init

Dockerfile

@@ -0,0 +1,8 @@
+FROM golang:1.25
+WORKDIR /app
+COPY go.* ./
+RUN go mod download
+COPY *.go ./
+RUN CGO_ENABLED=0 GOOS=linux go build -o /goprg
+EXPOSE 8080
+CMD ["/goprg"]

compose.yml

@@ -0,0 +1,15 @@
+version: "3.8"
+
+services:
+  ping-exporter:
+    image: ping-exporter:latest
+    container_name: ping-exporter
+    volumes:
+      - ./config.yaml:/config.yaml:ro
+    ports:
+      - "9101:9101"
+    # Variante 1: mit Cap
+    cap_add:
+      - NET_RAW
+      - NET_ADMIN
+    command: ["-config", "/config.yaml"]

config.go

@@ -0,0 +1,66 @@
+package main
+
+import (
+	"os"
+	"time"
+
+	"gopkg.in/yaml.v3"
+)
+
+type Config struct {
+	ListenAddr string         `yaml:"listen_addr"`
+	Defaults   TargetSettings `yaml:"defaults"`
+	Targets    []TargetConfig `yaml:"targets"`
+}
+
+type TargetSettings struct {
+	Interval    time.Duration `yaml:"interval"`
+	Timeout     time.Duration `yaml:"timeout"`
+	Size        int           `yaml:"size"`
+	HistorySize int           `yaml:"history_size"`
+	DNSServer   string        `yaml:"dns_server"`
+	DisableIPv6 bool          `yaml:"disable_ipv6"`
+}
+
+type TargetConfig struct {
+	Name string `yaml:"name"`
+	Host string `yaml:"host"`
+
+	// optional overrides
+	Interval    *time.Duration `yaml:"interval"`
+	Timeout     *time.Duration `yaml:"timeout"`
+	Size        *int           `yaml:"size"`
+	HistorySize *int           `yaml:"history_size"`
+	DNSServer   *string        `yaml:"dns_server"`
+	DisableIPv6 *bool          `yaml:"disable_ipv6"`
+}
+
+func LoadConfig(path string) (*Config, error) {
+	b, err := os.ReadFile(path)
+	if err != nil {
+		return nil, err
+	}
+	var cfg Config
+	if err := yaml.Unmarshal(b, &cfg); err != nil {
+		return nil, err
+	}
+
+	// defaults setzen, falls nicht da
+	if cfg.ListenAddr == "" {
+		cfg.ListenAddr = ":9101"
+	}
+	if cfg.Defaults.Interval == 0 {
+		cfg.Defaults.Interval = 5 * time.Second
+	}
+	if cfg.Defaults.Timeout == 0 {
+		cfg.Defaults.Timeout = 1 * time.Second
+	}
+	if cfg.Defaults.Size == 0 {
+		cfg.Defaults.Size = 56
+	}
+	if cfg.Defaults.HistorySize == 0 {
+		cfg.Defaults.HistorySize = 10
+	}
+
+	return &cfg, nil
+}

