Make it possible to set etcd version in kubemark

cluster/kubemark/config-default.sh

@@ -45,6 +45,11 @@ CLUSTER_IP_RANGE="${CLUSTER_IP_RANGE:-10.240.0.0/13}"
 RUNTIME_CONFIG="${KUBE_RUNTIME_CONFIG:-}"
 TERMINATED_POD_GC_THRESHOLD=${TERMINATED_POD_GC_THRESHOLD:-100}
 
+# Set etcd version (e.g. 3.0.4-migration.1) if you need non-default version.
+TEST_ETCD_VERSION="${TEST_ETCD_VERSION:-}"
+# Storage backend. 'etcd2' supported, 'etcd3' experimental.
+STORAGE_BACKEND=${STORAGE_BACKEND:-etcd2}
+
 # Default Log level for all components in test clusters and variables to override it in specific components.
 TEST_CLUSTER_LOG_LEVEL="${TEST_CLUSTER_LOG_LEVEL:---v=2}"
 KUBELET_TEST_LOG_LEVEL="${KUBELET_TEST_LOG_LEVEL:-$TEST_CLUSTER_LOG_LEVEL}"

test/kubemark/start-kubemark-master.sh

@@ -19,6 +19,11 @@
 EVENT_STORE_IP=$1
 EVENT_STORE_URL="http://${EVENT_STORE_IP}:4002"
 NUM_NODES=$2
+TEST_ETCD_VERSION=$3
+if [[ -z "${TEST_ETCD_VERSION}" ]]; then
+  # Default etcd version.
+  TEST_ETCD_VERSION="2.2.1"
+fi
 
 retry() {
 	for i in {1..4}; do
@@ -31,7 +36,7 @@ if [ "${EVENT_STORE_IP}" == "127.0.0.1" ]; then
 	# Retry starting etcd to avoid pulling image errors.
 	retry sudo docker run --net=host \
 		-v /var/etcd/data-events:/var/etcd/data -v /var/log:/var/log -d \
-		gcr.io/google_containers/etcd:2.2.1 /bin/sh -c "/usr/local/bin/etcd \
+		gcr.io/google_containers/etcd:${TEST_ETCD_VERSION} /bin/sh -c "/usr/local/bin/etcd \
 		--listen-peer-urls http://127.0.0.1:2381 \
 		--advertise-client-urls=http://127.0.0.1:4002 \
 		--listen-client-urls=http://0.0.0.0:4002 \
@@ -41,7 +46,7 @@ fi
 # Retry starting etcd to avoid pulling image errors.
 retry sudo docker run --net=host \
 	-v /var/etcd/data:/var/etcd/data -v /var/log:/var/log -d \
-	gcr.io/google_containers/etcd:2.2.1 /bin/sh -c "/usr/local/bin/etcd \
+	gcr.io/google_containers/etcd:${TEST_ETCD_VERSION} /bin/sh -c "/usr/local/bin/etcd \
 	--listen-peer-urls http://127.0.0.1:2380 \
 	--advertise-client-urls=http://127.0.0.1:2379 \
 	--listen-client-urls=http://0.0.0.0:2379 \

test/kubemark/start-kubemark.sh

@@ -25,6 +25,7 @@ source "${KUBE_ROOT}/test/kubemark/common.sh"
 function writeEnvironmentFiles() {
   cat > "${RESOURCE_DIRECTORY}/apiserver_flags" <<EOF
 ${APISERVER_TEST_ARGS}
+--storage-backend=${STORAGE_BACKEND}
 --service-cluster-ip-range="${SERVICE_CLUSTER_IP_RANGE}"
 EOF
 sed -i'' -e "s/\"//g" "${RESOURCE_DIRECTORY}/apiserver_flags"
@@ -145,7 +146,8 @@ gcloud compute copy-files --zone="${ZONE}" --project="${PROJECT}" \
   "${MASTER_NAME}":~
 
 gcloud compute ssh "${MASTER_NAME}" --zone="${ZONE}" --project="${PROJECT}" \
-  --command="chmod a+x configure-kubectl.sh && chmod a+x start-kubemark-master.sh && sudo ./start-kubemark-master.sh ${EVENT_STORE_IP:-127.0.0.1} ${NUM_NODES:-0}"
+  --command="chmod a+x configure-kubectl.sh && chmod a+x start-kubemark-master.sh && \
+             sudo ./start-kubemark-master.sh ${EVENT_STORE_IP:-127.0.0.1} ${NUM_NODES:-0} ${TEST_ETCD_VERSION:-}"
 
 # create kubeconfig for Kubelet:
 KUBECONFIG_CONTENTS=$(echo "apiVersion: v1