带有Google App Engine Go 1.11运行时的Stackdriver Trace

Question

I would like to get Stackdriver Trace to work on the new Go 1.11 standard runtime on Google App Engine . This is all still labeled as beta so maybe it just doesn't quite work yet. However, I followed the step-by-step directions and it isn't working. I deployed the code (almost) exactly as it is listed in the link and my traces are flat (ie doesn't include the waterfall view I would expect with the incoming request at the top and the outgoing request nested underneath).

Sample code

package main

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

    "contrib.go.opencensus.io/exporter/stackdriver"
    "contrib.go.opencensus.io/exporter/stackdriver/propagation"
    "go.opencensus.io/plugin/ochttp"
    "go.opencensus.io/trace"
)

func main() {
    // Create and register a OpenCensus Stackdriver Trace exporter.
    exporter, err := stackdriver.NewExporter(stackdriver.Options{
        ProjectID: os.Getenv("GOOGLE_CLOUD_PROJECT"),
    })
    if err != nil {
        log.Fatal(err)
    }
    trace.RegisterExporter(exporter)

    client := &http.Client{
        Transport: &ochttp.Transport{
            // Use Google Cloud propagation format.
            Propagation: &propagation.HTTPFormat{},
        },
    }

    handler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
        req, _ := http.NewRequest("GET", "https://www.google.com/robots.txt", nil)

        // The trace ID from the incoming request will be
        // propagated to the outgoing request.
        req = req.WithContext(r.Context())

        // The outgoing request will be traced with r's trace ID.
        resp, err := client.Do(req)
        if err != nil {
            log.Fatal(err)
        }
        defer resp.Body.Close()

        fmt.Fprint(w, "OK")
    })
    http.Handle("/foo", handler)
    log.Fatal(http.ListenAndServe(":"+os.Getenv("PORT"), &ochttp.Handler{}))
}

Sample trace:

Answer 1

As written in the reply comment in the original question, can you try the config for sampling?: trace.AlwaysSample()

You can find some comments about sampling rate in OpenCensus Trace documentation and godoc of OpenCensus Trace library :

By default, traces will be sampled relatively rarely. To change the sampling frequency for your entire program, call ApplyConfig. Use a ProbabilitySampler to sample a subset of traces, or use AlwaysSample to collect a trace on every run: