springcloud Zuul动态路由的实现

前言

Zuul 是Netflix 提供的一个开源组件,致力于在云平台上提供动态路由，监控，弹性，安全等边缘服务的框架。也有很多公司使用它来作为网关的重要组成部分，碰巧今年公司的架构组决定自研一个网关产品，集动态路由，动态权限，限流配额等功能为一体，为其他部门的项目提供统一的外网调用管理，最终形成产品(这方面阿里其实已经有成熟的网关产品了，但是不太适用于个性化的配置，也没有集成权限和限流降级)。

不过这里并不想介绍整个网关的架构，而是想着重于讨论其中的一个关键点，并且也是经常在交流群中听人说起的：动态路由怎么做？

再阐释什么是动态路由之前，需要介绍一下架构的设计。

传统互联网架构图

上图是没有网关参与的一个最典型的互联网架构(本文中统一使用book代表应用实例，即真正提供服务的一个业务系统)

加入eureka的架构图

book注册到eureka注册中心中，zuul本身也连接着同一个eureka，可以拉取book众多实例的列表。服务中心的注册发现一直是值得推崇的一种方式，但是不适用与网关产品。因为我们的网关是面向众多的其他部门的已有或是异构架构的系统，不应该强求其他系统都使用eureka，这样是有侵入性的设计。

最终架构图

要强调的一点是，gateway最终也会部署多个实例，达到分布式的效果，在架构图中没有画出，请大家自行脑补。

本博客的示例使用最后一章架构图为例，带来动态路由的实现方式，会有具体的代码。

动态路由

动态路由需要达到可持久化配置，动态刷新的效果。如架构图所示，不仅要能满足从spring的配置文件properties加载路由信息，还需要从数据库加载我们的配置。另外一点是，路由信息在容器启动时就已经加载进入了内存，我们希望配置完成后，实施发布，动态刷新内存中的路由信息，达到不停机维护路由信息的效果。

zuul–HelloWorldDemo

项目结构

 <groupId>com.sinosoft</groupId>
 <artifactId>zuul-gateway-demo</artifactId>
 <packaging>pom</packaging>
 <version>1.0</version>

 <parent>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-parent</artifactId>
  <version>1.5.2.RELEASE</version>
 </parent>

 <modules>
  <module>gateway</module>
  <module>book</module>
 </modules>

 <dependencyManagement>
  <dependencies>
   <dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-dependencies</artifactId>
    <version>Camden.SR6</version>
    <type>pom</type>
    <scope>import</scope>
   </dependency>
  </dependencies>
 </dependencyManagement>

tip：springboot-1.5.2对应的springcloud的版本需要使用Camden.SR6，一开始想专门写这个demo时，只替换了springboot的版本1.4.0->1.5.2，结果启动就报错了，最后发现是版本不兼容的锅。

gateway项目：

启动类：GatewayApplication.java

@EnableZuulProxy
@SpringBootApplication
public class GatewayApplication {

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

}

配置：application.properties

#配置在配置文件中的路由信息
zuul.routes.books.url=http://localhost:8090
zuul.routes.books.path=/books/**
#不使用注册中心,会带来侵入性
ribbon.eureka.enabled=false
#网关端口
server.port=8080

book项目：

启动类：BookApplication.java

@RestController
@SpringBootApplication
public class BookApplication {

 @RequestMapping(value = "/available")
 public String available() {
  System.out.println("Spring in Action");
  return "Spring in Action";
 }

 @RequestMapping(value = "/checked-out")
 public String checkedOut() {
  return "Spring Boot in Action";
 }

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

配置类：application.properties

server.port=8090

测试访问：http://localhost:8080/books/available

上述demo是一个简单的静态路由，简单看下源码，zuul是怎么做到转发，路由的。

@Configuration
@EnableConfigurationProperties({ ZuulProperties.class })
@ConditionalOnClass(ZuulServlet.class)
@Import(ServerPropertiesAutoConfiguration.class)
public class ZuulConfiguration {

 @Autowired
 //zuul的配置文件,对应了application.properties中的配置信息
 protected ZuulProperties zuulProperties;

 @Autowired
 protected ServerProperties server;

