zpool_influxdb produces InfluxDB-line-protocol-compatible metrics from
zpools.  Like the zpool command, zpool_influxdb reads the current pool
status and statistics.  Unlike the zpool command which is intended for
humans, zpool_influxdb formats the output in the InfluxDB line protocol.
The expected use is as a plugin to a metrics collector or aggregator,
such as Telegraf.