Configuration 
The dsn key contains the connection string used to connect to your MongoDB deployment. The format and available options are documented in the MongoDB documentation.
Instead of using a connection string, you can also use the host and port configuration options to have the connection string created for you.
php
'mongodb' => [
    'driver' => 'mongodb',
    'host' => env('DB_HOST', '127.0.0.1'),
    'port' => env('DB_PORT', 27017),
    'database' => env('DB_DATABASE', 'homestead'),
    'username' => env('DB_USERNAME', 'homestead'),
    'password' => env('DB_PASSWORD', 'secret'),
    'options' => [
        'appname' => 'homestead',
    ],
],
The options key in the connection configuration corresponds to the uriOptions parameter.