Update timing histograms (#1253)

* Use seconds for bucketing.
* Add template for high accuracy timing buckets to avoid copy-pasta.

plugin/metrics/vars/report.go

@@ -20,7 +20,7 @@ func Report(req request.Request, zone, rcode string, size int, start time.Time)
 	typ := req.QType()
 
 	RequestCount.WithLabelValues(zone, net, fam).Inc()
-	RequestDuration.WithLabelValues(zone).Observe(float64(time.Since(start) / time.Millisecond))
+	RequestDuration.WithLabelValues(zone).Observe(time.Since(start).Seconds())
 
 	if req.Do() {
 		RequestDo.WithLabelValues(zone).Inc()

plugin/metrics/vars/vars.go

@@ -18,9 +18,9 @@ var (
 	RequestDuration = prometheus.NewHistogramVec(prometheus.HistogramOpts{
 		Namespace: plugin.Namespace,
 		Subsystem: subsystem,
-		Name:      "request_duration_milliseconds",
-		Buckets:   append(prometheus.DefBuckets, []float64{50, 100, 200, 500, 1000, 2000, 3000, 4000, 5000, 10000}...),
-		Help:      "Histogram of the time (in milliseconds) each request took.",
+		Name:      "request_duration_seconds",
+		Buckets:   plugin.TimeBuckets,
+		Help:      "Histogram of the time (in seconds) each request took.",
 	}, []string{"zone"})
 
 	RequestSize = prometheus.NewHistogramVec(prometheus.HistogramOpts{

plugin/plugin.go

@@ -100,3 +100,6 @@ func ClientWrite(rcode int) bool {
 
 // Namespace is the namespace used for the metrics.
 const Namespace = "coredns"
+
+// TimeBuckets is based on Prometheus client_golang prometheus.DefBuckets
+var TimeBuckets = []float64{0.00025, 0.0005, 0.001, 0.0025, .005, .01, .025, .05, .1, .25, .5, 1, 2.5, 5, 10}

plugin/proxy/metrics.go

@@ -19,9 +19,9 @@ var (
 	RequestDuration = prometheus.NewHistogramVec(prometheus.HistogramOpts{
 		Namespace: plugin.Namespace,
 		Subsystem: "proxy",
-		Name:      "request_duration_milliseconds",
-		Buckets:   append(prometheus.DefBuckets, []float64{15, 20, 25, 30, 40, 50, 100, 200, 500, 1000, 2000, 3000, 4000, 5000, 10000}...),
-		Help:      "Histogram of the time (in milliseconds) each request took.",
+		Name:      "request_duration_seconds",
+		Buckets:   plugin.TimeBuckets,
+		Help:      "Histogram of the time (in seconds) each request took.",
 	}, []string{"proto", "proxy_proto", "family", "to"})
 )