zuul 动态路由

前言

在微服务架构体系下，随着时间的推移，不免会碰到因为前期服务粒度的划分不能彻底知足后续需求的增加，形成"微"服务的二度拆分。拆分不可避免的会致使服务在整个系统中的链路发生变化，如何保证链路上游服务在无感知的状况下完成链路下游服务的拆分，动态路由能够帮助咱们解决这个问题。
先介绍一下服务架构设计

一 待拆分链路(open)

二 拆分后链路

三 动态路由

基于spring cloud zuul
1.目标：实现一个通用的动态路由服务
2.参考：更深层次的探讨，请进 传送门
3.功能： 在zuul-gateway-demo的基础上，简化了路由配置表；新增路由刷新策略保证细粒度的path优先路由；自动刷新频率的配置化；

四 dynamic-route

1.项目依赖

<dependencies>
	<dependency>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter</artifactId>
	</dependency>
	<dependency>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-actuator</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>compile</scope>
	</dependency>

    <dependency>
		<groupId>org.mybatis.spring.boot</groupId>
		<artifactId>mybatis-spring-boot-starter</artifactId>
		<version>1.1.1</version>
	</dependency>

	<!-- 数据库 -->
	<dependency>
		<groupId>mysql</groupId>
		<artifactId>mysql-connector-java</artifactId>
		<version>${mysql.version}</version>
	</dependency>
	<dependency>
		<groupId>com.alibaba</groupId>
		<artifactId>druid</artifactId>
		<version>${alibaba.druid.version}</version>
	</dependency>
	
	<!-- spring cloud zuul -->
	<dependency>
		<groupId>org.springframework.cloud</groupId>
		<artifactId>spring-cloud-starter-zuul</artifactId>
		<version>${spring.cloud.version}</version>
	</dependency>

</dependencies>

2 配置文件

application.yml

zuul:
  host:
    socket-timeout-millis: 150000
    connect-timeout-millis: 150000
    max-total-connections: 200 # 路由最大链接数
    max-per-route-connections: 100 #每一个路由并发数
ribbon:
  eureka:
    enabled: false #不使用注册中心

# 路由自动刷新频率(分钟)
ebtce:
  routeRefresh: 15

3 服务启动

启动类 ：DynamicRouteApplication

//注入ZuulAutoFilter对象
@Bean
public ZuulAutoFilter zuulAutoFilter(){
	return new ZuulAutoFilter();
}

@Autowired
private ZuulRouteVoService zuulRouteVoService;

// 注入监听线程对象
@Autowired
private MonitorThread monitorThread;

@Autowired
public void  setInitialize(){
     //读取路由表，信息放入一个Map对象中
	zuulRouteVoService.initZuulRouteVoMap();
// 设置为守护线程
	monitorThread.setDaemon(true);
	monitorThread.start();
}

public static void main(String[] args) {
// 启动服务
	SpringApplication.run(DynamicRouteApplication.class, args);
// 控制监听线程的状态： 等待(0) 启动(1) 退出(-1)
	MonitorThreadControl.setState(1);
}

4 zuul 路由表生成

自定义路由配置类：CustomZuulConfig

@Bean
    public CustomRouteLocator routeLocator(){
        CustomRouteLocator routeLocator = new CustomRouteLocator(serverProperties().getServletPrefix(), zuulProperties());
        return routeLocator;
    }

路由发现：CustomRouteLocator

@Override
protected Map<String, ZuulProperties.ZuulRoute> locateRoutes(){
	// 加载配置信息
	LinkedHashMap<String, ZuulRouteVo> routeLinkedHashMap = ZuulRouteVoService.ZUUL_ROUTE_VO_MAP;

	//优化一下配置
	LinkedHashMap<String, ZuulProperties.ZuulRoute> values = new LinkedHashMap<>();
	log.info("========= dynamic route info ========== ");
	for(Map.Entry<String, ZuulRouteVo> entry : routeLinkedHashMap.entrySet()){
		String path = entry.getKey();
		if(!path.startsWith("/")){
			path = "/" + path;
		}

		if(StringUtils.hasText(this.properties.getPrefix())){
			path = this.properties.getPrefix();
			if(!path.startsWith("/")){
				path = "/" + path;
			}
		}

		ZuulProperties.ZuulRoute zuulRoute = new ZuulProperties.ZuulRoute();
		BeanUtils.copyProperties(entry.getValue(), zuulRoute);
		values.put(path, zuulRoute);

		log.info(JSON.toJSONString(zuulRoute));
	}
//  路由信息装配完成后，清除临时存放路由信息的Map对象
	ZuulRouteVoService.clearRouteMap();
	return values;
}

在这里咱们发现，zuul把路由信息写到了一个LinkedHashMap对象中，路径匹配时将循环LinkedHashMap对象，发现符合条件的路径表达式即将对其进行路由，先匹配先得。为保证细粒度的路径优先匹配，保证LinkedHashMap对象初始化时粒度细的表达式在前便可。
SELECT CONCAT(id, '') as id, host, path from dynamic_route where is_read = 1 ORDER BY path DESC

5 动态刷新

时间刷新路由：RefreshRouteService

// 1 事件触发路由刷新
public void refreshRoute(){
    // 读取路由表信息
	zuulRouteVoService.initZuulRouteVoMap();
    //有须要刷新的路由才触发刷新，若路径已存在，刷新将被重写
	if(!ZuulRouteVoService.ZUUL_ROUTE_VO_MAP.isEmpty()){
		RoutesRefreshedEvent routesRefreshedEvent = new RoutesRefreshedEvent(routeLocator);
		publisher.publishEvent(routesRefreshedEvent);
		log.info("== dynamic route refresh success! ==");
	}else{
		log.info("== routing information is not updated ==");
	}
}

// 2. 刷新事件监听线程
@Override
public void run(){
	while (true){
		int state = MonitorThreadControl.getState();
		if(state == 0)
			continue;

		if(state < 0){
			log.warn("============ MonitorThread EXIT  ===============");
			return;
		}

		try {

			// ensure that the last route refresh is completed
			if(ZuulRouteVoService.ZUUL_ROUTE_VO_MAP.isEmpty()){
				refreshRouteService.refreshRoute();
			}

		}catch (Exception e){
			log.error("", e);
		}

		try {
			Thread.sleep(refreshTime * (60 * 1000));
		} catch (InterruptedException e) {
		   log.error("", e);
		}
	}
}

6 路由数据模型

CREATE TABLE dynamic_route (
id int(10) unsigned NOT NULL AUTO_INCREMENT,
host varchar(100) NOT NULL,
path varchar(256) NOT NULL,
is_read tinyint(1) NOT NULL DEFAULT '0' COMMENT '1:路由 0：不路由',
PRIMARY KEY (id),
UNIQUE KEY idx_path (path)
) ENGINE=InnoDB AUTO_INCREMENT=6 DEFAULT CHARSET=utf8
id：路由服务id
host：对应路由url
path：路由路径表达式
is_read：是否读取/路由，控制路径的路由状态

五 源码获取

dynamic-route

后记

先取后予，欢迎你们讨论和补充！