Forecast alert for disk space for hundreds of machines


our Grafana (6.0.1) connects to an InfluxDB which is fed by collectd from each of our servers.
We would like to monitor used disk space for every machine and get alerted 24 hours prior to a filled up disk.
This is our select statement:
SELECT mean("value") as current, derivative(mean("value"), 6h) + mean("value") as forecast FROM "ten_min"."df_value" WHERE ("type" = 'percent_bytes' AND "type_instance" = 'used') AND $timeFilter GROUP BY time($__interval), "host", "instance" fill(none)
It generates two graphs for each FS. One with the actual disk usage and one interpolation by growth over the past 6 hours.

Grafana’s man page clearly states that it is not possible to use templates in such a query if you’d like to receive alerts.

There are over 200 servers in our InfluxDB.
How can I set up an alert for all filesystems on each server without manually creating a graph for every server?

Thanks in advance.