[erlang-questions] Can't connect to Erlang node in docker

[Roger Lipscombe]

I've got an Erlang node running in docker[1]. How do I connect to it
from the host?

I've tried every combination of -name, -sname, etc., that I can think
of, and all I'm getting is 'pang'.

I can telnet to the distribution port on the container; if I use
erl_epmd:names/1, passing the DNS name of the docker container, it
returns the expected Erlang nodes.

But I can't get Erlang distribution to connect from the host to the
node in the docker container.

Interestingly, if I connect from the node inside docker to a node on
the host, it all starts working. But that's not useful for what I'm
trying to do.

[1] actually several Erlang nodes in several docker containers.