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[home manager] [solved] Is there a way to automatically import all .nix files in a directory? (lemy.lol)

submitted 5 months ago* (last edited 5 months ago) by QuazarOmega@lemy.lol to c/nix@programming.dev

14 comments fedilink hide all child comments

My solution:

let

  nixFilesInDirectory = directory:
    (
      map (file: "${directory}/${file}")
      (
        builtins.filter
          (
            nodeName:
              (builtins.isList (builtins.match ".+\.nix$" nodeName)) &&
              # checking that it is NOT a directory by seeing
              # if the node name forcefully used as a directory is an invalid path
              (!builtins.pathExists "${directory}/${nodeName}/.")
          )
          (builtins.attrNames (builtins.readDir directory))
      )
    );

  nixFilesInDirectories = directoryList:
    (
      builtins.concatMap
        (directory: nixFilesInDirectory directory)
        (directoryList)
    );
  # ...
in {
  imports = nixFilesInDirectories ([
      "${./programs}"
      "${./programs/terminal-niceties}"
  ]);
  # ...
}

snippet from the full source code: quazar-omega/home-manager-config (L5-L26)

credits:

base script: comment on "getting all configs from folder" (Reddit)
Started developing from that piece that implements the general idea with only builtin functions, so I tried as best I could to stick to the builtins
isDir: nixpkgs (GitHub)
Used to filter out directories from the items to be included

I'm trying out Nix Home Manager and learning its features little by little.
I've been trying to split my app configurations into their own files now and saw that many do the following:

Make a directory containing all the app specific configurations:

programs/
└── helix.nix

Make a catch-all file default.nix that selectively imports the files inside:

programs/
├── default.nix
└── helix.nix

Content:

{
  imports = [
    ./helix.nix
  ];
}

Import the directory (picking up the default.nix) within the home-manager configuration:

{
  # some stuff...
  imports = [
    ./programs
  ];
 # some other stuff...
}

I'd like to avoid having to write each and every file I'll create into the imports of default.nix, that kinda defeats the point of separating it if I'll have to specify everything anyway, so is there a way to do so? I haven't found different ways to do this in various Nix discussions.

Example I'm looking at: https://github.com/fufexan/dotfiles/blob/main/home/terminal/default.nix

My own repository: https://codeberg.org/quazar-omega/home-manager-config

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[–] QuazarOmega@lemy.lol 1 points 5 months ago* (last edited 5 months ago)

I've analyzed the script a bit (..ok for more than 2 hours + 2 of refactoring), because the first time I absolutely didn't understand it, now I've got it, but still, I won't ever understand, why make the syntax so confusing?
My system definition shouldn't be a codegolfing competition (•ˋ _ ˊ•)

TL;DR: I liked your script as a challenge to learn even more and I'm glad I did! Now I know a quite a bit more about the functions that Nix provides and how to use them, not a lot, but better than my previous almost 0, so thank you!

Anyways, here's the unmangled thing explained for anyone else who's interested (wrote for plain evaluation, it's interesting what each part outputs):

{
  /*
  builtins.unsafeGetAttrPos "_" { _ = null; }

  yields:
  {
    column = 46;
    file = "/path/to/this/slightly-unholy-file-finder.nix";
    line = 14;
  };

  you want to get the value of the name (which is the "key" in this key-value list) "file"
  */
  filePath = (builtins.unsafeGetAttrPos "_" { _ = null; }).file; # absolute path to current file
  directoryEntries = builtins.readDir ./.;

  entryNames = map
    (node: "./${node}")
    (
      # get name of files
      builtins.attrNames
        (
          /**
          use the function from before to remove this file right here
          from the set (NOT a list) of nodes found by readDir
          (may be files, dirs, etc.)
          
          Why?
          Because we start reading from the path ./
          which is where this file is located, of course
          */
          builtins.removeAttrs
            (builtins.readDir ./.)
            [
              /*
              get the current file name with some built-in, 
              either un- or poorly documented function black magic fuckery
              (I really wasn't able to find any proper documentation on this function)
              */
              (baseNameOf (builtins.unsafeGetAttrPos "_" { _ = null; }).file)
            ]
        )
    );
}

run it with:

nix eval -f ./slightly-unholy-file-finder.nix

There were multiple problems with this solution as I tried it:

The missing baseName on line 39 which was needed to actually filter out the file path of the script that is being ran, because the paths I got out of readDir were relative (just for me? Did I change something in my environment? I'm not usre, the docs aren't very clear)
It doesn't filter out files that are not .nix files
It doesn't filter out directories (may be intentional though, I personally don't think that's a great idea as far as I got)

I'll post later my own further improved solution starting from my own (tbh, by now more like our) script.