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.
72 lines
1.8 KiB
Go
72 lines
1.8 KiB
Go
package cache
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import (
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"github.com/miekg/coredns/middleware"
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"github.com/miekg/dns"
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"github.com/prometheus/client_golang/prometheus"
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"golang.org/x/net/context"
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)
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// ServeDNS implements the middleware.Handler interface.
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func (c Cache) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
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state := middleware.State{W: w, Req: r}
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qname := state.Name()
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qtype := state.QType()
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zone := middleware.Zones(c.Zones).Matches(qname)
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if zone == "" {
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return c.Next.ServeDNS(ctx, w, r)
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}
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do := state.Do() // might need more from OPT record?
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if i, ok := c.Get(qname, qtype, do); ok {
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resp := i.toMsg(r)
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state.SizeAndDo(resp)
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w.WriteMsg(resp)
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cacheHitCount.WithLabelValues(zone).Inc()
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return dns.RcodeSuccess, nil
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}
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cacheMissCount.WithLabelValues(zone).Inc()
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crr := NewCachingResponseWriter(w, c.cache, c.cap)
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return c.Next.ServeDNS(ctx, crr, r)
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}
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func (c Cache) Get(qname string, qtype uint16, do bool) (*item, bool) {
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nxdomain := nameErrorKey(qname, do)
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if i, ok := c.cache.Get(nxdomain); ok {
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return i.(*item), true
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}
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successOrNoData := successKey(qname, qtype, do)
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if i, ok := c.cache.Get(successOrNoData); ok {
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return i.(*item), true
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}
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return nil, false
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}
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var (
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cacheHitCount = prometheus.NewCounterVec(prometheus.CounterOpts{
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Namespace: middleware.Namespace,
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Subsystem: subsystem,
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Name: "hit_count_total",
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Help: "Counter of DNS requests that were found in the cache.",
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}, []string{"zone"})
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cacheMissCount = prometheus.NewCounterVec(prometheus.CounterOpts{
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Namespace: middleware.Namespace,
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Subsystem: subsystem,
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Name: "miss_count_total",
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Help: "Counter of DNS requests that were not found in the cache.",
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}, []string{"zone"})
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)
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const subsystem = "cache"
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func init() {
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prometheus.MustRegister(cacheHitCount)
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prometheus.MustRegister(cacheMissCount)
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}
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