Symfony2 monolog swift db spool config

config_stag.yml

swiftmailer:
    default_mailer: db
    mailers:
        db:
            transport: "%mailer_transport%"
            host:      "%mailer_host%"
            username:  "%mailer_user%"
            password:  "%mailer_password%"
            spool:     { type: db }
        memory:
            transport: "%mailer_transport%"
            host:      "%mailer_host%"
            username:  "%mailer_user%"
            password:  "%mailer_password%"
            spool:     { type: memory }

monolog:
    handlers:
        main:
            type:         fingers_crossed
            action_level: error
            handler:      grouped
        console:
            type:  console
        grouped:
            type:    group
            members: [streamed, buffered]
        streamed:
            type:  stream
            path:  '%kernel.logs_dir%/%kernel.environment%.log'
            level: debug
        buffered:
            type:    buffer
            action_level: critical
            handler: swift
        swift:
            type:       swift_mailer
            mailer:     swiftmailer.mailer.memory
            from_email: 'from@from'
            to_email:   'to@to'
            subject:    '[ERROR][STAG]'
            level:      debug

service.yml

    my.database.swift_mailer.spool:
        class: My\NotificationBundle\Spool\DatabaseSpool
        arguments: ['@repository.email', '%my_spool_config%']
        calls:
          - [setMessageLimit, ['%my_spool_message_limit%']]
    swiftmailer.spool.db:
        alias: my.database.swift_mailer.spool
    swiftmailer.mailer.default.spool.db:
        alias: my.database.swift_mailer.spool
    swiftmailer.mailer.db.spool.db:
        alias: my.database.swift_mailer.spool