Remote debugging in Heroku

Hey there, fellow coder! Have you ever wished you could just step through your Node.js app running on Heroku like a local app? Well, grab your favorite drink and get comfy because we’re about to embark on a fun journey to set up remote debugging on Heroku!

Why Remote Debugging?

Debugging is a crucial part of development, ensuring your app runs smoothly and efficiently. Remote debugging is especially important when your app is deployed on a server, allowing you to diagnose issues that only appear in a deployed environment.

Prerequisites

Before we jump in, make sure you have:

• A Node.js application deployed on Heroku.
• The Heroku CLI installed on your machine.

Debugging Steps

Step 1: Enable Remote Debugging

First, we need to enable remote debugging for your Node.js app. Heroku uses the inspect flag to allow remote debugging.

1. Modify Your Procfile: Add the --inspect flag to your Procfile. It should look something like this:

web: node –inspect index.js

2. Deploy Changes to Heroku: Commit your changes and push to Heroku:

git add Procfile
git commit -m “Enable remote debugging”
git push heroku master

Step 2: Open a Remote Debugging Session

Now that your app is configured, it’s time to connect to the remote debugger.

1. Restart Your Heroku App: Restarting ensures the inspect flag is applied:

heroku restart

2. Forward Debugging Port: Forward traffic on a local port to a port inside a dyno; in this case both the local port and dyno port are 9229:

heroku ps:forward 9229

Step 3: Connect Your Debugger

With the SSH tunnel set up, you can now connect your favourite debugger. 

Using VS Code

1. Open VS Code: Launch VS Code and open your project.
2. Configure Debugger: Add a new configuration in your launch.json:

{
   "version": "0.2.0",
   "configurations": [{
       "address": "localhost",
       "localRoot": "${workspaceFolder}",
       "name": "Attach to Remote",
       "port": 9090,
       "remoteRoot": "/app",
       "request": "attach",
       "skipFiles": ["<node_internals>/**"],
       "type": "node",
   }]
}

3. Start Debugging: Select the "Attach to Heroku" configuration and start debugging. Set breakpoints, inspect variables, and step through your code like in a local environment.

Using IntelliJ IDEA / Webstorm

1. Open Run Config: Open your IDE and go to Run > Edit Configurations. 
2. Configure Debugger: Click the + button and select Attach to Node.js/Chrome:

3. Start Debugging: Select your newly created Node.js Remote Debug configuration, Click the debug icon and start debugging. Set breakpoints, inspect variables, and step through your code like in a local environment.

And there you have it! You’ve just set up remote debugging for your Node.js app on Heroku. High five!  Debugging in the cloud just became a whole lot cooler, right? If you hit any bumps along the way, double-check your SSH tunnel and configurations. Happy debugging!