ci: add basic workflow

Author: kid

.github/workflows/check.yml

@@ -0,0 +1,37 @@
+name: Nix Flake actions
+
+on:
+  pull_request:
+  push:
+    branches:
+      - main
+
+jobs:
+  nix-matrix:
+    runs-on: ubuntu-latest
+    outputs:
+      matrix: ${{ steps.set-matrix.outputs.matrix }}
+    steps:
+      - uses: actions/checkout@v4
+      - uses: cachix/install-nix-action@v30
+      - id: set-matrix
+        name: Generate Nix Matrix
+        run: |
+          set -Eeu
+          matrix="$(nix eval --json '.#githubActions.matrix')"
+          echo "matrix=$matrix" >> "$GITHUB_OUTPUT"
+
+  nix-build:
+    name: ${{ matrix.name }} (${{ matrix.system }})
+    needs: nix-matrix
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix: ${{fromJSON(needs.nix-matrix.outputs.matrix)}}
+    steps:
+      - uses: actions/checkout@v4
+      - uses: cachix/install-nix-action@v30
+      - uses: cachix/cachix-action@v15
+        with:
+          name: kidibox
+          authToken: "${{ secrets.CACHIX_AUTH_TOKEN }}"
+      - run: nix build -L '.#${{ matrix.attr }}'

.github/workflows/nix-github-actions.yml

@@ -33,6 +33,9 @@
     pre-commit-hooks-nix.url = "github:cachix/pre-commit-hooks.nix";
     pre-commit-hooks-nix.inputs.nixpkgs.follows = "nixpkgs";
 
+    nix-github-actions.url = "github:nix-community/nix-github-actions";
+    nix-github-actions.inputs.nixpkgs.follows = "nixpkgs";
+
     stylix = {
       url = "github:danth/stylix";
       inputs = {
@@ -72,7 +75,7 @@
 
   outputs =
     inputs@{ self, ... }:
-    inputs.snowfall-lib.mkFlake {
+    (inputs.snowfall-lib.mkFlake {
       inherit self inputs;
 
       src = ./.;
@@ -94,5 +97,10 @@
       outputs-builder = channels: {
         formatter = inputs.treefmt-nix.lib.mkWrapper channels.nixpkgs ./treefmt.nix;
       };
+    })
+    // {
+      githubActions = inputs.nix-github-actions.lib.mkGithubMatrix {
+        checks = inputs.nixpkgs.lib.getAttrs [ "x86_64-linux" "x86_64-darwin" ] self.checks;
+      };
     };
 }