Docker File
FROM tcnksm/centos-ruby:2.1
#throw errors if Gemfile has been modified since Gemfile.lock
RUN bundle config --global frozen 1
RUN mkdir -p /usr/src/app
WORKDIR /usr/src/app
ONBUILD COPY Gemfile /usr/src/app/
ONBUILD COPY Gemfile.lock /usr/src/app/
ONBUILD RUN bundle install
ONBUILD COPY . /usr/src/app
place Dockerfile at root of app
FROM sjeanpierre/sinatra-base
CMD ["rackup"]
Build
cd <application_root>
docker build -t <new_image_name> .
Run
docker run --rm -e "RACK_ENV=production" -p 9292:9292 -t -i <image_name>