In Microservices, Service Discovery helps us by providing a database of available service instances so that services can be discovered, registered, and de-registered based on usage. For a detailed explanation of Service Discovery please refer to this article Service Discovery and Service Registry in Microservices. In this article, we are going to develop Service Discovery with the help of Spring Cloud.
Step-by-Step Implementation
Step 1: Create a New Spring Boot Project in Spring Initializr
To create a new Spring Boot project, please refer to How to Create a Spring Boot Project in Spring Initializr and Run it in IntelliJ IDEA. For this project choose the following things
- Project: Maven
- Language: Java
- Packaging: Jar
- Java: 17
Please choose the following dependencies while creating the project.
- Eureka Server
Generate the project and run it in IntelliJ IDEA by referring to the above article. Below is the complete pom.xml file. Please cross-verify if you have missed some dependencies.
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>3.0.6</version> <relativePath/> <!-- lookup parent from repository --> </parent> <groupId>com.gfg.discovery-service</groupId> <artifactId>discovery-service</artifactId> <version>0.0.1-SNAPSHOT</version> <name>Discovery Service</name> <description>Demo project for Discovery Service</description> <properties> <java.version>17</java.version> <spring-cloud.version>2022.0.2</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> <repositories> <repository> <id>netflix-candidates</id> <name>Netflix Candidates</name> <snapshots> <enabled>false</enabled> </snapshots> </repository> </repositories> </project> |
Step 2: Modify DiscoveryServiceApplication Class
Go to the discovery-service > src > main > java > DiscoveryServiceApplication and annotate it with @EnableEurekaServer annotation. Below is the complete code for DiscoveryServiceApplication Class.
Java
package com.gfg.discoveryservice; import org.springframework.boot.SpringApplication;import org.springframework.boot.autoconfigure.SpringBootApplication;import org.springframework.cloud.netflix.eureka.server.EnableEurekaServer; @SpringBootApplication@EnableEurekaServerpublic class DiscoveryServiceApplication { public static void main(String[] args) { SpringApplication.run(DiscoveryServiceApplication.class, args); } } |
Step 3: Make Changes in Your application.properties File
Now make the following changes in your application.properties file.
# Recommend Port Number to Use for Eureka Server
# But you can use any
server.port=8761
spring.application.name=discovery-service
# By writing this we are saying discovery service
# that no need to fetch any registry from
# another discovery service.
# You are the only one here
eureka.client.fetchRegistry=false
# By writing this we are saying that there is
# no need to register yourself in
# your discover server registry
# I know your port number and IP and
# I know how to connect with you.
# You are here to discover other microservices not yourself
eureka.client.register-with-eureka=false
Why is this line eureka.client.fetchRegistry=false?
By writing this we are saying discovery service that no need to fetch any registry from another discovery service. You are the only one here.
Why is this line eureka.client.register-with-eureka=false?
By writing this we are saying that there is no need to register yourself in your discover server registry. It knows the port number and IP and it knows how to connect with you. You are here to discover other microservices not yourself.
Now run your discovery-service. If everything goes well then you may see the following screen in your console. Please refer to the below image.
Now hit the following URL in your browser
http://localhost:8761/
And you can see the Spring Eureka dashboard like below.
