https://github.com/neocrym/log-with-context

A thread-local, context-preserving, minimalist Python logger.
https://github.com/neocrym/log-with-context

logging minimalist python

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A thread-local, context-preserving, minimalist Python logger.

• Host: GitHub
• URL: https://github.com/neocrym/log-with-context
• Owner: neocrym
• License: mit
• Created: 2021-03-31T01:31:47.000Z (about 5 years ago)
• Default Branch: main
• Last Pushed: 2023-10-23T23:27:34.000Z (over 2 years ago)
• Last Synced: 2025-04-16T13:06:07.773Z (about 1 year ago)
• Topics: logging, minimalist, python
• Language: Python
• Homepage:
• Size: 47.9 KB
• Stars: 16
• Watchers: 2
• Forks: 0
• Open Issues: 1
• Metadata Files:
  • Readme: README.rst
  • Code of conduct: CODE_OF_CONDUCT.md

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README

          
log-with-context--a thread-local, context-preserving Python logger

==================================================================

``log-with-context`` is a Python logger that saves variables in a

thread-local context to be passed as `extra` to Python

`logging `_ methods.

Note that ``log-with-context`` assumes that you are passing context

in a multithreading sense--not in an asyncio sense.

Installation

------------

This library is available on PyPI and can be installed with

.. code:: bash

    python3 -m pip install log-with-context

Usage

-----

This library provides a wrapped Python logging.Logger that

adds a shared context to each logging message, passed as

the `extra` parameter.

**You will need an additional library** (like

`JSON-log-formatter `_)

**to actually output the logging messages**. We avoided putting this

functionality in this library to keep it lightweight and flexible.

We assumed that you already have a preferred way to format your

logging messages.

.. code:: python

    import logging

    import logging.config

    from log_with_context import add_logging_context, Logger

    logging.config.dictConfig({

        "version": 1,

        "disable_existing_loggers": True,

        "formatters": {

            "json": {"()": "json_log_formatter.JSONFormatter"},

        },

        "handlers": {

            "console": {

                "formatter": "json",

                "class": "logging.StreamHandler",

            }

        },

        "loggers": {

            "": {"handlers": ["console"], "level": "INFO"},

        },

    })

    LOGGER = Logger(__name__)

    LOGGER.info("First message. No context")

    with add_logging_context(current_request="hi"):

        LOGGER.info("Level 1")

        with add_logging_context(more_info="this"):

            LOGGER.warning("Level 2")

        LOGGER.info("Back to level 1")

    LOGGER.error("No context at all...")

The above program logs the following messages to standard error:

.. code:: json

    {"message": "First message. No context", "time": "2021-04-08T16:37:23.126099"}

    {"current_request": "hi", "message": "Level 1", "time": "2021-04-08T16:37:23.126336"}

    {"current_request": "hi", "more_info": "this", "message": "Level 2", "time": "2021-04-08T16:37:23.126389"}

    {"current_request": "hi", "message": "Back to level 1", "time": "2021-04-08T16:37:23.126457"}

    {"message": "No context at all...", "time": "2021-04-08T16:37:23.126514"}

This example may look trivial, but it is very handy to maintain a

logging context up and down a Python call stack without having

to pass additional variables to the functions and methods

that you call.

Implementation details

----------------------

Logging contexts are stored as thread-local variables. If you want

to share information between threads, you must create a Logging

context in each thread with the same information.

Similarly, logging contexts are *deliberately not copied* when

creating subprocesses. This is done to minimize bugs and make sure

that log-with-context behaves in the exact same manner across

operating systems.