Interesting.
I'm not really familiar with Supervisord but it seems to be not only
restarting the process but causing the redeployment of the topologies.
Is it making an Ambari API call to restart Knox or something like that?
The short term goal needs to be a restart that doesn't redeploy and the
reuse of the web.xml.
This would be just to verify that what you want to do works as expected
then we would need to add the error handling to the ShrinkWrap code that
generates the web.xml in the Knox deployment machinery.
If you are using a default.xml topology that sounds like you are using
Ambari and HDP?
Are you able to remove Knox from the Supervisord monitoring temporarily or
even just turn it off?
If so, we can then stop the Knox process via Ambari then restart Knox
manually.
If you restart from Ambari it will push out configuration again and you
will get a new deployment - so don't do that.
A simple restart without config being changed will just load the previous
web.xml and webapp without deploying a new one.
On Mon, Sep 9, 2019 at 7:10 PM jeff saremi <jeffsar...@hotmail.com> wrote:
> Larry
> I created a jar file out of a single ExceptionServlet and placed in
> GATEWAY_HOME/ext:
>
> root@gateway-0:/opt/knox# ls -l ext
> total 12
> -rw-r--r-- 1 root root 83 Sep 6 00:23 README
> -rwxr-xr-- 1 root root 1704 Sep 9 22:41 error-servlet.jar
> drwxr--r-- 2 root root 4096 Sep 6 00:23 native
>
> root@gateway-0:/opt/knox# jar tvf ext/error-servlet.jar
> 0 Mon Sep 09 15:24:44 UTC 2019 META-INF/
> 64 Mon Sep 09 15:24:44 UTC 2019 META-INF/MANIFEST.MF
> 2382 Mon Sep 09 15:23:54 UTC 2019 ExceptionHandlerServlet.class
>
> Since I appear to be using 'default' in my URLs I'm guessing that would be
> the right topology. So i went to data/deployments and modified the
> following web.xml:
> data/deployments/default.topo.16d08ec29f0
>
> updated web.xml:
>
>
> root@gateway-0:/opt/knox# tail -25
> data/deployments/default.topo.16d08ec29f0/%2F/WEB-INF/web.xml
> <param-value>/WEB-INF/rewrite.xml</param-value>
> </context-param>
>
> <error-page>
> <error-code>400</error-code>
> <location>/ExceptionHandler</location>
> </error-page>
> <error-page>
> <error-code>401</error-code>
> <location>/ExceptionHandler</location>
> </error-page>
> <error-page>
> <error-code>404</error-code>
> <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>
>
> I then killed the running process (since it was started by the Supervisor
> d) and it restarted itself
>
> The response were identical to before meaning that my servlet was never hit
>
> Looking at the deployment folder, I see that there's another 'default*'
> folder is created with updated timestamp. And the new web.xml there does
> not have any of my changes of course
>
> If I were to make these changes to the web.xml permenant, where would be
> the right location, given that the web.xml seems to be created on the fly.
>
>
>
> ------------------------------
> *From:* jeff saremi <jeffsar...@hotmail.com>
> *Sent:* Saturday, September 7, 2019 4:28 PM
> *To:* user@knox.apache.org <user@knox.apache.org>
> *Subject:* Re: Adding a web.xml to gateway.jar
>
> Great suggestions! Thanks Larry
> I will work on getting the web.xml and the servlet integrated
> Completely agreed on the vulnerability side. We may expose this in a DEBUG
> version and not the release or provide a config value...
> ------------------------------
> *From:* larry mccay <lmc...@apache.org>
> *Sent:* Friday, September 6, 2019 7:25 PM
> *To:* user@knox.apache.org <user@knox.apache.org>
> *Subject:* Re: Adding a web.xml to gateway.jar
>
> 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)
>
>
>
>
>
>
>
