Add rollback tool to etcd image

cluster/images/etcd/Dockerfile

@@ -13,8 +13,8 @@
 # limitations under the License.
 
 FROM BASEIMAGE
-MAINTAINER Dawn Chen <dawnchen@google.com>
+MAINTAINER Wojciech Tyczynski <wojtekt@google.com>
 
 EXPOSE 2379 2380 4001 7001
 COPY etcd* etcdctl* /usr/local/bin/
-COPY migrate-if-needed.sh attachlease /usr/local/bin/
+COPY migrate-if-needed.sh attachlease rollback /usr/local/bin/

cluster/images/etcd/Makefile

@@ -55,6 +55,10 @@ build:
 	# Compile attachlease
 	docker run -it -v $(shell pwd)/../../../:/go/src/k8s.io/kubernetes -v $(TEMP_DIR):/build -e GOARCH=$(ARCH) golang:$(GOLANG_VERSION) \
 		/bin/bash -c "CGO_ENABLED=0 go build -o /build/attachlease k8s.io/kubernetes/cluster/images/etcd/attachlease"
+	# Compile rollback
+	docker run -it -v $(shell pwd)/../../../:/go/src/k8s.io/kubernetes -v $(TEMP_DIR):/build -e GOARCH=$(ARCH) golang:$(GOLANG_VERSION) \
+		/bin/bash -c "CGO_ENABLED=0 go build -o /build/rollback k8s.io/kubernetes/cluster/images/etcd/rollback"
+
 
 ifeq ($(ARCH),amd64)
 

cluster/images/etcd/migrate-if-needed.sh

@@ -79,7 +79,7 @@ fi
 if [ ! -d "${DATA_DIRECTORY}" ]; then
   mkdir -p "${DATA_DIRECTORY}"
 fi
-if [ ! "$(ls -A ${DATA_DIRECTORY})" ]; then
+if [ -z "$(ls -A ${DATA_DIRECTORY})" ]; then
   echo "${DATA_DIRECTORY} is empty - skipping migration"
   echo "${TARGET_VERSION}/${TARGET_STORAGE}" > "${DATA_DIRECTORY}/${VERSION_FILE}"
 	exit 0