Programmatically: How to use Magento's custom logging system for custom logging and debugging

Step 1: Create a custom log writer

In your Magento module, create a new file Logger.php in the etc directory:

		// app/code/local/MyCompany/MyModule/etc/Logger.php
	namespace MyCompany\MyModule\Logger;

	class Logger
 {
    private $logger;

    public function __construct(\Magento\Framework\App\LoggerInterface $logger)
    {
        $this->logger = $logger;
    }

    public function log($message, $level = \Monolog\Logger::INFO)
    {
        $this->logger->log($level, $message);
    }
 }
	

Step 2: Use the custom logger in your module

Now, let's use this logger in one of your module's controllers or models. For example, let's create a IndexController in the MyCompany/MyModule module:

	// app/code/local/MyCompany/MyModule/Controller/IndexController.php
	namespace MyCompany\MyModule\Controller;

	class IndexController extends \Magento\Framework\App\Action\Action
  {
    private $logger;

    public function __construct(
        \MyCompany\MyModule\Logger\Logger $logger,
        \Magento\Framework\App\Action\Context $context
    ) {
        parent::__construct($context);
        $this->logger = $logger;
    }

    public function execute()
    {
        $this->logger->log('Custom log message from IndexController');
        // ... rest of your code ...
    }
 }
	

Step 3: Configure the logger

To configure the logger, you need to add a logging configuration to your Magento configuration file (app/etc/env.php):

	return [
    // ... other settings ...
    'log' => [
        'enabled' => true,
        'type' => 'stream',
        'handlers' => [
            'default' => [
                'logger' => \Monolog\Logger::DEBUG,
                'path' => 'var/log/magento.log',
                ' permissions' => 0644,
            ],
        ],
    ],
    ];
	

Step 4: Run the application and check the logs

Run your Magento application and trigger the IndexController action. You should see a log message in the magento.log file:

	[2023-02-20 14:30:00] DEBUG (7): Custom log message from IndexController