      defaultZone: http://localhost:8761/eureka

7. Calling Service by Name

webClient.get()
    .uri("http://USER-SERVICE/users/1")

8. Benefits

• Dynamic discovery
• Load balancing
• No hardcoded URLs

9. Common Mistakes

• Forgetting to start Eureka first
• Mixing IP and service names

10. Interview Notes

• Eureka enables client-side discovery
• Widely used with Spring Cloud

11. Summary

Service discovery is foundational for scalable microservices.

12. What’s Next

Introduce API Gateway for centralized routing.