簡單介紹一下, 其實 Zuul 是來自於 Netflix 的一個 軟體 閘道器, 那你一定會問....
用 Nginx 就好啦, 有比 HAProxy 快嗎?

軟體架構不是只有比快, 彈性也很重要, Zuul 透過我之前介紹自動發現機制, 他可以無須變更軟體組態, 只要服務發現新增了服務, 他就可以做一個內外部的代理功能, 其實自己也是 Service 的一種.

早期 Netflix 拿 Zuul 做 Gateway 的時候, Zuul 裡面也可以包含很多不同程度的功能 如 A/B 測試 金思雀部屬 等等..., 所以你大概可以想像, 他的客製化程度是很強的.

所以來看一下怎麼使用

新增 Proxy 機制

建立一個 reservation-client 專案

使用到的組件如下

下面是我們會使用到的一些依賴
build.gradle

dependencies {
    compile('org.springframework.boot:spring-boot-starter-actuator')
    compile('org.springframework.cloud:spring-cloud-starter-config')
    compile('org.springframework.cloud:spring-cloud-starter-eureka')
    compile('org.springframework.cloud:spring-cloud-starter-hystrix')
    compile('org.springframework.cloud:spring-cloud-starter-zuul')
    testCompile('org.springframework.boot:spring-boot-starter-test') 
}

把範例的 application.properties 刪掉並新增 bootstrap.properties

spring.application.name=reservation-client
spring.cloud.config.uri=http://localhost:8888

起動程式
ReservationClientApplication.java

package com.example;

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;

@EnableZuulProxy
@EnableDiscoveryClient
@SpringBootApplication
public class ReservationClientApplication {

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

在原先的範例程式上增加 @EnableZuulProxy 跟 @EnableDiscoveryClient
起動後即可 http://localhost:8050/reservation-service/reservations 取得原本 reservation-service 上的資料如下，可以很明顯的得出來多了一層 reservation-service 代理路徑

{
  "_embedded": {
    "reservations": [
      {
        "reservationName": "Dr. rod",
        "_links": {
          "self": {
            "href": "http://localhost:8050/reservation-service/reservations/1"
          },
          "reservation": {
            "href": "http://localhost:8050/reservation-service/reservations/1"
          }
        }
      },
      {
        "reservationName": "Dr. Syer",
        "_links": {
          "self": {
            "href": "http://localhost:8050/reservation-service/reservations/2"
          },
          "reservation": {
            "href": "http://localhost:8050/reservation-service/reservations/2"
          }
        }
      },
      {
        "reservationName": "Juergen",
        "_links": {
          "self": {
            "href": "http://localhost:8050/reservation-service/reservations/3"
          },
          "reservation": {
            "href": "http://localhost:8050/reservation-service/reservations/3"
          }
        }
      },
      {
        "reservationName": "ALL THE COMMUNITY",
        "_links": {
          "self": {
            "href": "http://localhost:8050/reservation-service/reservations/4"
          },
          "reservation": {
            "href": "http://localhost:8050/reservation-service/reservations/4"
          }
        }
      },
      {
        "reservationName": "Josh",
        "_links": {
          "self": {
            "href": "http://localhost:8050/reservation-service/reservations/5"
          },
          "reservation": {
            "href": "http://localhost:8050/reservation-service/reservations/5"
          }
        }
      }
    ]
  },
  "_links": {
    "self": {
      "href": "http://localhost:8050/reservation-service/reservations"
    },
    "profile": {
      "href": "http://localhost:8050/reservation-service/profile/reservations"
    },
    "search": {
      "href": "http://localhost:8050/reservation-service/reservations/search"
    }
  },
  "page": {
    "size": 20,
    "totalElements": 5,
    "totalPages": 1,
    "number": 0
  }
}