Use Go error handler instead of panic, simplify the previous commit a…

… bit

collector.go

@@ -27,18 +27,13 @@ const (
 
 var (
 	labelNames = []string{"ip", "host"}
-
-	pingResponseSeconds *prometheus.HistogramVec
-
-	hasRegistered bool
 )
 
 func init() {
-	hasRegistered = false
 }
 
-func setHistogramOptions(buckets []float64) {
-	pingResponseSeconds = prometheus.NewHistogramVec(
+func newPingResponseHistogram(buckets []float64) **prometheus.HistogramVec {
+	pingResponseSeconds := prometheus.NewHistogramVec(
 		prometheus.HistogramOpts{
 			Namespace: namespace,
 			Name:      "response_duration_seconds",
@@ -47,14 +42,7 @@ func setHistogramOptions(buckets []float64) {
 		},
 		labelNames,
 	)
-}
-
-func registerMetrics() {
-	if hasRegistered {
-		panic("ERROR: called registerMetrics() twice\n")
-	}
-	prometheus.MustRegister(pingResponseSeconds)
-	hasRegistered = true
+	return &pingResponseSeconds
 }
 
 // SmokepingCollector collects metrics from the pinger.
@@ -64,7 +52,7 @@ type SmokepingCollector struct {
 	requestsSent *prometheus.Desc
 }
 
-func NewSmokepingCollector(pingers *[]*ping.Pinger) *SmokepingCollector {
+func NewSmokepingCollector(pingers *[]*ping.Pinger, pingResponseSeconds prometheus.HistogramVec) *SmokepingCollector {
 	for _, pinger := range *pingers {
 		pinger.OnRecv = func(pkt *ping.Packet) {
 			pingResponseSeconds.WithLabelValues(pkt.IPAddr.String(), pkt.Addr).Observe(pkt.Rtt.Seconds())

main.go

@@ -62,17 +62,17 @@ func init() {
 	prometheus.MustRegister(version.NewCollector("smokeping_prober"))
 }
 
-func parseBuckets(buckets *string) (bucketlist []float64) {
+func parseBuckets(buckets *string) ([]float64, error) {
 	bucketstrings := strings.Split(*buckets, ",")
-	bucketlist = make([]float64, len(bucketstrings))
+	bucketlist := make([]float64, len(bucketstrings))
 	for n := 0; n < len(bucketstrings); n++ {
 		value, err := strconv.ParseFloat(bucketstrings[n], 64)
 		if err != nil {
-			panic(err)
+			return nil, err
 		}
 		bucketlist[n] = value
 	}
-	return bucketlist
+	return bucketlist, nil
 }
 
 func main() {
@@ -97,10 +97,15 @@ func main() {
 	if len(*buckets) == 0 {
 		bucketlist = prometheus.ExponentialBuckets(0.00005, 2, 20)
 	} else {
-		bucketlist = parseBuckets(buckets)
+		var err error
+		bucketlist, err = parseBuckets(buckets)
+		if err != nil {
+			log.Errorf("ERROR: %s\n", err.Error())
+			return
+		}
 	}
-	setHistogramOptions(bucketlist)
-	registerMetrics()
+	pingResponseSeconds := newPingResponseHistogram(bucketlist)
+	prometheus.MustRegister(*pingResponseSeconds)
 
 	pingers := make([]*ping.Pinger, len(*hosts))
 	for i, host := range *hosts {
@@ -119,7 +124,7 @@ func main() {
 		pingers[i] = pinger
 	}
 
-	prometheus.MustRegister(NewSmokepingCollector(&pingers))
+	prometheus.MustRegister(NewSmokepingCollector(&pingers, **pingResponseSeconds))
 
 	http.Handle(*metricsPath, promhttp.Handler())
 	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {