Don't swallow execeptions with zuul by reusing the spring boot error facilities.

docs/src/main/asciidoc/spring-cloud-netflix.adoc

@@ -484,3 +484,14 @@ This means that http calls to /users get forwarded to the users service.
 
 Since zuul, by default, intercepts all requests (`/*`), to enable actuator, you should set the `management.port`.
 
+To use the Spring Boot error facilities while using the standalone Zuul server, please set the following properties
+
+----
+# moves the Spring Dispatch Servlet to a path below `/`
+server:
+  servletPath: /app
+# sets the error path to use the Dispatch Servlet to resolve the error view
+error:
+  path: ${server.servletPath}/error
+----
+

spring-cloud-netflix-core/src/main/java/org/springframework/cloud/netflix/zuul/AbstractZuulConfiguration.java

@@ -6,9 +6,11 @@ import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.actuate.trace.TraceRepository;
 import org.springframework.boot.context.embedded.FilterRegistrationBean;
 import org.springframework.boot.context.embedded.ServletRegistrationBean;
+import org.springframework.cloud.netflix.zuul.filters.post.SendErrorFilter;
 import org.springframework.cloud.netflix.zuul.filters.post.SendResponseFilter;
 import org.springframework.cloud.netflix.zuul.filters.pre.DebugFilter;
 import org.springframework.cloud.netflix.zuul.filters.pre.PreDecorationFilter;
+import org.springframework.cloud.netflix.zuul.filters.pre.Servlet30WrapperFilter;
 import org.springframework.cloud.netflix.zuul.filters.route.RibbonRoutingFilter;
 import org.springframework.context.annotation.Bean;
 
@@ -62,6 +64,11 @@ public abstract class AbstractZuulConfiguration {
         return new PreDecorationFilter();
     }
 
+    @Bean
+    public Servlet30WrapperFilter servlet30WrapperFilter() {
+        return new Servlet30WrapperFilter();
+    }
+
     // route filters
     @Bean
     public RibbonRoutingFilter ribbonRoutingFilter() {
@@ -78,4 +85,8 @@ public abstract class AbstractZuulConfiguration {
         return new SendResponseFilter();
     }
 
+    @Bean
+    public SendErrorFilter sendErrorFilter() {
+        return new SendErrorFilter();
+    }
 }

spring-cloud-netflix-core/src/main/java/org/springframework/cloud/netflix/zuul/filters/post/SendErrorFilter.java

+package org.springframework.cloud.netflix.zuul.filters.post;
+
+import com.google.common.base.Throwables;
+import com.netflix.zuul.ZuulFilter;
+import com.netflix.zuul.context.RequestContext;
+import lombok.extern.slf4j.Slf4j;
+import org.springframework.beans.factory.annotation.Value;
+
+/**
+ * @author Spencer Gibb
+ */
+@Slf4j
+public class SendErrorFilter extends ZuulFilter {
+
+    @Value("${error.path:/error}")
+    private String errorPath;
+
+    @Override
+    public String filterType() {
+        return "post";
+    }
+
+    @Override
+    public int filterOrder() {
+        return 0;
+    }
+
+    @Override
+    public boolean shouldFilter() {
+        RequestContext ctx = RequestContext.getCurrentContext();
+        return ctx.containsKey("error.status_code");
+    }
+
+    @Override
+    public Object run() {
+        try {
+            RequestContext ctx = RequestContext.getCurrentContext();
+            int statusCode = (Integer)ctx.get("error.status_code");
+            if (ctx.containsKey("error.exception")) {
+                Object e = ctx.get("error.exception");
+                log.warn("Error during filtering", Throwable.class.cast(e));
+                ctx.getRequest().setAttribute("javax.servlet.error.exception", e);
+            }
+            ctx.getRequest().setAttribute("javax.servlet.error.status_code", statusCode);
+            ctx.getRequest().getRequestDispatcher(errorPath).forward(ctx.getRequest(), ctx.getResponse());
+        } catch (Exception e) {
+            Throwables.propagate(e);
+        }
+        return null;
+    }
+}

spring-cloud-netflix-core/src/main/java/org/springframework/cloud/netflix/zuul/filters/pre/PreDecorationFilter.java

@@ -12,6 +12,7 @@ import org.springframework.cloud.netflix.zuul.Routes;
 import org.springframework.cloud.netflix.zuul.ZuulProperties;
 
 import javax.annotation.Nullable;
+import javax.servlet.http.HttpServletResponse;
 import java.util.LinkedHashMap;
 
 public class PreDecorationFilter extends ZuulFilter {
@@ -78,7 +79,7 @@ public class PreDecorationFilter extends ZuulFilter {
             }
         } else {
             LOG.warn("No route found for uri: "+requestURI);
-            //TODO: 404
+            ctx.set("error.status_code", HttpServletResponse.SC_NOT_FOUND);
         }
         return null;
     }

spring-cloud-netflix-core/src/main/java/org/springframework/cloud/netflix/zuul/filters/pre/Servlet30WrapperFilter.java

