在微服務架構中,需要幾個基礎的服務治理組件,包括服務註冊與發現、服務消費、負載均衡、斷路器、智能路由、配置管理等,由這幾個基礎組件相互協作,共同組建了一個簡單的微服務系統。一個簡答的微服務系統如下圖:
在Spring Cloud微服務系統中,一種常見的負載均衡方式是,客戶端的請求首先經過負載均衡(zuul、Ngnix),再到達服務網關(zuul集羣),然後再到具體的服。,服務統一註冊到高可用的服務註冊中心集羣,服務的所有的配置文件由配置服務管理(下一篇文章講述),配置服務的配置文件放在git倉庫,方便開發人員隨時改配置。
一、Zuul簡介
Zuul的主要功能是路由轉發和過濾器。路由功能是微服務的一部分,比如/api/user轉發到到user服務,/api/shop轉發到到shop服務。zuul默認和Ribbon結合實現了負載均衡的功能。
zuul有以下功能:
- Authentication
- Insights
- Stress Testing
- Canary Testing
- Dynamic Routing
- Service Migration
- Load Shedding
- Security
- Static Response handling
- Active/Active traffic management
二、準備工作
繼續使用上一節的工程。在原有的工程上,創建一個新的工程。
三、創建service-zuul工程
其pom.xml文件如下:
<?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.forezp</groupId>
<artifactId>service-zuul</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>
<name>service-zuul</name>
<description>Demo project for Spring Boot</description>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.5.2.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.cloud</groupId>
<artifactId>spring-cloud-starter-eureka</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-web</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>
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在其入口applicaton類加上註解@EnableZuulProxy,開啓zuul的功能:
@EnableZuulProxy
@EnableEurekaClient
@SpringBootApplication
public class ServiceZuulApplication {
public static void main(String[] args) {
SpringApplication.run(ServiceZuulApplication.class, args);
}
}
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加上配置文件application.yml加上以下的配置代碼:
eureka:
client:
serviceUrl:
defaultZone: http://localhost:8761/eureka/
server:
port: 8767
spring:
application:
name: service-zuul
zuul:
routes:
api-a:
path: /api-a/**
serviceId: service-ribbon
api-b:
path: /api-b/**
serviceId: service-feign
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首先指定服務註冊中心的地址爲http://localhost:8761/eureka/,服務的端口爲8767,服務名爲service-zuul;以/api-a/ 開頭的請求都轉發給service-ribbon服務;以/api-b/開頭的請求都轉發給service-feign服務;
依次運行這五個工程;打開瀏覽器訪問:http://localhost:8767/api-a/hi?name=forezp ;瀏覽器顯示:
hi forezp,i am from port:8762
打開瀏覽器訪問:http://localhost:8767/api-b/hi?name=forezp ;瀏覽器顯示:
hi forezp,i am from port:8762
這說明zuul起到了路由的作用
四、服務過濾
zuul不僅只是路由,並且還能過濾,做一些安全驗證。繼續改造工程;
@Component
public class MyFilter extends ZuulFilter{
private static Logger log = LoggerFactory.getLogger(MyFilter.class);
@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();
log.info(String.format("%s >>> %s", request.getMethod(), request.getRequestURL().toString()));
Object accessToken = request.getParameter("token");
if(accessToken == null) {
log.warn("token is empty");
ctx.setSendZuulResponse(false);
ctx.setResponseStatusCode(401);
try {
ctx.getResponse().getWriter().write("token is empty");
}catch (Exception e){}
return null;
}
log.info("ok");
return null;
}
}
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- filterType:返回一個字符串代表過濾器的類型,在zuul中定義了四種不同生命週期的過濾器類型,具體如下:
- pre:路由之前
- routing:路由之時
- post: 路由之後
- error:發送錯誤調用
- filterOrder:過濾的順序
- shouldFilter:這裏可以寫邏輯判斷,是否要過濾,本文true,永遠過濾。
- run:過濾器的具體邏輯。可用很複雜,包括查sql,nosql去判斷該請求到底有沒有權限訪問。
這時訪問:http://localhost:8767/api-a/hi?name=forezp ;網頁顯示:
token is empty
訪問 http://localhost:8767/api-a/hi?name=forezp&token=22 ;
網頁顯示:
hi forezp,i am from port:8762