Ultimately I am trying to make sure when an HTTP 500 error happens the exception message and stacktrace are returned in the response, in the gateway So I decided to add a web.xml and overwrite parts of error handling there to the gateway project. (added to gateway-server-launcher/src/main/resources/META-INF/web.xml)
root@gateway-0:/opt/knox/bin# cat META-INF/web.xml <?xml version="1.0" encoding="UTF-8"?> <!-- Licensed to ... --> <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"; xmlns="http://java.sun.com/xml/ns/javaee"; xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"; version="3.0"> <error-page> <error-code>400</exception-type> <location>/ExceptionHandler</location> </error-page> <error-page> <error-code>401</exception-type> <location>/ExceptionHandler</location> </error-page> <error-page> <error-code>404</exception-type> <location>/ExceptionHandler</location> </error-page> <error-page> <exception-type>java.lang.Throwable</exception-type> <location>/ExceptionHandler</location> </error-page> <error-page> <exception-type>javax.servlet.ServletException</exception-type> <location>/ExceptionHandler</location> </error-page> </web-app> And then I added the following Servlet (added it to gateway-util-common/src/main/java/org/apache/knox/gateway/servlet/ExceptionHandlerServlet.java) @WebServlet("/ExceptionHandler") public class ExceptionHandlerServlet extends HttpServlet { private static final long serialVersionUID = 1L; protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { // Analyze the servlet exception Throwable throwable = (Throwable) request.getAttribute("javax.servlet.error.exception"); Integer statusCode = (Integer) request.getAttribute("javax.servlet.error.status_code"); String servletName = (String) request.getAttribute("javax.servlet.error.servlet_name"); if (servletName == null) { servletName = "Unknown"; } String requestUri = (String) request.getAttribute("javax.servlet.error.request_uri"); if (requestUri == null) { requestUri = "Unknown"; } // Set response content type response.setContentType("text/html"); PrintWriter out = response.getWriter(); out.write("<html><head><title>Exception/Error Details</title></head><body>"); if(statusCode != 500){ out.write("<h3>Error Details</h3>"); out.write("<strong>Status Code</strong>:"+statusCode+"<br>"); out.write("<strong>Requested URI</strong>:"+requestUri); } else { out.write("<h3>Exception Details</h3>"); out.write("<ul><li>Servlet Name:"+servletName+"</li>"); out.write("<li>Exception Name:"+throwable.getClass().getName()+"</li>"); out.write("<li>Requested URI:"+requestUri+"</li>"); out.write("<li>Exception Message:"+throwable.getMessage()+"</li>"); out.write("</ul>"); } out.write("<br><br>"); out.write("</body></html>"); } } I see that the application is launched using gateway.jar. And i also see my web.xml inside that jar. However I'm not able to get anything returned from this servlet! I honestly don't know how to repro a 500. But I could do a 400, 401, and 404. Neither of them got intercepted by the Exception servlet i wrote. Here are some examples I ran. Note in the first one, a 400 is returned along with some exception message. that's what i want to do for 500 or verify that it's being done. However I haven't been able to (using text search) find out where in the code this response is formed like this root@clustertest:/tests/knox# curl -iku root:goodpassword -X GET https://gateway-svc:8443/gateway/default/webhdfs/v1/?op=STATUS HTTP/1.1 400 Bad Request Date: Fri, 06 Sep 2019 23:42:42 GMT