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|
package metrics
import (
"log"
"net"
"net/http"
"sync"
"github.com/miekg/coredns/middleware"
"github.com/prometheus/client_golang/prometheus"
)
var (
requestCount *prometheus.CounterVec
requestDuration *prometheus.HistogramVec
responseSize *prometheus.HistogramVec
responseRcode *prometheus.CounterVec
)
// Metrics holds the prometheus configuration. The metrics' path is fixed to be /metrics
type Metrics struct {
Next middleware.Handler
Addr string
ln net.Listener
mux *http.ServeMux
Once sync.Once
ZoneNames []string
}
func (m *Metrics) Start() error {
m.Once.Do(func() {
define()
if ln, err := net.Listen("tcp", m.Addr); err != nil {
log.Printf("[ERROR] Failed to start metrics handler: %s", err)
return
} else {
m.ln = ln
}
m.mux = http.NewServeMux()
prometheus.MustRegister(requestCount)
prometheus.MustRegister(requestDuration)
prometheus.MustRegister(responseSize)
prometheus.MustRegister(responseRcode)
m.mux.Handle(path, prometheus.Handler())
go func() {
http.Serve(m.ln, m.mux)
}()
})
return nil
}
func (m *Metrics) Shutdown() error {
if m.ln != nil {
return m.ln.Close()
}
return nil
}
func define() {
requestCount = prometheus.NewCounterVec(prometheus.CounterOpts{
Namespace: middleware.Namespace,
Subsystem: subsystem,
Name: "request_count_total",
Help: "Counter of DNS requests made per zone and protocol.",
}, []string{"zone", "proto"})
requestDuration = prometheus.NewHistogramVec(prometheus.HistogramOpts{
Namespace: middleware.Namespace,
Subsystem: subsystem,
Name: "request_duration_seconds",
Buckets: append([]float64{.0001, .0005, .001, .0025}, prometheus.DefBuckets...),
Help: "Histogram of the time (in seconds) each request took.",
}, []string{"zone"})
responseSize = prometheus.NewHistogramVec(prometheus.HistogramOpts{
Namespace: middleware.Namespace,
Subsystem: subsystem,
Name: "response_size_bytes",
Help: "Size of the returns response in bytes.",
Buckets: []float64{0, 100, 200, 300, 400, 511, 1023, 2047, 4095, 8291, 16e3, 32e3, 48e3, 64e3},
}, []string{"zone"})
responseRcode = prometheus.NewCounterVec(prometheus.CounterOpts{
Namespace: middleware.Namespace,
Subsystem: subsystem,
Name: "response_rcode_count_total",
Help: "Counter of response status codes.",
}, []string{"zone", "rcode"})
}
const (
// Dropped indicates we dropped the query before any handling. It has no closing dot, so it can not be a valid zone.
Dropped = "dropped"
subsystem = "dns"
path = "/metrics"
)
|
