How to debug rails application which is running inside docker container
I don't know ruby or rails, but this is general "problem" with docker-compose up. The code execution will not stop in a running container in this case and instead fail when you hit a point for the debugger. You need to run the service in the foreground instead:
docker-compose stop <my-service-to-debug>docker-compose run --service-ports <my-service-to-debug> This will drop you into the debugger once your code hits that point. The important part here is the --service-ports flag which makes sure the same ports are exposed as you specified in your docker-compose.yml file. You can also use the --no-deps flag in case you don't want any linked containers to restart.