How to log while using a progress bar from rich without breaking formatting?

Hello,

I am trying to figure out the best way to use loguru to log while also using a rich progress bar. In order to avoid formatting issues, it would seem that I need to use the progress bar’s console.print function, since that is how you avoid breaking the progress bar and causing it to redraw.

I have a couple of thoughts on how to do this, but am still a bit lost:

• Based on rich’s documentation, it seems like maybe I could create a Console object for my app, add that as a sink somehow, and then pass that to the progress bar.
• There might also be a way to use the regular logging handler that rich provides, and have loguru propegate messages to that, but I’m not sure how/if that can be hooked up to a rich Console object.

Any advice would be much appreciated! Thanks!

[Delgan]

Hey @taranlu-houzz.

By default the logger send messages using regular sys.stderr.write() method. As you realized, this causes compatibility problems with Rich’s progressive bars. Both solutions you thought of should work.

You can either use Console.print() as a sink instead of sys.stderr. That way, Rich will be in charge of generating a proper output. As you said, it also requires to pass the console object to the Progress constructor.

import time
from loguru import logger
from rich.console import Console
from rich.progress import Progress

console = Console(color_system=None, stderr=None)

def work(i):
    logger.info("Working: {}", i)
    time.sleep(0.05)

def main():
    logger.info("Before")
    with Progress(console=console) as progress:
        for i in progress.track(range(100)):
            work(i)
    logger.info("After")


if __name__ == "__main__":
    logger.remove()  # Remove default 'stderr' handler

    # We need to specify end=''" as log message already ends with \n (thus the lambda function)
    # Also forcing 'colorize=True' otherwise Loguru won't recognize that the sink support colors
    logger.add(lambda m: console.print(m, end=""), colorize=True)

    main()

I guess it should work similarly using RichHandler(). Again, it seems you have to use your own console object.

handler = RichHandler(console=console)  # Note that RichHandler is adding extra info you may need to disable
logger.remove()
logger.add(handler, colorize=True)

[Delgan]

Thanks for the code snippets @taranlu-houzz!

The color codes are added due to colorize=True. As you realized, this works fine when logs are printed to the console but not when the output is redirected to a file.

As a workaround, you can replace colorize=True with colorize=sys.stderr.isatty(). When colorize=None (the default), Loguru automatically checks if the sink supports colors using the isatty() method. Due to the lambda function, you have to do the same thing explicitly.