CA: add release automation validation

Author: jackfrancis

cluster-autoscaler/Makefile

@@ -107,7 +107,20 @@ build-in-docker-arch-%: clean-arch-% docker-builder
 	docker run ${RM_FLAG} -v `pwd`:/gopath/src/k8s.io/autoscaler/cluster-autoscaler/:Z autoscaling-builder:latest \
 		bash -c 'cd /gopath/src/k8s.io/autoscaler/cluster-autoscaler && BUILD_TAGS=${BUILD_TAGS} LDFLAGS="${LDFLAGS}" make build-arch-$*'
 
-release: $(addprefix build-in-docker-arch-,$(ALL_ARCH)) execute-release
+release-extract-version = $(shell cat version/version.go | grep "Version =" | cut -d '"' -f 2)
+
+release-validate:
+	@if [ -z $(shell git tag --points-at HEAD | grep -e ^cluster-autoscaler-1.[1-9][0-9]*.[0-9][0-9]*$) ]; then \
+		echo "Can't release from this commit, there is no compatible git tag"; \
+		exit 1; \
+	fi
+	@if [ -z $(shell git tag --points-at HEAD | grep -e $(call release-extract-version)) ]; then \
+		echo "Can't release from this commit, git tag does not match version/version.go"; \
+		exit 1; \
+	fi
+
+release: TAG=v$(call release-extract-version)
+release: release-validate $(addprefix build-in-docker-arch-,$(ALL_ARCH)) execute-release
 	@echo "Full in-docker release ${TAG}${FOR_PROVIDER} completed"
 
 container: container-arch-$(GOARCH)