feat(ci): test out building packages in GHA

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

@@ -0,0 +1,33 @@
+name: Nix Flake actions
+
+on:
+  pull_request:
+  push:
+    branches:
+      - master
+      - main
+
+jobs:
+  nix-matrix:
+    runs-on: ubuntu-latest
+    outputs:
+      matrix: ${{ steps.set-matrix.outputs.matrix }}
+    steps:
+      - uses: actions/checkout@v4
+      - uses: cachix/install-nix-action@v24
+      - id: set-matrix
+        name: Generate Nix Matrix
+        run: |
+          set -Eeu
+          matrix="$(nix eval --json '.#githubActions.matrix')"
+          echo "matrix=$matrix" >> "$GITHUB_OUTPUT"
+
+  nix-build:
+    needs: nix-matrix
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix: ${{fromJSON(needs.nix-matrix.outputs.matrix)}}
+    steps:
+      - uses: actions/checkout@v4
+      - uses: cachix/install-nix-action@v24
+      - run: nix build -L ".#${{ matrix.attr }}"

flake.lock

@@ -21,6 +21,26 @@
         "type": "github"
       }
     },
+    "nix-github-actions": {
+      "inputs": {
+        "nixpkgs": [
+          "nixpkgs"
+        ]
+      },
+      "locked": {
+        "lastModified": 1703863825,
+        "narHash": "sha256-rXwqjtwiGKJheXB43ybM8NwWB8rO2dSRrEqes0S7F5Y=",
+        "owner": "nix-community",
+        "repo": "nix-github-actions",
+        "rev": "5163432afc817cf8bd1f031418d1869e4c9d5547",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nix-community",
+        "repo": "nix-github-actions",
+        "type": "github"
+      }
+    },
     "nixpkgs": {
       "locked": {
         "lastModified": 1704161960,
@@ -40,6 +60,7 @@
     "root": {
       "inputs": {
         "fenix": "fenix",
+        "nix-github-actions": "nix-github-actions",
         "nixpkgs": "nixpkgs",
         "rust-manifest": "rust-manifest",
         "systems": "systems"

flake.nix

@@ -8,6 +8,9 @@
   inputs.fenix.url = "github:nix-community/fenix";
   inputs.fenix.inputs.nixpkgs.follows = "nixpkgs";
 
+  inputs.nix-github-actions.url = "github:nix-community/nix-github-actions";
+  inputs.nix-github-actions.inputs.nixpkgs.follows = "nixpkgs";
+
   inputs.rust-manifest.url = "https://static.rust-lang.org/dist/2023-10-22/channel-rust-nightly.toml";
   inputs.rust-manifest.flake = false;
 
@@ -15,6 +18,7 @@
     self,
     nixpkgs,
     fenix,
+    nix-github-actions,
     systems,
     rust-manifest,
   }: let
@@ -29,5 +33,8 @@
   in {
     packages = eachSystem (system: packagesFn pkgs.${system});
     overlays.default = final: prev: packagesFn prev;
+    githubActions = nix-github-actions.lib.mkGithubMatrix {
+      checks = nixpkgs.lib.getAttrs [ "x86_64-linux" ] self.packages;
+    };
   };
 }