e2e: defend on kube version for snap-controller install

Currently the scripts/install-snapshot.sh script needs to be called
depending on the Kubernetes version. It would be much easier to use the
script if it is intelligent enough to decide itself whether kube snapshot
controller needs to be installed or not.

Partially Fixes: #1139
Signed-off-by: Prasanna Kumar Kalever <prasanna.kalever@redhat.com>

scripts/install-snapshot.sh

@@ -77,6 +77,29 @@ function delete_snapshot_crd() {
     kubectl delete -f "${VOLUME_SNAPSHOT}" --ignore-not-found
 }
 
+# parse the kubernetes version
+# v1.17.2 -> kube_version 1 -> 1  (Major)
+# v1.17.2 -> kube_version 2 -> 17 (Minor)
+function kube_version() {
+    echo "${KUBE_VERSION}" | sed 's/^v//' | cut -d'.' -f"${1}"
+}
+
+KUBE_VERSION=$(kubectl version --short 2>/dev/null | grep "^Server Version" | cut -d' ' -f3)
+if [[ -z ${KUBE_VERSION} ]]; then
+    echo "could not get kube server version"
+    echo "hint: check if you have specified the right host or port"
+    exit 1
+fi
+
+KUBE_MAJOR=$(kube_version 1)
+KUBE_MINOR=$(kube_version 2)
+
+# skip snapshot operation if kube version is less than 1.17.0
+if [[ "${KUBE_MAJOR}" -lt 1 ]] || [[ "${KUBE_MINOR}" -lt 17 ]]; then
+    echo "skipping: kube server version is < 1.17.0"
+    exit 1
+fi
+
 case "${1:-}" in
 install)
     install_snapshot_controller "$2"