[api] add an ignorePath option if you want to disregard the path of the ...

lib/http-proxy.js

@@ -39,6 +39,7 @@ module.exports.createProxyServer =
    *    secure : <true/false, verify SSL certificate>
    *    toProxy: <true/false, explicitly specify if we are proxying to another proxy>
    *    prependPath: <true/false, Default: true - specify whether you want to prepend the target's path to the proxy path>
+   *    ignorePath: <true/false, Default: false - specify whether you want to ignore the proxy path of the incoming request>
    *    localAddress : <Local interface string to bind for outgoing connections>
    *    changeOrigin: <true/false, Default: false - changes the origin of the host header to the target URL>
    *    hostRewrite: rewrites the location hostname on (301/302/307/308) redirects, Default: null.

lib/http-proxy/common.js

@@ -79,6 +79,13 @@ common.setupOutgoing = function(outgoing, options, req, forward) {
     ? url.parse(req.url).path
     : req.url;
 
+  //
+  // Remark: ignorePath will just straight up ignore whatever the request's
+  // path is. This can be labeled as FOOT-GUN material if you do not know what
+  // you are doing and are using conflicting options.
+  //
+  outgoingPath = !options.ignorePath ? outgoingPath : '/';
+
   outgoing.path = common.urlJoin(targetPath, outgoingPath);
 
   if (options.changeOrigin) {
@@ -158,9 +165,7 @@ common.urlJoin = function() {
   // joining e.g. ['', 'am']
   //
   retSegs = [
-    args.filter(function filter(a) {
-      return !!a;
-    }).join('/').replace(/\/+/g, '/').replace(/:\//g, '://')
+    args.filter(Boolean).join('/').replace(/\/+/g, '/').replace(/:\//g, '://')
   ];
 
   // Only join the query string if it exists so we don't have trailing a '?'

test/lib-http-proxy-common-test.js

@@ -239,6 +239,31 @@ describe('lib/http-proxy/common.js', function () {
       expect(outgoing.path).to.eql('/' + google);
     });
 
+    describe('when using ignorePath', function () {
+      it('should ignore the path of the `req.url` passed in but use the target path', function () {
+        var outgoing = {};
+        var myEndpoint = 'https://whatever.com/some/crazy/path/whoooo';
+        common.setupOutgoing(outgoing, {
+          target: url.parse(myEndpoint),
+          ignorePath: true
+        }, { url: '/more/crazy/pathness' });
+
+        expect(outgoing.path).to.eql('/some/crazy/path/whoooo/');
+      });
+
+      it('and prependPath: false, it should ignore path of target and incoming request', function () {
+         var outgoing = {};
+        var myEndpoint = 'https://whatever.com/some/crazy/path/whoooo';
+        common.setupOutgoing(outgoing, {
+          target: url.parse(myEndpoint),
+          ignorePath: true,
+          prependPath: false
+        }, { url: '/more/crazy/pathness' });
+
+        expect(outgoing.path).to.eql('/');
+      });
+    });
+
     describe('when using changeOrigin', function () {
       it('should correctly set the port to the host when it is a non-standard port using url.parse', function () {
         var outgoing = {};