Retry join command

Related-Prod: PRODX-0000
Change-Id: Ie573ebe543c24c12305ecb1fd73deb826965c9bf
diff --git a/de/heat-templates/scripts/instance_boot.sh b/de/heat-templates/scripts/instance_boot.sh
index 4936aaf..0bf7101 100644
--- a/de/heat-templates/scripts/instance_boot.sh
+++ b/de/heat-templates/scripts/instance_boot.sh
@@ -195,8 +195,7 @@
 function join_node {
     local type=${1}
     function retry_join_node {
-        cmd=$(docker swarm join-token $type |grep 'docker swarm join')
-        $cmd
+        env -i $(docker swarm join-token $type |grep 'docker swarm join' | xargs)
     }
     retry 10 "Failed to join node to swarm" retry_join_node
 }