contrib/internal/httptrace: add telemetry for inferred spans (#3119)

Co-authored-by: Rodrigo Arguello <[email protected]>

contrib/internal/httptrace/httptrace.go

@@ -11,9 +11,11 @@ import (
 	"context"
 	"fmt"
 	"gopkg.in/DataDog/dd-trace-go.v1/internal/log"
+	"gopkg.in/DataDog/dd-trace-go.v1/internal/telemetry"
 	"net/http"
 	"strconv"
 	"strings"
+	"sync"
 
 	"gopkg.in/DataDog/dd-trace-go.v1/ddtrace"
 	"gopkg.in/DataDog/dd-trace-go.v1/ddtrace/ext"
@@ -27,6 +29,8 @@ var (
 	cfg = newConfig()
 )
 
+var reportTelemetryConfigOnce sync.Once
+
 type inferredSpanCreatedCtxKey struct{}
 
 type FinishSpanFunc = func(status int, errorFn func(int) bool, opts ...tracer.FinishOption)
@@ -37,6 +41,15 @@ func StartRequestSpan(r *http.Request, opts ...ddtrace.StartSpanOption) (tracer.
 	// Append our span options before the given ones so that the caller can "overwrite" them.
 	// TODO(): rework span start option handling (https://github.com/DataDog/dd-trace-go/issues/1352)
 
+	// we cannot track the configuration in newConfig because it's called during init() and the the telemetry client
+	// is not initialized yet
+	reportTelemetryConfigOnce.Do(func() {
+		telemetry.GlobalClient.ConfigChange([]telemetry.Configuration{
+			{Name: "inferred_proxy_services_enabled", Value: cfg.inferredProxyServicesEnabled},
+		})
+		log.Debug("internal/httptrace: telemetry.ConfigChange called with cfg: %v:", cfg)
+	})
+
 	var ipTags map[string]string
 	if cfg.traceClientIP {
 		ipTags, _ = httpsec.ClientIPTags(r.Header, true, r.RemoteAddr)