SpringCloud Zuul在何种情况下使用Hystrix及问题小结

首先,引入spring-cloud-starter-zuul之后会间接引入:

hystrix依赖已经引入,那么何种情况下使用hystrix呢?

在Zuul的自动配置类ZuulServerAutoConfiguration和ZuulProxyAutoConfiguration中总共会向Spring容器注入3个Zuul的RouteFilter,分别是

•SimpleHostRoutingFilter

简单路由,通过HttpClient向预定的URL发送请求

生效条件:

RequestContext.getCurrentContext().getRouteHost() != null

 ​ && RequestContext.getCurrentContext().sendZuulResponse()

1、RequestContext中的routeHost不为空,routeHost就是URL,即使用URL直连

2、RequestContext中的sendZuulResponse为true,即是否将response发送给客户端,默认为true

•RibbonRoutingFilter

使用Ribbon、Hystrix和可插入的http客户端发送请求

生效条件:

(RequestContext.getRouteHost() == null && RequestContext.get(SERVICE_ID_KEY) != null

 ​ && RequestContext.sendZuulResponse())

1、RequestContext中的routeHost为空,即URL为空

2、RequestContext中的serviceId不为空

3、RequestContext中的sendZuulResponse为true,即是否将response发送给客户端,默认为true

•SendForwardFilter

forward到本地URL

生效条件:

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: 映射

2、RequestContext中SEND_FORWARD_FILTER_RAN为false,SEND_FORWARD_FILTER_RAN意为“send forward是否运行过了”,在SendForwardFilter#run()时会ctx.set(SEND_FORWARD_FILTER_RAN, true)

综上所述,在使用serviceId映射的方法路由转发的时候,会使用Ribbon+Hystrix

而哪种路由配置方式是“URL映射”,哪种配置方式又是“serviceId映射”呢?

Zuul有一个前置过滤器PreDecorationFilter用于通过RouteLocator路由定位器决定在何时以何种方式路由转发

RouteLocator是用于通过请求地址匹配到Route路由的,之后PreDecorationFilter再通过Route信息设置RequestContext上下文,决定后续使用哪个RouteFilter做路由转发

所以就引出以下问题:

•什么是Route

•RouteLocator路由定位器如何根据请求路径匹配路由

•匹配到路由后,PreDecorationFilter如何设置RequestContext请求上下文

什么是Route

我总共见到两个和Route相关的类

ZuulProperties.ZuulRoute,用于和zuul配置文件关联,保存相关信息

org.springframework.cloud.netflix.zuul.filters.Route, RouteLocator找到的路由信息就是这个类,用于路由转发

public static class ZuulRoute {

private String id; //ZuulRoute的id

private String path; //路由的pattern,如 /foo/**

private String serviceId; //要映射到此路由的服务id

private String url; //要映射到路由的完整物理URL

private boolean stripPrefix = true; //用于确定在转发之前是否应剥离此路由前缀的标志位

private Boolean retryable; //此路由是否可以重试,通常重试需要serviceId和ribbon

private Set<String> sensitiveHeaders = new LinkedHashSet(); //不会传递给下游请求的敏感标头列表

private boolean customSensitiveHeaders = false; //是否自定义了敏感头列表

}

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用于路由转发定位的属性location根据不同的情况,可能是一个具体的URL,可能是一个serviceId

RouteLocator路由定位器如何根据请求路径匹配路由

Zuul在自动配置加载时注入了2个RouteLocator

•CompositeRouteLocator: 组合的RouteLocator,在getMatchingRoute()时会依次调用其它的RouteLocator,先找到先返回;CompositeRouteLocator的routeLocators集合中只有DiscoveryClientRouteLocator

•DiscoveryClientRouteLocator: 可以将静态的、已配置的路由与来自DiscoveryClient服务发现的路由组合在一起,来自DiscoveryClient的路由优先;SimpleRouteLocator的子类(SimpleRouteLocator 基于加载到ZuulProperties中的配置定位Route路由信息)

其中CompositeRouteLocator是 @Primary 的,它是组合多个RouteLocator的Locator,其getMatchingRoute()方法会分别调用其它所有RouteLocator的getMatchingRoute()方法,通过请求路径匹配路由信息,只要匹配到了就马上返回

默认CompositeRouteLocator混合路由定位器的routeLocators只有一个DiscoveryClientRouteLocator,故只需分析DiscoveryClientRouteLocator#getMatchingRoute(path)

//----------DiscoveryClientRouteLocator是SimpleRouteLocator子类,其实是调用的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是保存路由信息的map,如果此时还未加载,调用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对path做微调

* 再根据path到routes中匹配到ZuulRoute

* 最后根据 ZuulRoute 和 adjustedPath 生成 Route

*/

String adjustedPath = adjustPath(path);

