Example #1
0
func TestTracer(t *testing.T) {
	log.SetFlags(0)

	var tracer ot.Tracer
	tracer = &Tracer{}
	ot.InitGlobalTracer(tracer)

	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		serverSpan, err := tracer.Join(
			"serverSpan",
			ot.TextMap,
			ot.HTTPHeaderTextMapCarrier(r.Header))
		if err != nil {
			panic(err)
		}
		time.Sleep(time.Second * 1)
		serverSpan.Finish()
		fmt.Fprintln(w, "Hello, client")
	}))
	defer ts.Close()

	span, nctx := ot.StartSpanFromContext(context.TODO(), "main_test")
	defer span.Finish()

	foo(nctx, "bar", 0)

	httpClient := &http.Client{}
	httpReq, _ := http.NewRequest("GET", ts.URL, nil)

	// Transmit the span's TraceContext as HTTP headers on our
	// outbound request.
	tracer.Inject(
		span,
		ot.TextMap,
		ot.HTTPHeaderTextMapCarrier(httpReq.Header))

	if _, err := httpClient.Do(httpReq); err != nil {
		panic(err)
	}
}
Example #2
0
// Endpoint is an example API endpoint. In a real application, the backend of
// your service would be contacting several external and internal API endpoints
// which may be the bottleneck of your application.
//
// For example purposes we just sleep for 200ms before responding to simulate a
// slow API endpoint as the bottleneck of your application.
func Endpoint(w http.ResponseWriter, r *http.Request) {
	// Extract the trace from the headers and join it with a new child span.
	carrier := opentracing.HTTPHeaderTextMapCarrier(r.Header)
	span, err := opentracing.GlobalTracer().Join(r.URL.Path, opentracing.TextMap, carrier)
	if err != nil {
		return
	}
	defer span.Finish()

	span.SetTag("Request.Host", r.Host)
	span.SetTag("Request.Method", r.Method)
	addHeaderTags(span, r.Header)

	time.Sleep(200 * time.Millisecond)
	fmt.Fprintf(w, "Slept for 200ms!")
}
Example #3
0
// Home is the homepage handler for our app.
func Home(w http.ResponseWriter, r *http.Request) {
	// Start a new root Span and therefore a new trace.
	span := opentracing.StartSpan(r.URL.Path)
	defer span.Finish()

	// OpenTracing allows for arbritary tags to be added to a Span.
	span.SetTag("Request.Host", r.Host)
	span.SetTag("Request.Address", r.RemoteAddr)
	addHeaderTags(span, r.Header)

	// Baggage Items are similar to tags, however they are propagated to all
	// children spans, so this will show up in the API calls.
	span.SetBaggageItem("User", os.Getenv("USER"))

	// We're going to make some API request, so we use the default HTTP client
	// to send HTTP requests with trace information placed inside the headers.
	httpClient := http.DefaultClient

	// Make three API requests using our HTTP client.
	for i := 0; i < 3; i++ {
		req, err := http.NewRequest("GET", "http://localhost:8699/endpoint", nil)
		if err != nil {
			log.Println("/endpoint:", err)
			continue
		}

		// We inject the span into the request headers before making the request.
		carrier := opentracing.HTTPHeaderTextMapCarrier(req.Header)
		span.Tracer().Inject(span, opentracing.TextMap, carrier)
		resp, err := httpClient.Do(req)
		if err != nil {
			log.Println("/endpoint:", err)

			// Log the error to the span.
			span.LogEvent(err.Error())
			continue
		}

		span.SetTag("Response.Status", resp.Status)
		resp.Body.Close()
	}

	// Render the page.
	fmt.Fprintf(w, `<p>Three API requests have been made!</p>`)
	fmt.Fprintf(w, `<p><a href="http://localhost:8700/traces" target="_">View the trace</a></p>`)
}