How to debug a rails (3.2) app started by foreman?

Question

I am trying to use foreman to start my rails app. Unfortunately I have difficulties connecting my IDE for debugging.

I read here about using

Debugger.wait_connection = true
Debugger.start_remote

to start a remote debugging session, but that does not really work out.

Question: Is there a way to debug a rails (3.2) app started by foreman? If so, what is the approach?

Answer 1

If you use several workers with full rails environment you could use the following initializer:

# Enabled debugger with foreman, see https://github.com/ddollar/foreman/issues/58
if Rails.env.development?
  require 'debugger'
  Debugger.wait_connection = true

  def find_available_port
    server = TCPServer.new(nil, 0)
    server.addr[1]
  ensure
    server.close if server
  end

  port = find_available_port
  puts "Remote debugger on port #{port}"
  Debugger.start_remote(nil, port)
end

And in the foreman's logs you'll be able to find debugger's ports:

$ foreman start
12:48:42 web.1     | started with pid 29916
12:48:42 worker.1  | started with pid 29921
12:48:44 web.1     | I, [2012-10-30T12:48:44.810464 #29916]  INFO -- : listening on addr=0.0.0.0:5000 fd=10
12:48:44 web.1     | I, [2012-10-30T12:48:44.810636 #29916]  INFO -- : Refreshing Gem list
12:48:47 web.1     | Remote debugger on port 59269
12:48:48 worker.1  | Remote debugger on port 41301

Now run debugger using:

rdebug -c -p [PORT]

Answer 2

One approach is to require debugger normally in your gemfile, and add debugger normally in your code as needed. When the server hits that line, it will stop, but foreman won't be verbose about it. In your foreman console you can blindly type irb, and only then will you see a prompt appear. Bad UX, right?

Another (augmentative) approach is to tail your logs:

tail -f log/development.log

Hope this helps.