exporter.go

@@ -0,0 +1,135 @@
+package main
+
+import (
+	"log"
+	"sync"
+	"time"
+
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+type TargetRunner struct {
+	name   string
+	host   string
+	config TargetSettings
+
+	history []float64
+	hidx    int
+	mu      sync.Mutex
+}
+
+func NewTargetRunner(name, host string, cfg TargetSettings) *TargetRunner {
+	return &TargetRunner{
+		name:    name,
+		host:    host,
+		config:  cfg,
+		history: make([]float64, cfg.HistorySize),
+	}
+}
+
+// Prometheus-Metrics
+var (
+	pingUp = prometheus.NewGaugeVec(
+		prometheus.GaugeOpts{
+			Name: "ping_up",
+			Help: "Whether the last ping was successful (1) or not (0)",
+		},
+		[]string{"target"},
+	)
+	pingRTT = prometheus.NewGaugeVec(
+		prometheus.GaugeOpts{
+			Name: "ping_rtt_seconds",
+			Help: "Last ping round trip time in seconds",
+		},
+		[]string{"target"},
+	)
+	pingRTTAvg = prometheus.NewGaugeVec(
+		prometheus.GaugeOpts{
+			Name: "ping_rtt_seconds_avg",
+			Help: "Average ping round trip time in seconds (over history)",
+		},
+		[]string{"target"},
+	)
+	pingPacketsSent = prometheus.NewCounterVec(
+		prometheus.CounterOpts{
+			Name: "ping_packets_sent_total",
+			Help: "Total number of ping packets sent",
+		},
+		[]string{"target"},
+	)
+	pingPacketsRecv = prometheus.NewCounterVec(
+		prometheus.CounterOpts{
+			Name: "ping_packets_received_total",
+			Help: "Total number of ping packets received",
+		},
+		[]string{"target"},
+	)
+)
+
+func init() {
+	prometheus.MustRegister(pingUp, pingRTT, pingRTTAvg, pingPacketsSent, pingPacketsRecv)
+}
+
+func (t *TargetRunner) Run(stop <-chan struct{}) {
+	lbl := prometheus.Labels{"target": t.name}
+
+	ticker := time.NewTicker(t.config.Interval)
+	defer ticker.Stop()
+
+	for {
+		select {
+		case <-ticker.C:
+			pingPacketsSent.With(lbl).Inc()
+
+			res := doPing(t.host, PingOptions{
+				Timeout:     t.config.Timeout,
+				Size:        t.config.Size,
+				DisableIPv6: t.config.DisableIPv6,
+				DNSServer:   t.config.DNSServer,
+			})
+
+			if res.Alive {
+				pingUp.With(lbl).Set(1)
+				pingPacketsRecv.With(lbl).Inc()
+
+				sec := res.RTT.Seconds()
+				pingRTT.With(lbl).Set(sec)
+
+				avg := t.addToHistoryAndAvg(sec)
+				pingRTTAvg.With(lbl).Set(avg)
+			} else {
+				pingUp.With(lbl).Set(0)
+				// RTT nicht ändern oder auf 0 setzen?
+				pingRTT.With(lbl).Set(0)
+				log.Printf("ping to %s failed: %v", t.name, res.Err)
+			}
+		case <-stop:
+			return
+		}
+	}
+}
+
+func (t *TargetRunner) addToHistoryAndAvg(v float64) float64 {
+	t.mu.Lock()
+	defer t.mu.Unlock()
+
+	if len(t.history) == 0 {
+		return v
+	}
+
+	t.history[t.hidx] = v
+	t.hidx = (t.hidx + 1) % len(t.history)
+
+	var sum float64
+	var cnt int
+	for _, x := range t.history {
+		if x > 0 {
+			sum += x
+			cnt++
+		}
+	}
+	if cnt == 0 {
+		return 0
+	}
+	return sum / float64(cnt)
+}

go.mod

@@ -0,0 +1,31 @@
+module git.send.nrw/sendnrw/prom-ping
+
+go 1.25.3
+
+require (
+	github.com/prometheus-community/pro-bing v0.7.0
+	gopkg.in/yaml.v3 v3.0.1
+)
+
+require (
+	github.com/beorn7/perks v1.0.1 // indirect
+	github.com/cespare/xxhash/v2 v2.3.0 // indirect
+	github.com/kr/text v0.2.0 // indirect
+	github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 // indirect
+	github.com/prometheus/client_model v0.6.2 // indirect
+	github.com/prometheus/common v0.66.1 // indirect
+	github.com/prometheus/procfs v0.16.1 // indirect
+	go.yaml.in/yaml/v2 v2.4.2 // indirect
+	golang.org/x/mod v0.24.0 // indirect
+	golang.org/x/tools v0.33.0 // indirect
+	google.golang.org/protobuf v1.36.8 // indirect
+)
+
+require (
+	github.com/google/uuid v1.6.0 // indirect
+	github.com/miekg/dns v1.1.68
+	github.com/prometheus/client_golang v1.23.2
+	golang.org/x/net v0.43.0 // indirect
+	golang.org/x/sync v0.14.0 // indirect
+	golang.org/x/sys v0.35.0 // indirect
+)

