Output metrics

Hi,
I would like to propose a feature (if it is not already present).
Add the metrics to the outputs too.

Working with graylog it is more and more required the system status, understood as **input / graylogs / output** and their **metrics**.
Nowadays it is possible to know if the inputs are active and their metrics, while the output we have just few information.

If we need to add an output to Amazon, for example, it is important to know how many messages are actually passing through (as some rules may discard some of them).

How would this scenario can be implemented currently?
Creating your own output and injecting a LocalMetricRegistry like the input implementation?

Thanks
Gianluca