Clash Royale CLAN TAG#URR8PPP

how to print in a specific log file using a logger without printing in the supervisord log file in a tornado application

I'm currently developing a Tornado application made from different indipendent modules.

The application run using supervisord, so right now, every time I use

logging.info()


the log is printed on the supervisor log and I'm ok with that.

The problem is that now the supervisor log file is full of very different stuff from different modules and very hard to read, so I now want that every module use a specific logger and every logger write on a different file.

So I created the logger:

def set_log_config(filename, when='h', interval=1, backupCount=0):
directory = os.path.dirname(os.path.abspath(filename))
create_folder(directory)

app_log = logging.getLogger("tornado.application.fiscal")

handler = logging.handlers.TimedRotatingFileHandler(filename, when=when, interval=interval, backupCount=backupCount)
formatter = logging.Formatter('[%(levelname)s %(asctime)s.%(msecs)d %(module)s:%(lineno)d] %(message)s', datefmt='%y%m%d %H:%M:%S')

handler.setFormatter(formatter)
app_log.addHandler(handler)
app_log.setLevel(logging.INFO)
return app_log

fiscal_logger = set_log_config(
'/home/dir/Trace/fiscal/fiscal_module_:%Y-%m-%d.log'.format(datetime.now(), when='midnight', interval=1, backupCount=21)
)


The logger works, it write on the specific file, but it also always write in the supervisor log file and I don't understand why.

So my question is: how can I write on the specific file when I use the fiscal_logger.info and on the supervisor file when I use logging.info?

1 Answer
1

First I explain why your logger also writes to the supervisor log file.

Writing to supervisor log file means there is a StreamHandler in your current logger chain.

StreamHandler

logging.info basically equals to logging.getLogger().info which means it uses root logger. Additionally, logging.xxx will automatically add a StreamHandler to root logger if root has no handler.

logging.info

logging.getLogger().info

root

logging.xxx

StreamHandler

root

root

And by default logs will be propagated along logger chain(For example, "tornado.application.fiscal"'s logger chain is root -> tornado -> application -> fiscal). So fiscal_logger's log is propagated to root logger and processed by root's StreamHandler. That's why you see those logs in the supervisor log file.

"tornado.application.fiscal"

root -> tornado -> application -> fiscal

fiscal_logger

root

root

StreamHandler

To fix this problem, you have two options at least.

logging.xxxx

console_logger

fiscal_logger.propagate

False

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