Is it possible to debug a currently running production Node application?

Question

Locally I debug by running node --debug and using the node-inspector tool. node-inspector must be running in the background, then I point my browser (not all browsers work; Chrome does) to http://127.0.0.1:8080/debug?port=5858 to debug.

Problem is I can't run a production server locally (missing private key files that don't belong on a dev machine), making it very hard to debug certain production problems, even if I'm willing to hack on a production machine. Is this still possible with Node inspector?

Answer 1

Yes, you just need to follow a few steps from node inspector's README:

1. node-inspector has to be running on the machine with the node process you are trying to debug. So, you must be able to install this there.
2. Presumably your production process did not start with the --debug flag. You can send a signal to achieve this though: kill -s USR1 <pid>. (pid can be obtained with something like ps aux | grep node.)
3. Make sure port 8080 is exposed to your local machine from your production machine.
4. Point your browser as normal; you're all set up.