 @Autowired(required = false)
 private ErrorController errorController;

 @Bean
 public HasFeatures zuulFeature() {
  return HasFeatures.namedFeature("Zuul (Simple)", ZuulConfiguration.class);
 }

 //核心类，路由定位器，最最重要
 @Bean
 @ConditionalOnMissingBean(RouteLocator.class)
 public RouteLocator routeLocator() {
  //默认配置的实现是SimpleRouteLocator.class
  return new SimpleRouteLocator(this.server.getServletPrefix(),
    this.zuulProperties);
 }

 //zuul的控制器，负责处理链路调用
 @Bean
 public ZuulController zuulController() {
  return new ZuulController();
 }

 //MVC HandlerMapping that maps incoming request paths to remote services.
 @Bean
 public ZuulHandlerMapping zuulHandlerMapping(RouteLocator routes) {
  ZuulHandlerMapping mapping = new ZuulHandlerMapping(routes, zuulController());
  mapping.setErrorController(this.errorController);
  return mapping;
 }

 //注册了一个路由刷新监听器，默认实现是ZuulRefreshListener.class，这个是我们动态路由的关键
 @Bean
 public ApplicationListener<ApplicationEvent> zuulRefreshRoutesListener() {
  return new ZuulRefreshListener();
 }

 @Bean
 @ConditionalOnMissingBean(name = "zuulServlet")
 public ServletRegistrationBean zuulServlet() {
  ServletRegistrationBean servlet = new ServletRegistrationBean(new ZuulServlet(),
    this.zuulProperties.getServletPattern());
  // The whole point of exposing this servlet is to provide a route that doesn't
  // buffer requests.
  servlet.addInitParameter("buffer-requests", "false");
  return servlet;
 }

 // pre filters

 @Bean
 public ServletDetectionFilter servletDetectionFilter() {
  return new ServletDetectionFilter();
 }

 @Bean
 public FormBodyWrapperFilter formBodyWrapperFilter() {
  return new FormBodyWrapperFilter();
 }

 @Bean
 public DebugFilter debugFilter() {
  return new DebugFilter();
 }

 @Bean
 public Servlet30WrapperFilter servlet30WrapperFilter() {
  return new Servlet30WrapperFilter();
 }

 // post filters

 @Bean
 public SendResponseFilter sendResponseFilter() {
  return new SendResponseFilter();
 }

 @Bean
 public SendErrorFilter sendErrorFilter() {
  return new SendErrorFilter();
 }

 @Bean
 public SendForwardFilter sendForwardFilter() {
  return new SendForwardFilter();
 }

 @Configuration
 protected static class ZuulFilterConfiguration {

  @Autowired
  private Map<String, ZuulFilter> filters;

  @Bean
  public ZuulFilterInitializer zuulFilterInitializer() {
   return new ZuulFilterInitializer(this.filters);
  }

 }

 //上面提到的路由刷新监听器
 private static class ZuulRefreshListener
   implements ApplicationListener<ApplicationEvent> {

  @Autowired
  private ZuulHandlerMapping zuulHandlerMapping;

  private HeartbeatMonitor heartbeatMonitor = new HeartbeatMonitor();

  @Override
  public void onApplicationEvent(ApplicationEvent event) {
   if (event instanceof ContextRefreshedEvent
     || event instanceof RefreshScopeRefreshedEvent
     || event instanceof RoutesRefreshedEvent) {
    //设置为脏,下一次匹配到路径时，如果发现为脏，则会去刷新路由信息
    this.zuulHandlerMapping.setDirty(true);
   }
   else if (event instanceof HeartbeatEvent) {
    if (this.heartbeatMonitor.update(((HeartbeatEvent) event).getValue())) {
     this.zuulHandlerMapping.setDirty(true);
    }
   }
  }

 }

}

我们要解决动态路由的难题，第一步就得理解路由定位器的作用。

很失望，因为从接口关系来看，spring考虑到了路由刷新的需求，但是默认实现的SimpleRouteLocator没有实现RefreshableRouteLocator接口，看来我们只能借鉴DiscoveryClientRouteLocator去改造SimpleRouteLocator使其具备刷新能力。

public interface RefreshableRouteLocator extends RouteLocator {
 void refresh();
}

