fix service enablement
diff --git a/stack.sh b/stack.sh
index 50a4bcf..8e871de 100755
--- a/stack.sh
+++ b/stack.sh
@@ -250,8 +250,11 @@
 # nova api crashes if we start it with a regular screen command,
 # so send the start command by forcing text into the window.
 function screen_it {
-    screen -S nova -X screen -t $1
-    screen -S nova -p $1 -X stuff "$2$NL"
+    # only run the services specified in $ENABLED_SERVICES
+    if [[ "$ENABLED_SERVICES" =~ "$1" ]]; then
+        screen -S nova -X screen -t $1
+        screen -S nova -p $1 -X stuff "$2$NL"
+    fi
 }
 
 screen_it g-api "cd $GLANCE_DIR; bin/glance-api --config-file=etc/glance-api.conf"