Remote Debugging Node.js in Docker with VS Code: Troubleshooting Your Debugging Setup

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If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
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Setup Summary

Here's a summary of the configuration you're facing:

Docker Configuration:

Port 9331 is exposed.

Verify with a command to check that the container is correctly publishing the port.

[[See Video to Reveal this Text or Code Snippet]]

Output example:

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VS Code Configuration:

Using "Attach to Running Container" feature.

[[See Video to Reveal this Text or Code Snippet]]

PM2 Setup:

Running your application with PM2 and trying different options for the inspect flag, such as --inspect=0.0.0.0:9331.

The Frustration

Despite configuring everything correctly, you find that the debugger won’t break at any of your specified statements when clicking on the play button to launch the debugger.

The Solution: Change PM2 Mode

Upon troubleshooting, it was discovered that the issue stemmed from the use of PM2’s Cluster Mode. Here’s how to adjust your setup for successful remote debugging:

Step 1: Switch from Cluster Mode to Fork Mode

To allow VS Code to correctly connect via the inspect port, the PM2 mode needs to be changed from cluster to fork. The reason behind this is straightforward:

Cluster Mode does not pass the inspect port, which is integral for debugging connections.

Change your PM2 configuration from:

[[See Video to Reveal this Text or Code Snippet]]

To:

[[See Video to Reveal this Text or Code Snippet]]

This adjustment allows for a more direct debugging connection, as it will ensure your application listens for incoming debugger connections on the specified port.

Step 2: Test Your Configuration

After making this change, restart your application using PM2 and test your connection in VS Code once more.

Open VS Code.

Click on the debugger panel and select your "Attach" configuration.

Run the debugger.

Conclusion