Magento 2 - Custom Logger

Data.php

<?php
namespace MagePsycho\Demo\Helper;

/**
 * @category   MagePsycho
 * @package    MagePsycho_Demo
 * @author     [email protected]
 * @website    http://www.magepsycho.com
 * @license    http://opensource.org/licenses/osl-3.0.php  Open Software License (OSL 3.0)
 */
class Data extends \Magento\Framework\App\Helper\AbstractHelper
{

	const XML_PATH_ENABLED          = 'magepsycho_demo/general/enabled';
	const XML_PATH_DEBUG            = 'magepsycho_demo/general/debug';

	/**
	 * @var \Psr\Log\LoggerInterface
	 */
	protected $_logger;

	/**
	 * @var \Magento\Framework\Module\ModuleListInterface
	 */
	protected $_moduleList;

	/**
	 * @param \Magento\Framework\App\Helper\Context $context
	 * @param \MagePsycho\Demo\Logger\Logger $logger
	 * @param \Magento\Framework\Module\ModuleListInterface $moduleList
	 */
	public function __construct(
		\Magento\Framework\App\Helper\Context $context,
		\MagePsycho\Demo\Logger\Logger $logger,
		\Magento\Framework\Module\ModuleListInterface $moduleList
	) {
		$this->_logger                  = $logger;
		$this->_moduleList              = $moduleList;

		parent::__construct($context);
	}

	public function getDebugStatus()
	{
		return $this->scopeConfig->getValue(
			self::XML_PATH_DEBUG,
			\Magento\Store\Model\ScopeInterface::SCOPE_STORE
		);
	}

	/**
	 *
	 * @param $message
	 * @param bool|false $useSeparator
	 */
	public function log($message, $useSeparator = false)
	{
		if ($this->getDebugStatus()) {
			if ($useSeparator) {
				$this->_logger->debug(str_repeat('=', 100));
			}

			$this->_logger->debug($message);
		}
	}

}

di.xml

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:ObjectManager/etc/config.xsd">
    <type name="MagePsycho\Demo\Logger\Handler">
        <arguments>
            <argument name="filesystem" xsi:type="object">Magento\Framework\Filesystem\Driver\File</argument>
        </arguments>
    </type>
    <type name="MagePsycho\Demo\Logger\Logger">
        <arguments>
            <argument name="name" xsi:type="string">DemoLoggerHandler</argument>
            <argument name="handlers"  xsi:type="array">
                <item name="debug" xsi:type="object">MagePsycho\Demo\Logger\Handler</item>
            </argument>
        </arguments>
    </type>
</config>

Handler.php

<?php

namespace MagePsycho\Demo\Logger;

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

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

Logger.php

<?php

namespace MagePsycho\Demo\Logger;

class Logger extends \Monolog\Logger
{

}