Dockerfile
from ruby:2.4.0
RUN gem install sinatra --no-document
ENV APP_PATH /opt/sinatra/src
RUN mkdir -p $APP_PATH
EXPOSE 4567
CMD ruby $APP_PATH/app.rb -o 0.0.0.0
Usage:
from mateusprado/sinatra
COPY . $APP_PATH
$ docker run -d -p 4567:4567 your-docker-image