Python logging split between stdout and stderr

Question

This question already has answers here:

How can INFO and DEBUG logging message be sent to stdout and higher level message to stderr (7 answers)

Closed 8 years ago.

Is it possible to have python logging messages which are INFO or DEBUG to go to stdout and WARNING or greater to go to stderr?

Answer 1

This seems to do what I want:

#!/usr/bin/python
import sys
import logging


class InfoFilter(logging.Filter):
    def filter(self, rec):
        return rec.levelno in (logging.DEBUG, logging.INFO)


logger = logging.getLogger("__name__")
logger.setLevel(logging.DEBUG)

h1 = logging.StreamHandler(sys.stdout)
h1.setLevel(logging.DEBUG)
h1.addFilter(InfoFilter())
h2 = logging.StreamHandler()
h2.setLevel(logging.WARNING)

logger.addHandler(h1)
logger.addHandler(h2)

Answer 2

I thought this would help: Handler.setLevel(lvl)

Sets the threshold for this handler to lvl. Logging messages which are less severe than lvl will be ignored. When a handler is created, the level is set to NOTSET (which causes all messages to be processed).

But now I see that it wouldn't do what you want (split INFO/DEBUG from WARNING/ERROR)

That being said, you could write a custom handler (a class extending logging.StreamHandler for example), and overwrite the Handler.handle() method.