Microservice - Spring Cloud Netflix Eureka Service Registry

Let’s go ahead and create our service registry project (terawarehouse-service-discovery). A service registry like Netflix Eureka is a fixed ...

Let’s go ahead and create our service registry project (terawarehouse-service-discovery). A service registry like Netflix Eureka is a fixed point that allows the services to find and communicate with each other without knowing the hostname nor the port but with only the Spring application name. Eureka enables client-side load balancing and with a peer setup each client can act as a server as each client communicates and synchronize with each other.

Let’s start with:

1. Setting up the Eureka Server - terawarehouse-service-discovery
2. Create a new SpringBoot project.
3. Add dependency to spring-cloud-starter-netflix-eureka-server which will provide the necessary dependencies to make this project a service registry server.
4. Add dependencies spring-boot-starter-web and spring-boot-starter-actuator to let us display the server information.
5. Annotate SpringBootApplication with EnableEurekaServer.
6. Create an application.yml configuration file with 2 profiles. Notice that I use different network IP for each profile. Don’t register the eureka server as a client.
1. instance1 - which we will deploy on our machine
2. instance2 - which we will deploy on another machine
7. Run the config server.
8. Run 2 instances with different profiles.
9. Check that they are a replica of each other.

Configuring the Client 

1. Add dependency to spring-cloud-starter-netflix-eureka-client. This will provide the needed dependencies for this project to connect to the service discovery server.
2. Annotate the SpringBoot class with EnableDiscoveryClient.
3. And finally add the eureka client information to our project’s configuration:
   eureka.client.register-with-eureka: true
   eureka.client.fetch-registry: true
   eureka.client.service-url.defaultZone:
   http://192.168.1.100:8761/eureka,http://192.168.1.101:8761/eureka
   eureka.client.instance.prefer-ip-address: true
   eureka.client.instance.ip-address: 192.168.1.100
4. Run the client.
5. Check if the client properly registers with the eureka server.

Later on, as we introduce new microservices (inventory, order, etc) we can use this service registry for the catalog to send a request to the inventory or simply allow REST communication between them with only the spring application name.

In the next lesson, we will introduce a server-side load balancer that will receive the requests from a client and forward it to the appropriate API using the service discovery information.

I hope everything is clear to this point. You can always ask questions in the comment section below and I’ll be sure to address them.

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I hope to catch you in the next one. Thanks for watching and have a nice day. Bye.

References

• https://spring.io/guides/gs/service-registration-and-discovery/

Repositories

• https://github.com/orgs/broodcamp
• https://github.com/orgs/terawarehouse

	server:
	address: 192.168.1.100
	eureka:
	instance:
	hostname: ${server.address}
	client:
	service-url:
	defaultZone: http://192.168.1.101:8761/eureka

view raw application-instance1.yml hosted with ❤ by GitHub

	server:
	address: 192.168.1.101
	port: 8761
	eureka:
	instance:
	hostname: ${server.address}
	client:
	service-url:
	defaultZone: http://192.168.1.100:8761/eureka

view raw application-instance2.yml hosted with ❤ by GitHub

	spring:
	application:
	name: terawarehouse-service-discovery
	profiles:
	active:
	- ${spring.profiles.active}
	server:
	port: 8761
	eureka:
	environment: ${spring.profiles.active}
	client:
	register-with-eureka: false
	fetch-registry: false
	instance:
	prefer-ip-address: true
	appname: eureka

