Update dockerfile and makefile for multiarch support

**What**
- Create multiarch Docker images and update Makefile
  to standardize the process
Signed-off-by: Lucas Roesler <[email protected]>

Dockerfile

@@ -1,12 +1,13 @@
 # syntax=docker/dockerfile:experimental
-FROM golang:1.14 as builder
+FROM golang:1.14-alpine as builder
 
 WORKDIR /app
 COPY go.mod go.sum ./
 RUN --mount=type=cache,target=/go/pkg/mod go mod download
 
 ENV GO111MODULE=on
 ENV CGO_ENABLED=0
+ARG go_opts
 ARG GOOS=linux
 ARG GIT_COMMIT=0
 ARG GIT_VERSION=dev
@@ -17,16 +18,31 @@ COPY cmd ./cmd
 COPY pkg ./pkg
 COPY main.go .
 
-RUN --mount=type=cache,target=/root/.cache/go-build --mount=type=cache,target=/go/pkg/mod go build -o /bin/openfaas-loki \
+RUN --mount=type=cache,target=/root/.cache/go-build --mount=type=cache,target=/go/pkg/mod \
+    env $go_opts go build -o /bin/openfaas-loki \
     -v -ldflags "\
     -X $REPO/pkg.GitCommit=$GIT_COMMIT -X $REPO/pkg.Version=$GIT_VERSION \
     -extldflags \"-static\"" \
     .
 
-FROM alpine:3.11 as image
+# we can't add user in next stage because it's from scratch
+# ca-certificates and tmp folder are also missing in scratch
+# so we add all of it here and copy files in next stage
+RUN addgroup -S app \
+    && adduser -S -g app app \
+    && mkdir /scratch-tmp
 
-RUN apk --no-cache --update add ca-certificates
+FROM scratch
 
+EXPOSE 9191
+
+ENV http_proxy      ""
+ENV https_proxy     ""
+USER app
+
+COPY --from=builder /etc/passwd /etc/group /etc/
+COPY --from=builder /etc/ssl/certs/ca-certificates.crt /etc/ssl/certs/
+COPY --from=builder --chown=app:app /scratch-tmp /tmp
 COPY --from=builder /bin/openfaas-loki /bin/openfaas-loki
 
 ENTRYPOINT ["openfaas-loki"]

Makefile

@@ -9,6 +9,9 @@ ifneq ($(.GIT_UNTRACKEDCHANGES),)
 	.GIT_COMMIT := $(.GIT_COMMIT)-dirty
 endif
 
+ARCHS=amd64 arm64 armhf ppc64le
+BUILD_ARGS=--build-arg GIT_COMMIT=$(.GIT_COMMIT) --build-arg GIT_VERSION=$(.GIT_VERSION)g
+
 ################################
 ################################
 .PHONY: help
@@ -54,17 +57,40 @@ install: $(shell find ./pkg ./cmd) ## Build the project and store the binaries i
 		"-X ${.PKG}/pkg.GitCommit=${.GIT_COMMIT} -X ${.PKG}/pkg.Version=${.GIT_VERSION}" \
 		.
 
-
 .PHONY: build
-build:  ## Create a docker image using the binary from make build
-	DOCKER_BUILDKIT=1 docker build \
-		-t ${.IMAGE_PREFIX}:latest \
-		-t ${.IMAGE_PREFIX}:dev \
-		--build-arg GIT_COMMIT=${.GIT_COMMIT} \
-		--build-arg GIT_VERSION=${.GIT_VERSION} \
+build: $(addprefix build-,$(ARCHS))  ## Build Docker images for all architectures
+
+.PHONY: build-%
+build-%:
+	DOCKER_BUILDKIT=1 docker build $(BUILD_ARGS) --build-arg go_opts="GOARCH=$*" \
+		-t ${.IMAGE_PREFIX}:latest-$* \
+		-f ./Dockerfile .
+
+build-armhf:
+	DOCKER_BUILDKIT=1 docker build $(BUILD_ARGS) --build-arg go_opts="GOARCH=arm GOARM=6" \
+		-t ${.IMAGE_PREFIX}:latest-armhf \
 		-f ./Dockerfile .
 
+.PHONY: push
+push: $(addprefix push-,$(ARCHS)) ## Push Docker images for all architectures
+
+.PHONY: push-%
+push-%:
+	docker push ${.IMAGE_PREFIX}:latest-$*
+
+.PHONY: manifest
+manifest: ## Create and push Docker manifest to combine all architectures in multi-arch Docker image
+	docker manifest create --amend ${.IMAGE_PREFIX}:latest $(addprefix ${.IMAGE_PREFIX}:latest-,$(ARCHS))
+	$(MAKE) $(addprefix manifest-annotate-,$(ARCHS))
+	docker manifest push -p ${.IMAGE_PREFIX}:latest
+
+.PHONY: manifest-annotate-%
+manifest-annotate-%:
+	docker manifest annotate ${.IMAGE_PREFIX}:latest ${.IMAGE_PREFIX}:latest-$* --os linux --arch $*
 
+.PHONY: manifest-annotate-armhf
+manifest-annotate-armhf:
+	docker manifest annotate ${.IMAGE_PREFIX}:latest ${.IMAGE_PREFIX}:latest-armhf --os linux --arch arm --variant v6
 
 .PHONY: package
 package:  ## Package the helm chart