multi arch support with docker buildx for the arm's race

Dockerfile.buildx

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+FROM --platform=$TARGETPLATFORM golang:1.13-alpine AS builder
+LABEL maintainer="joona@kuori.org"
+
+RUN apk add --update gcc musl-dev git
+
+ENV GOPATH /tmp/buildcache
+RUN git clone https://github.com/joohoi/acme-dns /tmp/acme-dns
+WORKDIR /tmp/acme-dns
+RUN CGO_ENABLED=1 go build
+
+FROM --platform=$TARGETPLATFORM alpine:latest
+
+WORKDIR /root/
+COPY --from=builder /tmp/acme-dns .
+RUN mkdir -p /etc/acme-dns
+RUN mkdir -p /var/lib/acme-dns
+RUN rm -rf ./config.cfg
+RUN apk --no-cache add ca-certificates && update-ca-certificates
+
+VOLUME ["/etc/acme-dns", "/var/lib/acme-dns"]
+ENTRYPOINT ["./acme-dns"]
+EXPOSE 53 80 443
+EXPOSE 53/udp

docker-buildx.sh

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+# Check buildx:
+#   docker buildx ls
+#
+# Should have output like: 
+#    default  default running linux/amd64, linux/386, linux/arm64, linux/riscv64, linux/ppc64le, linux/s390x, linux/arm/v7, linux/arm/v6             
+#     
+# If not, to setup buildx (if you are using docker desktop) and buildx command is there:
+#    make sure in:                 $USER/.docker/config.json
+#    (may not exist), you have:    {"experimental": "enabled"}
+# If you see "buildx command not recognized":
+#   export DOCKER_BUILDKIT=1 && docker build --platform=local -o . git://github.com/docker/buildx && mkdir -p ~/.docker/cli-plugins && mv buildx ~/.docker/cli-plugins/docker-buildx
+#
+# But normally let's say you start a brand new digitalocean droplet for builds, and you just do apt install -y docker.io or use the prebuilt docker, I've had to do the following:
+#   docker run --rm --privileged multiarch/qemu-user-static --reset -p yes && docker buildx rm builder && docker buildx create --name builder --driver docker-container --use && docker buildx inspect --bootstrap
+# 
+#  
+# Usage (assuming you have buildx, docker 18+):
+#   ./docker-buildx vX.X.X
+
+version=$1
+platforms="linux/arm64,linux/amd64"
+
+echo "Building $version of acme-dns for platfroms: $platforms!"
+
+docker buildx build \
+    --platform $platforms \
+    --rm \
+    --push \
+    --compress \
+    -t joohoi/acme-dns:$version \
+    -f ./Dockerfile.buildx .