main.go

package main

import (
	"fmt"
	"log"
	"net/http"
	"runtime"
	"time"

	"github.com/opentracing-contrib/go-stdlib/nethttp"
	opentracing "github.com/opentracing/opentracing-go"
	jaeger "github.com/uber/jaeger-client-go"
	"github.com/uber/jaeger-client-go/zipkin"
)

func indexHandler(w http.ResponseWriter, r *http.Request) {
	fmt.Fprintf(w, "hello world, I'm running on %s with an %s CPU ", runtime.GOOS, runtime.GOARCH)
}

func getTimeHandler(w http.ResponseWriter, r *http.Request) {
	log.Print("Received getTime request")
	t := time.Now()
	ts := t.Format("Mon Jan _2 15:04:05 2006")
	fmt.Fprintf(w, "The time is %s", ts)
}

func main() {
	zipkinPropagator := zipkin.NewZipkinB3HTTPHeaderPropagator()
	injector := jaeger.TracerOptions.Injector(opentracing.HTTPHeaders, zipkinPropagator)
	extractor := jaeger.TracerOptions.Extractor(opentracing.HTTPHeaders, zipkinPropagator)

	// Zipkin shares span ID between client and server spans; it must be enabled via the following option.
	zipkinSharedRPCSpan := jaeger.TracerOptions.ZipkinSharedRPCSpan(true)

	sender, _ := jaeger.NewUDPTransport("jaeger-agent.istio-system:5775", 0)
	tracer, closer := jaeger.NewTracer(
		"myhelloworld",
		jaeger.NewConstSampler(true),
		jaeger.NewRemoteReporter(
			sender,
			jaeger.ReporterOptions.BufferFlushInterval(1*time.Second)),
		injector,
		extractor,
		zipkinSharedRPCSpan,
	)
	defer closer.Close()

	http.HandleFunc("/", indexHandler)
	http.HandleFunc("/gettime", getTimeHandler)
	http.ListenAndServe(
		":8080",
		nethttp.Middleware(tracer, http.DefaultServeMux))
}