.github/workflows: add aarch64-linux runner

.github/actions/install-nix/action.yaml

@@ -1,4 +1,7 @@
 name: "Nix setup"
+inputs:
+  extra-conf:
+    required: false
 runs:
   using: "composite"
   steps:
@@ -6,6 +9,7 @@ runs:
       with:
         # Needs to be kept in sync with flake.nix
         extra-conf: |
+          fallback = true
           allow-import-from-derivation = false
           extra-substituters = https://hyprland.cachix.org
           extra-substituters = https://cache.garnix.io
@@ -19,4 +23,5 @@ runs:
           extra-trusted-public-keys = hercules-ci.cachix.org-1:ZZeDl9Va+xe9j+KqdzoBZMFJHVQ42Uu/c/1/KMC5Lw0=
           extra-trusted-public-keys = nrabulinski.cachix.org-1:Q5FD7+1c68uH74CQK66UWNzxhanZW8xcg1LFXxGK8ic=
           extra-trusted-public-keys = public:wIIyvCTlsk39uwKlBFOuVY+BXrPY3lUNAEpDN4H+O0Q=
+          ${{ inputs.extra-conf }}
     - uses: DeterminateSystems/magic-nix-cache-action@main

.github/workflows/build.yaml

@@ -59,3 +59,24 @@ jobs:
         run: |
           nix run .#attic -- login nrab-attic 'https://cache.nrab.lol/' ${{ secrets.ATTIC_TOKEN }}
           nix run .#attic -- push nrab-attic:public result
+
+  build-aarch64-linux:
+    runs-on: ubuntu-latest
+    needs: [matrix]
+    if: ${{ needs.matrix.outputs.aarch64-linux != '[]' && needs.matrix.outputs.aarch64-linux != '' }}
+    strategy:
+      fail-fast: false
+      matrix:
+        output: ${{ fromJson(needs.matrix.outputs.aarch64-linux )}}
+    steps:
+      - uses: actions/checkout@v3
+      - uses: docker/setup-qemu-action@v3
+      - uses: ./.github/actions/install-nix
+        with:
+          extra-conf: extra-platforms = aarch64-linux
+      - name: Build output
+        run: nix build .#${{ matrix.output }} -L
+      - name: Push output
+        run: |
+          nix run .#attic -- login nrab-attic 'https://cache.nrab.lol/' ${{ secrets.ATTIC_TOKEN }}
+          nix run .#attic -- push nrab-attic:public result