Alternative solution to #316: add requestModules capability

README.md

@@ -471,6 +471,24 @@ app.use('/', proxy('httpbin.org', {
 }));
 ```
 
+#### requestModules
+
+There are times when you may want the proxy to use a custom request module to make the requests on behalf of the proxy. A good example of this is to use the `follow-redirects` library to have the proxy automatically follow redirects.
+
+```js
+var { http, https } = require('follow-redirects');
+
+app.use('/', proxy('httpbin.org', {
+  requestModules: { http, https },
+  proxyReqOptDecorator: (proxyReqOpts, srcReq) => {
+    return {
+      ...proxyReqOpts,
+      maxRedirects: 10,
+    };
+  }
+}));
+```
+
 ##  Trace debugging
 
 The node-debug module is used to provide a trace debugging capability.
@@ -575,6 +593,7 @@ app.use('/', proxy('internalhost.example.com', {
 
 | Release | Notes |
 | --- | --- |
+| 1.7.0 | Support alternate request modules, such as from `follow-redirects`.
 | 1.6.3 | [#453] Author should be able to delete headers in userResHeaderDecorator.
 | 1.6.2 | Update node.js versions used by ci. |
 | 1.6.1 | Minor bug fixes and documentation. |

lib/requestOptions.js

@@ -1,6 +1,4 @@
 'use strict';
-var http = require('http');
-var https = require('https');
 var url = require('url');
 var getRawBody = require('raw-body');
 var isUnset = require('./isUnset');
@@ -45,7 +43,7 @@ function parseHost(Container) {
   return {
     host: parsed.hostname,
     port: parsed.port || (ishttps ? 443 : 80),
-    module: ishttps ? https : http,
+    module: ishttps ? options.requestModules.https : options.requestModules.http,
   };
 }
 

lib/resolveOptions.js

@@ -1,6 +1,8 @@
 'use strict';
 
 var debug = require('debug')('express-http-proxy');
+var http = require('http');
+var https = require('https');
 
 var isUnset = require('../lib/isUnset');
 
@@ -15,10 +17,7 @@ function resolveBodyEncoding(reqBodyEncoding) {
 
 // parse client arguments
 
-function resolveOptions(options) {
-  options = options || {};
-  var resolved;
-
+function judgeOptions(options) {
   if (options.decorateRequest) {
     throw new Error(
       'decorateRequest is REMOVED; use proxyReqOptDecorator and' +
@@ -40,7 +39,20 @@ function resolveOptions(options) {
     );
   }
 
-  resolved = {
+  if (options.requestModules &&
+    !(options.requestModules.http || options.requestModules.https)
+  ) {
+    throw new Error(
+      'requestModules requires at least one web protocol to be defined'
+    );
+  }
+}
+
+function resolveOptions(options) {
+  options = options || {};
+  judgeOptions(options);
+
+  var resolved = {
     limit: options.limit || '1mb',
     proxyReqPathResolver: options.proxyReqPathResolver
         || options.forwardPathAsync
@@ -63,7 +75,13 @@ function resolveOptions(options) {
     https: options.https,
     port: options.port,
     reqAsBuffer: options.reqAsBuffer,
-    timeout: options.timeout
+    timeout: options.timeout,
+
+    /*
+     * Allow optional injection of http and https request modules,
+     * such as from `follow-redirects`.
+     */
+    requestModules: options.requestModules || { http: http, https: https }
   };
 
   // automatically opt into stream mode if no response modifiers are specified