Hi Jeff -
This is an interesting idea and we should consider discussing this as a
feature of Knox rather than just something that you are trying to hack into
an existing release/deployment.
In order to get this to work, I would first change the web.xml in the
deployments directory for a given topology and add the servlet to the in a
jar within {GATEWAY_HOME}/ext directory.
Stop and start the server and it should hopefully pickup the changed
web.xml file.
In order to cause a 500, I think just dispatching to an invalid URL would
result in a 500 with a connection exception.
See if that web.xml will work and we can take it from there.
It should be noted that surfacing the details of a webappexception may
expose sensitive information about the server and you may not want to
always have this enabled.
HTH.
--larry
On Fri, Sep 6, 2019 at 9:37 PM jeff saremi <jeffsar...@hotmail.com> wrote:
>
> 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)
>
>
>
>
>
>
>
