How to debug a Kiosk Chrome application running on a Chromebox?

Question

A Chrome Kiosk application that I wrote has a problem only when running in Kiosk mode on a Chromebox. When staring the application manually after I log into the Chromebox it runs well. Also when testing the application on my development machine everything works well.

How can I attach a remote debug session, write remote logging information or in any other way get debugging information from the Kiosk application on the Chromebox to my development machine?

Answer 1

If you run Chrome with the --remote-debugging-port=9222 option it will provide access to DevTools at http://localhost:9222/. Now, on a Chromebox running in Kiosk mode that's not all that useful (or even possible) without some extra steps:

1. Put your device in "developer mode". Instructions vary depending on hardware model.
2. Make the file system writable so that you can modify chrome's command line arguments.
3. Add "--remote-debugging-port=9222" to /etc/chrome_dev.conf.
4. killall chrome or pkill chrome so that the command line changes take effect.
5. Use ssh to log into the Chromebox and forward the port locally: ssh -L9222:127.0.0.1:9222 chronos@<chromebox ip>
6. Access DevTools from your local machine at http://localhost:9222/

Given all this it is easier to debug a kiosk app if you can run it unpackaged in non-kiosk mode.