feat: Support Nix for development

- Install and enable Direnv to activate it when `cd`-ing into the project
- Cache Python packages in CI using the "linz" repository
- Lint and format the Nix code
- Create a symlink to the Python executable for easy IDE integration

.envrc

@@ -0,0 +1,4 @@
+#!/usr/bin/env bash
+watch_file poetry.lock pyproject.toml
+use nix
+ln --force --no-target-directory --symbolic "$(which python)" python

.github/workflows/format-tests.yml

@@ -15,13 +15,17 @@ jobs:
         uses: actions/setup-python@65d7f2d534ac1bc67fcd62888c5f4f3d2cb2b236 # v4
         with:
           python-version: "3.10.6"
+      - uses: cachix/install-nix-action@8887e596b4ee1134dae06b98d573bd674693f47c # v26
+      - uses: cachix/cachix-action@18cf96c7c98e048e10a83abd92116114cd8504be # v14
+        with:
+          name: linz
+          authToken: "${{ secrets.CACHIX_AUTH_TOKEN }}"
+      - name: Format
+        run: nix-shell --pure --run 'pre-commit run --all-files'
       - name: Install
         run: |
           pip install poetry
           poetry install
-      - name: Format
-        run: |
-          poetry run pre-commit run --all-files
       - name: Unit Tests
         run: |
           poetry run pytest --doctest-modules .

.gitignore

@@ -5,6 +5,7 @@
 *.pyc
 __pycache__
 /.pytest_cache
+/python
 Thumbs.db
 /.venv
 /.vscode

.pre-commit-config.yaml

@@ -11,6 +11,14 @@ repos:
         stages: [commit]
         types: [python]
 
+      - id: deadnix
+        name: deadnix
+        entry: deadnix
+        args: [--edit, --fail]
+        files: \.nix$
+        language: system
+        stages: [commit]
+
       - id: gitlint
         name: gitlint
         entry: gitlint
@@ -34,6 +42,13 @@ repos:
         types: [python]
         require_serial: true
 
+      - id: nixfmt
+        name: nixfmt
+        entry: nixfmt
+        files: \.nix$
+        language: system
+        stages: [commit]
+
       - id: pylint
         name: pylint
         entry: pylint
@@ -42,6 +57,15 @@ repos:
         types: [python]
         require_serial: true
 
+      - id: statix
+        name: statix
+        entry: statix
+        args: [check]
+        files: \.nix$
+        pass_filenames: false
+        language: system
+        stages: [commit]
+
   - repo: https://github.com/pre-commit/mirrors-prettier
     rev: a99a3fbe79a9d346cabd02a5e167ad0edafe616b # v2.3.0
     hooks:

shell.nix

@@ -0,0 +1,41 @@
+let
+  pkgs = import (builtins.fetchTarball {
+    name = "nixos-unstable-2024-06-05";
+    url = "https://github.com/nixos/nixpkgs/archive/57610d2f8f0937f39dbd72251e9614b1561942d8.tar.gz";
+    sha256 = "0k8az8vmfdk1n8xlza252sqk0hm1hfc7g67adin6jxqaab2s34n9";
+  }) { };
+  poetry2nix = import (builtins.fetchTarball {
+    name = "poetry2nix-2024.6.557458";
+    url = "https://github.com/nix-community/poetry2nix/archive/81662ae1ad31491eae3bb1d976fb74c71853bc63.tar.gz";
+    sha256 = "1zvlhzlc7mxr74qii3mkyn4iyd5rdivrm40yf7r7jvj9ry5gnbx9";
+  }) { inherit pkgs; };
+  poetryPackages = poetry2nix.mkPoetryPackages {
+    projectDir = ./.;
+    overrides = poetry2nix.overrides.withDefaults (
+      self: super: {
+        types-shapely = super.types-shapely.overridePythonAttrs (old: {
+          propagatedBuildInputs = old.propagatedBuildInputs or [ ] ++ [ self.setuptools ];
+        });
+      }
+    );
+  };
+  pythonWithPackages = poetryPackages.python.withPackages (_ps: poetryPackages.poetryPackages);
+in
+pkgs.mkShell {
+  packages = [
+    pythonWithPackages
+    pkgs.bashInteractive
+    pkgs.cacert
+    pkgs.deadnix
+    (pkgs.gdal.override { geos = pkgs.geos_3_11; })
+    pkgs.gitFull
+    pkgs.nixfmt-rfc-style
+    pkgs.nodejs
+    pkgs.poetry
+    pkgs.statix
+    pkgs.which
+  ];
+  shellHook = ''
+    ln --force --no-target-directory --symbolic "${pkgs.lib.getExe pythonWithPackages}" python
+  '';
+}