initial gha implementation

.github/workflows/build.yaml

@@ -10,3 +10,30 @@ jobs:
       - uses: actions/checkout@v3
       - uses: ./.github/actions/install-nix
       - run: nix flake check
+
+  matrix:
+    runs-on: ubuntu-latest
+    outputs:
+      aarch64-darwin: ${{ steps.generate_matrix.outputs.aarch64-darwin }}
+      aarch64-linux: ${{ steps.generate_matrix.outputs.aarch64-linux }}
+      x86_64-linux: ${{ steps.generate_matrix.outputs.x86_64-linux }}
+    steps:
+      - uses: actions/checkout@v3
+      - uses: ./.github/actions/install-nix
+      - id: generate_matrix
+        run: |
+          nix eval --raw .#github-matrix >> $GITHUB_OUTPUT
+
+  build-x86_64-linux:
+    runs-on: ubuntu-latest
+    needs: [matrix]
+    if: ${{ needs.matrix.outputs.x86_64-linux != '[]' && needs.matrix.outputs.x86_64-linux != '' }}
+    strategy:
+      fail-fast: false
+      matrix:
+        output: ${{ fromJson(needs.matrix.outputs.x86_64-linux )}}
+    steps:
+      - uses: actions/checkout@v3
+      - uses: ./.github/actions/install-nix
+      - name: Build output
+        run: nix build .#${{ matrix.output }} -L