Examples

Crystal Logging Setup

Setting Up Logging

Crystal logging setup with Log logs requests and errors.

Introduction to Crystal Logging

Setting up logging in a Crystal application is essential for monitoring and debugging purposes. The Crystal standard library includes the Log module, which facilitates logging requests and errors efficiently. This guide will walk you through setting up logging in your Crystal application.

Installing Dependencies

Before diving into logging, ensure that you have Crystal installed on your machine. You can verify the installation by running:

If Crystal is not installed, follow the official installation guide to set it up.

Basic Logging Example

Let's start with a simple logging example. Create a new file named logger_example.cr and add the following code:

In this example, we first require the log module, then create a logger for the current context using Log.for(self). We then log an informational message and an error message using the respective methods.

Logging to a File

To log messages to a file instead of the console, you can configure the logger to use a file backend. Here's how to modify the previous example to log to a file:

In this snippet, we open a file named app.log for writing and assign it as the backend for the logger. After logging, it's important to close the file to ensure all log entries are properly saved.

Advanced Logging Features

Crystal's Log module supports various advanced features, including log level configuration, custom formatters, and multiple backends. Here’s an example demonstrating how to set a custom log level:

By setting the logger's level to Log::Severity::ERROR, only error messages will be logged. This feature is particularly useful in production environments where you want to minimize log verbosity.

For more advanced configuration options, refer to the official Crystal Log module documentation.

Conclusion

Setting up logging in Crystal is straightforward with the Log module. Whether you're logging to the console, a file, or using custom configurations, Crystal provides a robust set of tools to handle your logging needs. Experiment with different configurations to suit your application's requirements.

Examples

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