Laravel 5.6 salvar Logger no mongo

Pessoal ,

Como posso fazer no laravel 5.6 , um canal especifico para salvar os logs no mongodb ? Nao estou conseguindo  meu configo/logging.php

<?php
use Monolog\Handler\StreamHandler;

return [
 'default' => env('LOG_CHANNEL', 'stack'),

 'channels' => [
 'stack' => [
 'driver' => 'stack',
 'channels' => ['custom' , 'slack'],
 ],

 'insightops' => [
 'driver' => 'monolog',
 'handler' => Monolog\Handler\SyslogUdpHandler::class,
 'handler_with' => [
 'token' => env('LOGENTRIES_TOKEN'),
 'host' => 'us.data.logs.insight.rapid7.com',
 'port' => '10000',
 ],
 ],

 'slack' => [
 'driver' => 'slack',
 'url' => env('LOG_SLACK_WEBHOOK_URL'),
 'username' => 'Laravel Log',
 'emoji' => ':boom:',
 'level' => 'critical',
 ],
 'daily' => [
 'driver' => 'daily',
 'path' => storage_path('logs/laravel.log'),
 'level' => 'debug',
 'days' => 7,
 ],
 'custom' => [
 'driver' => 'custom',
 'via' => App\Logging\LogentriesLogger::class,
 'level' => 'debug',
 ],
 'stderr' => [
 'driver' => 'monolog',
 'handler' => StreamHandler::class,
 'with' => [
 'stream' => 'php://stderr',
 ],
 ],
 'syslog' => [
 'driver' => 'syslog',
 'level' => 'debug',
 ],
 'errorlog' => [
 'driver' => 'errorlog',
 'level' => 'debug',
 ],
 ],
];

	E meu log customizado

	 

	 

<?php

namespace App\Logging;

use Monolog\Handler\MongoDBHandler;
use Monolog\Logger;
use MongoDB\Client;
use App\Adapters\LoggerAdapter;

class LogentriesLogger
{

/**
* Create a custom Monolog instance.
*
* @param array $config
* @return \Monolog\Logger
*/

 public function __invoke(array $config)
 {

 $log = new Logger('application');
 $mongodb = new MongoDBHandler(new Client('mongodb://' . config('database.connections.mongodb.host') . ':' . config('database.connections.mongodb.port')), config('database.connections.mongodb.database'), 'logs', LoggerAdapter::INFO);

 var_dump($log);
 die;
 //$log->pushHandler('teste',$mongodb);

 }
}

	Nao sei como pegar a mensagem de log para inserir no mongo , me ajudem please.