Connection Nodejs to Mongodb in Droplet

By default, the MongoDB listens on the local interface. In order to allow your Node application to access the MongoDB instance, modify the value of bindIp in /etc/mongod.conf If you do so, you are highly advised to first review the security checklist from the MongoDB documentation.

The relevant section of the config file should look like:

# [ ... ]
net:
  port: 27017
  bindIp: 127.0.0.1,ip_of_mongo_droplet
# [ ... ]

In addition to enabling one of the forms of authentication supported by MongoDB, you should set up a firewall to limit access to the MongoDB instance. You can do this with a DigitalOcean firewall or UFW which comes pre-installed on Ubuntu Droplets.

If you go with UFW, this command will allow access from the Node app’s IP address and nowhere else:

sudo ufw allow from node_ip_address to any port 27017

Now that MongoDB is listening for connections from the outside and has been secured with a firewall, you can connect to it from Node using the MongoDB Node.JS driver

const MongoClient = require('mongodb').MongoClient;
const assert = require('assert');

// Connection URL
const url = 'mongodb://mongo_ip_address:27017';

// Database Name
const dbName = 'myproject';

// Use connect method to connect to the server
MongoClient.connect(url, function(err, client) {
  assert.equal(null, err);
  console.log("Connected successfully to server");

  const db = client.db(dbName);

  client.close();
});

In order to make your app more portable, consider making the value of url in the above example configurable using an environment variable.