FROM ruby:2.3
RUN apt-get update \
&& apt-get install -y --no-install-recommends \
postgresql-client \
&& rm -rf /var/lib/apt/lists/*
WORKDIR /usr/src/app
COPY Gemfile* ./
RUN bundle install
COPY . .
EXPOSE 3000
CMD ["rails", "server", "-b", "0.0.0.0"]```