+package org.springframework.cloud.netflix.zuul.filters.pre;
+
+import com.google.common.base.Throwables;
+import com.netflix.zuul.ZuulFilter;
+import com.netflix.zuul.context.RequestContext;
+import com.netflix.zuul.http.HttpServletRequestWrapper;
+
+import javax.servlet.*;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+import javax.servlet.http.Part;
+import java.io.IOException;
+import java.lang.reflect.Field;
+import java.util.Collection;
+
+/**
+ * @author Spencer Gibb
+ */
+public class Servlet30WrapperFilter extends ZuulFilter {
+    protected Field requestField = null;
+
+    public Servlet30WrapperFilter() {
+        try {
+            requestField = HttpServletRequestWrapper.class.getDeclaredField("req");
+            requestField.setAccessible(true);
+        } catch (NoSuchFieldException e) {
+            Throwables.propagate(e);
+        }
+    }
+
+    @Override
+    public String filterType() {
+        return "pre";
+    }
+
+    @Override
+    public int filterOrder() {
+        return 0;
+    }
+
+    @Override
+    public boolean shouldFilter() {
+        return true; //TODO: only if in servlet 3.0 env
+    }
+
+    @Override
+    public Object run() {
+        RequestContext ctx = RequestContext.getCurrentContext();
+        HttpServletRequest request = ctx.getRequest();
+        if (request instanceof HttpServletRequestWrapper) {
+            try {
+                request = (HttpServletRequest) requestField.get(request);
+            } catch (IllegalAccessException e) {
+                Throwables.propagate(e);
+            }
+        }
+        ctx.setRequest(new Servlet30RequestWrapper(request));
+        //ctx.setResponse(new HttpServletResponseWrapper(ctx.getResponse()));
+        return null;
+    }
+
+    class Servlet30RequestWrapper extends HttpServletRequestWrapper {
+        private HttpServletRequest request;
+
+        Servlet30RequestWrapper(HttpServletRequest request) {
+            super(request);
+            this.request = request;
+        }
+
+        @Override
+        public boolean authenticate(HttpServletResponse response) throws IOException, ServletException {
+            return request.authenticate(response);
+        }
+
+        @Override
+        public void login(String username, String password) throws ServletException {
+            request.login(username, password);
+        }
+
+        @Override
+        public void logout() throws ServletException {
+            request.logout();
+        }
+
+        @Override
+        public Collection<Part> getParts() throws IOException, IllegalStateException, ServletException {
+            return request.getParts();
+        }
+
+        @Override
+        public Part getPart(String name) throws IOException, IllegalStateException, ServletException {
+            return request.getPart(name);
+        }
+
+        @Override
+        public ServletContext getServletContext() {
+            return request.getServletContext();
+        }
+
+        @Override
+        public AsyncContext startAsync() {
+            return request.startAsync();
+        }
+
+        @Override
+        public AsyncContext startAsync(ServletRequest servletRequest, ServletResponse servletResponse) {
+            return request.startAsync(servletRequest, servletResponse);
+        }
+
+        @Override
+        public boolean isAsyncStarted() {
+            return request.isAsyncStarted();
+        }
+
+        @Override
+        public boolean isAsyncSupported() {
+            return request.isAsyncSupported();
+        }
+
+        @Override
+        public AsyncContext getAsyncContext() {
+            return request.getAsyncContext();
+        }
+
+        @Override
+        public DispatcherType getDispatcherType() {
+            return request.getDispatcherType();
+        }
+    }
+}

spring-cloud-netflix-core/src/main/java/org/springframework/cloud/netflix/zuul/filters/route/RibbonRoutingFilter.java

@@ -10,6 +10,7 @@ import java.util.Map;
 import java.util.Map.Entry;
 
 import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
 import javax.ws.rs.core.MultivaluedMap;
 
 import org.apache.commons.io.IOUtils;
@@ -89,8 +90,10 @@ public class RibbonRoutingFilter extends SpringFilter {
 			return response;
 		}
 		catch (Exception e) {
-			throw new RuntimeException(e);
+			context.set("error.status_code", HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
+            context.set("error.exception", e);
 		}
+        return null;
 	}
 
 	private Map<String, Object> debug(Verb verb, String uri,

spring-cloud-netflix-core/src/test/java/org/springframework/cloud/netflix/zuul/sample/ZuulProxyApplication.java

@@ -17,7 +17,7 @@ public class ZuulProxyApplication {
 
     @RequestMapping("/testing123")
     public String testing123() {
-        return "testing123";
+        throw new RuntimeException("myerror");
     }
 
 	@RequestMapping("/")

spring-cloud-netflix-core/src/test/resources/application.yml

@@ -6,7 +6,8 @@ spring:
 eureka:
   server:
     enabled: false
-
+error:
+  path: /myerror
 zuul:
   proxy:
     mapping: /api

spring-cloud-netflix-zuul-server/src/test/resources/application.yml

 server:
   port: 9876
+  servletPath: /app
 management:
   port: 9877
 spring:
   application:
     name: testzuulserver
+error:
+  path: ${server.servletPath}/error
 
 zuul:
   server: