Handling a persistent MongoDB connection with mongoose from a Express.js server in Node.js

route.js

mongoose.connection.on("error", function(err) {
  console.error('> Failed to connect to MongoDB on startup ', err);
});

mongoose.connection.on('disconnected', function() {
  console.log('> Mongoose default connection to MongoDB disconnected');
});

var gracefulExit = function() {
  mongoose.connection.close(function() {
    console.log('> Mongoose default connection with MongoDB is disconnected through app termination');
    process.exit(0);
  });
};

process.on('SIGINT', gracefulExit).on('SIGTERM', gracefulExit);

try {
  mongoose.connect(settings.mongodb.path, settings.mongodb.options);
  console.log('> Trying to connect to MongoDB...');
} catch (err) {
  console.log('> Sever initialization failed ', err.message);
}