671d170619
prometheus.Handler is deprecated according to the godoc for the package so instead we're using promhttp. Additionally, we are exposing the Registry that metrics is using so other plugins that are not inside of coredns can read the registry. Otherwise, if we kept using the Default one, there's no way to access that from outside of the coredns repo since it is vendored.
114 lines
2.6 KiB
Go
114 lines
2.6 KiB
Go
// Package metrics implement a handler and plugin that provides Prometheus metrics.
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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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"os"
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"sync"
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"github.com/coredns/coredns/plugin"
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"github.com/coredns/coredns/plugin/metrics/vars"
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"github.com/prometheus/client_golang/prometheus"
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"github.com/prometheus/client_golang/prometheus/promhttp"
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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 plugin.Handler
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Addr string
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Reg *prometheus.Registry
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ln net.Listener
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mux *http.ServeMux
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zoneNames []string
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zoneMap map[string]bool
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zoneMu sync.RWMutex
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}
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// New returns a new instance of Metrics with the given address
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func New(addr string) *Metrics {
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met := &Metrics{
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Addr: addr,
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Reg: prometheus.NewRegistry(),
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zoneMap: make(map[string]bool),
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}
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// Add the default collectors
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met.Reg.MustRegister(prometheus.NewGoCollector())
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met.Reg.MustRegister(prometheus.NewProcessCollector(os.Getpid(), ""))
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// Add all of our collectors
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met.Reg.MustRegister(vars.RequestCount)
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met.Reg.MustRegister(vars.RequestDuration)
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met.Reg.MustRegister(vars.RequestSize)
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met.Reg.MustRegister(vars.RequestDo)
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met.Reg.MustRegister(vars.RequestType)
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met.Reg.MustRegister(vars.ResponseSize)
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met.Reg.MustRegister(vars.ResponseRcode)
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return met
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}
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// AddZone adds zone z to m.
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func (m *Metrics) AddZone(z string) {
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m.zoneMu.Lock()
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m.zoneMap[z] = true
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m.zoneNames = keys(m.zoneMap)
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m.zoneMu.Unlock()
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}
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// RemoveZone remove zone z from m.
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func (m *Metrics) RemoveZone(z string) {
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m.zoneMu.Lock()
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delete(m.zoneMap, z)
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m.zoneNames = keys(m.zoneMap)
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m.zoneMu.Unlock()
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}
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// ZoneNames returns the zones of m.
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func (m *Metrics) ZoneNames() []string {
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m.zoneMu.RLock()
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s := m.zoneNames
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m.zoneMu.RUnlock()
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return s
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}
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// OnStartup sets up the metrics on startup.
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func (m *Metrics) OnStartup() error {
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ln, err := net.Listen("tcp", m.Addr)
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if err != nil {
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log.Printf("[ERROR] Failed to start metrics handler: %s", err)
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return err
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}
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m.ln = ln
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ListenAddr = m.ln.Addr().String()
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m.mux = http.NewServeMux()
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m.mux.Handle("/metrics", promhttp.HandlerFor(m.Reg, promhttp.HandlerOpts{}))
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go func() {
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http.Serve(m.ln, m.mux)
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}()
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return nil
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}
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// OnShutdown tears down the metrics on shutdown and restart.
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func (m *Metrics) OnShutdown() 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 keys(m map[string]bool) []string {
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sx := []string{}
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for k := range m {
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sx = append(sx, k)
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}
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return sx
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}
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// ListenAddr is assigned the address of the prometheus listener. Its use is mainly in tests where
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// we listen on "localhost:0" and need to retrieve the actual address.
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var ListenAddr string
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