mirror of
https://github.com/coredns/coredns.git
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d3f2d4a291
* core: remove HostAddresses() config.HostAddresses() is a weird function that gathers some data from the server and returns a string. It is *only* used the trace plugin, to figure out what server starts the trace. Looks to be better to fit in the with metrics.WithServer label on the trace itself to show which server handled the trace. Remove HostAddresses() and cleanup trace a small bit.:w * lint
104 lines
2.3 KiB
Go
104 lines
2.3 KiB
Go
// Package trace implements OpenTracing-based tracing
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package trace
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import (
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"context"
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"fmt"
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"strings"
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"sync"
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"sync/atomic"
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"github.com/coredns/coredns/plugin"
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"github.com/coredns/coredns/plugin/metrics"
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// Plugin the trace package.
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_ "github.com/coredns/coredns/plugin/pkg/trace"
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ddtrace "github.com/DataDog/dd-trace-go/opentracing"
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"github.com/miekg/dns"
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ot "github.com/opentracing/opentracing-go"
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zipkin "github.com/openzipkin/zipkin-go-opentracing"
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)
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type trace struct {
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Next plugin.Handler
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Endpoint string
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EndpointType string
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tracer ot.Tracer
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serviceEndpoint string
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serviceName string
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clientServer bool
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every uint64
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count uint64
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Once sync.Once
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}
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func (t *trace) Tracer() ot.Tracer {
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return t.tracer
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}
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// OnStartup sets up the tracer
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func (t *trace) OnStartup() error {
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var err error
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t.Once.Do(func() {
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switch t.EndpointType {
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case "zipkin":
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err = t.setupZipkin()
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case "datadog":
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err = t.setupDatadog()
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default:
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err = fmt.Errorf("unknown endpoint type: %s", t.EndpointType)
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}
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})
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return err
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}
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func (t *trace) setupZipkin() error {
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collector, err := zipkin.NewHTTPCollector(t.Endpoint)
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if err != nil {
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return err
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}
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recorder := zipkin.NewRecorder(collector, false, t.serviceEndpoint, t.serviceName)
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t.tracer, err = zipkin.NewTracer(recorder, zipkin.ClientServerSameSpan(t.clientServer))
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return err
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}
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func (t *trace) setupDatadog() error {
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config := ddtrace.NewConfiguration()
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config.ServiceName = t.serviceName
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host := strings.Split(t.Endpoint, ":")
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config.AgentHostname = host[0]
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if len(host) == 2 {
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config.AgentPort = host[1]
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}
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tracer, _, err := ddtrace.NewTracer(config)
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t.tracer = tracer
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return err
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}
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// Name implements the Handler interface.
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func (t *trace) Name() string { return "trace" }
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// ServeDNS implements the plugin.Handle interface.
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func (t *trace) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
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trace := false
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if t.every > 0 {
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queryNr := atomic.AddUint64(&t.count, 1)
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if queryNr%t.every == 0 {
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trace = true
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}
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}
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if span := ot.SpanFromContext(ctx); span == nil && trace {
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span := t.Tracer().StartSpan("servedns:" + metrics.WithServer(ctx))
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defer span.Finish()
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ctx = ot.ContextWithSpan(ctx, span)
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}
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return plugin.NextOrFailure(t.Name(), t.Next, ctx, w, r)
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}
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