In this tutorials, we are going to see Spring Boot Eureka/ Spring Cloud Eureka.

Spring Boot Eureka:

Spring Cloud Eureka is a wrapper of Eureka which build from Netflix.

Doc: Spring Cloud Eureka is a Client-side service discovery allows each service to find and communicate with each other without hard coding hostname and port. The only ‘fixed point’ in such an architecture consists of a service registry with which each service has to register.

Spring Boot Eureka Server Example:

Here I am going to create two different micro-services, both are individual applications one will act as a server and another one is a client. Intermediately I am going to create a Eureka server as service registry it allows both client and servers to communicate with each other without knowing the hostname and port number.

Technologies Used:

• Spring Boot Starter 2.0.5
• Spring-cloud-starter-netflix-eureka-server
• Spring-cloud-dependencies
• Java 8
• IntelliJ Idea

Application Structure:

Dependencies for Eureka Server:

To implement eureka server as service registry we have to add the below dependencies in pom.xml

<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-test</artifactId>
    <scope>test</scope>
  </dependency>
</dependencies>
<dependencyManagement>
  <dependencies>
    <dependency>
      <groupId>org.springframework.cloud</groupId>
      <artifactId>spring-cloud-dependencies</artifactId>
      <version>${spring-cloud.version}</version>
      <type>pom</type>
      <scope>import</scope>
    </dependency>
  </dependencies>
</dependencyManagement>

Complete pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>

  <groupId>com.onlinetutorialspoint</groupId>
  <artifactId>SpringBoot_Eureka_Server</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <packaging>jar</packaging>

  <name>SpringBoot_Eureka_Server</name>
  <description>Spring Boot Eureka Server Example</description>

  <parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>2.0.5.RELEASE</version>
    <relativePath/> <!-- lookup parent from repository -->
  </parent>

  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
    <java.version>1.8</java.version>
    <spring-cloud.version>Finchley.SR1</spring-cloud.version>
  </properties>
  <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-test</artifactId>
      <scope>test</scope>
    </dependency>
  </dependencies>
  <dependencyManagement>
    <dependencies>
      <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-dependencies</artifactId>
        <version>${spring-cloud.version}</version>
        <type>pom</type>
        <scope>import</scope>
      </dependency>
    </dependencies>
  </dependencyManagement>
  <build>
    <plugins>
      <plugin>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-maven-plugin</artifactId>
      </plugin>
    </plugins>
  </build>
</project>

Service registry configuration in application.yml file.

spring:
  application:
    name: eureka_server
server:
  port: 8090

eureka:
  client:
    registerWithEureka: false
    fetchRegistry: false
    server:
      waitTimeInMsWhenSyncEmpty: 0

Here, I am mentioning application name as eureka_server and port as 8090. As this application act as a eureka server, it should not be registered with default eureka client so that we should make use of reisterWithEureka:false and fetchRegisty:false.

Enabling eureka server in spring boot application.

package com.onlinetutorialspoint;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.server.EnableEurekaServer;

@EnableEurekaServer
@SpringBootApplication
public class SpringBootEurekaServerApplication {

  public static void main(String[] args) {
    SpringApplication.run(SpringBootEurekaServerApplication.class, args);
  }
}

Enabling Eureka Server with Spring Boot as simple as annotating @EnableEurekaServer annotation on top of @SprinBootApplication.

Run the application:

mvn spring-boot:run

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::        (v2.0.5.RELEASE)

2018-10-07 20:41:23.423  INFO 2036 --- [           main] c.o.SpringBootEurekaServerApplication    : No active profile set, falling back to default profiles: default
2018-10-07 20:41:23.457  INFO 2036 --- [           main] ConfigServletWebServerApplicationContext : Refreshing org.springframework.boot.web.servlet.context.AnnotationConfigServletWebServerApplicationContext@53bc1328: startup date [Sun Oct 07 20:41:23 IST 2018]; parent: org.springframework.context.annotation.AnnotationConfigApplicationContext@39d9314d
2018-10-07 20:41:26.040  INFO 2036 --- [           main] o.s.cloud.context.scope.GenericScope     : BeanFactory id=e1e941da-179e-3162-9b2c-a5223c94cb1f
.........
.........

After running the application, we can see the eureka dashboard like below by accessing our application’s url.

http://localhost:8090/

On the above eureka dashboard, we can see the basic information about system status and current instances. Currently, we do not have any registered instances with eureka service.

References:

Spring Cloud Netflix Eureka

Happy Learning 🙂