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I've got an Elixir application running inside a Docker container (in my laptop). The Elixir application was executed with the following command:

iex \
  --name test@1.2.3.4 \
  --cookie secret \
  --erl '-kernel inet_dist_listen_min 9000'  \
  --erl '-kernel inet_dist_listen_max 9000' \
  -S mix phx.server

And the Docker container exposes the following ports:

0.0.0.0:4000->4000/tcp, 0.0.0.0:4369->4369/tcp, 0.0.0.0:9000->9000/tcp

  • 4000 for the Phoenix server
  • 4369 for EPMD
  • 9000 for the VM node

Then I try to connect using an IEx shell using the following command:

iex --name local@127.0.0.1 --cookie secret which results in this error: Protocol 'inet_tcp': register/listen error: epmd_close

This seems to be because the local epmd daemon is trying to allocate to port 4369, however, this is already allocated to the Docker container.

I then changed the EPMD port like so:

ERL_EPMD_PORT=4370 iex --name local@127.0.0.1 --cookie secret

and I manage to open up the IEx session. However, I cannot find the node running on the Docker container:

iex(local@127.0.0.1)1> Node.connect :'test@1.2.3.4'
false

I'm not sure how to solve this. I was following this blog post.

Sasha Fonseca
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  • Not sure if it applies but this previous [S O answer](https://stackoverflow.com/questions/17351882/how-to-connect-two-elixir-nodes-via-local-network) may have some bearing on your issue. – Onorio Catenacci Feb 27 '18 at 15:56

1 Answers1

2

Wouldn't an easier solution be to change the outward port of the docker container? Just change it to something like 4368

$ docker run -itd -p 4000:4000 4368:4369 9000:9000 <docker_image_name> iex \
  --name test@1.2.3.4 \
  --cookie secret \
  --erl '-kernel inet_dist_listen_min 9000'  \
  --erl '-kernel inet_dist_listen_max 9000' \
  -S mix phx.server`
sebisnow
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