PM2 deploy ecosystem.json production

I created an ecosystem.json

```

{
  "apps": [{
    "name": "question_system",
    "script": "./bin/www",
    "env":{
      "COMMON_VARIABLE": "true"
    },
    "env_production": {
      "NODE_ENV": "production"
    }
  }],
  "deploy": {
    "production": {
      "user": "wusong",
      "host": ["39.108.55.141"],
      "ref": "origin/master",
      "repo": "git@github.com:WUSO01/nodejs-question-system.git",
      "path": "/home/wusong/www/question/production",
      "ssh_options": "StrictHostKeyChecking=no",
      "post-deploy": "npm install && pm2 startOrRestart ecosystem.json --env production",
      "env": {
        "NODE_ENV": "production"
      }
    }
  }
}

```

This project was generated by express-generator,
the file of WWW

#!/usr/bin/env node

/**
 * Module dependencies.
 */

var app = require('../app');
var debug = require('debug')('nodezy1390qs:server');
var http = require('http');

/**
 * Get port from environment and store in Express.
 */

var port = normalizePort(process.env.PORT || '3000');
app.set('port', port);

/**
 * Create HTTP server.
 */

var server = http.createServer(app);

/**
 * Listen on provided port, on all network interfaces.
 */

server.listen(port);
server.on('error', onError);
server.on('listening', onListening);

/**
 * Normalize a port into a number, string, or false.
 */

function normalizePort(val) {
  var port = parseInt(val, 10);

  if (isNaN(port)) {
    // named pipe
    return val;
  }

  if (port >= 0) {
    // port number
    return port;
  }

  return false;
}

/**
 * Event listener for HTTP server "error" event.
 */

function onError(error) {
  if (error.syscall !== 'listen') {
    throw error;
  }

  var bind = typeof port === 'string'
    ? 'Pipe ' + port
    : 'Port ' + port;

  // handle specific listen errors with friendly messages
  switch (error.code) {
    case 'EACCES':
      console.error(bind + ' requires elevated privileges');
      process.exit(1);
      break;
    case 'EADDRINUSE':
      console.error(bind + ' is already in use');
      process.exit(1);
      break;
    default:
      throw error;
  }
}

/**
 * Event listener for HTTP server "listening" event.
 */

function onListening() {
  var addr = server.address();
  var bind = typeof addr === 'string'
    ? 'pipe ' + addr
    : 'port ' + addr.port;
  debug('Listening on ' + bind);
}

My mongodb database

const mongoose = require('mongoose');
mongoose.Promise = global.Promise;

var dbUrl = "mongodb://wusongQuestion:L****@127.0.0.1:/question-system"
if(env === "development"){
  mongoose.connect('mongodb://localhost/question-system');
}
mongoose.connect(dbUrl);

exports.mongoose = mongoose

Now I run command line: 'pm2 deploy ecosystem.json production', but it shows me

I have no idea, probably The root of the problem lies in my source code,

via WUSO01