my first custom logging handler not working

Question

I am trying to write custom handler for logging that would send logs to netcat

I can see on the receiving end that the connection is established and then closes, however, no messages are received and i can see no errors.

here is the code i am running

import socket
import time
import logging


hostname = '127.0.0.1'
port = '1234'
message = 'hello world!\n'

class Nc_handler(logging.Handler):
    def __init__(self, hostname, port):
        logging.Handler.__init__(self)
        self.socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        self.socket.connect((hostname, int(port)))

    def emit(self, content):
        log_entry = self.format(content)
        print("Checking if emit is run")
        self.socket.send(log_entry.encode())




logger = logging.getLogger(__name__)

# set format
nc_format = logging.Formatter('%(name)s - %(levelname)s - %(message)s')

# create nc handler
nc_handler = Nc_handler(hostname, port)

# set handler's level
nc_handler.setLevel(logging.INFO)

# set handler's format
nc_handler.setFormatter(nc_format)

logger.addHandler(nc_handler)
logger.info(message)

If i use nc_handler.emit('Hello') it throws an error:

  File "handler.py", line 35, in <module>
    nc_handler.emit(message)
  File "handler.py", line 17, in emit
    log_entry = self.format(content)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/logging/__init__.py", line 869, in format
    return fmt.format(record)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/logging/__init__.py", line 608, in format
    record.message = record.getMessage()
AttributeError: 'str' object has no attribute 'getMessage'

So i suspect i don't use Formatter correctly but I can't figure out what exactly I am doing wrong.

I would really appreciate any help or advice.

cestMoiBaliBalo · Accepted Answer · 2019-10-18 10:00:18Z

1

Method emit has a wrong signature: its argument must be a LogRecord object. Not a string.

That is because format method needs a LogRecord object.

That is the cause of the AttributeError exception.

I see also a confusion I don't understand: why using message as argument for logging.info?

message is an attribute of the LogRecord object too and is taken from what you logged explicitly.

Use a hard-coded string:

logging.info("Hello")

Or use a different variable:

myvar = "Hello"
logging.info(myvar)

Does it help?

answered Oct 18, 2019 at 10:00

cestMoiBaliBalo

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3 Comments

cestMoiBaliBalo Over a year ago

Sorry: didn't see the global variable message at the beginning of your script. Forget my second remark.

Askar Kopbayev Over a year ago

Thanks a lot. Yes, after I changed it def emit(self, record): everything worked!

Askar Kopbayev Over a year ago

Although, it only works when I use basicConfig. Doesn't work with logging.Formatter

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