view raw application.yml hosted with ❤ by GitHub

	# app
	spring.application.name=catalog
	server.port=8001
	spring.main.banner-mode=off
	spring.main.allow-bean-definition-overriding=true
	management.endpoints.web.exposure.include=*
	# api
	server.servlet.context-path=/api/v1/
	spring.data.rest.base-path=/api/spring/rest/
	# data source
	spring.datasource.url=jdbc:postgresql://localhost:5432/tw_catalog
	spring.datasource.username=kerri
	spring.datasource.password=kerri
	spring.datasource.driver-class-name=org.postgresql.Driver
	spring.jpa.properties.hibernate.dialect=org.hibernate.dialect.PostgreSQL9Dialect
	spring.jpa.properties.hibernate.jdbc.lob.non_contextual_creation=true
	#spring.jpa.hibernate.ddl-auto=create-drop
	spring.liquibase.change-log=classpath:db/changelog/db.changelog-rebuild.xml
	# basic auth credentials
	spring.security.user.name=client
	spring.security.user.password=client
	# config to connect to admin server
	spring.boot.admin.client.url=http://localhost:9990
	spring.boot.admin.client.username=admin
	spring.boot.admin.client.password=admin
	# config to send info to admin server
	spring.boot.admin.client.instance.metadata.user.name=${spring.boot.admin.client.username}
	spring.boot.admin.client.instance.metadata.user.password=${spring.boot.admin.client.username}
	# discovery client, will fail if not configured here
	eureka.client.register-with-eureka: true
	eureka.client.fetch-registry: true
	eureka.client.service-url.defaultZone: http://192.168.1.100:8761/eureka,http://192.168.1.101:8761/eureka
	eureka.client.instance.prefer-ip-address: true
	eureka.client.instance.ip-address: 192.168.1.100
	#spring.h2.console.enabled=true
	#logging.level.org.springframework=OFF
	#logging.level.root=OFF
	#logging.level.com.terawarehouse=debug
	#logging.level.com.broodcamp=debug

view raw catalog.properties hosted with ❤ by GitHub

	/**
	* An Open Source Inventory and Sales Management System
	* Copyright (C) 2019 Edward P. Legaspi (https://github.com/czetsuya)
	*
	* This program is free software: you can redistribute it and/or modify
	* it under the terms of the GNU General Public License as published by
	* the Free Software Foundation, either version 3 of the License, or
	* (at your option) any later version.
	*
	* This program is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	* GNU General Public License for more details.
	*
	* You should have received a copy of the GNU General Public License
	* along with this program. If not, see <https://www.gnu.org/licenses/>.
	*/
	package com.terawarehouse;
	import org.springframework.boot.SpringApplication;
	import org.springframework.boot.autoconfigure.SpringBootApplication;
	import org.springframework.boot.autoconfigure.domain.EntityScan;
	import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
	import org.springframework.context.annotation.ComponentScan;
	import org.springframework.data.jpa.repository.config.EnableJpaRepositories;
	import com.broodcamp.bean.ExtendedJPARepositoryFactoryBean;
	import com.broodcamp.data.repository.BaseRepositoryImpl;
	/**
	* @author Edward P. Legaspi | czetsuya@gmail.com
	*/
	@SpringBootApplication
	@EnableJpaRepositories( //
	basePackages = { "com.broodcamp.data.repository", "com.terawarehouse.data.repository" } //
	, repositoryBaseClass = BaseRepositoryImpl.class, repositoryFactoryBeanClass = ExtendedJPARepositoryFactoryBean.class)
	@EntityScan(basePackages = { "com.broodcamp.data.entity", "com.terawarehouse.data.entity" })
	@ComponentScan(basePackages = { "com.broodcamp", "com.terawarehouse" })
	@EnableDiscoveryClient
	public class TerawarehouseCatalogApplication {
	public static void main(String[] args) {
	SpringApplication.run(TerawarehouseCatalogApplication.class, args);
	}
	}

