【SpringCloud】Zuul在何種情況下使用Hystrix
首先,引入 spring-cloud-starter-zuul
之後會間接引入:
hystrix依賴已經引入,那麼何種情況下使用hystrix呢?
在Zuul的自動配置類 ZuulServerAutoConfiguration
和 ZuulProxyAutoConfiguration
中總共會向Spring容器注入3個Zuul的RouteFilter,分別是
-
SimpleHostRoutingFilter
簡單路由,通過HttpClient向預定的URL傳送請求
生效條件:
RequestContext.getCurrentContext().getRouteHost() != null
&& RequestContext.getCurrentContext().sendZuulResponse()
1、RequestContext中的routeHost不為空,routeHost就是URL,即使用URL直連
2、RequestContext中的sendZuulResponse為true,即是否將response傳送給客戶端,預設為true
-
RibbonRoutingFilter
-
SendForwardFilter
forward到本地URL
生效條件:
RequestContext.containsKey(FORWARD_TO_KEY)
&& !RequestContext.getBoolean(SEND_FORWARD_FILTER_RAN, false)
1、RequestContext中包含FORWARD_TO_KEY,即URL使用 forward: 對映
2、RequestContext中SEND_FORWARD_FILTER_RAN為false,SEND_FORWARD_FILTER_RAN意為“send forward是否執行過了”,在SendForwardFilter#run()時會
ctx.set(SEND_FORWARD_FILTER_RAN, true)
綜上所述,在使用serviceId對映的方法路由轉發的時候,會使用Ribbon+Hystrix
而哪種路由配置方式是“URL對映”,哪種配置方式又是“serviceId對映”呢?
Zuul有一個前置過濾器 PreDecorationFilter
用於通過 RouteLocator路由定位器
決定在何時以何種方式路由轉發
RouteLocator是用於通過請求地址匹配到Route路由的,之後 PreDecorationFilter
再通過Route資訊設定RequestContext上下文,決定後續使用哪個RouteFilter做路由轉發
所以就引出以下問題:
- 什麼是Route
- RouteLocator路由定位器如何根據請求路徑匹配路由
- 匹配到路由後,PreDecorationFilter如何設定RequestContext請求上下文
什麼是Route
我總共見到兩個和Route相關的類
ZuulProperties.ZuulRoute
,用於和zuul配置檔案關聯,儲存相關資訊
org.springframework.cloud.netflix.zuul.filters.Route
, RouteLocator找到的路由資訊就是這個類,用於路由轉發
public static class ZuulRoute { private String id;//ZuulRoute的id private String path;//路由的pattern,如 /foo/** private String serviceId;//要對映到此路由的服務id private String url;//要對映到路由的完整物理URL private boolean stripPrefix = true;//用於確定在轉發之前是否應剝離此路由字首的標誌位 private Boolean retryable;//此路由是否可以重試,通常重試需要serviceId和ribbon private Set<String> sensitiveHeaders = new LinkedHashSet(); //不會傳遞給下游請求的敏感標頭列表 private boolean customSensitiveHeaders = false; //是否自定義了敏感頭列表 }
public class Route { private String id; private String fullPath; private String path; private String location;//可能是 url 或 serviceId private String prefix; private Boolean retryable; private Set<String> sensitiveHeaders = new LinkedHashSet<>(); private boolean customSensitiveHeaders; }
可以看到 org.springframework.cloud.netflix.zuul.filters.Route
和 ZuulProperties.ZuulRoute
基本一致,只是Route用於路由轉發定位的屬性location根據不同的情況,可能是一個具體的URL,可能是一個serviceId
RouteLocator路由定位器如何根據請求路徑匹配路由
Zuul在自動配置載入時注入了2個RouteLocator
- CompositeRouteLocator : 組合的RouteLocator,在
getMatchingRoute()
時會依次呼叫其它的RouteLocator,先找到先返回;CompositeRouteLocator的routeLocators集合中只有DiscoveryClientRouteLocator - DiscoveryClientRouteLocator : 可以將靜態的、已配置的路由與來自DiscoveryClient服務發現的路由組合在一起,來自DiscoveryClient的路由優先;SimpleRouteLocator的子類(SimpleRouteLocator 基於載入到
ZuulProperties
中的配置定位Route路由資訊)
其中CompositeRouteLocator是 @Primary 的,它是組合多個RouteLocator的Locator,其 getMatchingRoute()
方法會分別呼叫其它所有RouteLocator的getMatchingRoute()方法,通過請求路徑匹配路由資訊,只要匹配到了就馬上返回
預設CompositeRouteLocator混合路由定位器的routeLocators只有一個DiscoveryClientRouteLocator,故只需分析 DiscoveryClientRouteLocator#getMatchingRoute(path)
//----------DiscoveryClientRouteLocator是SimpleRouteLocator子類,其實是呼叫的SimpleRouteLocator##getMatchingRoute(path) @Override public Route getMatchingRoute(final String path) { return getSimpleMatchingRoute(path); } protected Route getSimpleMatchingRoute(final String path) { if (log.isDebugEnabled()) { log.debug("Finding route for path: " + path); } // routes是儲存路由資訊的map,如果此時還未載入,呼叫locateRoutes() 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()); } /** * 下面的方法主要是先對path做微調 * 再根據path到routes中匹配到ZuulRoute * 最後根據 ZuulRoute 和 adjustedPath 生成 Route */ String adjustedPath = adjustPath(path); ZuulRoute route = getZuulRoute(adjustedPath); return getRoute(route, adjustedPath); }
