feat(multiarch): enable cross-platform docker image generation via do…

…cker buildx (#11)

* feat(multiarch): enable cross-platform docker image generation via docker buildx

* feat(multiarch): enable cross-platform docker image generation via docker buildx

build-docker-images.sh

@@ -49,11 +49,19 @@ if [[ "$BRANCH" == "master" ]]; then
   done
 fi
 
+# default build targets can be configured with the DOCKER_BUILD_PLATFORMS env var
+DOCKER_BUILD_DEFAULT_PLATFORMS='linux/amd64,linux/arm64,linux/arm/v7'
+DOCKER_BUILD_PLATFORMS=${DOCKER_BUILD_PLATFORMS:-$DOCKER_BUILD_DEFAULT_PLATFORMS}
+
 # log in to Docker Hub _before_ building to avoid rate limits
 docker login -u="$DOCKER_USERNAME" -p="$DOCKER_PASSWORD"
 
 # Build and push each tag (the built image will be reused after the first build)
 for tag in ${tags[@]}; do
-  docker build -t $tag .
-  docker push $tag
+  if [ $DOCKER_BUILD_PLATFORMS == "classic" ]; then
+    docker build -t $tag .
+    docker push $tag
+  else
+    docker buildx build --push --platform="$DOCKER_BUILD_PLATFORMS" -t $tag .
+  fi
 done