view raw spring_boot_client hosted with ❤ by GitHub

	@SpringBootApplication
	@EnableEurekaServer
	public class TerawarehouseServiceDiscoveryApplication {
	public static void main(String[] args) {
	SpringApplication.run(TerawarehouseServiceDiscoveryApplication.class, args);
	}
	}
	/**
	* An Open Source Inventory and Sales Management System
	* Copyright (C) 2019 Edward P. Legaspi (https://github.com/czetsuya)
	*
	* This program is free software: you can redistribute it and/or modify
	* it under the terms of the GNU General Public License as published by
	* the Free Software Foundation, either version 3 of the License, or
	* (at your option) any later version.
	*
	* This program is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	* GNU General Public License for more details.
	*
	* You should have received a copy of the GNU General Public License
	* along with this program. If not, see <https://www.gnu.org/licenses/>.
	*/
	package com.terawarehouse;
	import org.springframework.boot.SpringApplication;
	import org.springframework.boot.autoconfigure.SpringBootApplication;
	import org.springframework.boot.autoconfigure.domain.EntityScan;
	import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
	import org.springframework.context.annotation.ComponentScan;
	import org.springframework.data.jpa.repository.config.EnableJpaRepositories;
	import com.broodcamp.bean.ExtendedJPARepositoryFactoryBean;
	import com.broodcamp.data.repository.BaseRepositoryImpl;
	/**
	* @author Edward P. Legaspi | czetsuya@gmail.com
	*/
	@SpringBootApplication
	@EnableJpaRepositories( //
	basePackages = { "com.broodcamp.data.repository", "com.terawarehouse.data.repository" } //
	, repositoryBaseClass = BaseRepositoryImpl.class, repositoryFactoryBeanClass = ExtendedJPARepositoryFactoryBean.class)
	@EntityScan(basePackages = { "com.broodcamp.data.entity", "com.terawarehouse.data.entity" })
	@ComponentScan(basePackages = { "com.broodcamp", "com.terawarehouse" })
	@EnableDiscoveryClient
	public class TerawarehouseCatalogApplication {
	public static void main(String[] args) {
	SpringApplication.run(TerawarehouseCatalogApplication.class, args);
	}
	}

view raw spring_boot_service_discovery hosted with ❤ by GitHub

	<?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>2.2.0.RC1</version>
	<relativePath /> <!-- lookup parent from repository -->
	</parent>
	<groupId>com.terawarehouse</groupId>
	<artifactId>terawarehouse-service-discovery</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<name>terawarehouse-service-discovery</name>
	<description>Terawarehouse Service Discovery</description>
	<properties>
	<java.version>11</java.version>
	<maven.compiler.source>11</maven.compiler.source>
	<maven.compiler.target>11</maven.compiler.target>
	</properties>
	<repositories>
	<repository>
	<id>spring-milestones</id>
	<name>Spring Milestones</name>
	<url>https://repo.spring.io/milestone</url>
	</repository>
	</repositories>
	<pluginRepositories>
	<pluginRepository>
	<id>spring-milestones</id>
	<name>Spring Milestones</name>
	<url>https://repo.spring.io/milestone</url>
	</pluginRepository>
	</pluginRepositories>
	<build>
	<plugins>
	<plugin>
	<groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-maven-plugin</artifactId>
	</plugin>
	</plugins>
	</build>
	<dependencyManagement>
	<dependencies>
	<dependency>
	<groupId>com.terawarehouse</groupId>
	<artifactId>terawarehouse-bom</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<type>pom</type>
	<scope>import</scope>
	</dependency>
	</dependencies>
	</dependencyManagement>
	<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-actuator</artifactId>
	</dependency>
	<dependency>
	<groupId>javax.xml.bind</groupId>
	<artifactId>jaxb-api</artifactId>
	</dependency>
	<dependency>
	<groupId>org.glassfish.jaxb</groupId>
	<artifactId>jaxb-runtime</artifactId>
	</dependency>
	<dependency>
	<groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-devtools</artifactId>
	<scope>runtime</scope>
	<optional>true</optional>
	</dependency>
	<dependency>
	<groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-starter-test</artifactId>
	<scope>test</scope>
	<exclusions>
	<exclusion>
	<groupId>org.junit.vintage</groupId>
	<artifactId>junit-vintage-engine</artifactId>
	</exclusion>
	</exclusions>
	</dependency>
	</dependencies>
	</project>

view raw tw_service_discovery_pom.xml hosted with ❤ by GitHub