Remapping ports - radius

[ianpmurphy]

I've been trying to get a radius server up and running and, following through some examples I think it should be ok. However to actually use it I need to know what port to connect to.
I understand that I need to remap a port to the docker container but how on earth do you know which container. From examining the hostconfig.json files I get the impresion that Authentik is creating a docker instance for each service.

Am I supposed to make a change at the linux/docker level or does Authentik take care of mapping ports from the host machine?