Dockerfile

# Use an official, light-weight Ruby image
FROM ruby:2.2.3-slim

# Install essential Linux packages (use one RUN command to reduce layer complexity)
# IF YOU NEED ImageMagick, ADD THESE TO THE END OF THE LINE BELOW: libmagickwand-dev imagemagick
# IF YOU NEED MySQL, ADD THESE TO THE LINE BELOW: mysql-server mysql-client libmysqlclient-dev

RUN apt-get update -qq && apt-get install -y build-essential libpq-dev postgresql-client

# IF YOU NEED PostgreSQL, uncomment the line below:
# RUN echo "deb http://apt.postgresql.org/pub/repos/apt/ trusty-pgdg main" > /etc/apt/sources.list.d/pgdg.list && apt-get update && DEBIAN_FRONTEND=noninteractive apt-get install -y --force-yes libpq-dev

# Set the location for where application code will be stored
ENV RAILS_ROOT /var/www/myapp

# Create the directory where pid files will be stored
RUN mkdir -p $RAILS_ROOT/tmp/pids

# Set our working directory inside the image
WORKDIR $RAILS_ROOT

# Use the Gemfiles as Docker cache markers. Always bundle before copying app src.
# (the src likely changed and we don't want to invalidate Docker's cache too early)
# http://ilikestuffblog.com/2014/01/06/how-to-skip-bundle-install-when-deploying-a-rails-app-to-docker/

COPY Gemfile Gemfile
COPY Gemfile.lock Gemfile.lock

# Prevent bundler warnings; ensure that the bundler version executed is >= that which created Gemfile.lock
RUN gem install bundler

# Finish establishing our Ruby environment
RUN bundle install

# Copy the Rails application into place
COPY . .

# Define the script we want run once the container boots
# Use the "exec" form of CMD so our script shuts down gracefully on SIGTERM (i.e. `docker stop`)
CMD [ "config/containers/myapp.sh" ]