In this blog, we will show you the way to create a custom logger to log your own messages into it.

Step 1: Create a logger class

Firstly, create a logger class:


namespace Magenest\CustomLog\Logger;

class Logger extends \Monolog\Logger



namespace Magenest\CustomLog\Logger;

use Monolog\Logger;

class Handler extends \Magento\Framework\Logger\Handler\Base
    * Logging level
    * @var int
   protected $loggerType = Logger::NOTICE;

    * File name
    * @var string
   protected $fileName = '/var/log/magenest_custom_log.log';

The file name /var/log/magenest_custom_log.log is a relative path to the magento root folder, it means your log will be stored under <magento_root>/var/log/magenest_custom_log.log

The variable loggerType define the log level can be applied. 

Monolog/Logger has the following consts:

  • DEBUG = 100
  • INFO = 200
  • NOTICE = 250
  • WARNING = 300
  • ERROR = 400
  • CRITICAL = 500
  • ALERT = 550
  • EMERGENCY = 600 

For example, loggerType = NOTICE. It means the logger level will be from “NOTICE” and above such as “WARNING”, “ERROR”, “CRITICAL”, ... And can not log the level “DEBUG” and “INFO”.

Step 2: Declare the logger

The next step is to declare the logger in di.xml.


<?xml version="1.0"?>
<config xmlns:xsi=""
   <type name="Magenest\CustomLog\Logger\Handler">
           <argument name="filesystem" xsi:type="object">Magento\Framework\Filesystem\Driver\File</argument>
   <type name="Magenest\CustomLog\Logger\Logger">
           <argument name="name" xsi:type="string">Magenest_Custom_Log</argument>
           <argument name="handlers"  xsi:type="array">
               <item name="system" xsi:type="object">Magenest\CustomLog\Logger\Handler</item>

You have defined the handler with a unique name. The class Magenest\CustomLog\Logger\Logger will be handled by the handler Magenest\CustomLog\Logger\Handler

That’s it, your logger is ready to use. To test our logger, we will create a controller as the following:


namespace Magenest\CustomLog\Controller\Index;

use Magenest\CustomLog\Logger\Logger;
use Magento\Framework\App\Action\Action;
use Magento\Framework\App\Action\Context;
use Magento\Framework\View\Result\PageFactory;

class Index extends Action
    * Index action
    * @return $this
   /** @var PageFactory */
   protected $resultPageFactory;

    * @var Logger
   protected $logger;

   public function __construct(
       Context $context,
       PageFactory $resultPageFactory,
       Logger $logger
       $this->resultPageFactory = $resultPageFactory;
       $this->logger = $logger;

   public function execute()
       $this->logger->error('Log Error');
       $this->logger->emergency('Log Emergency');
       $this->logger->info('Log Info');
       $this->logger->debug('Log Debug');
       $resultPage = $this->resultPageFactory->create();
       return $resultPage;

Now you can find the log in var/log/magenest_custom_log.log file

var/log/magenest_custom_log.log file

As you can see, our logger can only print the log with the level from “NOTICE” and above, the lower level will not be printed.

Hope this guide is useful for you to create custom logger in Magento 2

Thank you for reading our blog and see you in the upcoming articles.