Dockerfile
FROM ruby:2.0.0-p643
# Install deps
RUN apt-get update \
&& apt-get install -y libreadline-dev nano vim \
&& apt-get purge -y --auto-remove
# Ensure Gemfile.lock is up to date
RUN bundle config --global frozen 1
# Install latest released Napa to get baseline dependencies
RUN gem install napa
# Add a simple Procfile parser
ADD contrib/start.rb /start
# Create directory for app
RUN mkdir -p /usr/src/app
WORKDIR /usr/src/app
# Copy Gemfile and Gemfile.lock and run bundle install
ONBUILD COPY Gemfile /usr/src/app/
ONBUILD COPY Gemfile.lock /usr/src/app/
ONBUILD RUN bundle install
# Copy rest of app
ONBUILD COPY . /usr/src/app
CMD ["/start", "web"]