Redirect to a different port keeping all the rest

Question

On the server (embedded Jetty), I need to redirect to a different port leaving everything else unchanged, e.g., redirect from

http://com.example.myserver:1234/whatever?with=params#and-hash?and=whoknowswhat

to

http://com.example.myserver:5678/whatever?with=params#and-hash?and=whoknowswhat

It look like I have to compose the resulting URL from things I don't really know:

the name of the server the browser used
the remaining part of the URL

score 6 · Accepted Answer · edited May 23 '17 at 12:33

Out-Of-The-Box Rewrite Handlers

http://wiki.eclipse.org/Jetty/Feature/Rewrite_Handler

I had a quick look at the rewrite handlers provided by Jetty out of the box. From what I can gather from the documentation/examples, they all appear to do the actual rewriting on only the path part of the URL (i.e. everything after the ports, not quite what we want) (please correct me if I'm wrong!).

Writing a Request Handler

A rudimentary example to get you started, if you want to only use jetty embedded, you could write a request handler that would redirect all requests to the given port.

The way it works is the PortRedirector handles HTTP requests using the handle method. It builds the original request URL, changes the port to the target "to" port, and redirects the client to the new URL.

In the following example, the server listens to port 1234, and redirects all requests to port 8080.

import org.eclipse.jetty.server.Request;
import org.eclipse.jetty.server.Server;
import org.eclipse.jetty.server.handler.AbstractHandler;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

public class Redirector {

    public static void main(String[] args) throws Exception {
        Server server = new Server(1234);
        server.setHandler(new PortRedirector(8080));
        server.start();
        server.dumpStdErr();
        server.join();
    }

    static class PortRedirector extends AbstractHandler {

        int to;

        PortRedirector(int to) {
            this.to = to;
        }

        public void handle(String target, Request baseRequest, HttpServletRequest request, HttpServletResponse response)
                throws IOException, ServletException {
            String uri = request.getScheme() + "://" +
                    request.getServerName() +
                    ":" + to +
                    request.getRequestURI() +
                    (request.getQueryString() != null ? "?" + request.getQueryString() : "");
            response.sendRedirect(uri);
        }
    }
}

References:

Get full URL and query string in Servlet for both HTTP and HTTPS requests

This is a nice trick but the correct answer should be the one given by Serge Ballesta because of the explanation he gave. — Vishrant, Apr 25 '18 at 18:15
I have added more explanation for this question https://stackoverflow.com/questions/25278350/redirect-to-a-different-port-keeping-all-the-rest/50029406#50029406 — Vishrant, Apr 25 '18 at 18:49

score 2 · Answer 2 · answered Aug 18 '14 at 08:00

That kind or redirection if normally not the job of the application server (jetty, tomcat, glassfish, etc.), but of a reverse proxy you add on the chain before the servlet of JEE container. Among the most common, you find the excellent Apache HTTPserver, or nginx.

For exemple, with Apache httpd, you would use the mod_proxy module and a virtual host :

<VirtualHost *:1234>
    ServerName com.example.myserver
    RequestHeader set X-Forwarded-Proto "http"
    ProxyPass / http://com.example.myserver:5678/
    ProxyPassReverse / http://com.example.myserver:5678/
</VirtualHost>

Those kink of reverse proxies are currently used to secure application servers : only the proxy is accessible from the outside.

Vishrant · Answer 3 · 2018-04-27T21:35:50.973

Adding more to Serge Ballesta explanation why you should use VirtualHost. It always comes down to the responsibility of an application which will improve the efficiency of the whole system. I recommend reading What does architect know? section in this link. The point that I want to highlight from that section is:

What components are in the system and what are their responsibilities

So in this question, the responsibly of redirecting the request should be with server and you don't want your application to deny all the request in case one server requires restart (in case you have cluster). Also you might consider changing the server, you might consider adding load balancer, in that case handling it on application side does not make any sense.

This file is for apache configuration for VirtualHost. which redirect request based on context path, in this file /splunk

#LoadModule proxy_module modules/mod_proxy.so
#LoadModule proxy_balancer_module modules/mod_proxy_balancer.so
#LoadModule proxy_http_module modules/mod_proxy_http.so
# Uncomment these to proxy FTP or HTTPS
#LoadModule proxy_ftp_module modules/mod_proxy_ftp.so
#LoadModule proxy_connect_module modules/mod_proxy_connect.so

<VirtualHost *:80>

    DocumentRoot "/var/www"

    # Your domain name
    ServerName Domain_NAME_HERE

    ProxyPreserveHost On

    ProxyPass "/splunk" "http://localhost:8000/splunk"
    ProxyPassReverse "/splunk" "http://localhost:8000/splunk"

</VirtualHost>

So the request coming at port 80 with context path /splunk will be redirected to http://localhost:8080/splunk

The above apache2 configuration will handle request coming on port 80 from DocumentRoot /var/www [you might have PHP files in this location]

You might have to connect your application to apache in this case change Splunk splunk/etc/system/default/web.conf configuration:

root_endpoint = /splunk

In case of tomcat:

<Connector port="<port_number>" enableLookups="false" redirectPort="<redirect_port>" protocol="AJP/1.3" />

Redirect to a different port keeping all the rest

3 Answers3