Buffet 🍜

Assemble many Dockerfiles in a single Dockerfile. This gives you the convenience of one Docker image with your favorite tools while keeping the modularity of a separate Dockerfile per tool.

See Code Cleaner Buffet for an application of this.

Installation

Run

stack install buffet

or

cabal install buffet

You are ready when

buffet --help

works.

Usage example

Say we work on a simple website with HTML code that we would like to format, clean up, and validate. For this purpose, we choose the tools Prettier and HTML Tidy, which we plan use in continuous integration via a Docker image.

For the following, we assume you first run

git clone https://github.com/evolutics/buffet.git
cd buffet

Building

In the subfolders of the example folder, you see a Dockerfile for Prettier and another Dockerfile for HTML Tidy. These Dockerfiles (called "dishes") are the modular toy blocks, which we now automatically combine to one Dockerfile (called "buffet") by running

buffet build example

This prints a Dockerfile based on the subfolders of example. From this, we can then build a Docker image mona_linta with

buffet build example | docker build \
  --build-arg prettier=1.19.1 --build-arg tidy=1 --tag mona_linta -

Note how we pass a --build-arg per tool, assigning each a nonempty value. In case of Prettier, we use this to parameterize the tool version. If we do not mention a tool in a --build-arg, it is not available in the image.

Testing

As a demo that our Docker image works as expected, run

docker run -it --rm mona_linta
prettier --version
tidy --version

To integrate a check like prettier --version as a test of the tool installation, add a HEALTHCHECK instruction as you see in the Dockerfile for Prettier. The exit status of such a command is then reported when you run our example test suite with

buffet test --arguments example/test_arguments.yaml example

The file test_arguments.yaml provides the --build-arg configuration for this test run.

If you like, try adding a test for HTML Tidy.

Documenting

You can generate documentation with

buffet document --template example/document_template.md.mustache example

This renders the template document_template.md.mustache. To print the raw template context, omit this option as in

buffet document example

Among others, data from LABEL instructions is integrated in the template context.

Terminology

• Buffet: A Dockerfile automatically assembled based on many dishes.
• Dish: A Dockerfile, usually providing a specific command-line tool.
• Menu: Configuration with a list of dishes to be assembled in a buffet.