Add non GA version check (#266)

* Add kNonGAversion

dell-csi-helm-installer/verify.sh

@@ -191,6 +191,18 @@ function verify_k8s_versions() {
   local MIN=${1}
   local MAX=${2}
   local V="${kMajorVersion}.${kMinorVersion}"
+
+  # check non supported version (k8s alpha/beta)
+  if [ -n "${kNonGAVersion}" ]; then
+    echo "Installing on an unreleased version of Kubernetes : "${kNonGAVersion}". Acknowledge and proceed with installation? (y/n)"
+    read -n 1 -p "Press 'y' to continue or any other key to exit: " CONT
+    decho
+      if [ "${CONT}" != "Y" -a "${CONT}" != "y" ]; then
+        decho "quitting at user request"
+        exit 2
+      fi
+   fi
+
   # check minimum
   log arrow
   log smart_step "Verifying minimum Kubernetes version" "small"
@@ -571,6 +583,7 @@ MASTER_NODES=$(run_command kubectl get nodes -o wide | awk ' /master/{ print $6;
 # Get the kubernetes major and minor version numbers.
 kMajorVersion=$(run_command kubectl version | grep 'Server Version' | sed -E 's/.*v([0-9]+)\.[0-9]+\.[0-9]+.*/\1/')
 kMinorVersion=$(run_command kubectl version | grep 'Server Version' | sed -E 's/.*v[0-9]+\.([0-9]+)\.[0-9]+.*/\1/')
+kNonGAVersion=$(run_command kubectl version | grep 'Server Version' | sed -n 's/.*\(-[alpha|beta][^ ]*\).*/\1/p')
 
 while getopts ":h-:" optchar; do
   case "${optchar}" in