Add env argument to cluster.fork

Fixes 2378

doc/api/cluster.markdown

@@ -72,9 +72,11 @@ in the master process via message passing:
 
 
 
-### cluster.fork()
+### cluster.fork([env])
 
 Spawn a new worker process. This can only be called from the master process.
+The function takes an optional `env` object. The propertyies in this object
+will be added to the process environment in the worker.
 
 ### cluster.isMaster
 ### cluster.isWorker

lib/cluster.js

@@ -24,8 +24,21 @@ var fork = require('child_process').fork;
 var net = require('net');
 var EventEmitter = require('events').EventEmitter;
 
-var cluster = module.exports = new EventEmitter();
+function isObject(o) {
+  return (typeof o === 'object' && o !== null);
+}
 
+function extendObject(origin, add) {
+  console.log('object: ', add);
+  for (var name in add) {
+    if (Object.hasOwnProperty.call(add, name)) {
+      origin[name] = add[name];
+    }
+  }
+  return origin;
+}
+
+var cluster = module.exports = new EventEmitter();
 
 var debug;
 if (process.env.NODE_DEBUG && /cluster/.test(process.env.NODE_DEBUG)) {
@@ -139,7 +152,7 @@ function eachWorker(cb) {
 }
 
 
-cluster.fork = function() {
+cluster.fork = function(env) {
   // This can only be called from the master.
   assert(cluster.isMaster);
 
@@ -147,15 +160,18 @@ cluster.fork = function() {
   startMaster();
 
   var id = ++ids;
-  var envCopy = {};
-
-  for (var x in process.env) {
-    envCopy[x] = process.env[x];
-  }
 
+  //Create env object
+  var envCopy = extendObject({}, process.env);
   envCopy['NODE_WORKER_ID'] = id;
+  if (isObject(env)) {
+    envCopy = extendObject(envCopy, env);
+  }
 
-  var worker = fork(workerFilename, workerArgs, { env: envCopy });
+  //fork worker
+  var worker = fork(workerFilename, workerArgs, {
+    'env': envCopy
+  });
 
   workers[id] = worker;
 

test/simple/test-cluster-fork-env.js

@@ -0,0 +1,66 @@
+// Copyright Joyent, Inc. and other Node contributors.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a
+// copy of this software and associated documentation files (the
+// "Software"), to deal in the Software without restriction, including
+// without limitation the rights to use, copy, modify, merge, publish,
+// distribute, sublicense, and/or sell copies of the Software, and to permit
+// persons to whom the Software is furnished to do so, subject to the
+// following conditions:
+//
+// The above copyright notice and this permission notice shall be included
+// in all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
+// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
+// USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+
+var common = require('../common');
+var assert = require('assert');
+var cluster = require('cluster');
+
+if (cluster.isWorker) {
+  process.send({
+    testcase: true,
+    prop: process.env['cluster_test_prop'],
+    overwrite: process.env['cluster_test_overwrite']
+  });
+
+} else if (cluster.isMaster) {
+
+  var checks = {
+    using: false,
+    overwrite: false
+  };
+
+  //To check that the cluster extend on the process.env we will overwrite a
+  //property
+  process.env['cluster_test_overwrite'] = 'old';
+
+  //Fork worker
+  var worker = cluster.fork({
+    'cluster_test_prop': 'custom',
+    'cluster_test_overwrite': 'new'
+  });
+
+  //Checks worker env
+  worker.on('message', function(data) {
+    if (data.testcase) {
+      checks.using = (data.prop === 'custom');
+      checks.overwrite = (data.overwrite === 'new');
+      process.exit(0);
+    }
+  });
+
+  process.once('exit', function() {
+    assert.ok(checks.using, 'The worker did not receive the correct env.');
+    assert.ok(checks.overwrite, 'The custom environment did not overwrite ' +
+              'the existing environment.');
+  });
+
+}