Example Dockerfile for Ruby

FROM ruby:2.5
RUN apt-get update -qq && apt-get install -y nodejs
RUN mkdir /myapp 
WORKDIR /myapp 
COPY Gemfile /myapp/Gemfile 
COPY Gemfile.lock /myapp/Gemfile.lock 
RUN bundle install 
COPY . /myapp 

# Add a script to be executed every time the container starts. 
COPY entrypoint.sh /usr/bin/ 
RUN chmod +x /usr/bin/entrypoint.sh 
ENTRYPOINT ["entrypoint.sh"] 
EXPOSE 3000 

# Start the main process. 
CMD ["rails", "server", "-b", "0.0.0.0"]