Sending a redirect form a zuul filter - spring-cloud

Question

I am implementing an addition to our set of zuul filters.
This additional filter would look at a header and decide that a request should be redirected to a known location that I would configure.
This is the body of the run method for the filter
#Override
public Object run() {
log.debug("Running the PreRouteTransMarkAndLoggingZuulFilter filter ");
// retrieve redirect URL
String redirectURL = filterConfigurationBean.getRedirectURL();
if (redirectURL.isEmpty()) {
return null;
}
// get the white list for allowed entries
Set<String> whiteList = new HashSet<>(Arrays.asList(filterConfigurationBean.getWhiteList().split(",")));
RequestContext ctx = RequestContext.getCurrentContext();
// if request url is part of white list then allow
String url = ctx.getRequest().getRequestURL().toString();
if (checkWhiteList(url, whiteList)) {
return null;
}
// get headers
// check if an authorization header is present
if (validHeader(ctx.getRequest())) {
return null;
}
// if it got to here then if no header then redirect request
try {
ctx.getResponse().sendRedirect(redirectURL);
} catch (IOException e) {
log.error("unable to send a redirect to the login page");
}
return null;
}
Ok, so I implemented and tested it (it is defined as a pre-filter since I don't want the request sent on in the route phase.
Somewhere, a bit further, it tosses an exception.
2017-06-26 17:00:36.482 WARN 6267 --- [tp1303192419-23] o.s.c.n.z.filters.post.SendErrorFilter : Error during filtering
com.netflix.zuul.exception.ZuulException: Filter threw Exception
at com.netflix.zuul.FilterProcessor.processZuulFilter(FilterProcessor.java:227)
at com.netflix.zuul.FilterProcessor.runFilters(FilterProcessor.java:157)
at com.netflix.zuul.FilterProcessor.postRoute(FilterProcessor.java:92)
at com.netflix.zuul.ZuulRunner.postRoute(ZuulRunner.java:87)
at com.netflix.zuul.http.ZuulServlet.postRoute(ZuulServlet.java:107)
at com.netflix.zuul.http.ZuulServlet.service(ZuulServlet.java:88)
at org.springframework.web.servlet.mvc.ServletWrappingController.handleRequestInternal(ServletWrappingController.java:157)
at org.springframework.cloud.netflix.zuul.web.ZuulController.handleRequest(ZuulController.java:44)
at org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter.handle(SimpleControllerHandlerAdapter.java:50)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:967)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:901)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:970)
at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:861)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:687)
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:790)
at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:841)
at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1650)
at org.eclipse.jetty.websocket.server.WebSocketUpgradeFilter.doFilter(WebSocketUpgradeFilter.java:206)
at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1637)
at org.springframework.boot.web.filter.ApplicationContextHeaderFilter.doFilterInternal(ApplicationContextHeaderFilter.java:55)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1637)
at org.springframework.boot.actuate.trace.WebRequestTraceFilter.doFilterInternal(WebRequestTraceFilter.java:110)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1637)
at org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:208)
at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:177)
at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:346)
at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:262)
at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1637)
at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:99)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1637)
at org.springframework.web.filter.HttpPutFormContentFilter.doFilterInternal(HttpPutFormContentFilter.java:105)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1637)
at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:81)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1637)
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:197)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1637)
at org.springframework.boot.actuate.autoconfigure.MetricsFilter.doFilterInternal(MetricsFilter.java:106)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1637)
at com.cisco.phisphere.routerservice.BasicCORSFilter.doFilter(BasicCORSFilter.java:78)
at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1637)
at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:533)
at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:143)
at org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:548)
at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:132)
at org.eclipse.jetty.server.handler.ScopedHandler.nextHandle(ScopedHandler.java:190)
at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:1595)
at org.eclipse.jetty.server.handler.ScopedHandler.nextHandle(ScopedHandler.java:188)
at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1253)
at org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:168)
at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:473)
at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:1564)
at org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:166)
at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1155)
at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:141)
at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:132)
at org.eclipse.jetty.server.Server.handle(Server.java:564)
at org.eclipse.jetty.server.HttpChannel.handle(HttpChannel.java:317)
at org.eclipse.jetty.server.HttpConnection.onFillable(HttpConnection.java:251)
at org.eclipse.jetty.io.AbstractConnection$ReadCallback.succeeded(AbstractConnection.java:279)
at org.eclipse.jetty.io.FillInterest.fillable(FillInterest.java:110)
at org.eclipse.jetty.io.ChannelEndPoint$2.run(ChannelEndPoint.java:124)
at org.eclipse.jetty.util.thread.Invocable.invokePreferred(Invocable.java:128)
at org.eclipse.jetty.util.thread.Invocable$InvocableExecutor.invoke(Invocable.java:222)
at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.doProduce(EatWhatYouKill.java:294)
at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.produce(EatWhatYouKill.java:126)
at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:672)
at org.eclipse.jetty.util.thread.QueuedThreadPool$2.run(QueuedThreadPool.java:590)
at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.reflect.UndeclaredThrowableException: null
at org.springframework.util.ReflectionUtils.rethrowRuntimeException(ReflectionUtils.java:317)
at org.springframework.cloud.netflix.zuul.filters.post.SendResponseFilter.run(SendResponseFilter.java:115)
at com.netflix.zuul.ZuulFilter.runFilter(ZuulFilter.java:112)
at com.netflix.zuul.FilterProcessor.processZuulFilter(FilterProcessor.java:193)
... 75 common frames omitted
Caused by: org.eclipse.jetty.io.EofException: Closed
at org.eclipse.jetty.server.HttpOutput.write(HttpOutput.java:476)
at org.springframework.cloud.netflix.zuul.filters.post.SendResponseFilter.writeResponse(SendResponseFilter.java:214)
at org.springframework.cloud.netflix.zuul.filters.post.SendResponseFilter.writeResponse(SendResponseFilter.java:183)
at org.springframework.cloud.netflix.zuul.filters.post.SendResponseFilter.run(SendResponseFilter.java:112)
... 77 common frames omitted
So the question I have is this. Is this the right way to perform redirects from zuul?
I have a well defined condition for redirection and a well defined location to send it. I don't want this request to continue if the condition is held but be redirected to an external location.
Thanks

