26d1432ae6
* Update all plugins to use plugin/pkg/log I wish this could have been done with sed. Alas manually changed all callers to use the new plugin/pkg/log package. * Error -> Info * Add docs to debug plugin as well
135 lines
3.4 KiB
Go
135 lines
3.4 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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"net"
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"net/http"
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"os"
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"runtime"
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"sync"
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"github.com/coredns/coredns/coremain"
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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/coredns/coredns/plugin/pkg/log"
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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.MustRegister(prometheus.NewGoCollector())
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met.MustRegister(prometheus.NewProcessCollector(os.Getpid(), ""))
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// Add all of our collectors
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met.MustRegister(buildInfo)
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met.MustRegister(vars.RequestCount)
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met.MustRegister(vars.RequestDuration)
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met.MustRegister(vars.RequestSize)
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met.MustRegister(vars.RequestDo)
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met.MustRegister(vars.RequestType)
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met.MustRegister(vars.ResponseSize)
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met.MustRegister(vars.ResponseRcode)
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// Initialize metrics.
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buildInfo.WithLabelValues(coremain.CoreVersion, coremain.GitCommit, runtime.Version()).Set(1)
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return met
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}
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// MustRegister wraps m.Reg.MustRegister.
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func (m *Metrics) MustRegister(c prometheus.Collector) { m.Reg.MustRegister(c) }
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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.Errorf("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 listener on shutdown and restart.
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func (m *Metrics) OnShutdown() error {
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// We allow prometheus statements in multiple Server Blocks, but only the first
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// will open the listener, for the rest they are all nil; guard against that.
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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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var (
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buildInfo = prometheus.NewGaugeVec(prometheus.GaugeOpts{
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Namespace: plugin.Namespace,
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Name: "build_info",
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Help: "A metric with a constant '1' value labeled by version, revision, and goversion from which CoreDNS was built.",
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}, []string{"version", "revision", "goversion"})
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)
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