DiscoveryClientRouteLocator比SimpleRouteLocator多了两个功能，第一是从DiscoveryClient（如Eureka）发现路由信息，之前的架构图已经给大家解释清楚了，我们不想使用eureka这种侵入式的网关模块，所以忽略它，第二是实现了RefreshableRouteLocator接口，能够实现动态刷新。

对SimpleRouteLocator.class的源码加一些注释，方便大家阅读：

public class SimpleRouteLocator implements RouteLocator {

 //配置文件中的路由信息配置
 private ZuulProperties properties;
 //路径正则配置器,即作用于path:/books/**
 private PathMatcher pathMatcher = new AntPathMatcher();

 private String dispatcherServletPath = "/";
 private String zuulServletPath;

 private AtomicReference<Map<String, ZuulRoute>> routes = new AtomicReference<>();

 public SimpleRouteLocator(String servletPath, ZuulProperties properties) {
  this.properties = properties;
  if (servletPath != null && StringUtils.hasText(servletPath)) {
   this.dispatcherServletPath = servletPath;
  }

  this.zuulServletPath = properties.getServletPath();
 }

 //路由定位器和其他组件的交互，是最终把定位的Routes以list的方式提供出去,核心实现
 @Override
 public List<Route> getRoutes() {
  if (this.routes.get() == null) {
   this.routes.set(locateRoutes());
  }
  List<Route> values = new ArrayList<>();
  for (String url : this.routes.get().keySet()) {
   ZuulRoute route = this.routes.get().get(url);
   String path = route.getPath();
   values.add(getRoute(route, path));
  }
  return values;
 }

 @Override
 public Collection<String> getIgnoredPaths() {
  return this.properties.getIgnoredPatterns();
 }

 //这个方法在网关产品中也很重要，可以根据实际路径匹配到Route来进行业务逻辑的操作，进行一些加工
 @Override
 public Route getMatchingRoute(final String path) {

  if (log.isDebugEnabled()) {
   log.debug("Finding route for path: " + path);
  }

  if (this.routes.get() == null) {
   this.routes.set(locateRoutes());
  }

  if (log.isDebugEnabled()) {
   log.debug("servletPath=" + this.dispatcherServletPath);
   log.debug("zuulServletPath=" + this.zuulServletPath);
   log.debug("RequestUtils.isDispatcherServletRequest()="
     + RequestUtils.isDispatcherServletRequest());
   log.debug("RequestUtils.isZuulServletRequest()="
     + RequestUtils.isZuulServletRequest());
  }

  String adjustedPath = adjustPath(path);

  ZuulRoute route = null;
  if (!matchesIgnoredPatterns(adjustedPath)) {
   for (Entry<String, ZuulRoute> entry : this.routes.get().entrySet()) {
    String pattern = entry.getKey();
    log.debug("Matching pattern:" + pattern);
    if (this.pathMatcher.match(pattern, adjustedPath)) {
     route = entry.getValue();
     break;
    }
   }
  }
  if (log.isDebugEnabled()) {
   log.debug("route matched=" + route);
  }

  return getRoute(route, adjustedPath);

 }

 private Route getRoute(ZuulRoute route, String path) {
  if (route == null) {
   return null;
  }
  String targetPath = path;
  String prefix = this.properties.getPrefix();
  if (path.startsWith(prefix) && this.properties.isStripPrefix()) {
   targetPath = path.substring(prefix.length());
  }
  if (route.isStripPrefix()) {
   int index = route.getPath().indexOf("*") - 1;
   if (index > 0) {
    String routePrefix = route.getPath().substring(0, index);
    targetPath = targetPath.replaceFirst(routePrefix, "");
    prefix = prefix + routePrefix;
   }
  }
  Boolean retryable = this.properties.getRetryable();
  if (route.getRetryable() != null) {
   retryable = route.getRetryable();
  }
  return new Route(route.getId(), targetPath, route.getLocation(), prefix,
    retryable,
    route.isCustomSensitiveHeaders() ? route.getSensitiveHeaders() : null);
 }

