Trace for AppEngine Standard with Go 1.9 (can't deploy as of 2018-11-26)

hello.go

// Copyright 2018 Google Inc. All rights reserved.
// Use of this source code is governed by the Apache 2.0
// license that can be found in the LICENSE file.

package main

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

	"contrib.go.opencensus.io/exporter/stackdriver"
	"go.opencensus.io/trace"
	"google.golang.org/appengine"
)

func main() {
	sd, err := stackdriver.NewExporter(stackdriver.Options{
		ProjectID: "spans-go19",
		// MetricPrefix helps uniquely identify your metrics.
		MetricPrefix: "demo-prefix",
	})
	if err != nil {
		log.Fatalf("Failed to create the Stackdriver exporter: %v", err)
	}
	// It is imperative to invoke flush before your main function exits
	defer sd.Flush()

	// Register it as a trace exporter
	trace.RegisterExporter(sd)

	http.HandleFunc("/", handle)
	appengine.Main()
}

func handle(w http.ResponseWriter, r *http.Request) {
	fmt.Fprintln(w, "Hello, VDE")
}