reteps/dockerfmt: Dockerfile format and parser. a modern dockfmt.

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Dockerfile format and parser, and a modern version of dockfmt. Built on top of the internal buildkit parser.

Binaries are available from the releases page.

A updated version of the dockfmt. Uses the dockerfile parser from moby/buildkit and the shell formatter from mvdan/sh.

Usage:
  dockerfmt [Dockerfile] [flags]
  dockerfmt [command]

Available Commands:
  completion  Generate the autocompletion script for the specified shell
  help        Help about any command
  version     Print the version number of dockerfmt

Flags:
  -c, --check         Check if the file(s) are formatted
  -h, --help          help for dockerfmt
  -i, --indent uint   Number of spaces to use for indentation (default 4)
  -n, --newline       End the file with a trailing newline
  -w, --write         Write the formatted output back to the file(s)

Use "dockerfmt [command] --help" for more information about a command.

You can add the following entry to your .pre-commit-config.yaml file to use
dockerfmt as a pre-commit hook:

repos:
  - repo: https://github.com/reteps/dockerfmt
    # run `pre-commit autoupdate` to pin the version
    rev: main
    hooks:
      - id: dockerfmt
        args:
          # optional: add additional arguments here
          - --indent=4
  • The RUN parser currently doesn’t support grouping or semicolons in commands
  • No line wrapping is performed for long JSON commands
  • The # escape=X directive is not supported

Contributions are welcome!

RUN <<EOF
echo "hello"
echo "world"
EOF
  • Support for basic inline comments in run steps:
RUN echo "hello" \
    # this is a comment
    && echo "world"
RUN echo "hello" \
    # this is a comment
    # that spans multiple lines
    && echo "world"

This is surprisingly non-trivial as we want to attach the comments to their position in the formatted output, but they are stripped by the parser beforehand.

The JS bindings are available in the js directory. More information on how to use them can be found in the README file.



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