Can't access the dockerized app launched from the command line from outside

Question

I have built a Docker image with Ruby and some gems as a starting point for my projects. Its available at: jikkujose/trial . I am trying this out in a Mac, using the default docker-toolbox.

I am trying to use it to host a single file app. I am launching it as follows:

docker run -itdP -v .:/app jikkujose/docker

The current directory contains a file app.rb with the following:

require 'sinatra'

class App < Sinatra::Base
  set :bind, "0.0.0.0"

  get '/' do
    'This is interesting :)'
  end
end

App.run!

I am able to attach to the container to launch the app. And the following is seen when I do: docker ps -a

CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS                        PORTS                     NAMES
92498cafd985        jikkujose/trial     "/bin/bash"              18 seconds ago      Up 18 seconds                 0.0.0.0:32780->4567/tcp   boring_meitner

And I am trying to access the application using the ip obtained via docker-machine ip default .

While trying to access the the app using curl , I am getting the following:

curl: (7) Failed to connect to 192.168.99.100 port 32780: Connection refused

Answer 1

Failed to connect to 192.168.99.100 port 32780: Connection refused

That should mean there is no listener, or, since a docker exec <container id> curl http://localhost:4567 does work, that the listener does not accept queries from broadcast, only from localhost...

Your entrypoint and cmd are :

ENTRYPOINT ["/opt/rubies/ruby-2.2.2/bin/ruby"]
CMD ["/app/app.rb"]

Check if others mean to launch a sinatra app would work better with a docker environment: for instance " Dockerizing simple Sinatra app using docker and fig " (fig is the old name of docker compose)

Before that, check if the mapped port is forwarded at the VirtualBox level :

VBoxManage controlvm boot2docker-vm natpf1 "name,tcp,127.0.0.1,32780,,32780"