下面我們來看看 locateRoutes()
是如何載入靜態的、已配置的路由與來自DiscoveryClient服務發現的路由的
//----------DiscoveryClientRouteLocator#locateRoutes()服務發現路由定位器的locateRoutes() @Override protected LinkedHashMap<String, ZuulRoute> locateRoutes() { //儲存ZuulRoute的LinkedHashMap LinkedHashMap<String, ZuulRoute> routesMap = new LinkedHashMap<String, ZuulRoute>(); //呼叫父類SimpleRouteLocator#locateRoutes() //載入ZuulProperties中的所有配置檔案中的路由資訊 routesMap.putAll(super.locateRoutes()); //如果服務發現客戶端discovery存在 if (this.discovery != null) { //將routesMap已經存在的配置檔案中的ZuulRoute放入staticServices<serviceId, ZuulRoute> Map<String, ZuulRoute> staticServices = new LinkedHashMap<String, ZuulRoute>(); for (ZuulRoute route : routesMap.values()) { String serviceId = route.getServiceId(); //如果serviceId為null,以id作為serviceId,此情況適合 zuul.routes.xxxx=/xxxx/** 的情況 if (serviceId == null) { serviceId = route.getId(); } if (serviceId != null) { staticServices.put(serviceId, route); } } // Add routes for discovery services by default List<String> services = this.discovery.getServices(); //到註冊中心找到所有service String[] ignored = this.properties.getIgnoredServices() .toArray(new String[0]); //遍歷services for (String serviceId : services) { // Ignore specifically ignored services and those that were manually // configured String key = "/" + mapRouteToService(serviceId) + "/**"; //如果註冊中心的serviceId在staticServices集合中,並且此路由沒有配置URL //那麼,更新路由的location為serviceId if (staticServices.containsKey(serviceId) && staticServices.get(serviceId).getUrl() == null) { // Explicitly configured with no URL, cannot be ignored // all static routes are already in routesMap // Update location using serviceId if location is null ZuulRoute staticRoute = staticServices.get(serviceId); if (!StringUtils.hasText(staticRoute.getLocation())) { staticRoute.setLocation(serviceId); } } //如果註冊中心的serviceId不在忽略範圍內,且routesMap中還沒有包含,新增到routesMap if (!PatternMatchUtils.simpleMatch(ignored, serviceId) && !routesMap.containsKey(key)) { // Not ignored routesMap.put(key, new ZuulRoute(key, serviceId)); } } } // 如果routesMap中有 /** 的預設路由配置 if (routesMap.get(DEFAULT_ROUTE) != null) { ZuulRoute defaultRoute = routesMap.get(DEFAULT_ROUTE); // Move the defaultServiceId to the end routesMap.remove(DEFAULT_ROUTE); routesMap.put(DEFAULT_ROUTE, defaultRoute); } //將routesMap中的資料微調後,放到values<String, ZuulRoute>,返回 LinkedHashMap<String, ZuulRoute> values = new LinkedHashMap<>(); for (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; }
此方法執行後就已經載入了配置檔案中所有路由資訊,以及註冊中心中的服務路由資訊,有的通過URL路由,有的通過serviceId路由
只需根據本次請求的requestURI與 路由的pattern匹配找到對應的路由
匹配到路由後,PreDecorationFilter如何設定RequestContext請求上下文
