Logging Extensions

Implements a few extensions for the standard python logging library.

Currently, this project lacks documentation. Sorry about that.

Logging Context Filter

Logging Context Filter injects context variables into LogRecord objects as extra fields.

Here's a usage example:

import logging
import sys

from loggingex.context import LoggingContextFilter, context

log = logging.getLogger()


def process_lines(lines):
    for index, line in enumerate(lines):
        line = line.strip()
        with context(current_line=index + 1):
            log.debug("processing line: %s", line)
            if not line:
                log.error("empty line!")
                continue
            log.info("processed line: %s", line)


def process_files(filenames):
    log.debug("starting...")
    for filename in filenames:
        with context(current_file=filename):
            log.info("processing file: %s", filename)
            with open(filename, "r") as f:
                process_lines(f)
            log.info("processed file: %s", filename)
    log.debug("work is complete!")


if __name__ == "__main__":
    formatter = logging.Formatter(
        "%(current_file)s:%(current_line)s:%(levelname)s: %(message)s"
    )
    handler = logging.StreamHandler(stream=sys.stdout)
    handler.setFormatter(formatter)
    handler.setLevel(logging.DEBUG)
    handler.addFilter(LoggingContextFilter())  # it's that simple
    logging.basicConfig(handlers=[handler], level=logging.DEBUG)

    with context(current_file="-", current_line="-"):
        # The context above sets default value, so that the formatter does
        # not crash, when they are not defined.
        process_files(sys.argv[1:])