# Remote debugging elixir on docker container

**URL:** <https://forum.elixirforum.com/t/remote-debugging-elixir-on-docker-container/39382>\
**Category:** Questions\
**Tags:** troubleshooting, observer, debug\
**Created:** [May 3, 2021, 2:51pm UTC](https://forum.elixirforum.com/t/remote-debugging-elixir-on-docker-container/39382 "2021-05-03T14:51:46Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![csuriano23](https://forum.elixirforum.com/user_avatar/forum.elixirforum.com/csuriano23/32/21862_2.png) [@csuriano23](https://forum.elixirforum.com/u/csuriano23)\
**Post date:** [May 3, 2021, 2:51pm UTC](https://forum.elixirforum.com/t/remote-debugging-elixir-on-docker-container/39382/1 "2021-05-03T14:51:46Z")

</div>

Hi there,  
on my macbook pro (OS Big Sur / Darwin 20.3.0) I am trying to setup the erlang observer on an elixir app running in a local docker container.

On container shell I can successfully run:

```sh
iex --name myserver@127.0.0.1 --cookie mycookie -S mix phx.server

```

and even:

```sh
iex --name someproc@127.0.0.1 --cookie mycookie -e "Node.connect(:'myserver@127.0.0.1')" -S mix run --no-start

```

The nodes can successfully see each other.

The container remaps the EPMD port from 4369 to 43691 and I’d like to launch a local shell like this:

```sh
iex --name user@127.0.0.1 --cookie mycookie -e "Node.connect(:'myserver@127.0.0.1')" -S mix run --no-start

```

but even if the repl starts, the Node.connect / Node.ping to [myserver@127.0.0.1](mailto:myserver@127.0.0.1) fails.

The most complete guide I’ve found in order to accomplish this goal is [here](https://sgeos.github.io/elixir/erlang/observer/2016/09/16/elixir_erlang_running_otp_observer_remotely.html), but I don’t know if - following that - it is correct to use 127.0.0.1 as `REMOTE_HOST` and even trying I cannot reach in the new shell the remote process.

Any clues/suggestions?

Thank you  
Carlo