Prometheus exporter reporting ethminer hashrate

$ make build

$ bin/ethminer_exporter

By default, ethminer_exporter starts listening on port 8555. Then, visit https://localhost:8555/metrics?target=1.2.3.4:1234 where 1.2.3.4 is the IP of target ethmier host and 1234 is the JSON-RPC port ethminer listening. To enable JSON-RPC API for ethminer, you need to run with --api-port and specify listening port. If they are specified correctly, ethminer_exporter reports its total hashrate at that time.

# HELP ethminer_totalhashrate Hashrate [H/s]
# TYPE ethminer_totalhashrate gauge
ethminer_totalhashrate 3.77168217e+08