How to host a RESTful Node.js server with MongoDB Atlas database on Heroku

Prerequisites

• Node.js - Installed
• MongoDB Atlas - AWS free tier cluster Account
• Text-editor - Visual Studio Code, Atom and etc.
• Git - Installed

Dependencies Used

• cors version 2.8.5
• express version 4.17.1
• mongoose version 5.7.12

Assumptions

The RESTful Node.js server with MongoDB database works when running on your localhost.

The MongoDB Connection String, you can find it by:

1. Sign-in at mongoDB Altas
2. Locate the cluster you're using for server
3. Click " CONNECT" > Click " Connect Your Application

Set MongoDB Altas - whitelist to 0.0.0.0/0

To set click 'Network Access' under Security tab > click 'ADD IP ADDRESS'

note

Whitelist - MongoDB Atlas allows client connections to the cluster from entries in the project’s whitelist. You must add an entry to the whitelist to connect the client.CIDR notation 0.0.0.0/0 is used to allow all client connections to the cluster. However, you can add a specific IP address/es.

• Go to Heroku dashboard > Select your server App > Settings > Reveal Config Vars

• Add ' MONGODB_URL ' as a Config Vars KEY in HEROKU, and add connection string as the VALUE then click 'Add'.

• Store Cluster - connection string as a node.js process environment variable called ' MONGODB_URL ' in the main server javascript file.

For Example: server.js

const db = process.env.MONGODB_URL;

const connectDB = async () => {
  try {
    await mongoose.connect(db, {
      useUnifiedTopology: true,
      useNewUrlParser: true
    });
    console.log("MongoDB is Connected...");
  } catch (err) {
    console.error(err.message);
    process.exit(1);
  }
};

To allow inbound requests to the server using CORS

• Add FrontEnd site URL where it says "Your FrontEnd Website URL"

For Example:

// cors origin URL - Allow inbound traffic from origin
corsOptions = {
  origin: "Your FrontEnd Website URL",
  optionsSuccessStatus: 200 // some legacy browsers (IE11, various SmartTVs) choke on 204
};
app.use(cors(corsOptions));

note

The code example above is for allowing a single-origin if you want to allow more than one origin refer here

To Deploy select your App then click "Deploy" and choose one of the deployment methods.

Troubleshooting Tips

• If you encounter Heroku runtime errors you can view logs below

note

• If you are getting errors stating Heroku can't find your modules when trying to deploy, it may be because you are using relative paths for example: const connectDB = require("./config/db");

You will have to use absolute paths because Heroku creates its own FileSystem at deployment.