What dark magic is this?

The past 2 days of my life have been consumed by this. And you, out of nowhere, somehow managed to bring me a solution. I never thought this would work. To be honest, I quite don’t understand why, but who cares, it works !

Summary

To summarize (since I am sure I will forget about this 4 steps of hell) I am putting it here everything I did.

All steps in local machine:

1. get the ports from the remote server:

   ssh remote-user@remote-ip "epmd -names"

   epmd: up and running on port 4369 with data:
   name super_duper_app at port 43175

2: create a ssh tunel with the ports:

ssh remote-user@remote-ip -L4369:localhost:4369 -L43175:localhost:43175

3. On another terminal in your local machine, run a iex terminal with the cookie the app in your remote server is using. Then connect to it and start observer:

   iex --name observer@127.0.0.1 --cookie super_duper_cookie

   Node.connect :"super_duper_app@127.0.0.1"
   true
   :observer.start

With observer started, select the machine from the Nodes menu.

I have this module that generate the instructions to connect that I’ve posted here, so you don’t need to get the epmd port every time. You need to replace some module variables, and beware @app is the same as remote user for us, not sure if it’s just gonna work for you.

Cheers

Something like

sudo lsof -t -i:4369

Should show you the process that has bound port 4369 locally. So you can run sudo lsof -t -i:4369 | xargs kill

If lsof isn’t working for you you could also try something like netstat -anl |grep 4369

Aren’t step 1 and 2 the same as in your original post? It sounds like the major issue you fixed is whatever was originally causing you this error after step 2:

bind [127.0.0.1]:4369: Address already in use
channel_setup_fwd_listener_tcpip: cannot listen to port: 4369

Following your suggestions to kill processes using the port also help immensely, that is true.

Thanks for the script and for the help. We will change some parts of the script but the overall idea is clear!