Spring Cloud —— Zuul 動態路由
阿新 • • 發佈：2018-12-16
推薦 Spring Boot/Cloud 視訊：
前言
Zuul 是Netflix 提供的一個開源元件,致力於在雲平臺上提供動態路由，監控，彈性，安全等邊緣服務的框架。也有很多公司使用它來作為閘道器的重要組成部分，碰巧今年公司的架構組決定自研一個閘道器產品，集動態路由，動態許可權，限流配額等功能為一體，為其他部門的專案提供統一的外網呼叫管理，最終形成產品(這方面阿里其實已經有成熟的閘道器產品了，但是不太適用於個性化的配置，也沒有整合許可權和限流降級)。
不過這裡並不想介紹整個閘道器的架構，而是想著重於討論其中的一個關鍵點，並且也是經常在交流群中聽人說起的：動態路由怎麼做？
再闡釋什麼是動態路由之前，需要介紹一下架構的設計。
傳統網際網路架構圖
加入eureka的架構圖
最終架構圖
要強調的一點是，gateway最終也會部署多個例項，達到分散式的效果，在架構圖中沒有畫出，請大家自行腦補。
本部落格的示例使用最後一章架構圖為例，帶來動態路由的實現方式，會有具體的程式碼。
動態路由
動態路由需要達到可持久化配置，動態重新整理的效果。如架構圖所示，不僅要能滿足從spring的配置檔案properties載入路由資訊，還需要從資料庫載入我們的配置。另外一點是，路由資訊在容器啟動時就已經載入進入了記憶體，我們希望配置完成後，實施釋出，動態重新整理記憶體中的路由資訊，達到不停機維護路由資訊的效果。
zuul–HelloWorldDemo
專案結構
<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對應的springcloud的版本需要使用Camden.SR6，一開始想專門寫這個demo時，只替換了springboot的版本1.4.0->1.5.2，結果啟動就報錯了，最後發現是版本不相容的鍋。 gateway專案： 啟動類：GatewayApplication.java
@EnableZuulProxy
@SpringBootApplication
public class GatewayApplication {
public static void main(String[] args) {
SpringApplication.run(GatewayApplication.class, args);
}
}
配置：application.properties
#配置在配置檔案中的路由資訊
zuul.routes.books.url=http://localhost:8090
zuul.routes.books.path=/books/**
#不使用註冊中心,會帶來侵入性
ribbon.eureka.enabled=false
#閘道器埠
server.port=8080
book專案： 啟動類：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);
}
}
配置類：application.properties
server.port=8090
上述demo是一個簡單的靜態路由，簡單看下原始碼，zuul是怎麼做到轉發，路由的。
@Configuration
@EnableConfigurationProperties({ ZuulProperties.class })
@ConditionalOnClass(ZuulServlet.class)
@Import(ServerPropertiesAutoConfiguration.class)
public class ZuulConfiguration {
@Autowired
//zuul的配置檔案,對應了application.properties中的配置資訊
protected ZuulProperties zuulProperties;
@Autowired
protected ServerProperties server;
@Autowired(required = false)
private ErrorController errorController;
@Bean
public HasFeatures zuulFeature() {
return HasFeatures.namedFeature("Zuul (Simple)", ZuulConfiguration.class);
}
//核心類，路由定位器，最最重要
@Bean
@ConditionalOnMissingBean(RouteLocator.class)
public RouteLocator routeLocator() {
//預設配置的實現是SimpleRouteLocator.class
return new SimpleRouteLocator(this.server.getServletPrefix(),
this.zuulProperties);
}
//zuul的控制器，負責處理鏈路呼叫
@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;
}
//註冊了一個路由重新整理監聽器，預設實現是ZuulRefreshListener.class，這個是我們動態路由的關鍵
@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);
}
}
//上面提到的路由重新整理監聽器
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) {
//設定為髒,下一次匹配到路徑時，如果發現為髒，則會去重新整理路由資訊
this.zuulHandlerMapping.setDirty(true);
}
else if (event instanceof HeartbeatEvent) {
if (this.heartbeatMonitor.update(((HeartbeatEvent) event).getValue())) {
this.zuulHandlerMapping.setDirty(true);
}
}
}
}
}
我們要解決動態路由的難題，第一步就得理解路由定位器的作用。
很失望，因為從介面關係來看，spring考慮到了路由重新整理的需求，但是預設實現的SimpleRouteLocator沒有實現RefreshableRouteLocator介面，看來我們只能借鑑DiscoveryClientRouteLocator去改造SimpleRouteLocator使其具備重新整理能力。
public interface RefreshableRouteLocator extends RouteLocator {
void refresh();
}
DiscoveryClientRouteLocator比SimpleRouteLocator多了兩個功能，第一是從DiscoveryClient（如Eureka）發現路由資訊，之前的架構圖已經給大家解釋清楚了，我們不想使用eureka這種侵入式的閘道器模組，所以忽略它，第二是實現了RefreshableRouteLocator介面，能夠實現動態重新整理。 對SimpleRouteLocator.class的原始碼加一些註釋，方便大家閱讀：
public class SimpleRouteLocator implements RouteLocator {
//配置檔案中的路由資訊配置
private ZuulProperties properties;
//路徑正則配置器,即作用於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();
}
//路由定位器和其他元件的互動，是最終把定位的Routes以list的方式提供出去,核心實現
@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();
}
//這個方法在閘道器產品中也很重要，可以根據實際路徑匹配到Route來進行業務邏輯的操作，進行一些加工
@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);
}
//注意這個類並沒有實現refresh介面，但是卻提供了一個protected級別的方法,旨在讓子類不需要重複維護一個private AtomicReference<Map<String, ZuulRoute>> routes = new AtomicReference<>();也可以達到重新整理的效果
protected void doRefresh() {
this.routes.set(locateRoutes());
}
//具體就是在這兒定位路由資訊的，我們之後從資料庫載入路由資訊，主要也是從這兒改寫
/**
* 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;
}
}
重寫過後的自定義路由定位器如下：
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);
}
//父類已經提供了這個方法，這裡寫出來只是為了說明這一個方法很重要！！！
// @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>();
//從application.properties中載入路由資訊
routesMap.putAll(super.locateRoutes());
//從db中載入路由資訊
routesMap.putAll(locateRoutesFromDB());
//優化一下配置
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;
}
}
}
配置這個自定義的路由定位器：
@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;
}
}
現在容器啟動時，就可以從資料庫和配置檔案中一起載入路由資訊了，離動態路由還差最後一步，就是實時重新整理，前面已經說過了，預設的ZuulConfigure已經配置了事件監聽器，我們只需要傳送一個事件就可以實現重新整理了。
public class RefreshRouteService {
@Autowired
ApplicationEventPublisher publisher;
@Autowired
RouteLocator routeLocator;
public void refreshRoute() {
RoutesRefreshedEvent routesRefreshedEvent = new RoutesRefreshedEvent(routeLocator);
publisher.publishEvent(routesRefreshedEvent);
}
}
具體的重新整理流程其實就是從資料庫重新載入了一遍，有人可能會問，為什麼不自己是手動重新載入Locator.dorefresh？非要用事件去重新整理。這牽扯到內部的zuul內部元件的工作流程，不僅僅是Locator本身的一個變數，具體想要了解的還得去看原始碼。
到這兒我們就實現了動態路由了，所以的例項程式碼和建表語句我會放到github上，下載的時候記得給我star QAQ
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