A Complete Guide - NodeJS Deploying Apps to Heroku

3. What does my project structure need to look like for deployment?

Heroku requires a specific project structure:

• package.json: This file contains all dependencies and metadata about the project.
• Procfile: A simple text file that declares process types and commands to run them. For a Node.js app, it might look like: web: node index.js.
• app.js or index.js: The entry point of your application. Heroku automatically looks for files named app.js or index.js. If your entry point is named differently, specify it in your Procfile.

4. How do I configure my environment variables for the app?

Environment variables can be added via the Heroku dashboard or using CLI commands:

• Dashboard Method:

  • Login to Heroku and navigate to your application’s settings.
  • Click on "Reveal Config Vars" to add new variables or edit existing ones.

• CLI Method: Use the heroku config:set command. Example:

  heroku config:set VAR_NAME=value
  

5. Why do I need to use npm start in package.json?

Heroku automatically runs npm start to launch your app. Ensure that your package.json has a start script defined as follows:

"scripts": { "start": "node index.js"
}

Replace index.js with the name of your entry file.

6. What is a Heroku dyno and how do I scale my app?

A dyno is Heroku's basic unit of computation, an isolated and virtualized machine. You can allocate one or more dynos to your application depending on your traffic requirements.

• Scaling:
  • Run heroku ps:scale web=<number-of-dynos>.

For example, to scale your app to 2 dynos, you'd use:

heroku ps:scale web=2

7. How do I specify the Node.js version for Heroku?

Heroku uses the latest stable version of Node.js by default. To specify a different version, include the engines field in your package.json:

"engines": { "node": "16.x", "npm": "8.x"
}

This ensures that Heroku uses the specified Node.js and npm versions.

8. How do I push my Node.js application to Heroku?

You must commit your code to git before deploying, as Heroku works with git:

• Initialize Git:

  git init
  git add .
  git commit -m "Initial commit"
  

• Login to Heroku:

  heroku login
  

• Create Heroku App:

  heroku create
  

  This creates an app with a random name. You can provide your own name with heroku create myapp.
• Push Code:

  git push heroku master
  

If you are using main branch instead of master, use git push heroku main instead.

9. How do I view the logs of my Node.js application running on Heroku?

Logs are crucial for debugging and monitoring. Check logs with:

heroku logs --tail

This command streams the live logs to your console. You can also access logs via the Heroku dashboard under "More" -> "View Logs".

10. How do I handle static files with Node.js on Heroku?

When serving static files in a Node.js application, use Express.js middleware to serve these files:

const express = require('express');
const path = require('path'); const app = express(); // Serve static files from the "public" directory
app.use(express.static(path.join(__dirname, 'public')));

Ensure that public is the directory where you store your static files. Heroku will automatically serve these files when your app is accessed through the URL.