Build containerd containers from Docker containers

Simplifies the build process, and makes testing easier as there is a
Docker container you can run to test things.

Replaces #994

Signed-off-by: Justin Cormack <justin.cormack@docker.com>

alpine/base/rngd/.gitignore

@@ -0,0 +1,5 @@
+bin
+dev
+proc
+sys
+usr

alpine/base/rngd/Dockerfile

@@ -0,0 +1,3 @@
+FROM scratch
+COPY . ./
+CMD ["/bin/tini", "/usr/sbin/rngd", "-f"]

alpine/base/rngd/Makefile

@@ -0,0 +1,53 @@
+# Tag: b6aed437bad8f1f4471b11f1affe3420eaf5d42f
+RNG_TOOLS_IMAGE=mobylinux/rng-tools@sha256:8e74e6a39b072ebee65ee4b83ebf224787afb473ea250c897dd24fa43b387d06
+RNGD_BINARY=usr/sbin/rngd
+
+# Tag 6b25b62f4d893de8721fd2581411039b17e8a253
+TINI_IMAGE=mobylinux/tini@sha256:39b4a459018ffc155a9fcbbf952fa625c77f5a8d7599b326eade529d3dc723fc
+TINI_BINARY=bin/tini
+
+.PHONY: tag push clean container
+default: push
+
+$(TINI_BINARY):
+	mkdir -p $(dir $@)
+	docker run --rm --net=none $(TINI_IMAGE) tar cf - $@ | tar xf -
+
+$(RNGD_BINARY):
+	mkdir -p $(dir $@)
+	docker run --rm --net=none $(RNG_TOOLS_IMAGE) tar cf - $@ | tar xf -
+
+SHA_IMAGE=alpine:3.5
+
+IMAGE=rngd
+
+DIRS=dev proc sys
+$(DIRS):
+	mkdir -p $@
+
+DEPS=$(DIRS) $(TINI_BINARY) $(RNGD_BINARY)
+
+container: Dockerfile $(DEPS)
+	tar cf - $^ | docker build --no-cache -t $(IMAGE):build -
+
+hash: Dockerfile $(DEPS)
+	DOCKER_CONTENT_TRUST=1 docker pull $(SHA_IMAGE)
+	tar cf - $^ | docker run --rm -i $(SHA_IMAGE) sha1sum - | sed 's/ .*//' > hash
+
+push: hash container
+	docker pull mobylinux/$(IMAGE):$(shell cat hash) || \
+		(docker tag $(IMAGE):build mobylinux/$(IMAGE):$(shell cat hash) && \
+		 docker push mobylinux/$(IMAGE):$(shell cat hash))
+	docker rmi $(IMAGE):build
+	rm -f hash
+
+tag: hash container
+	docker pull mobylinux/$(IMAGE):$(shell cat hash) || \
+		docker tag $(IMAGE):build mobylinux/$(IMAGE):$(shell cat hash)
+	docker rmi $(IMAGE):build
+	rm -f hash
+
+clean:
+	rm -rf hash $(DIRS) usr bin
+
+.DELETE_ON_ERROR: