Reverse-engineer a Dockerfile from a Docker image with dfimage

Might come in handy:

Similar to how the docker history command works, this Python script is able to re-create the Dockerfile (approximately) that was used to generate an image using the metadata that Docker stores alongside each image layer.

$ docker pull laniksj/dfimage
Using default tag: latest
latest: Pulling from dfimage

$ alias dfimage="docker run -v /var/run/docker.sock:/var/run/docker.sock --rm laniksj/dfimage"

$ dfimage imageID
FROM buildpack-deps:latest
RUN useradd -g users user
RUN apt-get update && apt-get install -y bison procps
RUN apt-get update && apt-get install -y ruby
ADD dir:03090a5fdc5feb8b4f1d6a69214c37b5f6d653f5185cddb6bf7fd71e6ded561c in /usr/src/ruby
WORKDIR /usr/src/ruby
RUN chown -R user:users .
USER user
RUN autoconf && ./configure --disable-install-doc
RUN make -j"$(nproc)"
RUN make check
USER root
RUN apt-get purge -y ruby
RUN make install
RUN echo 'gem: --no-rdoc --no-ri' >> /.gemrc
RUN gem install bundler
ONBUILD ADD . /usr/src/app
ONBUILD WORKDIR /usr/src/app
ONBUILD RUN [ ! -e Gemfile ] || bundle install --system

Docker File From Image →