Spring Cloud使用Zuul构建网关

不使用网关会存在的问题？

• 客户端多次请求不同的微服务，增加了客户端的复杂性。
• 存在跨域问题。
• 认证复杂，每个服务都需要独立认证。
• 难以重构，随着项目的迭代，可能需要重写划分微服务。
• 某些微服务可能使用了防火墙/浏览器不友好的协议，直接访问有一定困难。

什么是微服务网关？

微服务网关介于客户端与服务器端之间，所有的外部请求都会讲过微服务网关。

使用微服务网关的优点：

• 客户端只需和网关交互，而无需调用特定的微服务接口。
• 易于监控
• 易于认证
• 减少了客户端与各个微服务之间的交互次数

什么是Zuul？

Zuul是Netflix开源的微服务网关，可以和Eureka、Ribbon、Hystrix等组件配合使用。其核心似乎一系列过滤器，可完成如下功能。

• 身份认证与安全：识别每个资源的验证要求，拒绝不符合要求的请求。
• 审查与监控：在边缘位置追踪有意义的数据和统计结果，从而带来精确的生产视图。
• 动态路由：动态地将请求路由到不同地后端集群。
• 压力测试：逐渐增加指向集群的流量，以了解性能。
• 负载分配：为每一种负载类型分配对应地容量，并启用超出限定值的请求。
• 静态响应处理：在边缘位置直接建立部分响应，从而避免其转发到内部集群。
• 多区域弹性：跨越AWS Region进行请求路由，旨在实现ELB(Elastic Load Balancing)使用的多样化，已经让系统的边缘更贴近系统的使用者。

上述内容截取自书籍 《Spring Cloud与Docker微服务架构与实战》

Spring Cloud使用Zuul

(1)Eureka Server

pom.xml

<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>4.0.0modelVersion>
    <parent>
        <groupId>org.springframework.bootgroupId>
        <artifactId>spring-boot-starter-parentartifactId>
        <version>2.1.5.RELEASEversion>
        <relativePath/> 
    parent>
    <groupId>com.dfyanggroupId>
    <artifactId>eureka-serverartifactId>
    <version>0.0.1-SNAPSHOTversion>
    <name>eureka-servername>
    <description>Demo project for Spring Bootdescription>

    <properties>
        <java.version>1.8java.version>
    properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starterartifactId>
        dependency>
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starter-testartifactId>
            <scope>testscope>
        dependency>
        <dependency>
            <groupId>org.springframework.cloudgroupId>
            <artifactId>spring-cloud-starter-netflix-eureka-serverartifactId>
        dependency>
    dependencies>
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloudgroupId>
                <artifactId>spring-cloud-dependenciesartifactId>
                <version>Greenwich.RELEASEversion>
                <type>pomtype>
                <scope>importscope>
            dependency>
        dependencies>
    dependencyManagement>
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.bootgroupId>
                <artifactId>spring-boot-maven-pluginartifactId>
            plugin>
        plugins>
    build>
project>

application.xml

server:
  port: 8761
spring:
  application:
    name: eureka-server
eureka:
  client:
    #是否将自己注册到Eureka Server，由于当前应用为Eureka Service，故为false
    register-with-eureka: false
    #是否从Eureka Server获取注册信息，由于是单点，所以为false
    fetch-registry: false
    #与Eureka Server交互的地址
    serviceUrl:
      defaultZone: http://localhost:8761/eureka/

启动类

package com.dfyang;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.server.EnableEurekaServer;

@SpringBootApplication
@EnableEurekaServer
public class EurekaServerApplication {

    public static void main(String[] args) {
        SpringApplication.run(EurekaServerApplication.class, args);
    }
}

启动项目，访问localhost:8761成功跳转页面即编写成功

(2)服务投递者

pom.xml

<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>4.0.0modelVersion>
    <parent>
        <groupId>org.springframework.bootgroupId>
        <artifactId>spring-boot-starter-parentartifactId>
        <version>2.1.5.RELEASEversion>
        <relativePath/> 
    parent>
    <groupId>com.dfyanggroupId>
    <artifactId>service-producerartifactId>
    <version>0.0.1-SNAPSHOTversion>
    <name>service-producername>
    <description>Demo project for Spring Bootdescription>

