How can I determine if any errors were logged during a python program's execute?

Question

I have a python script which calls log.error() and log.exception() in several places. These exceptions are caught so that the script can continue to run, however, I would like to be able to determine if log.error() and/or log.exception() were ever called so I can exit the script with an error code by calling sys.exit(1). A naive implementation using an "error" variable is included below. It seems to me there must be a better way.

error = False

try:
  ...
except:
   log.exception("Something bad occurred.")
   error = True

if error:
   sys.exit(1)

Answer 1

I had the same issue as the original poster: I wanted to exit my Python script with an error code if any messages of error or greater severity were logged. For my application, it's desirable for execution to continue as long as no unhandled exceptions are raised. However, continuous integrations builds should fail if any errors are logged.

I found the errorhandler python package, which does just what we need. See the GitHub, PyPI page, and docs.

Below is the code I used:

import logging
import sys

import errorhandler

# Track if message gets logged with severity of error or greater
error_handler = errorhandler.ErrorHandler()

# Also log to stderr
stream_handler = logging.StreamHandler(stream=sys.stderr)
logger = logging.getLogger()
logger.setLevel(logging.INFO)  # Set whatever logging level for stderr
logger.addHandler(stream_handler)

# Do your program here

if error_handler.fired:
    logger.critical('Failure: exiting with code 1 due to logged errors')
    raise SystemExit(1)

Answer 2

You can check logger._cache. It returns a dictionary with keys corresponding to the numeric value of the error level logged. So for checking if an error was logged you could do:

if 40 in logger._cache and logger._cache[40]