only include non-empty IP addresses

Change-Id: Id0fe43c2ba7c7af30982afb9add431e3a0369cfd
diff --git a/automation/node.go b/automation/node.go
index a414820..9e045e6 100644
--- a/automation/node.go
+++ b/automation/node.go
@@ -113,7 +113,9 @@
 			linkObj, _ := link.GetMap()
 			ipObj, _ := linkObj["ip_address"]
 			ip, _ := ipObj.GetString()
-			result = append(result, ip)
+			if ip != "" {
+				result = append(result, ip)
+			}
 		}
 	}