# Buffet 🍜

[![Build](https://img.shields.io/travis/evolutics/buffet)](https://travis-ci.org/evolutics/buffet)
[![License](https://img.shields.io/github/license/evolutics/buffet)](LICENSE)
[![Package](https://img.shields.io/hackage/v/buffet)](https://hackage.haskell.org/package/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](https://github.com/evolutics/code-cleaner-buffet) for an application of this.

## Installation

Run

```bash
stack install buffet
```

or

```bash
cabal install buffet
```

You are ready when

```bash
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

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

### Assembling

In the subfolders of [`examples/quick_start`](examples/quick_start), you see a [Dockerfile for Prettier](examples/quick_start/prettier/Dockerfile) and another [Dockerfile for HTML Tidy](examples/quick_start/tidy/Dockerfile). These Dockerfiles (called "dishes") are the modular toy blocks, which we now automatically combine to one Dockerfile (called "buffet") by running

```bash
buffet assemble examples/quick_start
```

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

```bash
buffet assemble examples/quick_start | \
  docker build --build-arg prettier=1.19.1 --tag mona_linta -
```

Note how in case of Prettier, we pass a `--build-arg` to parameterize the tool version.

### Testing

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

```bash
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](examples/quick_start/prettier/Dockerfile). The exit status of such a command is then reported when you run our example test suite with

```bash
buffet test --arguments examples/quick_start/test_arguments.yaml \
  examples/quick_start
```

This builds a Docker image to then run the tests. The file [`test_arguments.yaml`](examples/quick_start/test_arguments.yaml) provides a map that is used for two things: firstly, its entries are used as `--build-arg` options when building the image, and secondly, only tests of dishes referred in this map are run.

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

### Documenting

You can generate documentation with

```bash
buffet document --template examples/quick_start/document_template.md.mustache \
  examples/quick_start
```

This renders the template [`document_template.md.mustache`](examples/quick_start/document_template.md.mustache). To print the raw template context, omit this option as in

```bash
buffet document examples/quick_start
```

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.