...
'components' => [
    'log' => [
        'traceLevel' => YII_DEBUG ? 3 : 0,
        'targets' => [
            [
                'class' => 'bilberrry\log\FluentdTarget',
                'levels' => ['error', 'warning'], // Log levels
                'host' => 'localhost', // Fluentd host
                'port' => '24224', // Fluentd port
                'options' => [], // Options for Fluentd client
                'tagFormat' => 'app.%level' // Tag format, available placeholders: %date, %timestamp, %level
            ],
        ],
    ],
...