Dockerfile
FROM ruby:2.5.3
MAINTAINER ldiez@podemos.info
ARG rails_env=staging
ARG secret_key_base=
ENV APP_HOME /code
ENV RAILS_ENV $rails_env
ENV SECRET_KEY_BASE $secret_key_base
RUN apt-get update
RUN curl -sL https://deb.nodesource.com/setup_5.x | bash && \
apt-get install -y nodejs
ADD Gemfile /tmp/Gemfile
ADD Gemfile.lock /tmp/Gemfile.lock
RUN cd /tmp && bundle install
RUN mkdir -p $APP_HOME
WORKDIR $APP_HOME
ADD . $APP_HOME
RUN bundle exec rake DATABASE_URL=postgresql://user:pass@127.0.0.1/dbname assets:precompile
CMD ["bundle", "exec", "rails", "s", "-b0.0.0.0"]