Monolog loggger configuration for Graylog2 (Symfony2)

config.yml

services:
    gelf.udp.transport:
        class: Gelf\Transport\UdpTransport
    gelf.publisher:
        class: Gelf\Publisher
        arguments: [@gelf.udp.transport]
    monolog.gelf_handler:
        class: Monolog\Handler\GelfHandler
        arguments: [@gelf.publisher]
        
monolog:
    handlers:
        main:
            type:         fingers_crossed # or buffer
            level:        error
            handler:      gelf
        app:
            type:         buffer
            action_level: info
            channels:     app
            handler:      gelf
        deprecation:
            type:         buffer
            action_level: warning
            channels:     deprecation
            handler:      gelf
        gelf:
            type: service
            id: monolog.gelf_handler
            level: debug