a412255ad1
Add prometheus metrics to the cache handler. This just used prometheus, if the metrics middleware does not setup the handler, there is nobody reading these metrics, but they are still reported. Seems the simplest solution while keeping the whole middleware separation in tact.
86 lines
2.4 KiB
Go
86 lines
2.4 KiB
Go
package metrics
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import (
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"log"
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"net/http"
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"sync"
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"github.com/miekg/coredns/middleware"
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"github.com/prometheus/client_golang/prometheus"
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)
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var (
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requestCount *prometheus.CounterVec
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requestDuration *prometheus.HistogramVec
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responseSize *prometheus.HistogramVec
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responseRcode *prometheus.CounterVec
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)
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const path = "/metrics"
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// Metrics holds the prometheus configuration. The metrics' path is fixed to be /metrics
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type Metrics struct {
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Next middleware.Handler
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Addr string // where to we listen
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Once sync.Once
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ZoneNames []string
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}
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func (m *Metrics) Start() error {
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m.Once.Do(func() {
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define("")
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prometheus.MustRegister(requestCount)
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prometheus.MustRegister(requestDuration)
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prometheus.MustRegister(responseSize)
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prometheus.MustRegister(responseRcode)
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http.Handle(path, prometheus.Handler())
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go func() {
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if err := http.ListenAndServe(m.Addr, nil); err != nil {
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log.Printf("[ERROR] Failed to start prometheus handler: %s", err)
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}
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}()
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})
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return nil
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}
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func define(subsystem string) {
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requestCount = prometheus.NewCounterVec(prometheus.CounterOpts{
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Namespace: middleware.Namespace,
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Subsystem: subsystem,
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Name: "request_count_total",
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Help: "Counter of DNS requests made per zone and protocol.",
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}, []string{"zone", "proto"})
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requestDuration = prometheus.NewHistogramVec(prometheus.HistogramOpts{
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Namespace: middleware.Namespace,
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Subsystem: subsystem,
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Name: "request_duration_seconds",
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Buckets: append([]float64{.0001, .0005, .001, .0025}, prometheus.DefBuckets...),
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Help: "Histogram of the time (in seconds) each request took.",
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}, []string{"zone"})
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responseSize = prometheus.NewHistogramVec(prometheus.HistogramOpts{
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Namespace: middleware.Namespace,
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Subsystem: subsystem,
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Name: "response_size_bytes",
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Help: "Size of the returns response in bytes.",
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Buckets: []float64{0, 100, 200, 300, 400, 511, 1023, 2047, 4095, 8291, 16e3, 32e3, 48e3, 64e3},
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}, []string{"zone"})
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responseRcode = prometheus.NewCounterVec(prometheus.CounterOpts{
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Namespace: middleware.Namespace,
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Subsystem: subsystem,
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Name: "response_rcode_count_total",
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Help: "Counter of response status codes.",
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}, []string{"zone", "rcode"})
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}
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const (
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// Dropped indicates we dropped the query before any handling. It has no closing dot, so it can not be a valid zone.
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Dropped = "dropped"
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subsystem = "dns"
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)
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