<?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.javainuse</groupId>
<artifactId>employee-zuul-service</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>
<name>SpringBootHelloWorld</name>
<description>Demo project for Spring Boot</description>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.4.1.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>
</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-zuul</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-eureka</artifactId>
</dependency>
</dependencies>
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-dependencies</artifactId>
<version>Camden.SR6</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>
Next define the following properties in application.properties-
zuul.routes.producer.url=http://localhost:8080
eureka.client.serviceUrl.defaultZone=http://localhost:8090/eureka
server.port=8079
Here zuul.routes.producer.url will route incoming traffic to request for /producer to the employee-producer microservice.
Similar routes can be added for other microservices as well.
Next name the application module in the bootstrap.properties file
spring.application.name=employee-zuul-service
Next we define the 4 types of filters supported by Zuul-
Define the ErrorFilter as follows-
package com.javainuse.filter;
import com.netflix.zuul.ZuulFilter;
public class ErrorFilter extends ZuulFilter {
@Override
public String filterType() {
return "error";
}
@Override
public int filterOrder() {
return 0;
}
@Override
public boolean shouldFilter() {
return true;
}
@Override
public Object run() {
System.out.println("Using Route Filter");
return null;
}
}
Define the PostFilter as follows-
package com.javainuse.filter;
import com.netflix.zuul.ZuulFilter;
public class PostFilter extends ZuulFilter {
@Override
public String filterType() {
return "post";
}
@Override
public int filterOrder() {
return 0;
}
@Override
public boolean shouldFilter() {
return true;
}
@Override
public Object run() {
System.out.println("Using Post Filter");
return null;
}
}
Define the PreFilter as follows-
package com.javainuse.filter;
import javax.servlet.http.HttpServletRequest;
import com.netflix.zuul.ZuulFilter;
import com.netflix.zuul.context.RequestContext;
public class PreFilter extends ZuulFilter {
@Override
public String filterType() {
return "pre";
}
@Override
public int filterOrder() {
return 0;
}
@Override
public boolean shouldFilter() {
return true;
}
@Override
public Object run() {
RequestContext ctx = RequestContext.getCurrentContext();
HttpServletRequest request = ctx.getRequest();
System.out.println(
"Request Method : " + request.getMethod() + " Request URL : " + request.getRequestURL().toString());
return null;
}
}
Define the RouteFilter as follows-
package com.javainuse.filter;
import com.netflix.zuul.ZuulFilter;
public class RouteFilter extends ZuulFilter {
@Override
public String filterType() {
return "route";
}
@Override
public int filterOrder() {
return 0;
}
@Override
public boolean shouldFilter() {
return true;
}
@Override
public Object run() {
System.out.println("Using Route Filter");
return null;
}
}
Finally we annotate the Spring Boot Main class with
@EnableZuulProxy.With this the module will act as a service proxy or gateway.
Also we create the beans for the filters defined above.
package com.javainuse;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.netflix.zuul.EnableZuulProxy;
import org.springframework.context.annotation.Bean;
import com.javainuse.filter.ErrorFilter;
import com.javainuse.filter.PostFilter;
import com.javainuse.filter.PreFilter;
import com.javainuse.filter.RouteFilter;
@SpringBootApplication
@EnableDiscoveryClient
@EnableZuulProxy
public class SpringBootHelloWorldApplication {
public static void main(String[] args) {
SpringApplication.run(SpringBootHelloWorldApplication.class, args);
}
@Bean
public PreFilter preFilter() {
return new PreFilter();
}
@Bean
public PostFilter postFilter() {
return new PostFilter();
}
@Bean
public ErrorFilter errorFilter() {
return new ErrorFilter();
}
@Bean
public RouteFilter routeFilter() {
return new RouteFilter();
}
}
Code changes for employee-consumer
The changes we make for the consumer module are
-
We fetch the Zuul Service instance instead of the the Employee Producer service we were doing earlier.
So in code we have discoveryClient.getInstances("EMPLOYEE-ZUUL-SERVICE") instead of discoveryClient.getInstances("EMPLOYEE-PRODUCER")
-
Append the URL to be hit with /producer since we have defined so in the applicatio.properties above.
baseUrl = baseUrl + "/producer/employee"
package com.javainuse.controllers;
import java.io.IOException;
import java.util.List;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cloud.client.ServiceInstance;
import org.springframework.cloud.client.discovery.DiscoveryClient;
import org.springframework.http.HttpEntity;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpMethod;
import org.springframework.http.MediaType;
import org.springframework.http.ResponseEntity;
import org.springframework.stereotype.Controller;
import org.springframework.web.client.RestClientException;
import org.springframework.web.client.RestTemplate;
@Controller
public class ConsumerControllerClient {
@Autowired
private DiscoveryClient discoveryClient;
public void getEmployee() throws RestClientException, IOException {
List<ServiceInstance> instances = discoveryClient.getInstances("EMPLOYEE-ZUUL-SERVICE");
ServiceInstance serviceInstance = instances.get(0);
String baseUrl = serviceInstance.getUri().toString();
baseUrl = baseUrl + "/producer/employee";
RestTemplate restTemplate = new RestTemplate();
ResponseEntity<String> response = null;
try {
response = restTemplate.exchange(baseUrl, HttpMethod.GET, getHeaders(), String.class);
} catch (Exception ex) {
System.out.println(ex);
}
System.out.println(response.getBody());
}
private static HttpEntity<?> getHeaders() throws IOException {
HttpHeaders headers = new HttpHeaders();
headers.set("Accept", MediaType.APPLICATION_JSON_VALUE);
return new HttpEntity<>(headers);
}
}
As we had done in previous posts- Start the following Spring Boot Applications-
-
eureka-server
-
employee-producer
-
employee-zuul-service
-
employee-consumer
On running the employee-consumer we get the output as follows-
The Zuul console output is as follows-
So the filters defined in the zuul gateway get executed.
Download Source Code
Download it -
Employee Producer Service for Zuul
Eureka Server Service for Zuul
Eureka Consumer Service for Zuul
Employee Zuul Service
See Also
Spring Boot Hello World Application- Create simple controller and jsp view using Maven
Spring Boot Tutorial-Spring Data JPA
Spring Boot + Simple Security Configuration
Pagination using Spring Boot Simple Example
Spring Boot + ActiveMQ Hello world Example
Spring Boot + Swagger Example Hello World Example
Spring Boot + Swagger- Understanding the various Swagger Annotations
Spring Boot Main Menu
Spring Boot Interview Questions
