Great docker! I can get rid of my standalone Pi now. Thanks!
I think the instructions need to be updated. The docker won't start without a FlightAware Feeder Key, and you cannot register a new receiver without starting the docker. I got it working by putting a bogus value into the docker config for FlightAware Feeder Key, starting the docker, claiming the receiver on the FlightAware website, and finally inserting the key from FlightAware website into the docker config.