Retry join node to swarm

Related-Prod: PRODX-00000
Change-Id: I3c0a650aaf141c5997c592ff7512765f78b34f17
diff --git a/de/heat-templates/scripts/instance_boot.sh b/de/heat-templates/scripts/instance_boot.sh
index a1928b0..30881d9 100644
--- a/de/heat-templates/scripts/instance_boot.sh
+++ b/de/heat-templates/scripts/instance_boot.sh
@@ -193,7 +193,10 @@
 
 
 function join_node {
-    env -i $(docker swarm join-token $1 |grep 'docker swarm join' | xargs)
+    function retry_join_node {
+        docker swarm join-token $1
+    }
+    retry 10 "Failed to join node to swarm" retry_join_node
 }
 
 function create_ucp_config {