[dnsdist] dnsdist metrics

[Winfried Angele]

Hi Simone,

> Is there a way to get QPS and/or metrics per seconds? Or I have to 
> manipulate data (how?)?

We use the non-negative-derivative "transformation" in InfluxQL:

https://docs.influxdata.com/influxdb/v1.8/query_language/functions/#non-negative-derivative

Something like:
SELECT non_negative_derivative(max("queries"), 1s) FROM "dnsdist" WHERE 
$timeFilter GROUP BY time($__interval)

Winfried