Cannot connect to MongoDB via env variable - node.js

Question

I am trying to conceal my connection string, so I installed env2 in my project. Then I made a config.env file that keeps my connection string like this:
export DB_URL='mongodb://user:userPassword#ds241968.mlab.com:41968/heroku_hc9xjmcl'
However when I use that variable as a connection string I cannot connect to Mlab I get the following error:
UnhandledPromiseRejectionWarning: MongoNetworkError: failed to connect to server [ds241968.mlab.com:41968] on first connect [MongoError: Authentication failed.]
But when I try to connect only with the string without using env2 I connect perfectly, so why does the ahuthentication fail when I use a env variable and how can I connect with one properly? Here is my server.js:
// Requiring the dependencies
const express = require('express');
const app = express();
const bodyParser = require('body-parser');
const cors = require('cors');
const mongoose = require('mongoose');
const PORT = process.env.PORT || 3009;
const itemRoutes = express.Router();
let Comment = require('./comment.model');
const env = require('env2')('../config.env');
console.log(process.env.DB_URL)
app.use(cors());
app.use(bodyParser.json());
const { DB_URL } = process.env;
mongoose.connect( DB_URL , { useNewUrlParser: true } )
const connection = mongoose.connection;
connection.once('open', function() {
console.log('Connection to MongoDB established succesfully!');
});
// Serve static assets
if(process.env.NODE_ENV === 'production') {
app.use(express.static('build'));
}
itemRoutes.route('/').get( async (req, res) => {
let collection = connection.collection("posts");
let response = await collection.find({})
.toArray();
res.send(response);
});
itemRoutes.route('/comments').get( async (req, res) => {
let collection = connection.collection("comments");
let response = await collection.find({})
.toArray();
res.send(response);
});
itemRoutes.route('/userComments')
.post((req, res) => {
res.setHeader('Content-Type', 'application/json');
let comment = new Comment(req.body);
comment.save()
.then(comment => {
res.status(200).json({comment})
})
.catch(err => {
res.status(400).send('failed')
})
});
app.use('/', itemRoutes);
app.use('/userComments', itemRoutes);
app.listen(PORT, function() {
console.log('Server is running on' + ' ' + PORT);
})

Answer 1

Looks like you are using Node and Heroku. In that case,
You should set Heroku Config Vars (you can do this either via CLI or your Heroku Dashboard)
Refer to the config var in your node application the same way you are referring to now.
Remove 'env2' related code as you won't need it for this purpose
For example, if you create Heroku config var called "MONGO_URI", refer to it as process.env.MONGO_URI in your node application.
Details can be found here: https://devcenter.heroku.com/articles/config-vars#managing-config-vars