makefile: build multi-arch image

Build multi-architecture image using buildah and qemu static utilities.
Creates an image with manifest which refs amd64 (x86_64) and arm64
(aarch64) architecture-specific sub-images. Using the same Dockerfile
regardless of the actual CPU architecture, and let buildah+qemu do all
the low-level logic.

Note: typically, qemu would emulate arm64 on x86_64 which yields longer
build time.

Signed-off-by: Shachar Sharon <ssharon@redhat.com>

Author: synarete

Makefile

@@ -17,6 +17,9 @@ BUNDLE_METADATA_OPTS?=$(BUNDLE_CHANNELS) $(BUNDLE_DEFAULT_CHANNEL)
 COMMIT_ID=$(shell git describe --abbrev=40 --always --exclude='*' --dirty=+ 2>/dev/null)
 GIT_VERSION=$(shell git describe --match='v[0-9]*.[0-9]' --match='v[0-9]*.[0-9].[0-9]' 2>/dev/null || echo "(unset)")
 
+# List of supported CPU architectures
+ARCH_LIST:=amd64 arm64
+
 CONFIG_KUST_DIR:=config/default
 CRD_KUST_DIR:=config/crd
 MGR_KUST_DIR:=config/manager
@@ -187,6 +190,28 @@ image-build-buildah: build
 	$(BUILDAH_CMD) config --entrypoint='["/manager"]' $$cn && \
 	$(BUILDAH_CMD) commit $$cn $(IMG)
 
+.PHONY: image-build-multiarch
+image-build-multiarch: qemu-utils
+	$(BUILDAH_CMD) manifest create $(IMG)
+	for arch in $(ARCH_LIST); do \
+		$(BUILDAH_CMD) bud \
+			--manifest $(IMG) \
+			--arch $${arch} \
+			--tag "$(IMG)-$${arch}" \
+			--build-arg=GIT_VERSION="$(GIT_VERSION)" \
+			--build-arg=COMMIT_ID="$(COMMIT_ID)" \
+			--build-arg=ARCH="$${arch}" . ; \
+	done
+	$(BUILDAH_CMD) manifest inspect $(IMG)
+
+.PHONY: image-push-multiarch
+image-push-multiarch:
+	$(BUILDAH_CMD) manifest push --all $(IMG) "docker://$(IMG)"
+
+.PHONY: image-multiarch
+image-multiarch: image-build-multiarch image-push-multiarch
+
+
 # Push the container image
 docker-push: container-push
 container-push:
@@ -322,3 +347,12 @@ GITLINT=$(GOBIN_ALT)/gitlint
 else
 GITLINT=$(shell command -v gitlint ;)
 endif
+
+.PHONY: qemu-utils
+qemu-utils:
+ifeq (, $(shell command -v qemu-x86_64-static ;))
+	$(error "qemu-x86_64-static not found in PATH")
+endif
+ifeq (, $(shell command -v qemu-aarch64-static ;))
+	$(error "qemu-aarch64-static not found in PATH")
+endif