dockerfile-plus/README.md

# Dockerfile+

This project provides Dockerfile syntax extensions that have been rejected by the moby project or haven't been addressed in a long time.

Currently, the project adds an `INCLUDE+` Dockerfile directive that allows you to import the content of another file into your Dockerfile. There are plans to add more features in the near future.

- [Getting started](#getting-started)
- [Features](#features)
  - [INCLUDE+](#include)
- [Roadmap](#roadmap)
- [Feedback](#feedback)

## Getting started

- First, you need to make sure you are running a compatible version of Docker: you need at least Docker 18.09. If you are using an older version, you are out of luck. Sorry!
- Export the following environment variables to enable Buildkit: `DOCKER_BUILDKIT=1` and `COMPOSE_DOCKER_CLI_BUILD=1` (this might not be necessary for newer installations of Docker)

Once your Docker is set, you just need to add the following line as your first line in your Dockerfile:

```Dockerfile
# syntax = edrevo/dockerfile-plus
```

That's it!

## Features

### INCLUDE+

Right now there is just one extra instruction: `INCLUDE+`. All Dockerfile+ commands will end up with a `+` sign to avoid any potential future collisions with Dockerfile commands.

`INCLUDE+` will import the verbatim contents of another file into your Dockerfile. Here's an example Dockerfile which uses the `INCLUDE+` instruction:

```Dockerfile
# syntax = edrevo/dockerfile-plus

FROM alpine

INCLUDE+ Dockerfile.common

ENTRYPOINT [ "mybin" ]
```

If Dockerfile.common contained a single line that said `RUN echo "Hello World"`, then the resulting Docker image would be identical to the one generated by this Dockerfile:


```Dockerfile
FROM alpine

RUN echo "Hello World"

ENTRYPOINT [ "mybin" ]
```

## Roadmap

The next features in line would be:

- `ENVFILE+` command, which would read a .env file and import all of those environment variable definitions into the Dockerfile
- `RUN+ --no-cache`, which would disable the cache only for a specific RUN step (useful for non-idempotent commands, for example those that clone git repos)
- `TAG` command
- improvements to .dockerignore, like recursive dockerignore files

## Feedback

Found a bug? Want to contribute a PR? Want to improve documentation or add a cool logo for the project? All contributions are welcome!

### Development environment

Install cargo (you can use [rustup.rs](https://rustup.rs/)) and run:

```bash
$ cargo build
```

### Creating a local release of the Buildkit frontend

```bash
$ docker build -f dockerfile-plus/Dockerfile .
```

### Creating multi-arch build
- Enable Experiment in docker config. Add {"experimental": true} to docker daemon.json
- Setup BuildKit local build container
```
docker run --rm --privileged multiarch/qemu-user-static --reset -p yes
docker buildx create --name multiarch --driver docker-container --use
docker buildx inspect --bootstrap
```
- Run following to start multi-arch build
```
docker buildx build \                                                                   
--platform linux/arm64/v8,linux/amd64 \
--tag edrevo/dockerfile-plus:latest \
-f dockerfile-plus/Dockerfile \
--load ## or --push to push DockerHub \ 
.
```