 //注意这个类并没有实现refresh接口，但是却提供了一个protected级别的方法,旨在让子类不需要重复维护一个private AtomicReference<Map<String, ZuulRoute>> routes = new AtomicReference<>();也可以达到刷新的效果
 protected void doRefresh() {
  this.routes.set(locateRoutes());
 }

 //具体就是在这儿定位路由信息的，我们之后从数据库加载路由信息，主要也是从这儿改写
 /**
  * Compute a map of path pattern to route. The default is just a static map from the
  * {@link ZuulProperties}, but subclasses can add dynamic calculations.
  */
 protected Map<String, ZuulRoute> locateRoutes() {
  LinkedHashMap<String, ZuulRoute> routesMap = new LinkedHashMap<String, ZuulRoute>();
  for (ZuulRoute route : this.properties.getRoutes().values()) {
   routesMap.put(route.getPath(), route);
  }
  return routesMap;
 }

 protected boolean matchesIgnoredPatterns(String path) {
  for (String pattern : this.properties.getIgnoredPatterns()) {
   log.debug("Matching ignored pattern:" + pattern);
   if (this.pathMatcher.match(pattern, path)) {
    log.debug("Path " + path + " matches ignored pattern " + pattern);
    return true;
   }
  }
  return false;
 }

 private String adjustPath(final String path) {
  String adjustedPath = path;

  if (RequestUtils.isDispatcherServletRequest()
    && StringUtils.hasText(this.dispatcherServletPath)) {
   if (!this.dispatcherServletPath.equals("/")) {
    adjustedPath = path.substring(this.dispatcherServletPath.length());
    log.debug("Stripped dispatcherServletPath");
   }
  }
  else if (RequestUtils.isZuulServletRequest()) {
   if (StringUtils.hasText(this.zuulServletPath)
     && !this.zuulServletPath.equals("/")) {
    adjustedPath = path.substring(this.zuulServletPath.length());
    log.debug("Stripped zuulServletPath");
   }
  }
  else {
   // do nothing
  }

  log.debug("adjustedPath=" + path);
  return adjustedPath;
 }

}

重写过后的自定义路由定位器如下：

public class CustomRouteLocator extends SimpleRouteLocator implements RefreshableRouteLocator{

 public final static Logger logger = LoggerFactory.getLogger(CustomRouteLocator.class);

 private JdbcTemplate jdbcTemplate;

 private ZuulProperties properties;

 public void setJdbcTemplate(JdbcTemplate jdbcTemplate){
  this.jdbcTemplate = jdbcTemplate;
 }

 public CustomRouteLocator(String servletPath, ZuulProperties properties) {
  super(servletPath, properties);
  this.properties = properties;
  logger.info("servletPath:{}",servletPath);
 }

 //父类已经提供了这个方法，这里写出来只是为了说明这一个方法很重要！！！
// @Override
// protected void doRefresh() {
//  super.doRefresh();
// }

 @Override
 public void refresh() {
  doRefresh();
 }

 @Override
 protected Map<String, ZuulRoute> locateRoutes() {
  LinkedHashMap<String, ZuulRoute> routesMap = new LinkedHashMap<String, ZuulRoute>();
  //从application.properties中加载路由信息
  routesMap.putAll(super.locateRoutes());
  //从db中加载路由信息
  routesMap.putAll(locateRoutesFromDB());
  //优化一下配置
  LinkedHashMap<String, ZuulRoute> values = new LinkedHashMap<>();
  for (Map.Entry<String, ZuulRoute> entry : routesMap.entrySet()) {
   String path = entry.getKey();
   // Prepend with slash if not already present.
   if (!path.startsWith("/")) {
    path = "/" + path;
   }
   if (StringUtils.hasText(this.properties.getPrefix())) {
    path = this.properties.getPrefix() + path;
    if (!path.startsWith("/")) {
     path = "/" + path;
    }
   }
   values.put(path, entry.getValue());
  }
  return values;
 }

