db.js

var mysql      = require('mysql');

var db_config = {
  host     : process.env.DB_HOST,
  user     : process.env.DB_USER,
  password : process.env.DB_PASSWORD,
  database : process.env.DB_NAME
};

var connection;

function handleDisconnect() {
  connection = mysql.createConnection(db_config);

  connection.connect(function(err) {
    if(err) {
      console.log('error when connecting to db:', err);
      setTimeout(handleDisconnect, 2000);
    }
  });

  connection.on('error', function(err) {
    console.log('db error', err);
    if(err.code === 'PROTOCOL_CONNECTION_LOST' || err.code === 'connect ETIMEDOUT') {
      handleDisconnect();
    } else {
      throw err;
    }
  });
}

handleDisconnect();
global.db = connection;


/*var connection = mysql.createConnection({
  host     : process.env.DB_HOST,
  user     : process.env.DB_USER,
  password : process.env.DB_PASSWORD,
  database : process.env.DB_NAME
  });

connection.connect();*/