How to Use Python Logging to Manage Multiple Loggers with yaml Configuration

Описание: Discover how to configure multiple `Python` loggers to log to different files using a `yaml` configuration. Learn about common mistakes and their solutions in logging.
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This video is based on the question https://stackoverflow.com/q/72517380/ asked by the user 'AbianG' ( https://stackoverflow.com/u/1909607/ ) and on the answer https://stackoverflow.com/a/72520104/ provided by the user 'AbianG' ( https://stackoverflow.com/u/1909607/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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How to Use Python Logging to Manage Multiple Loggers with YAML Configuration

When implementing logging in Python, a common requirement is to maintain multiple loggers that write to different log files. This process can be confusing, especially when dealing with configuration files in YAML format. In this post, we'll explore how to configure two loggers to log messages to their respective files, troubleshoot common issues, and ensure everything works seamlessly.

The Problem

Imagine you're working on a Python application and you want to log different types of information to separate log files. You decide to set up two loggers in a logger.yaml configuration file. However, you encounter a frustrating issue: one logger works perfectly, but the second logger doesn't log any messages to its assigned file.

Example of the Configuration

Here’s what your logger.yaml configuration might look like:

[[See Video to Reveal this Text or Code Snippet]]

Understanding the Code

Your Python script initializes logging using the above configuration:

[[See Video to Reveal this Text or Code Snippet]]

While the first logger (logger1) successfully writes to applog.log, the second logger (logger2) does not log anything to applog2.log.

The Solution

After thorough investigation of the configuration file and the code, the root cause was identified: a typo in the second logger definition. The original line mistakenly used handles instead of the correct handlers.

Correcting the Typo

To resolve this issue, update the logger.yaml configuration as follows:

[[See Video to Reveal this Text or Code Snippet]]

By making this change, you properly instruct the logger to utilize the file2 handler.

Testing the Changes

After updating the configuration, re-run your Python script. Both loggers should now function correctly, logging messages to their respective files:

applog.log for logger1

applog2.log for logger2

Conclusion

Setting up multiple loggers in Python using a yaml configuration file can sometimes lead to confusing issues. However, with careful attention to detail—especially in terms of configuration keys like handlers—you're well on your way to achieving a robust logging strategy. Always test your changes after making updates to ensure everything works as intended.

By following the outlined steps and troubleshooting tips, you should now have a clear framework for managing multiple loggers in your Python applications. Happy logging!