Support Connect tracing through the plugin API (#381)

PR-URL: #381

config.js

@@ -41,9 +41,10 @@ module.exports = {
     // all.
     // This field is experimental.
     plugins: {
-      'restify': path.join(__dirname, 'src/plugins/plugin-restify.js'),
+      'connect': path.join(__dirname, 'src/plugins/plugin-connect.js'),
       'koa': path.join(__dirname, 'src/plugins/plugin-koa.js'),
-      'mongodb-core': path.join(__dirname, 'src/plugins/plugin-mongodb-core.js')
+      'mongodb-core': path.join(__dirname, 'src/plugins/plugin-mongodb-core.js'),
+      'restify': path.join(__dirname, 'src/plugins/plugin-restify.js')
     },
 
     // Valid entries are:

src/hooks/index.js

@@ -48,8 +48,6 @@ var toInstrument = Object.create(null, {
   'mysql': { enumerable: true, value: { file: './userspace/hook-mysql.js',
       patches: {} } },
   'redis': { enumerable: true, value: { file: './userspace/hook-redis.js',
-      patches: {} } },
-  'connect': { enumerable: true, value: { file: './userspace/hook-connect.js',
       patches: {} } }
 });
 

src/plugins/plugin-connect.js

@@ -0,0 +1,85 @@
+/**
+ * Copyright 2015 Google Inc. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+'use strict';
+
+var urlParse = require('url').parse;
+
+var SUPPORTED_VERSIONS = '3.x';
+
+function middleware(api, req, res, next) {
+  var options = {
+    name: urlParse(req.originalUrl).pathname,
+    traceContext: req.headers[api.constants.TRACE_CONTEXT_HEADER_NAME.toLowerCase()],
+    skipFrames: 3
+  };
+  api.runInRootSpan(options, function(root) {
+    if (!root) {
+      return next();
+    }
+
+    api.wrapEmitter(req);
+    api.wrapEmitter(res);
+
+    var url = (req.headers['X-Forwarded-Proto'] || 'http') +
+      '://' + req.headers.host + req.originalUrl;
+
+    // we use the path part of the url as the span name and add the full
+    // url as a label
+    root.addLabel(api.labels.HTTP_METHOD_LABEL_KEY, req.method);
+    root.addLabel(api.labels.HTTP_URL_LABEL_KEY, url);
+    root.addLabel(api.labels.HTTP_SOURCE_IP, req.connection.remoteAddress);
+
+    var context = root.getTraceContext();
+    if (context) {
+      res.setHeader(api.constants.TRACE_CONTEXT_HEADER_NAME, context);
+    }
+
+    // wrap end
+    var originalEnd = res.end;
+    res.end = function(data, encoding, callback) {
+      res.end = originalEnd;
+      var returned = res.end(data, encoding, callback);
+
+      if (req.route && req.route.path) {
+        root.addLabel(
+          'connect/request.route.path', req.route.path);
+      }
+
+      root.addLabel(
+        api.labels.HTTP_RESPONSE_CODE_LABEL_KEY, res.statusCode);
+      root.endSpan();
+
+      return returned;
+    };
+
+    next();
+  });
+}
+
+module.exports = [
+  {
+    file: '',
+    versions: SUPPORTED_VERSIONS,
+    intercept: function(connect, api) {
+      return function() {
+        var app = connect();
+        app.use(middleware.bind(null, api));
+        return app;
+      };
+    }
+  }
+];
+