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Logging in MSAL for Python

The Microsoft Authentication Library (MSAL) apps generate log messages that can help diagnose issues. An app can configure logging with a few lines of code, and have custom control over the level of detail and whether or not personal and organizational data is logged. We recommend you create an MSAL logging implementation and provide a way for users to submit logs when they have authentication issues.

Logging in MSAL Python is designed to use the standard Python logging mechanisms, so all your previous knowledge of Python logging applies to MSAL Python.

  • By default, the logging in any Python script is turned off. If you want to enable debug logging for ALL modules in your entire Python script, you use logging.basicConfig(level=logging.DEBUG).
  • Most of the MSAL Python logs are already in debug level, which would be turned off by default. But if you want to enable debug logging to debug the OTHER modules in your Python script, therefore want to silence MSAL, you simply turn off the logger used by MSAL Python: logging.getLogger("msal").setLevel(logging.WARN).
  • MSAL Python does not log Personal Identifiable Information (PII). So there is not even a turn-on-PII-logging toggle in MSAL Python. App developers could still use standard Python logging to log whatever content. By doing so, the app takes responsibility for safely handling highly sensitive data and following regulatory requirements.

Logging levels

MSAL provides several levels of logging detail:

  • LogAlways: No level filtering is done on this log level. Log messages of all levels will be logged.
  • Critical: Logs that describe an unrecoverable application or system crash, or a catastrophic failure that requires immediate attention.
  • Error: Indicates something has gone wrong and an error was generated. Used for debugging and identifying problems.
  • Warning: There hasn't necessarily been an error or failure, but are intended for diagnostics and pinpointing problems.
  • Informational: MSAL will log events intended for informational purposes not necessarily intended for debugging.
  • Verbose (Default): MSAL logs the full details of library behavior.


Not all log levels are available for all MSAL libraries.

Personal and organizational data

By default, the MSAL logger doesn't capture any highly sensitive personal or organizational data. The library provides the option to enable logging personal and organizational data if you decide to do so.

The following sections provide more details about MSAL error logging for your application.

MSAL for Python logging

Logging in MSAL for Python leverages the logging module in the Python standard library. You can configure MSAL logging as follows (and see it in action in the username_password_sample):

Enable debug logging for all modules

By default, the logging in any Python script is turned off. If you want to enable verbose logging for all Python modules in your script, use logging.basicConfig with a level of logging.DEBUG:

import logging


This will print all log messages given to the logging module to the standard output.

Configure MSAL logging level

You can configure the logging level of the MSAL for Python log provider by using the logging.getLogger() method with the logger name "msal":

import logging


Configure MSAL logging with Azure App Insights

Python logs are given to a log handler, which by default is the StreamHandler. To send MSAL logs to an Application Insights with an Instrumentation Key, use the AzureLogHandler provided by the opencensus-ext-azure library.

To install, opencensus-ext-azure add the opencensus-ext-azure package from PyPI to your dependencies or pip install:

pip install opencensus-ext-azure

Then change the default handler of the "msal" log provider to an instance of AzureLogHandler with an instrumentation key set in the APP_INSIGHTS_KEY environment variable:

import logging
import os

from opencensus.ext.azure.log_exporter import AzureLogHandler



Personal and organizational data in Python

MSAL for Python does not log personal data or organizational data. There is no property to turn personal or organization data logging on or off.

You can use standard Python logging to log whatever you want, but you are responsible for safely handling sensitive data and following regulatory requirements.

For more information about logging in Python, please refer to Python's Logging: how-to.