fix: fix trace rest api propagation (#3214)

Signed-off-by: Song Gao <disxiaofei@163.com>

internal/server/rest.go

@@ -31,6 +31,7 @@ import (
 	"github.com/gorilla/handlers"
 	"github.com/gorilla/mux"
 	"github.com/lf-edge/ekuiper/contract/v2/api"
+	"go.opentelemetry.io/otel/propagation"
 	"golang.org/x/text/cases"
 	"golang.org/x/text/language"
 
@@ -138,9 +139,14 @@ func jsonByteResponse(buffer bytes.Buffer, w http.ResponseWriter, logger api.Log
 func traceMiddleware(next http.Handler) http.Handler {
 	t := tracer.GetTracer()
 	return http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
-		_, span := t.Start(context.Background(), req.URL.Path)
+		propagator := propagation.TraceContext{}
+		originCtx := context.Background()
+		ctx := propagator.Extract(originCtx, propagation.HeaderCarrier(req.Header))
+		if ctx != originCtx {
+			_, span := t.Start(ctx, req.URL.Path)
+			defer span.End()
+		}
 		next.ServeHTTP(w, req)
-		span.End()
 	})
 }
 

pkg/tracer/manager.go

@@ -38,11 +38,11 @@ type SpanExporter struct {
 	spanStorage      LocalSpanStorage
 }
 
-func NewSpanExporter(remoteCollector bool) (*SpanExporter, error) {
+func NewSpanExporter(remoteCollector bool, remoteEndpoint string) (*SpanExporter, error) {
 	s := &SpanExporter{}
 	if remoteCollector {
 		exporter, err := otlptracehttp.New(context.Background(),
-			otlptracehttp.WithEndpoint(conf.Config.OpenTelemetry.RemoteEndpoint),
+			otlptracehttp.WithEndpoint(remoteEndpoint),
 			otlptracehttp.WithInsecure(),
 		)
 		if err != nil {

pkg/tracer/tracer.go

@@ -75,7 +75,7 @@ func (g *GlobalTracerManager) SetTracer(enableRemote bool, serviceName, endpoint
 	g.ServiceName = serviceName
 	g.EnableRemoteEndpoint = enableRemote
 	g.RemoteEndpoint = endpoint
-	exporter, err := NewSpanExporter(enableRemote)
+	exporter, err := NewSpanExporter(enableRemote, endpoint)
 	if err != nil {
 		return err
 	}