OpenTelemetry zPages instrumentation example for Go (golang)

go.mod

module zpages-demo

go 1.17

require (
	go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.34.0
	go.opentelemetry.io/contrib/zpages v0.34.0
	go.opentelemetry.io/otel v1.9.0
	go.opentelemetry.io/otel/exporters/stdout/stdouttrace v1.9.0
	go.opentelemetry.io/otel/sdk v1.9.0
	go.opentelemetry.io/otel/trace v1.9.0
)

require (
	github.com/felixge/httpsnoop v1.0.3 // indirect
	github.com/go-logr/logr v1.2.3 // indirect
	github.com/go-logr/stdr v1.2.2 // indirect
	go.opentelemetry.io/otel/metric v0.31.0 // indirect
	golang.org/x/sys v0.0.0-20210423185535-09eb48e85fd7 // indirect
)

go.sum

github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
github.com/felixge/httpsnoop v1.0.3 h1:s/nj+GCswXYzN5v2DpNMuMQYe+0DDwt5WVCU6CWBdXk=
github.com/felixge/httpsnoop v1.0.3/go.mod h1:m8KPJKqk1gH5J9DgRY2ASl2lWCfGKXixSwevea8zH2U=
github.com/go-logr/logr v1.2.2/go.mod h1:jdQByPbusPIv2/zmleS9BjJVeZ6kBagPoEUsqbVz/1A=
github.com/go-logr/logr v1.2.3 h1:2DntVwHkVopvECVRSlL5PSo9eG+cAkDCuckLubN+rq0=
github.com/go-logr/logr v1.2.3/go.mod h1:jdQByPbusPIv2/zmleS9BjJVeZ6kBagPoEUsqbVz/1A=
github.com/go-logr/stdr v1.2.2 h1:hSWxHoqTgW2S2qGc0LTAI563KZ5YKYRhT3MFKZMbjag=
github.com/go-logr/stdr v1.2.2/go.mod h1:mMo/vtBO5dYbehREoey6XUKy/eSumjCCveDpRre4VKE=
github.com/google/go-cmp v0.5.8 h1:e6P7q2lk1O+qJJb4BtCQXlK8vWEO8V1ZeuEdJNOqZyg=
github.com/google/go-cmp v0.5.8/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
github.com/stretchr/objx v0.4.0/go.mod h1:YvHI0jy2hoMjB+UWwv71VJQ9isScKT/TqJzVSSt89Yw=
github.com/stretchr/testify v1.7.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
github.com/stretchr/testify v1.8.0 h1:pSgiaMZlXftHpm5L7V1+rVB+AZJydKsMxsQBIJw4PKk=
github.com/stretchr/testify v1.8.0/go.mod h1:yNjHg4UonilssWZ8iaSj1OCr/vHnekPRkoO+kdMU+MU=
go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.34.0 h1:9NkMW03wwEzPtP/KciZ4Ozu/Uz5ZA7kfqXJIObnrjGU=
go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.34.0/go.mod h1:548ZsYzmT4PL4zWKRd8q/N4z0Wxzn/ZxUE+lkEpwWQA=
go.opentelemetry.io/contrib/zpages v0.34.0 h1:8ZXfrPkhegp/5GQYrO0pWMv2k3DQ7f+VBjaS6fMaBLM=
go.opentelemetry.io/contrib/zpages v0.34.0/go.mod h1:zuVCe4eoOREH+liRJLCtGITqL3NiUvkdr6U/4j9iQRg=
go.opentelemetry.io/otel v1.8.0/go.mod h1:2pkj+iMj0o03Y+cW6/m8Y4WkRdYN3AvCXCnzRMp9yvM=
go.opentelemetry.io/otel v1.9.0 h1:8WZNQFIB2a71LnANS9JeyidJKKGOOremcUtb/OtHISw=
go.opentelemetry.io/otel v1.9.0/go.mod h1:np4EoPGzoPs3O67xUVNoPPcmSvsfOxNlNA4F4AC+0Eo=
go.opentelemetry.io/otel/exporters/stdout/stdouttrace v1.9.0 h1:0uV0qzHk48i1SF8qRI8odMYiwPOLh9gBhiJFpj8H6JY=
go.opentelemetry.io/otel/exporters/stdout/stdouttrace v1.9.0/go.mod h1:Fl1iS5ZhWgXXXTdJMuBSVsS5nkL5XluHbg97kjOuYU4=
go.opentelemetry.io/otel/metric v0.31.0 h1:6SiklT+gfWAwWUR0meEMxQBtihpiEs4c+vL9spDTqUs=
go.opentelemetry.io/otel/metric v0.31.0/go.mod h1:ohmwj9KTSIeBnDBm/ZwH2PSZxZzoOaG2xZeekTRzL5A=
go.opentelemetry.io/otel/sdk v1.9.0 h1:LNXp1vrr83fNXTHgU8eO89mhzxb/bbWAsHG6fNf3qWo=
go.opentelemetry.io/otel/sdk v1.9.0/go.mod h1:AEZc8nt5bd2F7BC24J5R0mrjYnpEgYHyTcM/vrSple4=
go.opentelemetry.io/otel/trace v1.8.0/go.mod h1:0Bt3PXY8w+3pheS3hQUt+wow8b1ojPaTBoTCh2zIFI4=
go.opentelemetry.io/otel/trace v1.9.0 h1:oZaCNJUjWcg60VXWee8lJKlqhPbXAPB51URuR47pQYc=
go.opentelemetry.io/otel/trace v1.9.0/go.mod h1:2737Q0MuG8q1uILYm2YYVkAyLtOofiTNGg6VODnOiPo=
golang.org/x/sys v0.0.0-20210423185535-09eb48e85fd7 h1:iGu644GcxtEcrInvDsQRCwJjtCIOlT2V7IRt6ah2Whw=
golang.org/x/sys v0.0.0-20210423185535-09eb48e85fd7/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