ZuulRoute route = getZuulRoute(adjustedPath);

return getRoute(route, adjustedPath);

}

下面我们来看看locateRoutes()是如何加载静态的、已配置的路由与来自DiscoveryClient服务发现的路由的

//----------DiscoveryClientRouteLocator#locateRoutes() 服务发现路由定位器的locateRoutes()

@Override

protected LinkedHashMap<String, ZuulRoute> locateRoutes() {

//保存ZuulRoute的LinkedHashMap

LinkedHashMap<String, ZuulRoute> routesMap = new LinkedHashMap<String, ZuulRoute>();

//调用父类SimpleRouteLocator#locateRoutes()

//加载ZuulProperties中的所有配置文件中的路由信息

routesMap.putAll(super.locateRoutes());

//如果服务发现客户端discovery存在

if (this.discovery != null) {

//将routesMap已经存在的配置文件中的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为null,以id作为serviceId,此情况适合 zuul.routes.xxxx=/xxxx/** 的情况

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(); //到注册中心找到所有service

String[] ignored = this.properties.getIgnoredServices()

.toArray(new String[0]);

//遍历services

for (String serviceId : services) {

// Ignore specifically ignored services and those that were manually

// configured

String key = "/" + mapRouteToService(serviceId) + "/**";

//如果注册中心的serviceId在staticServices集合中,并且此路由没有配置URL

//那么,更新路由的location为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);

}

}

//如果注册中心的serviceId不在忽略范围内,且routesMap中还没有包含,添加到routesMap

if (!PatternMatchUtils.simpleMatch(ignored, serviceId)

&& !routesMap.containsKey(key)) {

// Not ignored

routesMap.put(key, new ZuulRoute(key, serviceId));

}

}

}

// 如果routesMap中有 /** 的默认路由配置

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);

}

//将routesMap中的数据微调后,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;

}

此方法运行后就已经加载了配置文件中所有路由信息,以及注册中心中的服务路由信息,有的通过URL路由,有的通过serviceId路由

只需根据本次请求的requestURI与 路由的pattern匹配找到对应的路由

匹配到路由后,PreDecorationFilter如何设置RequestContext请求上下文

//----------PreDecorationFilter前置过滤器

@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

//----------------到上面为止是已经分析过的,根据requestURI找到匹配的Route信息

// ==== 匹配到路由信息

if (route != null) {

String location = route.getLocation();

if (location != null) {

ctx.put(REQUEST_URI_KEY, route.getPath());//RequestContext设置 requestURI:路由的pattern路径

ctx.put(PROXY_KEY, route.getId());//RequestContext设置 proxy:路由id

//设置需要忽略的敏感头信息,要么用全局默认的,要么用路由自定义的

if (!route.isCustomSensitiveHeaders()) {

this.proxyRequestHelper

.addIgnoredHeaders(this.properties.getSensitiveHeaders().toArray(new String[0]));

}

else {

this.proxyRequestHelper.addIgnoredHeaders(route.getSensitiveHeaders().toArray(new String[0]));

}

//设置重试信息

if (route.getRetryable() != null) {

ctx.put(RETRYABLE_KEY, route.getRetryable());

}

//如果location是 http/https开头的,RequestContext设置 routeHost:URL

//如果location是 forward:开头的,RequestContext设置 forward信息、routeHost:null

//其它 RequestContext设置 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);

}

//是否添加代理头信息 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);

}

//是否添加Host头信息

if (this.properties.isAddHostHeader()) {

ctx.addZuulRequestHeader(HttpHeaders.HOST, toHostHeader(ctx.getRequest()));

}

}

}

// ==== 没有匹配到路由信息

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;

}

总结:

•只要引入了spring-cloud-starter-zuul就会间接引入Ribbon、Hystrix

•路由信息可能是从配置文件中加载的,也可能是通过DiscoveryClient从注册中心加载的

•zuul是通过前置过滤器PreDecorationFilter找到与当前requestURI匹配的路由信息,并在RequestContext中设置相关属性的,后续的Route Filter会根据RequestContext中的这些属性判断如何路由转发

•Route Filter主要使用 SimpleHostRoutingFilter 和 RibbonRoutingFilter

•当RequestContext请求上下文中存在routeHost,即URL直连信息时,使用SimpleHostRoutingFilter简单Host路由

•当RequestContext请求上下文中存在serviceId,即服务id时(可能会与注册中心关联获取服务列表,或者读取配置文件中serviceId.ribbon.listOfServers的服务列表),使用RibbonRoutingFilter,会使用Ribbon、Hystrix

总结

以上所述是小编给大家介绍的SpringCloud Zuul在何种情况下使用Hystrix,希望对大家有所帮助,如果大家有任何疑问请给我留言,小编会及时回复大家的。在此也非常感谢大家对网站的支持!

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