Use multi arch build for all platforms

Dockerfile

@@ -1,17 +1,21 @@
-FROM gliderlabs/logspout:latest AS builder
+FROM --platform=${BUILDPLATFORM:-linux/amd64} gliderlabs/logspout:latest AS builder
+
 RUN apk add --no-cache --update go build-base git mercurial ca-certificates
 RUN mkdir -p /go/src/github.com/gliderlabs && \
     cp -r /src /go/src/github.com/gliderlabs/logspout
 WORKDIR /go/src/github.com/gliderlabs/logspout
-ARG ARCH=amd64
-ARG OS=linux
-ENV GOARCH=${ARCH}
-ENV GOOS=${OS}
-ENV GOPATH=/go
-ENV CGO_ENABLED=0
-RUN go get
-RUN go build -ldflags "-X main.Version=$(cat VERSION)-logdna" -o /bin/logspout
 
+ARG TARGETPLATFORM
+ARG BUILDPLATFORM
+ARG TARGETOS
+ARG TARGETARCH
+
+RUN go get
+RUN CGO_ENABLED=0 \
+    GOOS=${TARGETOS} \
+    GOARCH=${TARGETARCH} \
+    go build \
+    -ldflags="-w -s -X main.Version=$(cat VERSION)-logdna" -o /bin/logspout
 
 FROM scratch
 COPY --from=builder /etc/ssl/certs/ca-certificates.crt /etc/ssl/certs/

Makefile

@@ -2,31 +2,24 @@ TAG          = $(if $(CIRCLE_TAG),$(CIRCLE_TAG),PRTEST)
 REPO         = ${USERNAME}
 NAME         = logspout
 IMAGE        = $(REPO)/$(NAME)
-IMAGE_AMD64  = $(IMAGE):$(TAG)-amd64
-IMAGE_ARM64  = $(IMAGE):$(TAG)-arm64
 
-# Enable 'docker manifest' commands (still experimental in Docker v20.10.5)
-export DOCKER_CLI_EXPERIMENTAL = enabled
+.DEFAULT_GOAL := default
 
+export DOCKER_CLI_EXPERIMENTAL=enabled
+
+.PHONY: build # Build the container image
 build:
-	docker build --pull -t $(IMAGE_AMD64) \
-		--build-arg ARCH=amd64 \
-		--build-arg OS=linux \
-		-f Dockerfile .
-	docker build --pull -t $(IMAGE_ARM64) \
-		--build-arg ARCH=arm64 \
-		--build-arg OS=linux \
-		-f Dockerfile .
-	docker save -o image.tar $(IMAGE_AMD64) $(IMAGE_ARM64)
+	@docker buildx create --use --name=crossplat --node=crossplat && \
+	docker buildx build \
+		--output "type=docker,push=false" \
+		--tag $(IMAGE) \
+		.
 
+.PHONY: publish # Push the image to the remote registry
 publish:
-	docker login --username ${USERNAME} --password ${PASSWORD}
-	docker load -i ./image.tar
-	docker push $(IMAGE_AMD64)
-	docker push $(IMAGE_ARM64)
-	docker manifest create $(IMAGE):$(TAG) $(IMAGE_AMD64) $(IMAGE_ARM64)
-	docker manifest annotate $(IMAGE):$(TAG) $(IMAGE_ARM64) --arch arm64 --os linux
-	docker manifest push --purge $(IMAGE):$(TAG)
-	docker manifest create $(IMAGE):latest $(IMAGE_AMD64) $(IMAGE_ARM64)
-	docker manifest annotate $(IMAGE):latest $(IMAGE_ARM64) --arch arm64 --os linux
-	docker manifest push --purge $(IMAGE):latest
+	@docker buildx create --use --name=crossplat --node=crossplat && \
+	docker buildx build \
+		--platform linux/386,linux/amd64,linux/arm/v6,linux/arm/v7,linux/arm64,linux/ppc64le,linux/s390x \
+		--output "type=image,push=true" \
+		--tag $(IMAGE) \
+		.