content: # 1: Use ruby 2.2.6 as base:
  FROM ruby:2.2.6
  
  # 2: We'll set the application path as the working directory
  WORKDIR /usr/src/app
  
  # 3: We'll set the working dir as HOME and add the app's binaries path to $PATH:
  ENV HOME=/usr/src/app PATH=/usr/src/app/bin:$PATH
  
  # 4: Expose the app web port:
  EXPOSE 3000
  
  # 5: Set the default command:
  CMD ["rails", "server", "-b", "0.0.0.0", "-p", "3000"]
  
  # 6: Install node as a javascript runtime for asset compilation:
  # gpg keys listed at https://github.com/nodejs/node
  RUN set -ex \
    && for key in \
      9554F04D7259F04124DE6B476D5A82AC7E37093B \
      94AE36675C464D64BAFA68DD7434390BDBE9B9C5 \
      0034A06D9D9B0064CE8ADF6BF1747F4AD2306D93 \
      FD3A5288F042B6850C66B31F09FE44734EB7990E \
      71DCFD284A79C3B38668286BC97EC7A07EDE3FC1 \
      DD8F2338BAE7501E3DD5AC78C273792F7D83545D \
      B9AE9905FFD7803F25714661B63B535A4C206CA9 \
      C4F0DFFF4E8C1A8236409D08E73BC641CC11F4C8 \
    ; do \
      gpg --keyserver ha.pool.sks-keyservers.net --recv-keys "$key"; \
    done \
    && export NPM_CONFIG_LOGLEVEL=info \
    && export NODE_VERSION=6.3.1 \
    && curl -SLO "https://nodejs.org/dist/v$NODE_VERSION/node-v$NODE_VERSION-linux-x64.tar.xz" \
    && curl -SLO "https://nodejs.org/dist/v$NODE_VERSION/SHASUMS256.txt.asc" \
    && gpg --batch --decrypt --output SHASUMS256.txt SHASUMS256.txt.asc \
    && grep " node-v$NODE_VERSION-linux-x64.tar.xz\$" SHASUMS256.txt | sha256sum -c - \
    && tar -xJf "node-v$NODE_VERSION-linux-x64.tar.xz" -C /usr/local --strip-components=1 \
    && rm "node-v$NODE_VERSION-linux-x64.tar.xz" SHASUMS256.txt.asc SHASUMS256.txt
  
  # 7: Install the current project gems - they can be safely changed later during
  # development via `bundle install` or `bundle update`:
  ADD Gemfile* /usr/src/app/
  RUN set -ex && bundle --retry 3
  