    <properties>
        <java.version>1.8java.version>
    properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starterartifactId>
        dependency>
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starter-webartifactId>
        dependency>
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starter-testartifactId>
            <scope>testscope>
        dependency>
        <dependency>
            <groupId>org.springframework.cloudgroupId>
            <artifactId>spring-cloud-starter-netflix-eureka-clientartifactId>
        dependency>
    dependencies>
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloudgroupId>
                <artifactId>spring-cloud-dependenciesartifactId>
                <version>Greenwich.RELEASEversion>
                <type>pomtype>
                <scope>importscope>
            dependency>
        dependencies>
    dependencyManagement>
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.bootgroupId>
                <artifactId>spring-boot-maven-pluginartifactId>
            plugin>
        plugins>
    build>
project>

application.xml

server:
  port: 8080
spring:
  application:
    name: service-producer
eureka:
  client:
    serviceUrl:
      defaultZone: http://localhost:8761/eureka/

启动类

package com.dfyang;

import com.netflix.hystrix.contrib.metrics.eventstream.HystrixMetricsStreamServlet;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.servlet.ServletRegistrationBean;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
import org.springframework.cloud.netflix.hystrix.EnableHystrix;
import org.springframework.cloud.netflix.hystrix.dashboard.EnableHystrixDashboard;
import org.springframework.cloud.netflix.turbine.EnableTurbine;
import org.springframework.context.annotation.Bean;

@SpringBootApplication
@EnableEurekaClient
public class ServiceProducerApplication {

    public static void main(String[] args) {
        SpringApplication.run(ServiceProducerApplication.class, args);
    }
}

提供的服务

package com.dfyang.serviceProducer.Controller;

import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class ProducerController {
    @RequestMapping("/serviceA")
    public String serviceA() {
        return "服务A";
    }

    @RequestMapping("/serviceB")
    public String serviceB() {
        return "服务B";
    }
}

启动项目，访问localhost:8761，出现如下即成功

(3)服务消费者

pom.xml

<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>4.0.0modelVersion>
    <parent>
        <groupId>org.springframework.bootgroupId>
        <artifactId>spring-boot-starter-parentartifactId>
        <version>2.1.5.RELEASEversion>
        <relativePath/> 
    parent>
    <groupId>com.dfyanggroupId>
    <artifactId>service-consumerartifactId>
    <version>0.0.1-SNAPSHOTversion>
    <name>service-consumername>
    <description>Demo project for Spring Bootdescription>

    <properties>
        <java.version>1.8java.version>
    properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starterartifactId>
        dependency>
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starter-webartifactId>
        dependency>
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starter-testartifactId>
            <scope>testscope>
        dependency>
        <dependency>
            <groupId>org.springframework.cloudgroupId>
            <artifactId>spring-cloud-starter-netflix-eureka-clientartifactId>
        dependency>
        <dependency>
            <groupId>org.springframework.cloudgroupId>
            <artifactId>spring-cloud-starter-openfeignartifactId>
        dependency>
    dependencies>
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloudgroupId>
                <artifactId>spring-cloud-dependenciesartifactId>
                <version>Greenwich.RELEASEversion>
                <type>pomtype>
                <scope>importscope>
            dependency>
        dependencies>
    dependencyManagement>
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.bootgroupId>
                <artifactId>spring-boot-maven-pluginartifactId>
            plugin>
        plugins>
    build>
project>

application.yml

server:
  port: 8082
spring:
  application:
    name: service-consumer
eureka:
  client:
    service-url:
      defaultZone: http://localhost:8761/eureka/

启动类

package com.dfyang;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.openfeign.EnableFeignClients;

@SpringBootApplication
@EnableEurekaClient
@EnableFeignClients
public class ServiceConsumerApplication {

    public static void main(String[] args) {
        SpringApplication.run(ServiceConsumerApplication.class, args);
    }
}

