首先,
在书籍源代码中:
[Air@host sinatra]$ cat dockerbook-code/code/5/sinatra/webapp/Dockerfile
FROM ubuntu:16.04
LABEL maintainer="james@example.com"
ENV REFRESHED_AT 2014-06-01
RUN apt-get -qq update && apt-get -qq install ruby ruby-dev build-essential redis-tools
RUN gem install --no-rdoc --no-ri sinatra json redis
RUN mkdir -p /opt/webapp
EXPOSE 4567
CMD [ "/opt/webapp/bin/webapp"