server.go

//https://opentracing.io/guides/golang/quick-start/
// docker run -d -p 6831:6831/udp -p 16686:16686 jaegertracing/all-in-one:latest
package main
import (
    "log"
	"time"
	"fmt"
    opentracing "github.com/opentracing/opentracing-go"
    "github.com/uber/jaeger-lib/metrics"
    "github.com/uber/jaeger-client-go"
    jaegercfg "github.com/uber/jaeger-client-go/config"
    jaegerlog "github.com/uber/jaeger-client-go/log"
	"net/http"
	"github.com/opentracing/opentracing-go/ext"
)
func main() {
    // Sample configuration for testing. Use constant sampling to sample every trace
    // and enable LogSpan to log every span via configured Logger.
    cfg := jaegercfg.Configuration{
        ServiceName: "your_service_name",
        Sampler:     &jaegercfg.SamplerConfig{
            Type:  jaeger.SamplerTypeConst,
            Param: 1,
        },
        Reporter:    &jaegercfg.ReporterConfig{
            LogSpans: true,
        },
    }
    // Example logger and metrics factory. Use github.com/uber/jaeger-client-go/log
    // and github.com/uber/jaeger-lib/metrics respectively to bind to real logging and metrics
    // frameworks.
    jLogger := jaegerlog.StdLogger
    jMetricsFactory := metrics.NullFactory

    // Initialize tracer with a logger and a metrics factory
    tracer, closer, err := cfg.NewTracer(
        jaegercfg.Logger(jLogger),
        jaegercfg.Metrics(jMetricsFactory),
    )
	if err != nil {
		panic(fmt.Sprintf("ERROR: cannot init Jaeger: %v\n", err))
	}
    // Set the singleton opentracing.Tracer with the Jaeger tracer.
    opentracing.SetGlobalTracer(tracer)
    defer closer.Close()
	http.HandleFunc("/publish", func(w http.ResponseWriter, r *http.Request) {
        // Extract the context from the headers
        spanCtx, _ := tracer.Extract(opentracing.HTTPHeaders, opentracing.HTTPHeadersCarrier(r.Header))
        serverSpan := tracer.StartSpan("server", ext.RPCServerOption(spanCtx))
		time.Sleep(time.Second)
        defer serverSpan.Finish()
    })
    log.Fatal(http.ListenAndServe(":8083", nil))
}