Dockerfile
FROM ruby:2.1.5
RUN apt-get update -qq && apt-get install -y build-essential
# for postgres
RUN apt-get install -y libpq-dev
# for nokogiri
RUN apt-get install -y libxml2-dev libxslt1-dev
# for capybara-webkit
RUN apt-get install -y libqt4-webkit libqt4-dev xvfb
# for a JS runtime
RUN apt-get install -y nodejs
ENV APP_HOME /code
RUN mkdir $APP_HOME
WORKDIR $APP_HOME
ADD Gemfile* $APP_HOME/
RUN bundle install
ADD . $APP_HOME
EXPOSE 3000