使用Fegin远程调用服务

package com.dfyang.serviceConsumer.controller;

import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.stereotype.Service;
import org.springframework.web.bind.annotation.GetMapping;

@Service
@FeignClient(name = "service-producer")
public interface ProducerService {

    @GetMapping("/serviceA")
    public String serviceA();

    @GetMapping("/serviceB")
    public String serviceB();
}

消费服务

package com.dfyang.serviceConsumer.controller;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class ConsumerController {

    @Autowired
    private ProducerService producerService;


    @GetMapping("/consumeA")
    public String consumeA() {
        return producerService.serviceA();
    }

    @GetMapping("/consumeB")
    public String consumeB() {
        return producerService.serviceB();
    }
}

启动项目，输入localhost:8761

访问 localhost:8082/consumeA 和 localhost:8082/consumeB


成功！

(4)Zuul网关

pom.xml

<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>4.0.0modelVersion>
    <parent>
        <groupId>org.springframework.bootgroupId>
        <artifactId>spring-boot-starter-parentartifactId>
        <version>2.1.5.RELEASEversion>
        <relativePath/> 
    parent>
    <groupId>com.dfyanggroupId>
    <artifactId>eureka-zuulartifactId>
    <version>0.0.1-SNAPSHOTversion>
    <name>eureka-zuulname>
    <description>Demo project for Spring Bootdescription>

    <properties>
        <java.version>1.8java.version>
    properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starter-webartifactId>
        dependency>
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starter-testartifactId>
            <scope>testscope>
        dependency>
        <dependency>
            <groupId>org.springframework.cloudgroupId>
            <artifactId>spring-cloud-starter-netflix-eureka-clientartifactId>
        dependency>
        <dependency>
            <groupId>org.springframework.cloudgroupId>
            <artifactId>spring-cloud-starter-netflix-zuulartifactId>
        dependency>
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starter-actuatorartifactId>
        dependency>
    dependencies>
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloudgroupId>
                <artifactId>spring-cloud-dependenciesartifactId>
                <version>Greenwich.RELEASEversion>
                <type>pomtype>
                <scope>importscope>
            dependency>
        dependencies>
    dependencyManagement>
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.bootgroupId>
                <artifactId>spring-boot-maven-pluginartifactId>
            plugin>
        plugins>
    build>
project>

application.yml

server:
  port: 8084
spring:
  application:
    name: eureka-zuul
eureka:
  client:
    service-url:
      defaultZone: http://localhost:8761/eureka/
#为应用程序显示详细的健康指标，并未actuator开启所有的endpoint
management:
  endpoints:
    web:
      exposure:
        include: "*"
  endpoint:
    health:
      show-details: always

启动类

package com.dfyang;

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

@SpringBootApplication
@EnableZuulProxy
public class EurekaZuulApplication {

    public static void main(String[] args) {
        SpringApplication.run(EurekaZuulApplication.class, args);
    }
}

启动项目，访问localhost:8761

输入localhost:8084/service-consumer/consumeA 和 localhost:8084/service-consumer/consumeB
将出现与访问 localhost:8082/consumeA 和 localhost:8082/consumeB相同的结果

也就是我们所有的请求都交给了Zuul，再由Zuul将请求转发到微服务。
访问 http://localhost:8084/actuator/routes

从上面可以看出
请求的格式为： http://zuul_host:zuul_port/微服务在Eureka的serviceId/**
如果我们需要将 [微服务在Eureka的serviceId] 替换为别的，只需要添加如下

zuul:
  routes:
    service-producer: /producer/**
    service-consumer: /consumer/**

访问ocalhost:8084/consumer/consumeA 和 localhost:8084/consumer/consumeB（但之前的仍然可以访问）

可以添加忽略的服务

zuul:
  routes:
    service-producer: /producer/**
    service-consumer: /consumer/**
  ignored-services: service-producer,service-consumer

再次访问，成功！