Thanks for the helping hand, Giovanni.
I believe my first problem was understanding which VM in my InfluxDB Enterprise install was the correct one to use for the [[outputs.influxdb]] config in telegraf.conf.
I believe the load balancer is the right one. In my Azure install, the load balancer front-end (LBFE) has a private IP, 10.0.0.100. So I now have this in telegraf.conf
urls = [“http://10.0.0.100:8086”]
…and I am now seeing activity in /var/log/telegraf/telegraf.log. In other words log entries seem to appear synchronously with measurement writing attempts. I think telegraf.conf is good now
But I believe I have some networking problem now, writing attempts are failing and timing-out:
2020-11-11T17:08:51Z E! [agent] Error writing to outputs.influxdb: could not write any address
2020-11-11T17:08:56Z W! [outputs.influxdb] When writing to [ht_p://10.0.0.100:8086]: database “cdr” creation failed: Post ht_p://10.0.0.100:8086/query: net/ht
tp: request canceled while waiting for connection (Client.Timeout exceeded while awaiting headers)
2020-11-11T17:09:01Z W! [agent] [“outputs.influxdb”] did not complete within its flush interval
2020-11-11T17:09:01Z D! [outputs.influxdb] Buffer fullness: 1670 / 10000 metrics
2020-11-11T17:09:01Z E! [outputs.influxdb] When writing to [ht_p://10.0.0.100:8086]: Post http://10.0.0.100:8086/write?db=cdr: net/http: request canceled whil
e waiting for connection (Client.Timeout exceeded while awaiting headers)
This may be the firewall problem you were anticipating
I will continue to debug. This was a plain vanilla installation of InfluxDB Enterprise from the Azure Marketplace; I was hoping for a more plug-and-play experience. If anyone has had these problems before and cares to share, thank you in advance.