gnusocial/config/packages/messenger.yaml

framework:
    messenger:
        failure_transport: failed
        transports:
            failed: 'doctrine://default?queue_name=failed'
            high: '%env(MESSENGER_TRANSPORT_DSN_HIGH)%'
            low: '%env(MESSENGER_TRANSPORT_DSN_LOW)%'

        routing:
            'App\Core\Queue\MessageHigh': high
            'App\Core\Queue\MessageLow': low