nix-gitignore

(for nix 2.0 or higher)

This implements primitive a gitignore filter for builtins.filterSource via translation to regexes. I just wanted to see how far I could get with the current approach and as it turns out that I can get quite far.

Please add give this a star iff this project proves to be useful to you.

• Motivation
• Example
• Usage
• Testing
• Notes

Motivation

If you want to deploy your code from the development directory, it would make sense to clean out the development/tmp/cache files before copying your project's source to the nix store. The set of development files you'll want to clean is likely the same one your gitignore patterns match, so this is why this is useful.

Example

Replace the rev and sha256 lines with the output of this command:

nix-prefetch-git https://github.com/siers/nix-gitignore 2> /dev/null | jq -r '"rev = \"\(.rev)\";\nsha256 = \"\(.sha256)\";"'

in this snippet:

with (import <nixpkgs> {});

let
  gitignore = import (pkgs.fetchFromGitHub {
    owner = "siers";
    repo = "nix-gitignore";
    rev = "…";
    sha256 = "…";
  }) { inherit lib; };
in
  with gitignore;

let
  additionalIgnores = ''
    /this
    /that/**.html
  '';

  source = gitignoreSourceAux additionalIgnores ./source;
in
  "use ${source} here"

Usage

The default.nix exports (among other things) six functions. Three of these are:

gitignoreSourcePure "ignore-this\nignore-that\n" ./source
    # Use this string as the gitignore file.

gitignoreSourcePure ["ignore-this\nignore-that\n", ~/.gitignore] ./source
    # It also accepts a list (of strings and paths) that will be concatenated
    # once the paths are turned to strings via readFile.

gitignoreSourceAux "supplemental-ignores\n" ./source
    # This one reads ./source/.gitignore and concats the auxiliary ignores.

gitignoreSource ./source
    # The one stop shop for all your ignoring needs.
    # gitignoreSource = gitignoreSourceAux "";

They're all derived from the Filter functions with the first filter argument hardcoded as (_: _: true):

gitignoreSourcePure = gitignoreFilterSourcePure (_: _: true);
gitignoreSourceAux = gitignoreFilterSourceAux (_: _: true);
gitignoreSource = gitignoreFilterSource (_: _: true);

The filter accepts the same arguments the filterSource function would pass to its filters. Thus fn: gitignoreFilterSourcePure fn "" is extensionally equivalent to filterSource.

If you want to make your own filter from scratch, you may use

gitignoreFilter = ign: root: filterPattern (gitignoreToPatterns ign) root;

Testing

I highly recommend taking a look at the test files test.nix and test.sh which show how closely the actual git implementation's being mimicked. If you find any deviances, please file an issue. I wouldn't be surprised that some inconsistencies would pop up if one tried to fuzz this.