Set-Cookie: KNOXSESSIONID=node01q5krk3jp1c9dzv3fc3t5tkgh4.node0;Path=/gateway/default;Secure;HttpOnly Expires: Thu, 01 Jan 1970 00:00:00 GMT Set-Cookie: rememberMe=deleteMe; Path=/gateway/default; Max-Age=0; Expires=Thu, 05-Sep-2019 23:42:43 GMT Date: Fri, 06 Sep 2019 23:42:43 GMT Cache-Control: no-cache Expires: Fri, 06 Sep 2019 23:42:45 GMT Date: Fri, 06 Sep 2019 23:42:45 GMT Pragma: no-cache X-FRAME-OPTIONS: SAMEORIGIN Content-Type: application/json;charset=utf-8 Transfer-Encoding: chunked Server: Jetty(9.4.12.v20180830) {"RemoteException":{"exception":"IllegalArgumentException","javaClassName":"java.lang.IllegalArgumentException","message":"Invalid value for webhdfs parameter \"op\": STATUS is not a valid GET operation."}} root@clustertest:/tests/knox# curl -iku root:goodpassword -X GET https://gateway-svc:8443/gateway/default/webhdfs/v1/?op=LISTSTATUS HTTP/1.1 200 OK Date: Fri, 06 Sep 2019 23:43:29 GMT Set-Cookie: KNOXSESSIONID=node0iz11bxvbn318h7zow5z977pc5.node0;Path=/gateway/default;Secure;HttpOnly Expires: Thu, 01 Jan 1970 00:00:00 GMT Set-Cookie: rememberMe=deleteMe; Path=/gateway/default; Max-Age=0; Expires=Thu, 05-Sep-2019 23:43:30 GMT Date: Fri, 06 Sep 2019 23:43:30 GMT Cache-Control: no-cache Expires: Fri, 06 Sep 2019 23:43:30 GMT Date: Fri, 06 Sep 2019 23:43:30 GMT Pragma: no-cache X-FRAME-OPTIONS: SAMEORIGIN Content-Type: application/json;charset=utf-8 Transfer-Encoding: chunked Server: Jetty(9.4.12.v20180830) {"FileStatuses":{"FileStatus":[{"accessTime":0,"blockSize":0,"childrenNum":0,"fileId":16411,"group":"supergroup","length":0,"modificationTime":1567812978306,"owner":"root","pathSuffix":"jar","permission":"755","replication":0,"storagePolicy":0,"type":"DIRECTORY"},{"accessTime":0,"blockSize":0,"childrenNum":6,"fileId":16389,"group":"supergroup","length":0,"modificationTime":1567812975255,"owner":"root","pathSuffix":"livy","permission":"755","replication":0,"storagePolicy":0,"type":"DIRECTORY"},{"accessTime":0,"blockSize":0,"childrenNum":1,"fileId":16386,"group":"supergroup","length":0,"modificationTime":1567812943856,"owner":"root","pathSuffix":"spark","permission":"775","replication":0,"storagePolicy":0,"type":"DIRECTORY"},{"accessTime":0,"blockSize":0,"childrenNum":1,"fileId":16387,"group":"supergroup","length":0,"modificationTime":1567813293988,"owner":"root","pathSuffix":"spark-events","permission":"733","replication":0,"storagePolicy":0,"type":"DIRECTORY"},{"accessTime":0,"blockSize":0,"childrenNum":2,"fileId":16395,"group":"supergroup","length":0,"modificationTime":1567813273907,"owner":"root","pathSuffix":"tmp","permission":"1777","replication":0,"storagePolicy":0,"type":"DIRECTORY"},{"accessTime":0,"blockSize":0,"childrenNum":1,"fileId":16412,"group":"supergroup","length":0,"modificationTime":1567813267540,"owner":"root","pathSuffix":"user","permission":"777","replication":0,"storagePolicy":0,"type":"DIRECTORY"}]}} root@clustertest:/tests/knox# curl -iku root:goodpassword -X GET https://gateway-svc:8443/gateway/default/webhdfs/v2/?op=LISTSTATUS HTTP/1.1 404 Not Found Date: Fri, 06 Sep 2019 23:43:53 GMT Content-Length: 0 Server: Jetty(9.4.12.v20180830) root@clustertest:/tests/knox# curl -iku root:badpassword -X GET https://gateway-svc:8443/gateway/default/webhdfs/v1/?op=LISTSTATUS HTTP/1.1 401 Unauthorized Date: Fri, 06 Sep 2019 23:44:17 GMT Set-Cookie: rememberMe=deleteMe; Path=/gateway/default; Max-Age=0; Expires=Thu, 05-Sep-2019 23:44:17 GMT WWW-Authenticate: BASIC realm="application" Content-Length: 0 Server: Jetty(9.4.12.v20180830)
