Spring Cloud - Service Discovery

Introduction

Service discovery is one of the most critical parts when an application is deployed as microservices in the cloud. This is because for any use operation, an application in a microservice architecture may require access to multiple services and the communication amongst them.

Service discovery helps tracking the service address and the ports where the service instances can be contacted to. There are three components at play here −

• Service Instances − Responsible to handle incoming request for the service and respond to those requests.

• Service Registry − Keeps track of the addresses of the service instances. The service instances are supposed to register their address with the service registry.

• Service Client − The client which wants access or wants to place a request and get response from the service instances. The service client contacts the service registry to get the address of the instances.

Apache Zookeeper, Eureka and Consul are a few well-known components which are used for Service Discovery. In this tutorial, we will use Eureka

Dependencies for Eureka Server/Registry

For setting up Eureka Server, we need to update the POM file to contain the following dependency −

<dependencies>
   <dependency>
      <groupId>org.springframework.cloud</groupId>
      <artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
   </dependency>
   <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-web</artifactId>
   </dependency>
</dependencies>