Spring Boot - Zuul Proxy Server and Routing

Creating Zuul Server Application

The Zuul Server is bundled with Spring Cloud dependency. You can download the Spring Boot project from Spring Initializer page https://start.spring.io/ and choose the Zuul Server dependency.

Add the @EnableZuulProxy annotation on your main Spring Boot application. The @EnableZuulProxy annotation is used to make your Spring Boot application act as a Zuul Proxy server.

package com.howcodex.zuulserver;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.zuul.EnableZuulProxy;

@SpringBootApplication
@EnableZuulProxy
public class ZuulserverApplication {
   public static void main(String[] args) {
      SpringApplication.run(ZuulserverApplication.class, args);
   }
}

You will have to add the Spring Cloud Starter Zuul dependency in our build configuration file.

Maven users will have to add the following dependency in your pom.xml file −

<dependency>
   <groupId>org.springframework.cloud</groupId>
   <artifactId>spring-cloud-starter-zuul</artifactId>
</dependency>

For Gradle users, add the below dependency in your build.gradle file

compile('org.springframework.cloud:spring-cloud-starter-zuul')

For Zuul routing, add the below properties in your application.properties file or application.yml file.

spring.application.name = zuulserver
zuul.routes.products.path = /api/demo/**
zuul.routes.products.url = http://localhost:8080/
server.port = 8111

This means that http calls to /api/demo/ get forwarded to the products service. For example, /api/demo/products is forwarded to /products.

yaml file users can use the application.yml file shown below −

server:
   port: 8111
spring:
   application:  
      name: zuulserver
zuul:

routes:
   products:
      path: /api/demo/**
      url: http://localhost:8080/

Note − The http://localhost:8080/ application should already be running before routing via Zuul Proxy.

The complete build configuration file is given below.

Maven users can use the pom.xml file given below −

<?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.howcodex</groupId>
   <artifactId>zuulserver</artifactId>
   <version>0.0.1-SNAPSHOT</version>
   <packaging>jar</packaging>

   <name>zuulserver</name>
   <description>Demo project for Spring Boot</description>

   <parent>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-parent</artifactId>
      <version>1.5.9.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>Edgware.RELEASE</spring-cloud.version>
   </properties>

   <dependencies>
      <dependency>
         <groupId>org.springframework.cloud</groupId>
         <artifactId>spring-cloud-starter-zuul</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>

Gradle users can use the build.gradle file given below −

buildscript {
   ext {
      springBootVersion = '1.5.9.RELEASE'
   }
   repositories {
      mavenCentral()
   }
   dependencies {
      classpath("org.springframework.boot:spring-boot-gradle-plugin:${springBootVersion}")
   }
}

apply plugin: 'java'
apply plugin: 'eclipse'
apply plugin: 'org.springframework.boot'

group = 'com.howcodex'
version = '0.0.1-SNAPSHOT'
sourceCompatibility = 1.8

repositories {
   mavenCentral()
}
ext {
   springCloudVersion = 'Edgware.RELEASE'
}
dependencies {
   compile('org.springframework.cloud:spring-cloud-starter-zuul')
   testCompile('org.springframework.boot:spring-boot-starter-test')
}
dependencyManagement {
   imports {
      mavenBom "org.springframework.cloud:spring-cloud-dependencies:${springCloudVersion}"
   }
}

You can create an executable JAR file, and run the Spring Boot application by using the Maven or Gradle commands given below −

For Maven, you can use the command given below −

mvn clean install

After “BUILD SUCCESS”, you can find the JAR file under the target directory.

For Gradle, you can use the command given below −

gradle clean build

After “BUILD SUCCESSFUL”, you can find the JAR file under the build/libs directory.

Now, run the JAR file by using the command shown below −

java –jar <JARFILE>

You can find the application has started on the Tomcat port 8111 as shown here.

Now, hit the URL http://localhost:8111/api/demo/products in your web browser and you can see the output of /products REST Endpoint as shown below −

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