labs: add script to shut down controller node

Add a single-purpose script to shut down the controller node from
another node.

Change-Id: Ic70e211a8fd3e8ad4c448045b65000be209b00de

labs/scripts/shutdown_controller.sh

@@ -0,0 +1,18 @@
+#!/usr/bin/env bash
+set -o errexit -o nounset
+TOP_DIR=$(cd $(dirname "$0")/.. && pwd)
+source "$TOP_DIR/config/paths"
+source "$LIB_DIR/functions.guest"
+
+indicate_current_auto
+
+exec_logfile
+
+echo "Shutting down the controller node."
+
+ssh \
+    -o "UserKnownHostsFile /dev/null" \
+    -o "StrictHostKeyChecking no" \
+    -i "$HOME/.ssh/vagrant" \
+    controller-mgmt \
+    sudo /sbin/shutdown -P now