initial commit

.gitignore

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+out*
+run*

Makefile

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+default: env-test
+	@make -f test.mk OUT=out2
+	@make -f test.mk OUT=out1
+	@printf "Docker Version: %s\n" "$(shell docker --version)"
+	@printf "Docker Image Store: %s\n" "$(shell docker info -f '{{ .DriverStatus }} ')"
+	@for f in out1 out2; do \
+		printf "%-35s" "$${f} - docker save archive hash: "; \
+		sha256sum $${f}/dockersave.tar | awk '{ print $$1 }'; \
+	done
+	@for f in out1 out2; do \
+		printf "%-35s" "$${f} - docker buildx archive hash: "; \
+		sha256sum $${f}/buildx.tar | awk '{ print $$1 }'; \
+	done
+	@for f in out1 out2; do \
+		printf "%-35s" "$${f} - docker save digest: "; \
+		tar -xf $${f}/dockersave.tar index.json -O | jq -r '.manifests[].digest | sub("sha256:";"")'; \
+	done
+	@for f in out1 out2; do \
+		printf "%-35s" "$${f} - docker buildx digest: "; \
+		tar -xf $${f}/buildx.tar index.json -O | jq -r '.manifests[].digest | sub("sha256:";"")'; \
+	done
+	@diffoscope --exclude-directory-metadata=yes out1 out2
+
+.PHONY: clean
+clean:
+	docker container rm -f $$(cat $(OUT)/registry.id)
+	docker buildx rm digest-test
+	rm -rf out1 out2
+
+.PHONY: env-test
+env-test:
+	which jq
+	which docker
+
+run:
+	mkdir $@
+
+run/registry.id: run
+	docker container create \
+		--publish 5000:5000 \
+		--restart always \
+		--name test-registry \
+		registry:2 \
+		> $@
+
+run/registry.run: run/registry.id
+	docker container start $$(cat run/registry.id)
+	touch $@
+
+run/driver.run: run
+	docker buildx create \
+		--name digest-test \
+		--driver docker-container \
+		--node digest-test
+	docker buildx use digest-test
+	touch $@
+
+run/driver.run: run
+	docker buildx create \
+		--name digest-test \
+		--driver docker-container \
+		--node digest-test
+	touch $@

test.mk

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+OUT =: $(OUT)
+
+default: all
+
+.PHONY: all
+all: $(OUT)/dockersave.tar $(OUT)/buildx.tar $(OUT)/metadata.json
+	touch -hcd "@0" $(OUT)/*
+	sha256sum $(OUT)/dockersave.tar
+	sha256sum $(OUT)/buildx.tar
+
+$(OUT):
+	mkdir -p $(OUT)
+
+$(OUT)/Dockerfile $(OUT)/noopfile: $(OUT)
+	printf "from scratch\nADD noopfile ." > $(OUT)/Dockerfile
+	printf "1" > $(OUT)/noopfile
+	touch -hcd "@0" $(OUT)/noopfile
+
+$(OUT)/buildx.tar $(OUT)/buildx_metadata.json: $(OUT)/Dockerfile
+	DOCKER_BUILDKIT=1 \
+	SOURCE_DATE_EPOCH=1 \
+	/bin/docker buildx build \
+		--tag local/digest-test \
+		--no-cache \
+		--metadata-file $(OUT)/metadata.json \
+		--output type=oci,force-compression=true,name=local/digest-test,dest=$(OUT)/buildx.tar \
+		$(OUT)
+
+$(OUT)/dockersave.tar: $(OUT)/Dockerfile
+	DOCKER_BUILDKIT=1 \
+	SOURCE_DATE_EPOCH=1 \
+	/bin/docker buildx build \
+		--tag local/digest-test \
+		--no-cache \
+		--load \
+		$(OUT)
+	docker save local/digest-test -o $@