Logging

Magento supports the messages logging mechanism via its \Psr\Log\LoggerInterface class. The LoggerInterface class has a preference defined within app/etc/di.xml file for the Magento\Framework\Logger\Monolog class type. The actual crux of implementation is actually in the Monolog parent class named Monolog\Logger, which comes from the Monolog vendor.

The LoggerInterface class uses the following eight methods to write logs to the eight RFC 5424 levels:

• debug

• info

• notice

• warning

• error

• critical

• alert

• emergency

To use a logger, we need to pass the LoggerInterface class to a constructor of a class from within we want to use it and then simply make one of the following method calls:

$this->logger->log(\Monolog\Logger::DEBUG, 'debug msg');
$this->logger->log(\Monolog\Logger::INFO, 'info msg');
$this->logger->log(\Monolog\Logger::NOTICE, 'notice msg');
$this->logger->log(\Monolog\Logger::WARNING, 'warning msg');
$this->logger->log(\Monolog\Logger::ERROR, 'error msg');
...