Apparently, I shouldn't have spent sleepless night trying to debug an application. I wanted to restart my nginx and discovered that its config file is empty. I don't remember truncating it, but fat fingers and reduced attention probably played their part.
I don't have backup of that config file. I know I should have made it.
Good for me, current nginx daemon is still running. Is there a way to dump its configuration to a config file that it'll understand later?