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Eureka Server And Eureka Client

Eureka Server

Eureka server is a discovery server its knows the informations about the registered service client, like IP address and port number. So we can collect the all registerd microservice host and portnumer in one place. In this blog I give the sample code for Eureak Server and Euraka Client.

To enable the eureak server, you annotate the Startup class with @EnableEurekaServer annotation

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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>2.5.5</version>
		<relativePath/> <!-- lookup parent from repository -->
	</parent>
	<groupId>com.samplecoder.euraeka</groupId>
	<artifactId>eureka</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<name>eureka</name>
	<description>Demo project for Spring Boot</description>
	<properties>
		<java.version>1.8</java.version>
		<spring-cloud.version>2020.0.4</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-web</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>

application.properties

spring.application.name=eureka
server.port= 8761

eureka.client.service-url.defaultZone = http://localhost:8761/eureka/
eureka.client.register-with-eureka=false
eureka.client.fetch-registry=false

EurekaApplication.java

package com.samplecoder.eureka;

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

@SpringBootApplication
@EnableEurekaServer
public class EurekaApplication{

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

EurekaClient

Every client should be registered with eureka server then only the eureka server know the client details. To make your application is eureka client the stater class should be annotated with the @EnableEurekaClient

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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>2.5.5</version>
		<relativePath/> <!-- lookup parent from repository -->
	</parent>
	<groupId>com.samplecoder.serviceapp</groupId>
	<artifactId>serviceapp</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<name>serviceapp</name>
	<description>Demo project for Spring Boot</description>
	<properties>
		<java.version>1.8</java.version>
		<spring-cloud.version>2020.0.4</spring-cloud.version>
	</properties>
	<dependencies>
		
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-web</artifactId>
		</dependency>
		<dependency>
			<groupId>org.springframework.cloud</groupId>
			<artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
		</dependency>
		<dependency>
			<groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-actuator</artifactId>
		</dependency>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-test</artifactId>
			<scope>test</scope>
		</dependency>
		<!-- <dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-amqp</artifactId>
		</dependency>
		<dependency>
			<groupId>org.springframework.amqp</groupId>
			<artifactId>spring-rabbit-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>

application.properties

spring.application.name=samplemicro

management.endpoints.web.exposure.include=*

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

ServiceappApplication.java (Eureka Client Starter class)

package com.samplecoder.serviceapp;

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

@SpringBootApplication
@EnableEurekaClient
public class ServiceappApplication {

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

}

AppController.java (Rest Controller)

package com.samplecoder.serviceapp.controller;

import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
@RequestMapping("/api")
public class AppController {
	
	@GetMapping("/sayHi")
	private ResponseEntity<String> sayHi() {
		return new ResponseEntity<String>("Hi",HttpStatus.OK);
	}
}

Result

  • You should run the eureka server application first then only run the client application. otherwise client application get failed while registering the themself as a service with server.
  • you can check the eureka server http://localhost:8761/
eureka server
eureka server

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