only check secrets for service create if requested

Signed-off-by: Evan Hazlett <ejhazlett@gmail.com>

cli/command/service/create.go

@@ -62,13 +62,17 @@ func runCreate(dockerCli *command.DockerCli, opts *serviceOptions) error {
 		return err
 	}
 
+	specifiedSecrets := opts.secrets.Value()
+	if len(specifiedSecrets) > 0 {
 		// parse and validate secrets
-	secrets, err := parseSecrets(apiClient, opts.secrets.Value())
+		secrets, err := parseSecrets(apiClient, specifiedSecrets)
 		if err != nil {
 			return err
 		}
 		service.TaskTemplate.ContainerSpec.Secrets = secrets
 
+	}
+
 	ctx := context.Background()
 
 	// only send auth if flag was set