Added support for multi-platform builds

Author: jtroberts

.github/workflows/docker-build.yml

@@ -28,6 +28,7 @@ env:
   # Will be "NASA-AMMOS/Veloserver" for the main repo, for forks "user-name-of-fork/Veloserver"
   # For generating the tag, all will be converted to lowercase
   IMAGE_SLUG: ${{ github.repository }}
+  DOCKER_PLATFORMS: linux/amd64,linux/arm64  # Add this line
 
 jobs:
   # Push image to GitHub Container Registry.
@@ -107,11 +108,22 @@ jobs:
           echo "REGISTRY_TAGS_PR_NUMBER=$PR_NUMBER" >> $GITHUB_OUTPUT
           echo "SHA_SHORT=$SHA_SHORT" >> $GITHUB_OUTPUT
 
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+
       - name: Login to GHCR
         run: echo ${{ secrets.GITHUB_TOKEN }} | docker login -u ${{ github.actor }} --password-stdin ghcr.io
 
-      - name: Docker build
-        run: docker build --no-cache ${{ steps.generate.outputs.REGISTRY_TAGS }} .
-
-      - name: Docker push
-        run: docker push ${{ steps.generate.outputs.IMAGE_ID }} --all-tags
+      - name: Docker build and push
+        env:
+          DOCKER_PLATFORM_OPTION: linux/amd64,linux/arm64
+        run: |
+          # Convert REGISTRY_TAGS format for buildx
+          BUILDX_TAGS=$(echo "${{ steps.generate.outputs.REGISTRY_TAGS }}" | sed 's/-t /--tag /g')
+          
+          docker buildx build \
+            --platform $DOCKER_PLATFORM_OPTION \
+            --push \
+            --no-cache \
+            $BUILDX_TAGS \
+            .