CI: build & cache

.github/workflows/nix.yml

@@ -0,0 +1,24 @@
+name: Nix
+
+on:
+  workflow_call:
+    inputs:
+      command:
+        required: true
+        type: string
+    secrets:
+      CACHIX_AUTH_TOKEN:
+        required: false
+
+jobs:
+  nix:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - uses: DeterminateSystems/nix-installer-action@main
+      - uses: DeterminateSystems/magic-nix-cache-action@main
+      - uses: cachix/cachix-action@v12
+        with:
+          name: nix-gaming
+          authToken: "${{ secrets.CACHIX_AUTH_TOKEN }}"
+      - run: ${{ inputs.command }}