Raw Custom Logs in Google App Engine Flexible Environment

I've used the following code in a Flexible (VM) Environment on Google App Engine to separate custom logs with a specific formatting requirement from other application logs: import logging as std_logging std_logging.basicConfig() custom_formatter = std_logging.Formatter('%(created)ft%(message)s') custom_handler = std_logging.FileHandler('/var/log/app_engine/custom_logs/custom.log') custom_handler.setFormatter(custom_formatter) custom_logging = std_logging.getLogger('custom') custom_logging.addHandler(custom_handler) In a normal Python environment, these would write to the log file as plain-text lines in the format specified. However, after dumping the logs produced from App Engine to Cloud Storage, I noticed that App Engine has wrapped each log with other information. E.g. (formatted for clarity) { "insertId":"vsdacv1235jj1", "log":"appengine.googleapis.com/custom.var.log.app_engine.app.custom_logs.custom.log", "metadata":{ "labels":{ "appengine.googleapis.com/module_id":"default", "appengine.googleapis.com/version_id":"1", "compute.googleapis.com/resource_id":"1234256789901203", "compute.googleapis.com/resource_name":"bbq23asd123", "compute.googleapis.com/resource_type":"instance" }, "projectId":"my-project", "serviceName":"appengine.googleapis.com", "timestamp":"2016-06-24T20:16:15Z", "zone":"us-central1-f" }, "textPayload":"1466799374933tthis is my custom message" } The value of the textPayload field is the actual log I produced, but is wrapped by App Engine. Is there a way to prevent this behaviour? It is undesirable to re-process these logs in order to format them correctly.