Answer 1

Ok, so I played around and figured it out.
You need to make sure that the RibbonRoutingFilter doesn't trigger by setting ctx.setSendZuulResponse(false) since that filter uses this to figure out if it should fire.
Next set ctx.put(FORWARD_TO_KEY, redirectURL) to make sure that the SendForward filter will fire. Set the redirectURL to where you want it to go.
Also set ctx.getResponse().sendRedirect(redirectURL) or it will tack on the routing path to the original service as a prefix and the redirect will fail.
#Override
public Object run() {
log.debug("Running the AuthorizationPassFilter filter ");
// retrieve redirect URL
String redirectURL = filterConfigurationBean.getRedirectURL();
if (redirectURL.isEmpty()) {
return null;
}
// get the white list for allowed entries
Set<String> whiteList = new HashSet<>(Arrays.asList(filterConfigurationBean.getWhiteList().split(",")));
RequestContext ctx = RequestContext.getCurrentContext();
// if request url is part of white list then allow
String url = ctx.getRequest().getRequestURL().toString();
if (checkWhiteList(url, whiteList)) {
return null;
}
// get headers
// check if an authorization header is present
if (validHeader(ctx.getRequest())) {
return null;
}
// if it got to here then if no header then redirect request
try {
ctx.setSendZuulResponse(false);
ctx.put(FORWARD_TO_KEY, redirectURL);
ctx.setResponseStatusCode(HttpStatus.SC_TEMPORARY_REDIRECT);
ctx.getResponse().sendRedirect(redirectURL);
} catch (IOException e) {
log.error("unable to send a redirect to the login page");
}
return null;
}