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Dockerfile Cheat Sheet

Dockerfile provides the instructions needed to build a container and the commands to be executed when the container runs.

Inheritance 

FROM ruby:2.2.2

Variables 

ENV APP_HOME /myapp
RUN mkdir $APP_HOME

Initialization 

RUN bundle install
WORKDIR /myapp

Onbuild 

ONBUILD RUN bundle install
# when used with another file

Commands 

EXPOSE 5900
CMD    ["bundle", "exec", "rails", "server"]