You used an elixir debugger on production?

Elixir REPL in production yeah. Not to modify anything, but to inspect the state of the world and figure out why some OTP apps were dying. I'm drawing a blank on the name of the build tool, but the "launch binary" it produces has an option to fire up a second copy of your app, keep the console alive, and connect it to the cluster as another node. Worked like a charm, although it's something I wouldn't want to do on a regular basis :)