NodeJs MongoDB connection using mongoose

mongoose_connection.js

/**
 * @package [db] - Application db connection & schema loading 
 * @author [anikett] smartData Inc 
 */

'use strict';

/* DB */
var mongoose = require('mongoose');
mongoose.Promise = Promise;

require('../api/models/Component');
require('../api/models/User');
require('../api/models/Category');

/* database uri */
var uri = 'mongodb://' + process.env.DB_HOST + ':' + process.env.DB_PORT + '/' + process.env.DB_NAME;

var options = {
    user: process.env.DB_USERNAME,
    pass: process.env.DB_PASSWORD,
    server: {
        socketOptions: {
            keepAlive: 1,
            connectTimeoutMS: 30000
        }
    },
    replset: {
        socketOptions: {
            keepAlive: 1,
            connectTimeoutMS: 30000
        }
    }
}

mongoose.connect(uri, options);

var db = mongoose.connection;
db.on('error', console.error.bind(console, 'connection error:'));
db.once('open', function(callback) {
    console.log('Database connection successful!');
});
/* end DB */