ci: run all flake checks

Adds *fake* hydra-like CI tests for the flake checks.

Signed-off-by: Christina Sørensen <[email protected]>

.github/workflows/checks.yml

@@ -0,0 +1,33 @@
+name: "Flake Checks"
+on:
+  push:
+    branches:
+      - "master"
+  pull_request:
+    branches:
+      - "master"
+jobs:
+  nix_flake_check:
+    name: Nix ${{ matrix.systems }} ${{ matrix.checks }}
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        checks: [build, formatting, pre-commit-check, vm_integration_tests]
+        os: [ubuntu-latest, macos-latest]
+        systems: ["x86_64-linux", "aarch64-linux","x86_64-darwin", "aarch64-darwin"]
+        include:
+          - os: ubuntu-latest
+            systems: ["x86_64-linux", "aarch64-linux"]
+            checks: [build, formatting, pre-commit-check, vm_integration_tests]
+          - os: macos-latest
+            systems: ["x86_64-darwin", "aarch64-darwin"]
+            checks: [build, formatting, pre-commit-check, vm_integration_tests]
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+      - name: Install Nix
+        uses: DeterminateSystems/nix-installer-action@main
+      - name: Setup Nix cache
+        uses: DeterminateSystems/magic-nix-cache-action@main
+      - name: Nix Flake Check
+        run: nix build ./#checks.${{ matrix.systems }}.${{ matrix.checks }} -L