Add Nix package

.gitattributes

@@ -0,0 +1 @@
+nix/** linguist-generated

README.md

@@ -43,6 +43,29 @@ pip install image-tools-stackabletech
 pip install git+https://github.com/stackabletech/image-tools.git@main
 ```
 
+Or via Nix Shell:
+
+```nix
+{ lib, pkgs, ... }:
+with lib;
+let
+  image-tools = pkgs.callPackage (pkgs.fetchFromGitHub {
+    owner = "stackabletech";
+    repo = "image-tools";
+    rev = "caa4d993bcbb8b884097c89a54ee246f975e2ec6";
+    hash = "sha256-gjTCroHw4iJhXPW+s3mHBzIH8seIKH1tPb82lUb8+a0="; # comment out to find new hashes when upgrading
+  } + "/image-tools.nix") {};
+in
+{
+  packages = with pkgs; [
+    image-tools
+    # ...
+  ];
+
+  // ...
+}
+```
+
 ## Release a new version
 
 Update the version in:

default.nix

@@ -0,0 +1,8 @@
+{ sources ? import ./nix/sources.nix # managed by https://github.com/nmattia/niv
+, nixpkgs ? sources.nixpkgs
+, pkgs ? import nixpkgs {}
+}:
+
+{
+  image-tools = pkgs.callPackage ./image-tools.nix {};
+}

image-tools.nix

@@ -0,0 +1,35 @@
+{ python3, runCommand, lib }:
+let
+  # I wish there was a better way. If the command fails, it is very hard to see 
+  # that the problem is here. Perhaps there is some way to evaluate it in python
+  # and reference __version__ directly?
+  version = builtins.readFile (runCommand "image-tools-version" {} ''
+    PYTHONPATH=${./src} ${python3}/bin/python -c 'import image_tools.version; print(image_tools.version.__version__)' > $out
+  '');
+  manifest = (lib.importTOML ./pyproject.toml).project;
+in
+python3.pkgs.buildPythonApplication {
+  pname = manifest.name;
+  # The version is no longer set in pyproject.toml, so we have to jump through
+  # hoops to extract it from a python script.
+  # version = manifest.version;
+  inherit version;
+
+  format = "pyproject";
+
+  src = builtins.path {
+    path = ./.;
+    name = manifest.name;
+  };
+
+  nativeBuildInputs = with python3.pkgs; [
+    setuptools
+  ];
+
+  propagatedBuildInputs = with python3.pkgs; [
+    jinja2
+    pyyaml
+  ];
+}
+
+