Automatically Re-create Log Files with Logrus and Lumberjack on macOS

Learn how to make your application re-create log files automatically in Go using `Logrus` and `Lumberjack`, even when deleted.
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Automatically Re-create Log Files with Logrus and Lumberjack on macOS

Are you using Go, Logrus, and Lumberjack for logging in your macOS applications, but experiencing issues when the log file is deleted? Many developers find that deleted log files do not get automatically recreated while their application continues to run. This can lead to confusion and frustration, especially if you're expecting continuous logging. In this post, we'll dive into how to solve this problem by implementing a monitoring system that detects when log files are deleted and triggers the recreation of the log file.

The Problem

When using Logrus and Lumberjack for logging in your Go application, the logging configuration is straightforward, as shown in the code below:

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

Upon starting the application, the log file is created as expected. However, if you manually delete the log file while the application is running, it will not be recreated until you restart the application. This poses a problem if you need continuous logging without interruptions.

The Solution

To tackle this issue, we can utilize a package called fsnotify, which allows us to monitor the log file and react to deletions. By setting up a watcher, we can instruct Lumberjack to perform a rotation when the log file is deleted. Here's a step-by-step breakdown of how to implement this solution.

Step 1: Install fsnotify

Make sure you first have the fsnotify library installed. You can add it to your Go project by running the following command:

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

Step 2: Set Up Your Logger

We'll start by configuring your logger just as you did before, but with an additional setup for the file watcher. Below is the complete example code:

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

Step 3: Explanation of the Code

File watcher setup: We create a new watcher and defer its closure at the end of the main function. The go statement starts a separate goroutine that listens for file events.

Event Handling: In the goroutine, we check if the log file has been deleted (using fsnotify.Remove). If it has, we call logger.Rotate() to handle the re-creation of the log file.

Continuous Logging: Finally, a loop continuously writes the current timestamp to the log file every three seconds.

Conclusion

By following the steps outlined above, you can ensure that your application will automatically re-create the log file whenever it is deleted, thereby maintaining uninterrupted logging functionality. Implementing fsnotify allows you to monitor the log files effectively and respond to changes in real-time.

Now that you have the tools needed, go ahead and integrate this solution into your Go applications for seamless logging!