Add .github/workflows/test-import-using-nix.yml

Author: rolfschr

.github/workflows/test-import-using-nix.yml

@@ -0,0 +1,27 @@
+on:
+  workflow_dispatch: # allow manual execution
+  push:
+  pull_request:
+  schedule:
+    # run on the 3rd each month at 10:00am
+    - cron: '0 10 3 * *'
+
+jobs:
+  nix-check-and-import:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v2
+        with:
+          fetch-depth: 0
+      - uses: cachix/install-nix-action@v11
+        with:
+          nix_path: nixpkgs=https://github.com/NixOS/nixpkgs/archive/20.09.tar.gz
+          install_url: https://github.com/numtide/nix-flakes-installer/releases/download/nix-3.0pre20201007_5257a25/install
+          extra_nix_config: |
+            experimental-features = nix-command flakes
+      - name: run checks
+        run: |
+          cd etc/nix
+          nix --print-build-logs flake check
+          ./test-import-using-nix.sh --all