go.sum

@@ -0,0 +1,60 @@
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+github.com/beorn7/perks v1.0.1/go.mod h1:G2ZrVWU2WbWT9wwq4/hrbKbnv/1ERSJQ0ibhJ6rlkpw=
+github.com/cespare/xxhash/v2 v2.3.0 h1:UL815xU9SqsFlibzuggzjXhog7bL6oX9BbNZnL2UFvs=
+github.com/cespare/xxhash/v2 v2.3.0/go.mod h1:VGX0DQ3Q6kWi7AoAeZDth3/j3BFtOZR5XLFGgcrjCOs=
+github.com/creack/pty v1.1.9/go.mod h1:oKZEueFk5CKHvIhNR5MUki03XCEU+Q6VDXinZuGJ33E=
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/google/go-cmp v0.7.0 h1:wk8382ETsv4JYUZwIsn6YpYiWiBsYLSJiTsyBybVuN8=
+github.com/google/go-cmp v0.7.0/go.mod h1:pXiqmnSA92OHEEa9HXL2W4E7lf9JzCmGVUdgjX3N/iU=
+github.com/google/uuid v1.6.0 h1:NIvaJDMOsjHA8n1jAhLSgzrAzy1Hgr+hNrb57e+94F0=
+github.com/google/uuid v1.6.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
+github.com/klauspost/compress v1.18.0 h1:c/Cqfb0r+Yi+JtIEq73FWXVkRonBlf0CRNYc8Zttxdo=
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+github.com/kr/pretty v0.3.1 h1:flRD4NNwYAUpkphVc1HcthR4KEIFJ65n8Mw5qdRn3LE=
+github.com/kr/pretty v0.3.1/go.mod h1:hoEshYVHaxMs3cyo3Yncou5ZscifuDolrwPKZanG3xk=
+github.com/kr/text v0.2.0 h1:5Nx0Ya0ZqY2ygV366QzturHI13Jq95ApcVaJBhpS+AY=
+github.com/kr/text v0.2.0/go.mod h1:eLer722TekiGuMkidMxC/pM04lWEeraHUUmBw8l2grE=
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+gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c h1:Hei/4ADfdWqJk1ZMxUNpqntNwaWcugrBjAiHlqqRiVk=
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main.go

@@ -0,0 +1,72 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"log"
+	"net/http"
+	"os"
+	"os/signal"
+	"syscall"
+
+	"github.com/prometheus/client_golang/prometheus/promhttp"
+)
+
+func main() {
+	cfgFile := flag.String("config", "config.yaml", "path to config file")
+	flag.Parse()
+
+	cfg, err := LoadConfig(*cfgFile)
+	if err != nil {
+		log.Fatalf("error loading config: %v", err)
+	}
+
+	// HTTP server für Prometheus
+	http.Handle("/metrics", promhttp.Handler())
+	go func() {
+		log.Printf("listening on %s", cfg.ListenAddr)
+		if err := http.ListenAndServe(cfg.ListenAddr, nil); err != nil {
+			log.Fatalf("http server error: %v", err)
+		}
+	}()
+
+	// Targets starten
+	stop := make(chan struct{})
+	for _, t := range cfg.Targets {
+		settings := mergeSettings(cfg.Defaults, t)
+		r := NewTargetRunner(t.Name, t.Host, settings)
+		go r.Run(stop)
+	}
+
+	// sauber beenden
+	sig := make(chan os.Signal, 1)
+	signal.Notify(sig, os.Interrupt, syscall.SIGTERM)
+	<-sig
+	close(stop)
+	fmt.Println("shutting down...")
+}
+
+func mergeSettings(def TargetSettings, t TargetConfig) TargetSettings {
+	out := def
+
+	if t.Interval != nil {
+		out.Interval = *t.Interval
+	}
+	if t.Timeout != nil {
+		out.Timeout = *t.Timeout
+	}
+	if t.Size != nil {
+		out.Size = *t.Size
+	}
+	if t.HistorySize != nil {
+		out.HistorySize = *t.HistorySize
+	}
+	if t.DNSServer != nil {
+		out.DNSServer = *t.DNSServer
+	}
+	if t.DisableIPv6 != nil {
+		out.DisableIPv6 = *t.DisableIPv6
+	}
+
+	return out
+}

