com.example.simple.plist

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
  <dict>
    <key>EnvironmentVariables</key>
    <dict>
      <key>NODE_ENV</key>
      <string>production</string>
    </dict>
    <key>Label</key>
    <string>com.example.simple</string>
    <key>ProgramArguments</key>
    <array>
      <string>/opt/local/bin/node</string>
      <string>master.js</string>
    </array>
    <key>Sockets</key>
    <dict>
      <key>HTTPSocket</key>
      <dict>
        <key>SockFamily</key>
        <string>IPv4v6</string>
        <key>SockServiceName</key>
        <integer>3000</integer>
      </dict>
    </dict>
    <key>WorkingDirectory</key>
    <string>/path/to/simple</string>
  </dict>
</plist>

master.js

var cluster = require('cluster');

cluster.setupMaster({
  exec: 'server.js'
});

var env = {};

if (!process.env.PORT) {
  env.LAUNCHD_SOCKET = require('node-launchd').getSocketFileDescriptorForName('HTTPSocket');
}

var numWorkers = require('os').cpus().length;

for (var i = 0; i < numWorkers; ++i) {
  cluster.fork(env);
}

cluster.on('exit', exited);

function exited(worker, code, signal) {
  console.log('worker ' + worker.process.pid + ' exited');
}

server.js

var http = require('http');

function app(req, res) {
  res.writeHead(200, {'Content-Type': 'text/plain'});
  res.end('worker ' + process.pid + '\n');
}

var server = http.createServer(app);

var portOrHandle = process.env.PORT || {
  fd: +process.env.LAUNCHD_SOCKET || require('node-launchd').getSocketFileDescriptorForName('HTTPSocket')
};

server.listen(portOrHandle, listening);

function listening() {
  console.log('worker ' + process.pid + ' listening');
}