-let host = Helm_registry.get "rdfly.mysql_connection.host";;
-let database = Helm_registry.get "rdfly.mysql_connection.database";;
-let port = Helm_registry.get_int "rdfly.mysql_connection.port";;
-let password = Helm_registry.get "rdfly.mysql_connection.password";;
-let user = Helm_registry.get "rdfly.mysql_connection.user";;
+let get_option key =
+ try
+ Some (Helm_registry.get key)
+ with Helm_registry.Key_not_found _ -> None
+
+let get_int_option key =
+ try
+ Some (Helm_registry.get_int key)
+ with Helm_registry.Key_not_found _ -> None
+
+let host = get_option "rdfly.mysql_connection.host";;
+let database = get_option "rdfly.mysql_connection.database";;
+let port = get_int_option "rdfly.mysql_connection.port";;
+let password = get_option "rdfly.mysql_connection.password";;
+let user = get_option "rdfly.mysql_connection.user";;