fix(proxy): handle proxied socket.io websocket transport upgrade

Fixes websocket upgrade handling for proxied routes.
This was motivated by long (10s) default timeouts when socket.io
attempts to use websockets and fails to perform the upgrade.

lib/middleware/proxy.js

@@ -3,7 +3,6 @@ var httpProxy = require('http-proxy');
 
 var log = require('../logger').create('proxy');
 
-
 var parseProxyConfig = function(proxies) {
   var proxyConfig = {};
   var endsWithSlash = function(str) {
@@ -57,15 +56,19 @@ var parseProxyConfig = function(proxies) {
  * @param proxies a map of routes to proxy url
  * @return {Function} handler function
  */
-var createProxyHandler = function(proxy, proxyConfig, proxyValidateSSL) {
+var createProxyHandler = function(proxy, proxyConfig, proxyValidateSSL, urlRoot) {
   var proxies = parseProxyConfig(proxyConfig);
   var proxiesList = Object.keys(proxies).sort().reverse();
 
   if (!proxiesList.length) {
-    return function(request, response, next) {
+    var nullProxy = function createNullProxy(request, response, next) {
       return next();
     };
+    nullProxy.upgrade = function upgradeNullProxy() {
+    };
+    return nullProxy;
   }
+
   proxy.on('proxyError', function(err, req) {
     if (err.code === 'ECONNRESET' && req.socket.destroyed) {
       log.debug('failed to proxy %s (browser hung up the socket)', req.url);
@@ -74,7 +77,7 @@ var createProxyHandler = function(proxy, proxyConfig, proxyValidateSSL) {
     }
   });
 
-  return function(request, response, next) {
+  var middleware = function createProxy(request, response, next) {
     for (var i = 0; i < proxiesList.length; i++) {
       if (request.url.indexOf(proxiesList[i]) === 0) {
         var proxiedUrl = proxies[proxiesList[i]];
@@ -92,9 +95,30 @@ var createProxyHandler = function(proxy, proxyConfig, proxyValidateSSL) {
 
     return next();
   };
-};
 
+  middleware.upgrade = function upgradeProxy(request, socket, head) {
+    // special-case karma's route to avoid upgrading it
+    if (request.url.indexOf(urlRoot) === 0) {
+      log.debug('NOT upgrading proxyWebSocketRequest %s', request.url);
+      return;
+    }
+    for (var i = 0; i < proxiesList.length; i++) {
+      if (request.url.indexOf(proxiesList[i]) === 0) {
+        var proxiedUrl = proxies[proxiesList[i]];
+        log.debug('upgrade proxyWebSocketRequest %s to %s:%s',
+          request.url, proxiedUrl.host, proxiedUrl.port);
+        proxy.proxyWebSocketRequest(request, socket, head,
+          { host: proxiedUrl.host, port: proxiedUrl.port });
+      }
+    }
+  };
+
+  return middleware;
+};
 
-exports.create = function(/* config.proxies */ proxies, /* config.proxyValidateSSL */ validateSSL) {
-  return createProxyHandler(new httpProxy.RoutingProxy({changeOrigin: true}), proxies, validateSSL);
+exports.create = function(/* config */ config, /* config.proxies */ proxies,
+  /* config.proxyValidateSSL */ validateSSL) {
+  log.debug('createProxyHandler urlRoot=%s', config.urlRoot);
+  return createProxyHandler(new httpProxy.RoutingProxy({changeOrigin: true}),
+    proxies, validateSSL, config.urlRoot);
 };

lib/server.js

@@ -202,6 +202,8 @@ start.$inject = ['injector', 'config', 'launcher', 'emitter', 'preprocess', 'fil
 
 var createSocketIoServer = function(webServer, executor, config) {
   var server = io.listen(webServer, {
+    // avoid destroying http upgrades from socket.io to get proxied websockets working
+    'destroy upgrade': false,
     logger: logger.create('socket.io', constant.LOG_ERROR),
     resource: config.urlRoot + 'socket.io',
     transports: config.transports

lib/web-server.js

@@ -9,6 +9,7 @@ var karmaMiddleware = require('./middleware/karma');
 var sourceFilesMiddleware = require('./middleware/source-files');
 var proxyMiddleware = require('./middleware/proxy');
 
+var log = require('./logger').create('web-server');
 
 var createCustomHandler = function(customFileHandlers, /* config.basePath */ basePath) {
   return function(request, response, next) {
@@ -48,21 +49,30 @@ var createWebServer = function(injector, emitter) {
     }
   };
 
+  var proxyMiddlewareInstance = injector.invoke(proxyMiddleware.create);
+
   var handler = connect()
       .use(connect.compress(compressOptions))
       .use(injector.invoke(runnerMiddleware.create))
       .use(injector.invoke(karmaMiddleware.create))
       .use(injector.invoke(sourceFilesMiddleware.create))
       // TODO(vojta): extract the proxy into a plugin
-      .use(injector.invoke(proxyMiddleware.create))
+      .use(proxyMiddlewareInstance)
       // TODO(vojta): remove, this is only here because of karma-dart
       // we need a better way of custom handlers
       .use(injector.invoke(createCustomHandler))
       .use(function(request, response) {
         common.serve404(response, request.url);
       });
 
-  return http.createServer(handler);
+  var server = http.createServer(handler);
+
+  server.on('upgrade', function (req, socket, head) {
+    log.debug('upgrade %s', req.url);
+    proxyMiddlewareInstance.upgrade(req, socket, head);
+  });
+
+  return server;
 };