 private Map<String, ZuulRoute> locateRoutesFromDB(){
  Map<String, ZuulRoute> routes = new LinkedHashMap<>();
  List<ZuulRouteVO> results = jdbcTemplate.query("select * from gateway_api_define where enabled = true ",new BeanPropertyRowMapper<>(ZuulRouteVO.class));
  for (ZuulRouteVO result : results) {
   if(org.apache.commons.lang3.StringUtils.isBlank(result.getPath()) || org.apache.commons.lang3.StringUtils.isBlank(result.getUrl()) ){
    continue;
   }
   ZuulRoute zuulRoute = new ZuulRoute();
   try {
    org.springframework.beans.BeanUtils.copyProperties(result,zuulRoute);
   } catch (Exception e) {
    logger.error("=============load zuul route info from db with error==============",e);
   }
   routes.put(zuulRoute.getPath(),zuulRoute);
  }
  return routes;
 }

 public static class ZuulRouteVO {

  /**
   * The ID of the route (the same as its map key by default).
   */
  private String id;

  /**
   * The path (pattern) for the route, e.g. /foo/**.
   */
  private String path;

  /**
   * The service ID (if any) to map to this route. You can specify a physical URL or
   * a service, but not both.
   */
  private String serviceId;

  /**
   * A full physical URL to map to the route. An alternative is to use a service ID
   * and service discovery to find the physical address.
   */
  private String url;

  /**
   * Flag to determine whether the prefix for this route (the path, minus pattern
   * patcher) should be stripped before forwarding.
   */
  private boolean stripPrefix = true;

  /**
   * Flag to indicate that this route should be retryable (if supported). Generally
   * retry requires a service ID and ribbon.
   */
  private Boolean retryable;

  private Boolean enabled;

  public String getId() {
   return id;
  }

  public void setId(String id) {
   this.id = id;
  }

  public String getPath() {
   return path;
  }

  public void setPath(String path) {
   this.path = path;
  }

  public String getServiceId() {
   return serviceId;
  }

  public void setServiceId(String serviceId) {
   this.serviceId = serviceId;
  }

  public String getUrl() {
   return url;
  }

  public void setUrl(String url) {
   this.url = url;
  }

  public boolean isStripPrefix() {
   return stripPrefix;
  }

  public void setStripPrefix(boolean stripPrefix) {
   this.stripPrefix = stripPrefix;
  }

  public Boolean getRetryable() {
   return retryable;
  }

  public void setRetryable(Boolean retryable) {
   this.retryable = retryable;
  }

  public Boolean getEnabled() {
   return enabled;
  }

  public void setEnabled(Boolean enabled) {
   this.enabled = enabled;
  }
 }
}

配置这个自定义的路由定位器：

@Configuration
public class CustomZuulConfig {

 @Autowired
 ZuulProperties zuulProperties;
 @Autowired
 ServerProperties server;
 @Autowired
 JdbcTemplate jdbcTemplate;

 @Bean
 public CustomRouteLocator routeLocator() {
  CustomRouteLocator routeLocator = new CustomRouteLocator(this.server.getServletPrefix(), this.zuulProperties);
  routeLocator.setJdbcTemplate(jdbcTemplate);
  return routeLocator;
 }

}

现在容器启动时，就可以从数据库和配置文件中一起加载路由信息了，离动态路由还差最后一步，就是实时刷新，前面已经说过了，默认的ZuulConfigure已经配置了事件监听器，我们只需要发送一个事件就可以实现刷新了。

public class RefreshRouteService {

 @Autowired
 ApplicationEventPublisher publisher;

 @Autowired
 RouteLocator routeLocator;

 public void refreshRoute() {
  RoutesRefreshedEvent routesRefreshedEvent = new RoutesRefreshedEvent(routeLocator);
  publisher.publishEvent(routesRefreshedEvent);
 }

}

具体的刷新流程其实就是从数据库重新加载了一遍，有人可能会问，为什么不自己是手动重新加载Locator.dorefresh？非要用事件去刷新。这牵扯到内部的zuul内部组件的工作流程，不仅仅是Locator本身的一个变量，具体想要了解的还得去看源码。

到这儿我们就实现了动态路由了，所以的实例代码和建表语句我会放到github上，下载的时候记得给我star QAQ ！！！

链接：https://github.com/lexburner/zuul-gateway-demo

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持我们。