bc301be5ee
Adds a middleware to enable tracing with OpenTracing/OpenZipkin. Enabling tracing will have a large impact on performance so it is not advisable in production.
64 lines
1.4 KiB
Go
64 lines
1.4 KiB
Go
// Package trace implements OpenTracing-based tracing
|
|
package trace
|
|
|
|
import (
|
|
"fmt"
|
|
"sync"
|
|
|
|
"golang.org/x/net/context"
|
|
|
|
"github.com/miekg/coredns/middleware"
|
|
"github.com/miekg/dns"
|
|
ot "github.com/opentracing/opentracing-go"
|
|
zipkin "github.com/openzipkin/zipkin-go-opentracing"
|
|
)
|
|
|
|
// Trace holds the tracer and endpoint info
|
|
type Trace struct {
|
|
Next middleware.Handler
|
|
ServiceEndpoint string
|
|
Endpoint string
|
|
EndpointType string
|
|
Tracer ot.Tracer
|
|
Once sync.Once
|
|
}
|
|
|
|
// OnStartup sets up the tracer
|
|
func (t *Trace) OnStartup() error {
|
|
var err error
|
|
t.Once.Do(func() {
|
|
switch t.EndpointType {
|
|
case "zipkin":
|
|
err = t.setupZipkin()
|
|
default:
|
|
err = fmt.Errorf("Unknown endpoint type: %s", t.EndpointType)
|
|
}
|
|
})
|
|
return err
|
|
}
|
|
|
|
func (t *Trace) setupZipkin() error {
|
|
|
|
collector, err := zipkin.NewHTTPCollector(t.Endpoint)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
|
|
recorder := zipkin.NewRecorder(collector, false, t.ServiceEndpoint, "coredns")
|
|
t.Tracer, err = zipkin.NewTracer(recorder, zipkin.ClientServerSameSpan(false))
|
|
if err != nil {
|
|
return err
|
|
}
|
|
return nil
|
|
}
|
|
|
|
func (t *Trace) Name() (string) {
|
|
return "trace"
|
|
}
|
|
|
|
func (t *Trace) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
|
|
span := t.Tracer.StartSpan("servedns")
|
|
defer span.Finish()
|
|
ctx = ot.ContextWithSpan(ctx, span)
|
|
return middleware.NextOrFailure(t.Name(), t.Next, ctx, w, r)
|
|
}
|