Docker: Combine multiple images

Question

Is it possible with Docker to combine two images into one?

Like this here:

genericA --
            \\
             ---> specificAB
            /
g         


        

Answer 1

Docker doesn't directly support this, but you can use DockerMake (full disclosure: I wrote it) to manage this sort of "inheritance". It uses a YAML file to set up the individual pieces of the image, then drives the build by generating the appropriate Dockerfiles.

Here's how you would build this slightly more complicated example:

                                     --> genericA --
                                    /                \
      debian:jessie -->  customBase                   ---> specificAB
                                    \                /
                                      --> genericB --

You would use this DockerMake.yml file:

specificAB:
  requires:
    - genericA
    - genericB

genericA:
  requires:
     - customBase
  build_directory: [some local directory]
  build: |
    #Dockerfile commands go here, such as
    ADD installA.sh
    RUN ./installA.sh

genericB:
  requires:
    - customBase
  build: |
    #Here are some other commands you could run
    RUN apt-get install -y genericB
    ENV PATH=$PATH:something

customBase:
  FROM: debian:jessie
  build: |
    RUN apt-get update && apt-get install -y buildessentials

After installing the docker-make CLI tool (pip install dockermake), you can then build the specificAB image just by running

docker-make specificAB