main.go

package main

import (
	"context"
	"fmt"
	"io"
	"log"
	"net/http"
	"time"

	"go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp"
	"go.opentelemetry.io/contrib/zpages"
	"go.opentelemetry.io/otel"
	"go.opentelemetry.io/otel/attribute"
	stdout "go.opentelemetry.io/otel/exporters/stdout/stdouttrace"
	"go.opentelemetry.io/otel/propagation"
	"go.opentelemetry.io/otel/sdk/resource"
	sdktrace "go.opentelemetry.io/otel/sdk/trace"
	semconv "go.opentelemetry.io/otel/semconv/v1.12.0"
	"go.opentelemetry.io/otel/trace"
)

func initTracer(zsp *zpages.SpanProcessor) (*sdktrace.TracerProvider, error) {
	// Create stdout exporter to be able to retrieve
	// the collected spans.
	exporter, err := stdout.New()
	if err != nil {
		return nil, err
	}

	// For the demonstration, use sdktrace.AlwaysSample sampler to sample all traces.
	// In a production application, use sdktrace.ProbabilitySampler with a desired probability.
	tp := sdktrace.NewTracerProvider(
		sdktrace.WithSampler(sdktrace.AlwaysSample()),
		sdktrace.WithBatcher(exporter),
		sdktrace.WithResource(resource.NewWithAttributes(semconv.SchemaURL, semconv.ServiceNameKey.String("ExampleService"))),
		sdktrace.WithSpanProcessor(zsp),
	)
	otel.SetTracerProvider(tp)
	otel.SetTextMapPropagator(propagation.NewCompositeTextMapPropagator(propagation.TraceContext{}, propagation.Baggage{}))
	return tp, err
}

func main() {
	zsp := zpages.NewSpanProcessor()

	tp, err := initTracer(zsp)
	if err != nil {
		log.Fatal(err)
	}
	defer func() {
		if err := tp.Shutdown(context.Background()); err != nil {
			log.Printf("Error shutting down tracer provider: %v", err)
		}
	}()

	helloHandler := func(w http.ResponseWriter, req *http.Request) {
		ctx := req.Context()
		span := trace.SpanFromContext(ctx)
		span.AddEvent("handling", trace.WithAttributes(attribute.Key("foo").Int64(time.Now().Unix())))

		time.Sleep(time.Millisecond)

		ctx, s := otel.Tracer("usecase").Start(ctx, "deeper")
		defer s.End()
		time.Sleep(5 * time.Millisecond)

		_, _ = io.WriteString(w, "Hello, world!\n")
	}

	otelHandler := otelhttp.NewHandler(http.HandlerFunc(helloHandler), "Hello")

	http.Handle("/hello", otelHandler)

	http.Handle("/debug/zpages/tracez", zpages.NewTracezHandler(zsp))

	fmt.Println("View tracez at http://localhost:7777/debug/zpages/tracez, public API at http://localhost:7777/hello")
	err = http.ListenAndServe("localhost:7777", nil)
	if err != nil {
		log.Fatal(err)
	}
}