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Eureka Service Discovery Guide

Aug 9, 2024

Spring Cloud Eureka Tutorial

What is Eureka?

  • A service registry provided by Netflix, integrated with the Spring framework.
  • Used for deploying microservices.

Use of Eureka

  • In microservice architecture, we develop separate services and expose APIs as service endpoints.
  • Services communicate internally via REST APIs.
  • Avoids tight coupling of clients with individual service URLs.

Microservice Communication Model

  • Diagram Explanation:
    • Service 1, Service 2, and Service 3 can be accessed by a client using their respective URLs.
    • Example: http://localhost:8081/service1, http://localhost:8082/service2, etc.
  • Challenge: Clients need to know multiple service URLs, which can be cumbersome.
  • Solution: Use a service registry (Eureka) to dynamically resolve service URLs.

How Eureka Works

  1. Client requests service through the Eureka server instead of directly hitting the service URL.
  2. Eureka server holds the registry of services and their endpoints.
  3. Eureka forwards requests to the correct microservice based on service name and URL.

Creating a Eureka Server

  • Project Setup:
    • Create a Spring Boot project named "Amazon Server Eureka server".
    • Add dependencies: Dev Tools, Web, Eureka Server.
  • Server Configuration:
    • Annotate class with @EnableEurekaServer.
    • Create a YAML configuration file:
      • Set registerWithEureka: false
      • Set server.port: 8761
      • Set spring.application.name: Amazon Server
  • Run Application: Check Eureka dashboard at http://localhost:8761.

Developing a Microservice

  1. Create Payment Service:
    • Create another Spring Boot project named "Payment Service".
    • Add dependencies: Eureka Discovery, Dev Tools.
    • Annotate class with @EnableEurekaClient.
  2. Expose API:
    • Create a Controller with a GET method to handle payment requests.
    • Use @RestController and @GetMapping for defining the endpoint.
  3. Register with Eureka:
    • Create a YAML configuration file for this payment service:
      • Set eureka.client.registerWithEureka: true
      • Set eureka.client.service-url.defaultZone: http://localhost:8761/eureka/
      • Specify a unique service name.

Creating the Client Application

  1. Project Setup:
    • Create a Spring Boot project named "Amazon Shopping".
    • Add dependencies: Web, Eureka Discovery.
    • Annotate class with @EnableEurekaClient.
  2. Invoke Payment Service:
    • Create a Controller to handle incoming requests.
    • Use RestTemplate to call the payment service through Eureka.
    • Example of service invocation using the registered service name instead of the actual URL.
  3. YAML Configuration for Client:
    • Set eureka.client.service-url.defaultZone and unique service name.

Testing the Implementation

  • Postman: Use Postman to send requests to the client service, which in turn accesses the payment service through Eureka.
  • Response Verification: Check responses and timings to confirm dynamic routing through Eureka.

Conclusion

  • The tutorial demonstrated setting up a Eureka server, registering microservices, and invoking them through a client using Eureka for service discovery.
  • Potential for creating more complex use cases and scaling microservices dynamically.

For additional resources, refer to the provided blog and video links. Subscribe for updates and more tutorials.

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