Can Docker Merge Multiple Images into a Single, Functional Composite Image?

Building Composite Docker Images

Query: Can Docker merge multiple images into a single one, combining their functionalities? For instance, creating an image that bundles Java and MySQL from individual images containing each component separately?

Solution:

Docker itself does not natively support image combination, but DockerMake, an external tool, enables this functionality. It leverages a YAML configuration file to define the dependencies and build instructions for each image component. Using DockerMake, you can create a composite image by inheriting from multiple base images.

For example, to construct an image with both Java and MySQL, you would define a DockerMake configuration similar to the one provided below:

<code class="yaml">specificAB:
  requires:
    - genericA
    - genericB

genericA:
  requires:
     - customBase
  build_directory: [local directory containing build instructions]
  build: |
    # Build commands for genericA, e.g., ADD installA.sh, RUN ./installA.sh

genericB:
  requires:
    - customBase
  build: |
    # Build commands for genericB, e.g., RUN apt-get install -y genericB, ENV PATH=$PATH:something

customBase:
  FROM: debian:jessie
  build: |
    # Common build instructions for both genericA and genericB, e.g., RUN apt-get update & apt-get install -y buildessentials</code>

With DockerMake installed (via pip), simply execute the command docker-make specificAB to build the desired composite image.

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