pinger.go

@@ -0,0 +1,116 @@
+package main
+
+import (
+	"errors"
+	"net"
+	"time"
+
+	"github.com/miekg/dns"
+	probing "github.com/prometheus-community/pro-bing"
+)
+
+type PingResult struct {
+	RTT   time.Duration
+	Alive bool
+	Err   error
+	IP    string
+}
+
+type PingOptions struct {
+	Timeout     time.Duration
+	Size        int
+	DisableIPv6 bool
+	DNSServer   string
+}
+
+func resolveWithCustomDNS(server, host string) (string, error) {
+	c := new(dns.Client)
+	m := new(dns.Msg)
+	m.SetQuestion(dns.Fqdn(host), dns.TypeA)
+
+	resp, _, err := c.Exchange(m, server)
+	if err != nil {
+		return "", err
+	}
+
+	for _, ans := range resp.Answer {
+		if a, ok := ans.(*dns.A); ok {
+			return a.A.String(), nil
+		}
+	}
+
+	return "", errors.New("no A record found")
+}
+
+func resolveHost(host, dnsServer string, disableIPv6 bool) (string, error) {
+	if ip := net.ParseIP(host); ip != nil {
+		return host, nil
+	}
+
+	if dnsServer != "" {
+		if _, _, err := net.SplitHostPort(dnsServer); err != nil {
+			dnsServer = net.JoinHostPort(dnsServer, "53")
+		}
+		return resolveWithCustomDNS(dnsServer, host)
+	}
+
+	if disableIPv6 {
+		ips, err := net.LookupIP(host)
+		if err != nil {
+			return "", err
+		}
+		for _, ip := range ips {
+			if ip.To4() != nil {
+				return ip.String(), nil
+			}
+		}
+		return "", errors.New("no IPv4 address found")
+	}
+
+	ip, err := net.ResolveIPAddr("ip", host)
+	if err != nil {
+		return "", err
+	}
+	return ip.IP.String(), nil
+}
+
+func doPing(host string, opts PingOptions) PingResult {
+	ip, err := resolveHost(host, opts.DNSServer, opts.DisableIPv6)
+	if err != nil {
+		return PingResult{Alive: false, Err: err}
+	}
+
+	pinger, err := probing.NewPinger(ip)
+	if err != nil {
+		return PingResult{Alive: false, Err: err, IP: ip}
+	}
+
+	if opts.DisableIPv6 {
+		pinger.SetNetwork("ip4")
+	}
+
+	pinger.Count = 1
+	pinger.Timeout = opts.Timeout
+	pinger.Size = opts.Size
+
+	// falls du im Container kein CAP_NET_RAW gibst:
+	pinger.SetPrivileged(false) // oder aus Config
+	// wenn du CAP_NET_RAW vergibst:
+	// pinger.SetPrivileged(true)
+
+	if err := pinger.Run(); err != nil {
+		return PingResult{Alive: false, Err: err, IP: ip}
+	}
+
+	stats := pinger.Statistics()
+	if stats.PacketsRecv < 1 {
+		return PingResult{Alive: false, Err: errors.New("no reply"), IP: ip}
+	}
+
+	return PingResult{
+		RTT:   stats.AvgRtt,
+		Alive: true,
+		IP:    ip,
+	}
+
+}