Feature Request to resolve Virtual-IPs to Hostnames in ipvs collector

node_exporter version: 0.15.2

Feature request for the collector ipvs:

• Option to resolve Virtual-IPs to hostnames

Currently the ipvs collector provides Virtual IPs associated to Real-server IPs, and I set up a dashboard in Grafana with a multitude of label_replace to show off the Virtual IPs as hostnames. What about a flag for ipvs to resolve the IPs?

For example:

# curl -s <SERVER>:9100/metrics
# HELP node_ipvs_backend_connections_active The current active connections by local and remote address.
# TYPE node_ipvs_backend_connections_active gauge
node_ipvs_backend_connections_active{local_address="<VIRTUAL-IP>",local_port="443",proto="TCP",remote_address="<IP-REAL-SERVER>",remote_port="443"} 0
[...]

The collector could have an option to provide both fields local_address and local_fqdn:

node_ipvs_backend_connections_active{local_address="<VIRTUAL-IP>",local_fqdn="<FQDN>",local_port="443",proto="TCP",remote_address="<IP-REAL-SERVER>",remote_port="443"} 0

Start at the ipvs collector and inspect the node_ipvs_backend_connections_active metrics exposed by the /metrics endpoint. Determine how an optional resolution setting should add local_fqdn alongside local_address, and verify that the collector produces both labels when enabled.