logaugment

Python logging library for augmenting log records with additional information.

This library supports Python 2.7.x and Python 3.1+.

If you want custom keys in your logged string:

formatter = logging.Formatter("%(message)s: %(custom_key)s")

then this library allows you to set them easily:

logaugment.set(logger, custom_key='custom_value')
logger.warn("My message")
# My message: custom_value

This allows you to safely make logging calls without getting exceptions that those keys are missing. See below if you wish to override the value for a particular logging call.

Installation

You can install the library with pip:

$ pip install logaugment

Overview

This library provides three functions:

# Sets the custom keys and values for the logger.
logaugment.set(logger, custom_key='custom_value')

# Adds custom keys and values in addition to those already set.
logaugment.add(logger, custom_key='custom_value')

# Removes all custom keys and values for the logger.
logaugment.reset(logger)

You can use logaugment.set to specify custom values for a given logger.

You can use logaugment.add to keep the custom values that were already set and add new ones. If you're redefining a custom key / value then this value will be used instead of the earlier value. You should not repeatedly call logaugment.add just to change the value; in that case it's better to use logaugment.set.

You can use logaugment.reset to remove all additional values that were added using the logaugment library.

Why?

If you need to add custom keys to your Python logging strings you need to pass them in with each logging call. That is inconvenient so this library allows you to add values just once and they're then available for all logging calls afterwards.

Here is a full example:

import logging

import logaugment

logger = logging.getLogger()
handler = logging.StreamHandler()
formatter = logging.Formatter("%(message)s: %(custom_key)s")
handler.setFormatter(formatter)
logger.addHandler(handler)

logaugment.add(logger, custom_key='custom_value')
logger.warn("My message")
# My message: custom_value

Examples

You can use keywords to specify additional values:

logaugment.add(logger, custom_key='custom_value')
logger.warn("My message")
# My message: custom_value

You can also use a dictionary or subclasses of collections.Mapping to specify the keys / values:

logaugment.add(logger, {'custom_key': 'custom_value'})
logger.warn("My message")
# My message: custom_value

You can also use a function which returns a dictionary:

def process_record(record):
    return {'custom_key': record.levelname}

logaugment.add(logger, process_record)
logger.warn("My message")
# My message: WARNING

You can pass an extra dictionary in the call which overrides the augmented data:

logaugment.add(logger, {'custom_key': 'custom_value'})
logger.warn("My message", extra={'custom_key': 'extra_value'})
# My message: extra_value