Spring Cloud - routing gateways zuul Spring Cloud Start Tutorial (IX): Routing Gateway zuul

Spring Cloud Getting Started tutorial (IX): Routing Gateway zuul

In the micro-services architecture requires several key components, service registration and discovery, service consumption, load balancing, circuit breakers, intelligent routing, configuration management, the formation of these components can be a simple micro-services architecture. All configuration files to client requests first pass through load balancing (zuul, Ngnix), and then reach the service gateway (zuul cluster), and then to specific services, service uniform registered with the service registry clusters highly available, served by the configuration service management (under article describes), configure the service configuration file in Git repository to facilitate developers to change the configuration at any time.

Introduction 1. Zuul

The main function is to route Zuul and filters. Routing function is part of the micro and services, such as / api / user mapped to the service user, / api / shop map to the service shop. zuul achieve load balancing. The following is a micro-service structure, the basic flow of Zuul. In the next step, we'll create a zuul service, the / api-feign / ** mapped to feign-service before we create the / api-ribbon / ** mapped before the ribbon-service services.

2. Create Zuul's Maven project, which is dependent on zuul

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

Complete pom.xml as follows:

<?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>cm.chry</groupId>
<artifactId>spring.helloworld.zuul.service</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>spring.helloworld.zuul.service</name>
<description>zuul service demo</description>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.5.3.RELEASE</version>
<relativePath/> 
</parent>

<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-eureka</artifactId>
</dependency>
<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.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>Dalston.RC1</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>spring-milestones</id>
<name>Spring Milestones</name>
<url>https://repo.spring.io/milestone</url>
<snapshots>
<enabled>false</enabled>
</snapshots>
</repository>
</repositories>
</project>

pom.xml

3. Create a startup class: Use @EnableZuulProxy comment

 1 package spring.helloworld.zuul.service;
 2 
 3 import org.springframework.boot.SpringApplication;
 4 import org.springframework.boot.autoconfigure.SpringBootApplication;
 5 import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
 6 import org.springframework.cloud.netflix.zuul.EnableZuulProxy;
 7 
 8 @EnableZuulProxy
 9 @EnableEurekaClient
10 @SpringBootApplication
11 public class ServiceZuulApplication {
12     public static void main(String[] args) {
13         SpringApplication.run(ServiceZuulApplication.class, args);
14     }
15 }

4. Write zuul service configuration:

Simple to configure two routes, a route to the ribbon, a route to feign; are registered due to eureka service center, so are used to discover services specifically address serviceId, path is the address mapping relationship routing

 1 eureka:
 2     client:
 3         serviceUrl:
 4             defaultZone: http://localhost:8761/eureka/
 5 server:
 6     port: 8904
 7 spring:
 8     application:
 9         name: service-zuul
10 zuul:
11   routes:
12     ribbo:
13       path: /api-ribbon/**
14       serviceId: service-ribbon
15     feign:
16       path: /api-feign/**
17       serviceId: service-feign

这时启动zuul服务，然后访问http://localhost:8904/api-ribbon可直接路由到http://localhost:8901/.

http://localhost:8904/api-feign/hello可路由到http://localhost:8902/hello

5. Zuul过滤器

zuul还提供了过滤功能，只要实现接口ZuulFilter即可对请求先进行筛选和过滤之后再路由到具体服务。

 1 package spring.helloworld.zuul.service;
 2 
 3 import javax.servlet.http.HttpServletRequest;
 4 
 5 import org.slf4j.Logger;
 6 import org.slf4j.LoggerFactory;
 7 import org.springframework.stereotype.Component;
 8 
 9 import com.netflix.zuul.ZuulFilter;
10 import com.netflix.zuul.context.RequestContext;
11 
12 @Component
13 public class DemoFilter extends ZuulFilter {
14     private static Logger log = LoggerFactory.getLogger(DemoFilter.class);
15     @Override
16     public String filterType() {
17         return "pre";
18     }
19 
20     @Override
21     public int filterOrder() {
22         return 0;
23     }
24 
25     @Override
26     public boolean shouldFilter() {
27         return true;
28     }
29 
30     @Override
31     public Object run() {
32         RequestContext ctx = RequestContext.getCurrentContext();
33         HttpServletRequest request = ctx.getRequest();
34         String s = String.format("%s >>> %s", request.getMethod(), request.getRequestURL().toString());
35         log.info(s);
36         return null;
37     }
38 }

filterType：返回一个字符串代表过滤器的类型，在zuul中定义了四种不同生命周期的过滤器类型，具体如下：

pre：路由之前
routing：路由之时
post：路由之后
error：发送错误调用

filterOrder：过滤的顺序

pre：路由之前
routing：路由之时
post：路由之后
error：发送错误调用

shouldFilter：这里可以写逻辑判断，是否要过滤，本文true,永远过滤。

run：过滤器的具体逻辑，这里只是将请求的URL简单些到日志中

在微服务架构中，需要几个关键的组件，服务注册与发现、服务消费、负载均衡、断路器、智能路由、配置管理等，由这几个组件可以组建一个简单的微服务架构。客户端的请求首先经过负载均衡（zuul、Ngnix），再到达服务网关（zuul集群），然后再到具体的服务，服务统一注册到高可用的服务注册中心集群，服务的所有的配置文件由配置服务管理（下一篇文章讲述），配置服务的配置文件放在Git仓库，方便开发人员随时改配置。

1. Zuul介绍

Zuul的主要功能是路由和过滤器。路由功能是微服务的一部分，比如／api/user映射到user服务，/api/shop映射到shop服务。zuul实现了负载均衡。以下是微服务结构中，Zuul的基本流程。在接下来的步骤中，我们来创建一个zuul服务，将/api-feign/**映射到我们之前创建feign-service, 将/api-ribbon/**映射到之前的ribbon-service服务。

2. 创建Zuul的Maven工程，其中关于zuul的依赖是

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

完整pom.xml如下：

<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>

pom.xml

3. 创建启动类: 使用@EnableZuulProxy注解

 1 package spring.helloworld.zuul.service;
 2 
 3 import org.springframework.boot.SpringApplication;
 4 import org.springframework.boot.autoconfigure.SpringBootApplication;
 5 import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
 6 import org.springframework.cloud.netflix.zuul.EnableZuulProxy;
 7 
 8 @EnableZuulProxy
 9 @EnableEurekaClient
10 @SpringBootApplication
11 public class ServiceZuulApplication {
12     public static void main(String[] args) {
13         SpringApplication.run(ServiceZuulApplication.class, args);
14     }
15 }

4. 编写zuul服务配置：

简单配置两个路由，一个路由到ribbon，一个路由到feign；由于都注册到eureka服务中心，所以都用通过serviceId来发现服务具体地址， path是路由的地址映射关系

 1 eureka:
 2     client:
 3         serviceUrl:
 4             defaultZone: http://localhost:8761/eureka/
 5 server:
 6     port: 8904
 7 spring:
 8     application:
 9         name: service-zuul
10 zuul:
11   routes:
12     ribbo:
13       path: /api-ribbon/**
14       serviceId: service-ribbon
15     feign:
16       path: /api-feign/**
17       serviceId: service-feign