Deploying nodejs/mongoose to heroku - node.js

Question

This is my first try at Heroku. I was able to "deploy successful" on heroku, but when visiting my app, it says "application failed."
I followed this guide:
https://scotch.io/tutorials/use-mongodb-with-a-node-application-on-heroku
I think the tricky thing is because I'm using Mongoose, it may not relate well with the URI. I'm also using mlab addon.
Here's my setup for my backend:
var request = require('request');
var app = express();
var mongoCredentialss = require('/mongo_credentialss.json');
var conn = mongoose.connection;
var path = require('path');
// connect to the database
mongoose.connect('mongodb://' + mongoCredentials.username + ':' + mongoCredentialss.password + '#ds012345.mlab.com:12345/mydatabase-db');
mongoose.Promise = Promise;
app.listen(3000, function() {
console.log('Listening on 3000...');
});
I didn't really understand the .env, to make it work locally, I just stored my username and password in a hidden .json file thanks to .gitignore. From the guide though, I just tried embedding URI straight into my node file as a variable to see if that even works. I'm not too sure how 'hidden environments' work...
Later on when I started over, I also kept having a recurring problem with heroku not detecting its standard buildpacks:set heroku/nodejs
****EDIT:
Still seeing some issues. I took out my 'mongo creds' so my server.js file now looks like this:
var express = require('express');
var mongoose = require('mongoose');
mongoose.connect(process.env.MONGODB_URI);
var Promise = require('bluebird');
var bodyParser = require('body-parser');
var randtoken = require('rand-token');
var cors = require('cors');
var request = require('request');
var app = express();
var conn = mongoose.connection;
var fs = require('fs');
var path = require('path');
app.listen(3000, function() {
console.log('Our app is running on http://localhost:' + 3000);
});
Some further context: I have one main project folder, which houses 2 sub folders: backend and frontend. When I deploy it to heroku, I change directory into the main folder to deploy everything.
Also, if it helps, here's what my package.json looks like:
"dependencies": {
"bluebird": "^3.4.1",
"body-parser": "^1.15.2",
"cors": "^2.7.1",
"express": "^4.14.0",
"mongoose": "^4.5.3",
"my-bcrypt": "^1.0.2",
"rand-token": "^0.2.1",
"request": "^2.74.0"
},
"engines": {
"node": "==6.0.0"
}
}
******EDIT 2:
heroku logs can't find my 'backend.js'. Right now, I've got one main project folder directory, inside it is 2 folders: --->backend.js (node) and --->frontend.js (angular)
My package.json looks like this:
**"main": "frontend.js",**
"scripts": {
**"start": "node backend.js",**
"test": "echo \"Error: no test specified\" && exit 1"
},
I may be misunderstanding how heroku is finding my main .js files. From my understanding 'start' is for the node file, and the 'main' file is for the frontend stuff like angular/html stuff.

Answer 1

You should be able to connect Mongoose to your MLab database by doing this:
mongoose.connect(process.env.MONGODB_URI);
When you are using an addon on Heroku, the provider (MLab in this case) will create a database for you, and then store the connection details (the URL with the database host, username, password, port, etc.) as an environment variable that your application can use.
That's why you need to pass that environment variable process.env.MONGODB_URI into mongoose.connect: it will connect you to the right database =)
UPDATE: Since you updated your question, I noticed another issue that will prevent this from running. You need to tell your app to listen on a specific Heroku port (not 3000).
What you should do is modify your app.listen(3000) call to instead say: app.listen(process.env.PORT || 3000); This will force your application run correctly on both Heroku AND you local development box.

Answer 2

You require mongo using this line:
var mongoCredentialss = require('/mongo_credentialss.json');
but you've set your password in your mongoCredentials as:
mongoose.connect('mongodb://' + mongoCredentials.username + ':' + mongoCredentialss.password + '#ds012345.mlab.com:12345/mydatabase-db');
your username is bound to mongoCredentials.username rather than the mongoCredentialss.username
Simple typo in the code which is bound to lead to db connection errors.