Add --overlay option in charmed installer

Change-Id: I99e2e8a27f7a930380a2fa686e2352b8fea69c7e
Signed-off-by: David Garcia <david.garcia@canonical.com>
diff --git a/installers/charmed_install.sh b/installers/charmed_install.sh
index e1a45d0..123b29c 100755
--- a/installers/charmed_install.sh
+++ b/installers/charmed_install.sh
@@ -33,6 +33,7 @@
     while [ $# -gt 0 ] ; do
         case $1 in
             --bundle) BUNDLE="$2" ;;
+            --overlay) OVERLAY="$2" ;;
             --k8s) KUBECFG="$2" ;;
             --vca) CONTROLLER="$2" ;;
             --lxd) LXD_CLOUD="$2" ;;
@@ -249,10 +250,14 @@
     fi
     [ -v TAG ] && generate_images_overlay && images_overlay="--overlay $IMAGES_OVERLAY_FILE"
 
+    if [ -v OVERLAY ]; then
+        extra_overlay="--overlay $OVERLAY"
+    fi
+
     if [ -v BUNDLE ]; then
-        juju deploy -m $MODEL_NAME $BUNDLE --overlay ~/.osm/vca-overlay.yaml $images_overlay
+        juju deploy -m $MODEL_NAME $BUNDLE --overlay ~/.osm/vca-overlay.yaml $images_overlay $extra_overlay
     else
-        juju deploy -m $MODEL_NAME $OSM_BUNDLE --overlay ~/.osm/vca-overlay.yaml $images_overlay
+        juju deploy -m $MODEL_NAME $OSM_BUNDLE --overlay ~/.osm/vca-overlay.yaml $images_overlay $extra_overlay
     fi
 
     if [ ! -v KUBECFG ]; then