macOS runs a service on port 5000 by default. this doesn't actually
prevent the backend server from *starting*, or the rate limiter proxy
from working, but it *does* mean that when the backend restarts, if the
proxy sends a request, it will stop working until it's restarted.
the easiest way to work around this is by just changing the port the
backend listens on. this does not change the ports used in the docker
configuration.
