nix: init flake + CI

.github/workflows/cmake.yml

@@ -5,10 +5,10 @@ on: [push,pull_request]
 jobs:
   build-ubuntu:
 
-    runs-on: [ubuntu-22.04]
+    runs-on: ubuntu-24.04
 
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
 
     - name: Run project tests
       run: |
@@ -24,7 +24,6 @@ jobs:
         set -e
         set -x
         cd _unittests
-        ln -s .. cmake
         CMAKE_BIN="cmake"
         $CMAKE_BIN --version
         $CMAKE_BIN -P test_pkg-config.cmake

.github/workflows/nix.yml

@@ -0,0 +1,25 @@
+name: "CI - Nix"
+
+on:
+  push:
+    branches:
+      - master
+  pull_request:
+    branches:
+      - master
+
+jobs:
+  tests:
+    name: "Nix build on ${{ matrix.os }}"
+    runs-on: "${{ matrix.os }}-latest"
+    strategy:
+      matrix:
+        os: [ubuntu, macos]
+    steps:
+      - uses: actions/checkout@v4
+      - uses: cachix/install-nix-action@v27
+      - uses: cachix/cachix-action@v15
+        with:
+          name: gepetto
+          authToken: '${{ secrets.CACHIX_AUTH_TOKEN }}'
+      - run: nix build -L

.github/workflows/update-flake-lock.yml

@@ -0,0 +1,19 @@
+name: update-flake-lock
+
+on:
+  workflow_dispatch:
+  schedule:
+    - cron: '0 19 3 * *'
+
+jobs:
+  lockfile:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+      - name: Install Nix
+        uses: DeterminateSystems/nix-installer-action@main
+      - name: Update flake.lock
+        uses: DeterminateSystems/update-flake-lock@main
+        with:
+          token: ${{ secrets.GH_TOKEN_FOR_UPDATES }}

_unittests/cmake

@@ -0,0 +1 @@
+..

flake.nix

@@ -0,0 +1,55 @@
+{
+  description = "CMake utility toolbox";
+
+  inputs = {
+    flake-parts.url = "github:hercules-ci/flake-parts";
+    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
+  };
+
+  outputs =
+    inputs:
+    inputs.flake-parts.lib.mkFlake { inherit inputs; } {
+      systems = inputs.nixpkgs.lib.systems.flakeExposed;
+      perSystem =
+        { pkgs, self', ... }:
+        {
+          packages = {
+            default = self'.packages.jrl-cmakemodules;
+            jrl-cmakemodules = pkgs.jrl-cmakemodules.overrideAttrs (super: {
+              src = pkgs.lib.fileset.toSource {
+                root = ./.;
+                fileset = pkgs.lib.fileset.gitTracked ./.;
+              };
+
+              # TODO: remove all this once it is in nixpkgs
+              postPatch = ''
+                patchShebangs _unittests/run_unit_tests.sh
+              '';
+
+              outputs = [ "out" "doc" ];
+              nativeBuildInputs = super.nativeBuildInputs ++ [
+                pkgs.sphinxHook
+              ];
+              sphinxRoot = "../.docs";
+
+              doCheck = true;
+              checkInputs = [
+                pkgs.python3
+              ];
+              checkPhase = ''
+                runHook preCheck
+
+                pushd ../_unittests
+                ./run_unit_tests.sh
+                cmake -P test_pkg-config.cmake
+
+                rm -rf build install
+                popd
+
+                runHook postCheck
+              '';
+            });
+          };
+        };
+    };
+}