Issue with getting RubyMine debugger to work with Docker - ruby-on-rails

Question

I'm setting up RubyMine Debugger with Docker but I believe I have an issue with the matching the ports and I can't find documentation that thoroughly explains what the "configuration form in ruby mine is asking for and how to find the related information for the form input fields" all I can find is generic information.
I have had many error messages and even crashing when I click the debugger button. I have tried a lot more then what I'm posting but I never wrote it down. This is just where I am at this current moment
I have followed https://confluence.jetbrains.com/display/RUBYDEV/How+to+setup+and+run+ruby+remote+debug+session
I have added ports to the docker-compose.yml file.
Setup configuration for remote Remote Ruby SDK and Gem.
Setup Ruby remote debug configuration.
I have tried working my way through every error but I just get more as I go.
This app uses docker-compose and I'm not familiar with it at all other then all the reading I been doing to get this debugger setup
docker-compose.yml file
app:
build: wffffffe_api
dockerfile: Dockerfile-development
command: rails server --port 3000 --binding 0.0.0.0
stdin_open: true
tty: true
ports:
- "3000:3000"
- "1234:1234"
- "26162:26162"
volumes:
- './wfffffe_api:/var/www/weffffffe_api'
- './dotfiles/.vimrc-basic:/root/.vimrc'
The debugger configuration
Remote host: 0.0.0.0
Remote port: 3000
Remote root folder: /var/www/wffffffe_api
local port: 26162
local root folder: /Users/josh/Work/wffffffe_api
I have tried doing
docker-compose exec app rdebug-ide --host 0.0.0.0 --port 3000 --dispatcher-port 26162 -- bin/rails server
If the docker container is already running I get:
Fatal exception in DebugThread loop:
Address already in use - bind(2) for "0.0.0.0" port 3000
If the docker container is not already running I get:
Fast Debugger (ruby-debug-ide 0.6.1, debase 0.2.2, file filtering is supported) listens on 0.0.0.0:3000
I then do docker-compose up --build -d
ERROR: for app Cannot start service app: b'driver failed programming external connectivity on endpoint work_app_1 (1e830daaecd39fab784b817a03893b592635542a8dfe3de69859c0ba7d39b483): Error starting userland proxy: Bind for 0.0.0.0:3000 failed: port is already allocated'
Do I need to have two separate servers running?

Answer 1

Your problem is that you are trying to debug on port 3000, which already bound by your rails application.
The --port of rdebug-ide specify the port that RubyMine will use for its debug protocol.
When you execute rails server --port 3000 --binding 0.0.0.0, you are binding port 3000 as your rails application (and not as debug port).
Change your remote port debug to 1234 (which you already exposed in your docker-compose.yml) and it should work.
To summarise, your command should look like:
docker-compose exec app rdebug-ide --host 0.0.0.0 --port 1234 --dispatcher-port 26162 -- bin/rails server --port 3000 --binding 0.0.0.0