ping.go

package main

import (
	"flag"
	"log"
	"net"
	"net/http"
	"strings"
	"time"

	"github.com/prometheus/client_golang/prometheus"
	"github.com/prometheus/client_golang/prometheus/promhttp"
	"github.com/tatsushid/go-fastping"
)

var pings *prometheus.HistogramVec

func init() {
	pings = prometheus.NewHistogramVec(prometheus.HistogramOpts{
		Name: "ping_seconds",
		Help: "Ping RTT in seconds",
		// Buckets: prometheus.LinearBuckets(*normMean-5**normDomain, .5**normDomain, 20),
	}, []string{"hostname"})
	prometheus.MustRegister(pings)
}

func ping(hostname string) error {
	p := fastping.NewPinger()
	defer p.Stop()

	netProto := "ip4:icmp"
	if strings.Index(hostname, ":") != -1 {
		netProto = "ip6:ipv6-icmp"
	}
	ra, err := net.ResolveIPAddr(netProto, hostname)
	if err != nil {
		return err
	}

	p.AddIPAddr(ra)

	p.OnRecv = func(addr *net.IPAddr, t time.Duration) {
		pings.With(prometheus.Labels{"hostname": hostname}).Observe(t.Seconds())
	}

	p.MaxRTT = 10 * time.Second
	t := time.NewTicker(10 * time.Second)
	for _ = range t.C {
		err := p.Run()
		if err != nil {
			return err
		}
	}

	return nil
}

func main() {
	var hosts, addr string

	flag.StringVar(&addr, "http.addr", ":6060", "http address")
	flag.StringVar(&hosts, "hosts", "1.1.1.1", "host to ping")
	flag.Parse()

	for _, hostname := range strings.Split(hosts, ",") {
		hostname := hostname
		go func() {
			err := ping(hostname)
			if err != nil {
				log.Fatal(err)
			}
		}()
	}

	// Expose the registered metrics via HTTP.
	http.Handle("/metrics", promhttp.Handler())
	log.Fatal(http.ListenAndServe(addr, nil))
}