add SetUntraceableEndpoints for add UntraceableEndpoints like Health urls

Author: sergeylanzman

plugin/ochttp/client.go

@@ -63,7 +63,7 @@ type Transport struct {
 // RoundTrip implements http.RoundTripper, delegating to Base and recording stats and traces for the request.
 func (t *Transport) RoundTrip(req *http.Request) (*http.Response, error) {
 	rt := t.base()
-	if isHealthEndpoint(req.URL.Path) {
+	if isUntraceableEndpoints(req.URL.Path) {
 		return rt.RoundTrip(req)
 	}
 	// TODO: remove excessive nesting of http.RoundTrippers here.

plugin/ochttp/server.go

@@ -82,7 +82,7 @@ func (h *Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 }
 
 func (h *Handler) startTrace(w http.ResponseWriter, r *http.Request) (*http.Request, func()) {
-	if isHealthEndpoint(r.URL.Path) {
+	if isUntraceableEndpoints(r.URL.Path) {
 		return r, func() {}
 	}
 	var name string

plugin/ochttp/trace.go

@@ -28,6 +28,13 @@ import (
 
 var defaultFormat propagation.HTTPFormat = &b3.HTTPFormat{}
 
+// Disable canonical health checking endpoints
+// like /healthz and /_ah/health for now.
+var untraceableEndpoints = map[string]bool{
+	"/healthz":    true,
+	"/_ah/health": true,
+}
+
 // Attributes recorded on the span for the requests.
 // Only trace exporters will need them.
 const (
@@ -205,13 +212,18 @@ var codeToStr = map[int32]string{
 	trace.StatusCodeUnauthenticated:    `"UNAUTHENTICATED"`,
 }
 
-func isHealthEndpoint(path string) bool {
-	// Health checking is pretty frequent and
-	// traces collected for health endpoints
-	// can be extremely noisy and expensive.
-	// Disable canonical health checking endpoints
-	// like /healthz and /_ah/health for now.
-	if path == "/healthz" || path == "/_ah/health" {
+// Set Untraceable Endpoints like Health checking
+// is pretty frequent and traces collected
+// for health endpoints can be extremely noisy and expensive.
+func SetUntraceableEndpoints(newUntraceableEndpoints []string) {
+	untraceableEndpoints = map[string]bool{}
+	for _, endpoint := range newUntraceableEndpoints {
+		untraceableEndpoints[endpoint] = true
+	}
+}
+
+func isUntraceableEndpoints(path string) bool {
+	if _, exist := untraceableEndpoints[path]; exist {
 		return true
 	}
 	return false