How to debug a rails app in docker with pry?

to use pry you have to run it differently:

docker-compose run --service-ports web

check out this article for more info:

http://blog.carbonfive.com/2015/03/17/docker-rails-docker-compose-together-in-your-development-workflow/

I had this same issue when I was running pry in Passenger. Try changing "pry-rails" in the Gemfile to gem "pry-remote", which will initiate a dRuby, or distributed protocol with no dependencies.

Where you want to stop the code in execution call "binding.remote_pry" as opposed to "binding.pry"

Then just call remote-pry in the console to access it. It should work the same. In your test environment just the usual binding.pry works fine.

as Gabe Kopley answer, assume your rails container is called app, set stdin_open and tty to true:

app:
  stdin_open: true
  tty: true

and I wrote a bash script to make life easier, save it to bin/dev:

#!/bin/bash
docker-compose up -d && docker attach $(docker-compose ps -q app)

don't forget to make dev be executable by chmod +x bin/dev

In your terminal, type bin/dev, it will automatically run up containers and attach the app container. when binding.pry called, you can type to the terminal directly.

If you're using docker-compose, you can add these flags to docker-compose.yml:

app:
  tty: true
  stdin_open: true

And then attach to your process with docker attach project_app_1. pry-rails works here now. Ensure less is installed on your container for the optimal pry experience.

cf. https://github.com/docker/compose/issues/423#issuecomment-141995398