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https://github.com/coredns/coredns.git
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9e9d72655d
Make middleware that sets up a (http) handler survive a graceful restart. We calls the middleware's Shutdown function(s). If restart fails the Start function is called again. * middleware/health: OK * middleware/pprof: OK * middleware/metrics: OK All restart OK.
102 lines
2.6 KiB
Go
102 lines
2.6 KiB
Go
package metrics
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import (
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"log"
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"net"
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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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// 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
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ln net.Listener
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mux *http.ServeMux
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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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if ln, err := net.Listen("tcp", m.Addr); err != nil {
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log.Printf("[ERROR] Failed to start metrics handler: %s", err)
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return
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} else {
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m.ln = ln
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}
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m.mux = http.NewServeMux()
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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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m.mux.Handle(path, prometheus.Handler())
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go func() {
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http.Serve(m.ln, m.mux)
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}()
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})
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return nil
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}
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func (m *Metrics) Shutdown() error {
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if m.ln != nil {
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return m.ln.Close()
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}
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return nil
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}
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func define() {
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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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path = "/metrics"
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)
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