fix some debugging for PublicIpAddress

builder/amazon/common/step_run_source_instance.go

@@ -110,13 +110,16 @@ func (s *StepRunSourceInstance) Run(state multistep.StateBag) multistep.StepActi
 	}
 
 	s.instance = latestInstance.(*ec2.Instance)
-	log.Printf("Public IP: %s", s.instance.PublicIpAddress)
 
 	if s.Debug {
 		if s.instance.DNSName != "" {
 			ui.Message(fmt.Sprintf("Public DNS: %s", s.instance.DNSName))
 		}
 
+		if s.instance.PublicIpAddress != "" {
+			ui.Message(fmt.Sprintf("Public IP: %s", s.instance.PublicIpAddress))
+		}
+
 		if s.instance.PrivateIpAddress != "" {
 			ui.Message(fmt.Sprintf("Private IP: %s", s.instance.PrivateIpAddress))
 		}