Some monitoring refactoring

middleware/prometheus/handler.go

 package metrics
 
 import (
-	"strconv"
 	"time"
 
 	"golang.org/x/net/context"
@@ -12,7 +11,6 @@ import (
 
 func (m Metrics) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
 	state := middleware.State{W: w, Req: r}
-
 	qname := state.Name()
 	qtype := state.Type()
 	zone := middleware.Zones(m.ZoneNames).Matches(qname)
@@ -24,10 +22,14 @@ func (m Metrics) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg)
 	rw := middleware.NewResponseRecorder(w)
 	status, err := m.Next.ServeDNS(ctx, rw, r)
 
+	m.Report(zone, qtype, rw)
+
+	return status, err
+}
+
+func (m Metrics) Report(zone, qtype string, rw *middleware.ResponseRecorder) {
 	requestCount.WithLabelValues(zone, qtype).Inc()
 	requestDuration.WithLabelValues(zone, qtype).Observe(float64(time.Since(rw.Start()) / time.Second))
 	responseSize.WithLabelValues(zone, qtype).Observe(float64(rw.Size()))
-	responseRcode.WithLabelValues(zone, strconv.Itoa(rw.Rcode()), qtype).Inc()
-
-	return status, err
+	responseRcode.WithLabelValues(zone, rw.Rcode(), qtype).Inc()
 }

middleware/prometheus/metrics.go

@@ -62,7 +62,7 @@ func define(subsystem string) {
 		Namespace: namespace,
 		Subsystem: subsystem,
 		Name:      "request_duration_seconds",
-		Buckets:   append([]float64{0, 0001, 0.0005, 0.001, 0.0025}, prometheus.DefBuckets...),
+		Buckets:   append([]float64{.0001, .0005, .001, .0025}, prometheus.DefBuckets...),
 		Help:      "Histogram of the time (in seconds) each request took.",
 	}, []string{"zone", "qtype"})
 

middleware/recorder.go

 package middleware
 
 import (
+	"strconv"
 	"time"
 
 	"github.com/miekg/dns"
@@ -58,8 +59,11 @@ func (r *ResponseRecorder) Size() int {
 }
 
 // Rcode returns the rcode.
-func (r *ResponseRecorder) Rcode() int {
-	return r.rcode
+func (r *ResponseRecorder) Rcode() string {
+	if rcode, ok := dns.RcodeToString[r.rcode]; ok {
+		return rcode
+	}
+	return "RCODE" + strconv.Itoa(r.rcode)
 }
 
 // Start returns the start time of the ResponseRecorder.