Make install-cni.sh check if the etcd cert file exist.

This will prevent it from terminating because `stat` returns non-zero
when called a non-existing file and also stat_output ends up being an
unbound variable.

k8s-install/scripts/install-cni.sh

@@ -191,14 +191,16 @@ while [ "$should_sleep" == "true"  ]; do
 	# version to the host. Just check the timestamp on the certificate to see if it
 	# has been updated.  A bit hokey, but likely good enough.
 	if [ "$(ls ${SECRETS_MOUNT_DIR} 2>/dev/null)" ];
-	then
-        stat_output=$(stat -c%y ${SECRETS_MOUNT_DIR}/etcd-cert 2>/dev/null)
-        sleep 10;
-        if [ "$stat_output" != "$(stat -c%y ${SECRETS_MOUNT_DIR}/etcd-cert 2>/dev/null)" ]; then
-            echo "Updating installed secrets at: $(date)"
-            cp -p ${SECRETS_MOUNT_DIR}/* /host/etc/cni/net.d/calico-tls/
-        fi
+  then
+    if [ -e ${SECRETS_MOUNT_DIR}/etcd-cert ]; then
+      stat_output=$(stat -c%y ${SECRETS_MOUNT_DIR}/etcd-cert 2>/dev/null)
+      sleep 10;
+      if [ "$stat_output" != "$(stat -c%y ${SECRETS_MOUNT_DIR}/etcd-cert 2>/dev/null)" ]; then
+        echo "Updating installed secrets at: $(date)"
+        cp -p ${SECRETS_MOUNT_DIR}/* /host/etc/cni/net.d/calico-tls/
+      fi
     else
-        sleep 10
+      sleep 10
     fi
+  fi
 done