Python logging how to track hostname in logs?

Question

I am using Python logging in this manner:

logger = logging.getLogger("my_logger")
logger.info("Some text.")

I have a bunch of IoT devices all running (making logs). They stream their log data to a database. To differentiate the source, I need to include the source IP address.

Is there a way to get hostname using logging? Is IP Address or hostname tracked/trackable in LogRecords?

In general, what is the best way to add in hostname to a LogRecord?

Asked By: Intrastellar Explorer

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Source

Answer 1

You can do that by adding a custom log filter and formatter that puts the host name in the log messages.

import logging, platform

class HostnameFilter(logging.Filter):
    hostname = platform.node()

    def filter(self, record):
        record.hostname = HostnameFilter.hostname
        return True

handler = logging.StreamHandler()
handler.addFilter(HostnameFilter())
handler.setFormatter(logging.Formatter('%(asctime)s %(hostname)s: %(message)s', datefmt='%b %d %H:%M:%S'))

logger = logging.getLogger()
logger.addHandler(handler)
logger.setLevel(logging.INFO)

logger.info('Hello, world!')

Answered By: rdas

Answer 2

A simpler solution would be to pre-populate the format line with the hostname. For example:

logging.basicConfig(
   #... your logging configuration,
   format="%(asctime)s {} %(message)s".format(socket.gethostname())
)

would generate a format line like

"%(asctime)s some-hostname %(message)s"

The drawback is that if the host name changes you’d need to restart your service/application. This is usually not a problem for most applications, especially if running on docker/k8s

Answered By: Filipe

Answer 3

The easiest way to do this is available through the Polog library.

Install it:

$ pip install pip

And use:

from polog import log, config, file_writer

config.add_handlers(file_writer())
config.set(service_name='my_host_name')

log('message')

After executing the code, you will see in the console something similar:

[2022-10-26 19:26:04.759310] |    1    | UNKNOWN | MANUAL | "message" | where: my_host_name.?

Answered By: Evgeniy Blinov

Python logging how to track hostname in logs?

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