ci: add multi-architecture build testing with caching

Author: jonlabelle

.github/workflows/cd.yml

@@ -13,7 +13,33 @@ env:
   IMAGE_NAME: network-tools
 
 jobs:
+  # Test building on multiple architectures
+  test:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        platform: [linux/amd64, linux/arm64]
+    steps:
+      - name: Check out repository
+        uses: actions/checkout@main
+
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@master
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@master
+
+      - name: Test build for ${{ matrix.platform }}
+        uses: docker/build-push-action@master
+        with:
+          context: .
+          platforms: ${{ matrix.platform }}
+          push: false
+          cache-from: type=gha
+          cache-to: type=gha,mode=max
+
   publish:
+    needs: test
     runs-on: ubuntu-latest
     if: ${{ github.event_name != 'pull_request' }}