CODEWITHSUNDEEP
python-3.xtornadopython-logging
VilleLipponen
VilleLipponen

Reputation: 656

How to prevent Python Tornado from logging to stdout/console?

I need to disable Tornado from logging to STDOUT. I am using Python 3.8 and is running on Ubuntu 18.04. I want my log statements to be handled by a rotating file logger only. The issue is that logged statements are logged into the file and also to console:

import logging
from logging.handlers import RotatingFileHandler

logger = logging.getLogger("ex_logger")

nh = logging.NullHandler()

rfh = RotatingFileHandler(filename="./logs/process.log", mode='a', maxBytes=50000000, backupCount=25, encoding=None, delay=False)
rfh.setLevel(logging.DEBUG)
formatter = logging.Formatter('%(asctime)s - %(name)s - %(levelname)s - %(message)s')
rfh.setFormatter(formatter)

logger.handlers = []
logger.propagete = False
logger.addHandler(rfh)

logging.getLogger("tornado.access").handlers = []
logging.getLogger("tornado.application").handlers = []
logging.getLogger("tornado.general").handlers = []

logging.getLogger("tornado.access").addHandler(nh)
logging.getLogger("tornado.application").addHandler(nh)
logging.getLogger("tornado.general").addHandler(nh)

logging.getLogger("tornado.access").propagate = False
logging.getLogger("tornado.application").propagate = False
logging.getLogger("tornado.general").propagate = False

....

def main():

    ######
    # this message eppears in both the output log file and stdout
    ######
    logger.info(" application init ... ")
    
    asyncio.set_event_loop_policy(tornado.platform.asyncio.AnyThreadEventLoopPolicy())
    tornado.options.parse_command_line()
    app = Application()
    app.listen(options.port)
    tornado.ioloop.IOLoop.current().start()


if __name__ == "__main__":
    main()

Upvotes: 0

Views: 632

Answers (2)

Joooeey
Joooeey

Reputation: 3866

The problem is that from the moment you start up your IDE, logging.getLogger("tornado") may have a StreamHandler attached. This doesn't happen with every IDE but it does happen with Spyder. So that is the one you have to replace by a NullHandler:

import logging
nh = logging.NullHandler()
tornado_logger = logging.getLogger("tornado")
tornado_logger.handlers.clear()
# tornado_logger.handlers = []  # would work instead of .clear() but it's best practice to change the list and not replace it, just in case some other variable name somewhere else still refers to it.
tornado_logger.addHandler(nh)

You don't need to do anything with the children of the "tornado" logger, e.g. "tornado.access", et cetera.

Upvotes: 2

Ben Darnell
Ben Darnell

Reputation: 22134

You also need to define a logging policy for the root handler (logging.getLogger("")). Tornado looks at the root handler to decide whether logging has already been configured or needs a default setup.

Upvotes: 0

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