Determine hosts

.github/workflows/build.yml

@@ -0,0 +1,34 @@
+name: "Build"
+on:
+  pull_request:
+
+jobs:
+  determine_hosts:
+    name: "Determining hosts to build"
+    runs-on: ubuntu-latest
+    container:
+      image: catthehacker/ubuntu:act-latest
+
+    steps:
+      - uses: actions/checkout@v5
+      - uses: https://github.com/cachix/install-nix-action@v31
+        with:
+          nix_path: nixpkgs=channel:nixos-unstable
+      - name: "List hosts"
+        id: hosts
+        run: nix eval .#nixosConfigurations --apply builtins.attrNames --json
+    outputs:
+      hosts: ${{ steps.hosts.outputs }}
+
+  build:
+    runs-on: ubuntu-latest
+    container:
+      image: catthehacker/ubuntu:act-latest
+    needs: determine_hosts
+    strategy:
+      matrix:
+        hostname: ${{ fromJSON(needs.determine_hosts.outputs.hosts) }}
+
+    steps:
+      - run: echo "${{ matrix.hostname }}"
+