Python logger not printing Info

user_3828311 0
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Looking at the python docs, if I set my logger level to INFO, it should print out all logs at level INFO and above.

However, the code snipper below only prints "error"

import logging
logger = logging.getLogger()
logger.setLevel(logging.INFO)
logger.info("Info")
logger.error("error")
logger.info("info")

Output

error

What could be the reason for this?

logging python
2 Answers

Use logging.basicConfig to set a default level and a default handler:

import logging

logger = logging.getLogger()
logging.basicConfig(level=logging.INFO)

logger.info("Info")
logger.error("error")
logger.info("info")

prints:

INFO:root:Info
ERROR:root:error
INFO:root:info

The logging module is powerful yet confusing. Look into the HOWTO in the docs for a tutorial. I've made my own helper function that logs to stderr and a file that I've detailed on my blog. You might like to adapt it to your needs.

user_29580700

The reason for this behaviour is that there are no logging handlers defined. In this case the handler "logging.lastResort" is used. Per default this handler is "<_StderrHandler (WARNING)>". It logs to stderr but only starting from level "WARNING".

For your example you could do the following (logging to stdout):

import logging
import sys
logger = logging.getLogger()
logger.setLevel(logging.INFO)
logger.addHandler(logging.StreamHandler(sys.stdout))
logger.info("info")

Output

info

In the howto you can find other useful handlers.

user_164470730
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