What I think might fix your problem
Disclaimer: I have used neither Heroku nor MongoDB Atlas but I am looking into them.
According to a Github issue I found, you will get that error message if you haven't whitelisted the server IP addresses in MongoDB Atlas.
Reading the MongoDB Atlas docs, the only way I see to do this in combination with Heroku dynos is to add 0.0.0.0/0 (i.e. all addresses) to your MongoDB Atlas whitelist.
Give that a try and please report back whether you can instantiate a connection.
On SSL
Trying to reply to the SSL question, I do not think that you need to enable it on Heroku based on what I read, although I am not totally sure.
If the MongoDB server performed certificate validation, the Node.js code for connecting to it would have to look like the following (taken from the Node.js driver documentation):
var MongoClient = require('mongodb').MongoClient,
f = require('util').format,
fs = require('fs');
// Read the certificates
var ca = [fs.readFileSync(__dirname + "/ssl/ca.pem")];
var cert = fs.readFileSync(__dirname + "/ssl/client.pem");
var key = fs.readFileSync(__dirname + "/ssl/client.pem");
// Connect validating the returned certificates from the server
MongoClient.connect("mongodb://localhost:27017/test?ssl=true", {
server: {
sslValidate:true
, sslCA:ca
, sslKey:key
, sslCert:cert
, sslPass:'10gen'
}
}, function(err, db) {
db.close();
});
If the MongoDB server does not check for any SSL certificates, you can simply use code like the following (also taken from the Node.js driver documentation):
var MongoClient = require('mongodb').MongoClient;
MongoClient.connect("mongodb://localhost:27017/test?ssl=true", function(err, db) {
db.close();
});
Given that the Atlas documentation contains the following example code for connecting to it from Node.js, I think that you do not have to enable SSL on Heroku:
var MongoClient = require('mongodb').MongoClient;
var uri = "mongodb://kay:[email protected]:27017,mycluster0-shard-00-01-wpeiv.mongodb.net:27017,mycluster0-shard-00-02-wpeiv.mongodb.net:27017/admin?ssl=true&replicaSet=Mycluster0-shard-0&authSource=admin";
MongoClient.connect(uri, function(err, db) {
db.close();
});
