src/Logger.php
private function _initLoggerCascade($configFile, $loggerName)
    {
        $err = '';
        try {
            $fs = $this->_obm->get(Filesystem::class);
            if ($fs->isAbsolutePath($configFile)) {
                $fileName = $configFile;
            } else {
                $fileName = BP . '/' . $configFile;
            }
            $realPath = realpath($fileName);
            if ($realPath) {
                Cascade::fileConfig($realPath);
                $this->_logger = Cascade::getLogger($loggerName);
            } else {
                $err = "Cannot open logging configuration file '$fileName'. Default Magento logger is used.";
            }
        } catch (\Exception $e) {
            $err = $e->getMessage();
        } finally {
            if (is_null($this->_logger)) {
                $this->_logger = $this->_obm->get(\Magento\Framework\Logger\Monolog::class);
                $this->warning($err);
            }
        }
    }
private function _initLoggerCascade($configFile, $loggerName)
    {
        $err = '';
        try {
            $fs = $this->_obm->get(Filesystem::class);
            if ($fs->isAbsolutePath($configFile)) {
                $fileName = $configFile;
            } else {
                $fileName = BP . '/' . $configFile;
            }
            $realPath = realpath($fileName);
            if ($realPath) {
                Cascade::fileConfig($realPath);
                $this->_logger = Cascade::getLogger($loggerName);
            } else {
                $err = "Cannot open logging configuration file '$fileName'. Default Magento logger is used.";
            }
        } catch (\Exception $e) {
            $err = $e->getMessage();
        } finally {
            if (is_null($this->_logger)) {
                $this->_logger = $this->_obm->get(\Magento\Framework\Logger\Monolog::class);
                $this->warning($err);
            }
        }
    }
Configure Cascaded Monolog logger and use it.

@param        $configFile
@param string $loggerName