//----------PreDecorationFilter前置過濾器 @Override public Object run() { RequestContext ctx = RequestContext.getCurrentContext(); final String requestURI = this.urlPathHelper.getPathWithinApplication(ctx.getRequest()); Route route = this.routeLocator.getMatchingRoute(requestURI); //找到匹配的路由 //----------------到上面為止是已經分析過的,根據requestURI找到匹配的Route資訊 // ==== 匹配到路由資訊 if (route != null) { String location = route.getLocation(); if (location != null) { ctx.put(REQUEST_URI_KEY, route.getPath());//RequestContext設定 requestURI:路由的pattern路徑 ctx.put(PROXY_KEY, route.getId());//RequestContext設定 proxy:路由id //設定需要忽略的敏感頭資訊,要麼用全域性預設的,要麼用路由自定義的 if (!route.isCustomSensitiveHeaders()) { this.proxyRequestHelper .addIgnoredHeaders(this.properties.getSensitiveHeaders().toArray(new String[0])); } else { this.proxyRequestHelper.addIgnoredHeaders(route.getSensitiveHeaders().toArray(new String[0])); } //設定重試資訊 if (route.getRetryable() != null) { ctx.put(RETRYABLE_KEY, route.getRetryable()); } //如果location是 http/https開頭的,RequestContext設定 routeHost:URL //如果location是 forward:開頭的,RequestContext設定 forward資訊、routeHost:null //其它 RequestContext設定 serviceId、routeHost:null、X-Zuul-ServiceId if (location.startsWith(HTTP_SCHEME+":") || location.startsWith(HTTPS_SCHEME+":")) { ctx.setRouteHost(getUrl(location)); ctx.addOriginResponseHeader(SERVICE_HEADER, location); } else if (location.startsWith(FORWARD_LOCATION_PREFIX)) { ctx.set(FORWARD_TO_KEY, StringUtils.cleanPath(location.substring(FORWARD_LOCATION_PREFIX.length()) + route.getPath())); ctx.setRouteHost(null); return null; } else { // set serviceId for use in filters.route.RibbonRequest ctx.set(SERVICE_ID_KEY, location); ctx.setRouteHost(null); ctx.addOriginResponseHeader(SERVICE_ID_HEADER, location); } //是否新增代理頭資訊 X-Forwarded-For if (this.properties.isAddProxyHeaders()) { addProxyHeaders(ctx, route); String xforwardedfor = ctx.getRequest().getHeader(X_FORWARDED_FOR_HEADER); String remoteAddr = ctx.getRequest().getRemoteAddr(); if (xforwardedfor == null) { xforwardedfor = remoteAddr; } else if (!xforwardedfor.contains(remoteAddr)) { // Prevent duplicates xforwardedfor += ", " + remoteAddr; } ctx.addZuulRequestHeader(X_FORWARDED_FOR_HEADER, xforwardedfor); } //是否新增Host頭資訊 if (this.properties.isAddHostHeader()) { ctx.addZuulRequestHeader(HttpHeaders.HOST, toHostHeader(ctx.getRequest())); } } } // ==== 沒有匹配到路由資訊 else { log.warn("No route found for uri: " + requestURI); String fallBackUri = requestURI; String fallbackPrefix = this.dispatcherServletPath; // default fallback // servlet is // DispatcherServlet if (RequestUtils.isZuulServletRequest()) { // remove the Zuul servletPath from the requestUri log.debug("zuulServletPath=" + this.properties.getServletPath()); fallBackUri = fallBackUri.replaceFirst(this.properties.getServletPath(), ""); log.debug("Replaced Zuul servlet path:" + fallBackUri); } else { // remove the DispatcherServlet servletPath from the requestUri log.debug("dispatcherServletPath=" + this.dispatcherServletPath); fallBackUri = fallBackUri.replaceFirst(this.dispatcherServletPath, ""); log.debug("Replaced DispatcherServlet servlet path:" + fallBackUri); } if (!fallBackUri.startsWith("/")) { fallBackUri = "/" + fallBackUri; } String forwardURI = fallbackPrefix + fallBackUri; forwardURI = forwardURI.replaceAll("//", "/"); ctx.set(FORWARD_TO_KEY, forwardURI); } return null; }
總結:
- 只要引入了spring-cloud-starter-zuul就會間接引入Ribbon、Hystrix
- 路由資訊可能是從配置檔案中載入的,也可能是通過DiscoveryClient從註冊中心載入的
- zuul是通過前置過濾器PreDecorationFilter找到與當前requestURI匹配的路由資訊,並在RequestContext中設定相關屬性的,後續的Route Filter會根據RequestContext中的這些屬性判斷如何路由轉發
- Route Filter主要使用 SimpleHostRoutingFilter 和 RibbonRoutingFilter
- 當RequestContext請求上下文中存在routeHost,即URL直連資訊時,使用SimpleHostRoutingFilter簡單Host路由
- 當RequestContext請求上下文中存在serviceId,即服務id時(可能會與註冊中心關聯獲取服務列表,或者讀取配置檔案中serviceId.ribbon.listOfServers的服務列表),使用RibbonRoutingFilter,會使用Ribbon、Hystrix