packagesFromDirectoryRecursive

lib.filesystem.packagesFromDirectoryRecursive

Docs pulled from | This Revision | about 3 hours ago

Transform a directory tree containing package files suitable for callPackage into a matching nested attribute set of derivations.

For a directory tree like this:

my-packages
├── a.nix
├── b.nix
├── c
│  ├── my-extra-feature.patch
│  ├── package.nix
│  └── support-definitions.nix
└── my-namespace
   ├── d.nix
   ├── e.nix
   └── f
      └── package.nix

packagesFromDirectoryRecursive will produce an attribute set like this:

# packagesFromDirectoryRecursive {
#   callPackage = pkgs.callPackage;
#   directory = ./my-packages;
# }
{
  a = pkgs.callPackage ./my-packages/a.nix { };
  b = pkgs.callPackage ./my-packages/b.nix { };
  c = pkgs.callPackage ./my-packages/c/package.nix { };
  my-namespace = {
    d = pkgs.callPackage ./my-packages/my-namespace/d.nix { };
    e = pkgs.callPackage ./my-packages/my-namespace/e.nix { };
    f = pkgs.callPackage ./my-packages/my-namespace/f/package.nix { };
  };
}

In particular:

If the input directory contains a package.nix file, then callPackage <directory>/package.nix { } is returned.
Otherwise, the input directory's contents are listed and transformed into an attribute set.
- If a file name has the .nix extension, it is turned into attribute where:
  - The attribute name is the file name without the .nix extension
  - The attribute value is callPackage <file path> { }
- Other files are ignored.
- Directories are turned into an attribute where:
  - The attribute name is the name of the directory
  - The attribute value is the result of calling packagesFromDirectoryRecursive { ... } on the directory.
  As a result, directories with no .nix files (including empty directories) will be transformed into empty attribute sets.

Type

packagesFromDirectoryRecursive :: {
  callPackage :: Path -> {} -> a,
  directory :: Path,
  ...
} -> AttrSet

Inputs

callPackage: The function used to convert a Nix file's path into a leaf of the attribute set. It is typically the callPackage function, taken from either pkgs or a new scope corresponding to the directory.
directory: The directory to read package files from.

Basic use of `lib.packagesFromDirectoryRecursive`

packagesFromDirectoryRecursive {
  inherit (pkgs) callPackage;
  directory = ./my-packages;
}
=> { ... }

In this case, callPackage will only search pkgs for a file's input parameters. In other words, a file cannot refer to another file in the directory in its input parameters.

Create a scope for the nix files found in a directory

lib.makeScope pkgs.newScope (
  self: packagesFromDirectoryRecursive {
    inherit (self) callPackage;
    directory = ./my-packages;
  }
)
=> { ... }

For example, take the following directory structure:

my-packages
├── a.nix    → { b }: assert b ? b1; ...
└── b
   ├── b1.nix  → { a }: ...
   └── b2.nix

Here, b1.nix can specify { a } as a parameter, which callPackage will resolve as expected. Likewise, a.nix receive an attrset corresponding to the contents of the b directory.

a.nix cannot directly take as inputs packages defined in a child directory, such as b1.

As of now, lib.packagesFromDirectoryRecursive cannot create nested scopes for sub-directories.

In particular, files under b/ can only require (as inputs) other files under my-packages, but not to those in the same directory, nor those in a parent directory; e.g, b2.nix cannot directly require b1.

Noogle detected

Aliases

lib.packagesFromDirectoryRecursive

Implementation

The following is the current implementation of this function.

packagesFromDirectoryRecursive =
    {
      callPackage,
      directory,
      ...
    }:
    let
      inherit (lib) concatMapAttrs removeSuffix;
      inherit (lib.path) append;
      defaultPath = append directory "package.nix";
    in
    if pathExists defaultPath then
      # if `${directory}/package.nix` exists, call it directly
      callPackage defaultPath {}
    else concatMapAttrs (name: type:
      # otherwise, for each directory entry
      let path = append directory name; in
      if type == "directory" then {
        # recurse into directories
        "${name}" = packagesFromDirectoryRecursive {
          inherit callPackage;
          directory = path;
        };
      } else if type == "regular" && hasSuffix ".nix" name then {
        # call .nix files
        "${removeSuffix ".nix" name}" = callPackage path {};
      } else if type == "regular" then {
        # ignore non-nix files
      } else throw ''
        lib.filesystem.packagesFromDirectoryRecursive: Unsupported file type ${type} at path ${toString path}
      ''
    ) (builtins.readDir directory);