loggingex 1.2.0

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:])