Merge pull request #32 from trbngr/master

Enable subscription to the http-proxy on onProxyReq event.

Author: chimurai

README.md

@@ -208,6 +208,14 @@ var server = app.listen(3000);
     }
     ```
 
+*  **option.onProxyReq**: function, subscribe to http-proxy's proxyReq event.
+    ```javascript
+    function onProxyReq(proxyReq, req, res) {
+        // add custom header to request
+        proxyReq.setHeader('x-added', 'foobar');
+        // or log the req
+    }
+
 * (DEPRECATED) **option.proxyHost**: Use `option.changeOrigin = true` instead.
 
 The following options are provided by the underlying [http-proxy](https://www.npmjs.com/package/http-proxy).

index.js

@@ -23,6 +23,11 @@ var httpProxyMiddleware = function (context, opts) {
         proxy.on('proxyRes', proxyOptions.onProxyRes);
     }
 
+    // Custom listener for the `proxyReq` event on `proxy`.
+    if (_.isFunction(proxyOptions.onProxyReq)) {
+        proxy.on('proxyReq', proxyOptions.onProxyReq);
+    }
+
     // Custom listener for the `error` event on `proxy`.
     var onProxyError = getProxyErrorHandler();
     // handle error and close connection properly

test/http-proxy-middleware.spec.js

@@ -424,6 +424,44 @@ describe('http-proxy-middleware in actual server', function () {
         });
     });
 
+    describe('option.onProxyReq', function () {
+        var proxyServer, targetServer;
+        var receivedRequest;
+
+        beforeEach(function (done) {
+            var fnOnProxyReq = function (proxyReq, req, res) {
+                proxyReq.setHeader('x-added', 'foobar');                // add custom header to request
+            };
+
+            var mw_proxy = proxyMiddleware('/api', {
+                target: 'http://localhost:8000',
+                onProxyReq: fnOnProxyReq
+            });
+
+            var mw_target = function (req, res, next) {
+                receivedRequest = req;
+                res.write(req.url);                                       // respond with req.url
+                res.end();
+            };
+
+            proxyServer = createServer(3000, mw_proxy);
+            targetServer = createServer(8000, mw_target);
+
+            http.get('http://localhost:3000/api/foo/bar', function () {
+                done();
+            });
+        });
+
+        afterEach(function () {
+            proxyServer.close();
+            targetServer.close();
+        });
+
+        it('should add `x-added` as custom header to request"', function () {
+            expect(receivedRequest.headers['x-added']).to.equal('foobar');
+        });
+    });
+
     describe('option.pathRewrite', function () {
         var proxyServer, targetServer;
         var responseBody;