more information on how debugging a rails container is hard?

[noahpatterson]

You mentioned it was difficult to develop and debug rails in a container, do you have any blog links that talk about this?

Thanks!

[jhirn]

Sorry I don't know of any blogs that talk about this specifically but I can tell you what I find inconvenient about running the app itself from within a container.

• I need full env locally for executing tests. Also consider editor integration for test execution. Can't see this being easy at the moment.
• I also need this for running rails console.
• I rely heavily on debugging with pry. Not sure how this works when it's ran from within container but if it involves remote debugger, it's already more complicated.

I did recently do this to run sidekiq workers from within a container because those are mostly background but I then discovered another issue. Every time the Gemfile is modified you need to rerun bundle install via fig build and the prior layer isn't cached, so it's a clean bundle install (2-5 minutes depending on, well, bundler). I plan to blog about that soon but this is the Dockerfile and fig.yml I used:

sidekiq:
  build: .
  working_dir: /my_app
  command: bundle exec sidekiq
  environment:
    - DOCKER_IP
  volumes:
    - .:/my_app
  links:
    - db
    - redis

FROM ubuntu-debootstrap:trusty
MAINTAINER Joe Hirn <[email protected]>

RUN locale-gen en_US.UTF-8

ENV HOME /root
ENV PATH $HOME/.rbenv/bin:$HOME/.rbenv/shims:$PATH
ENV SHELL /bin/bash
ENV LANG en_US.UTF-8
ENV LC_ALL en_US.UTF-8
ENV RBENV_ROOT $HOME/.rbenv
RUN apt-get -q update \
  && DEBIAN_FRONTEND=noninteractive apt-get -q -y install wget autoconf bison build-essential libssl-dev libyaml-dev zlib1g-dev git \
  && apt-get -q clean \
  && apt-get autoremove -y

RUN git clone https://github.com/sstephenson/rbenv.git $RBENV_ROOT \
  && mkdir -p $RBENV_ROOT/plugins \
  && git clone https://github.com/sstephenson/ruby-build.git $RBENV_ROOT/plugins/ruby-build \
  && echo 'eval "$(rbenv init -)"' >> $HOME/.profile \
  && echo 'eval "$(rbenv init -)"' >> $HOME/.bashrc

# APP specific

ENV RUBY_VERSION 2.1.5

RUN rbenv install $RUBY_VERSION \
  && rbenv global $RUBY_VERSION \
  && gem install --no-ri --no-rdoc bundler \
  && rbenv rehash

RUN apt-get -y install libcurl4-openssl-dev libpq-dev nodejs

RUN mkdir /my_app
WORKDIR /my_app
ADD Gemfile Gemfile
ADD Gemfile.lock Gemfile.lock
RUN bundle -j4 && rbenv rehash