add default propagation for trace (#919)

* add default propagation for trace

* add trace carrier

middleware/tracing/carrier.go

@@ -0,0 +1,41 @@
+package tracing
+
+import (
+	"google.golang.org/grpc/metadata"
+)
+
+// MetadataCarrier is grpc metadata carrier
+type MetadataCarrier metadata.MD
+
+// Get returns the value associated with the passed key.
+func (mc MetadataCarrier) Get(key string) string {
+	values := metadata.MD(mc).Get(key)
+	if len(values) == 0 {
+		return ""
+	}
+	return values[0]
+}
+
+// Set stores the key-value pair.
+func (mc MetadataCarrier) Set(key string, value string) {
+	metadata.MD(mc).Set(key, value)
+}
+
+// Keys lists the keys stored in this carrier.
+func (mc MetadataCarrier) Keys() []string {
+	keys := make([]string, 0, metadata.MD(mc).Len())
+	for key := range metadata.MD(mc) {
+		keys = append(keys, key)
+	}
+	return keys
+}
+
+// Del delete key
+func (mc MetadataCarrier) Del(key string) {
+	delete(mc, key)
+}
+
+// Clone copy MetadataCarrier
+func (mc MetadataCarrier) Clone() MetadataCarrier {
+	return MetadataCarrier(metadata.MD(mc).Copy())
+}

middleware/tracing/tracer.go

@@ -0,0 +1,75 @@
+package tracing
+
+import (
+	"context"
+	"fmt"
+
+	"go.opentelemetry.io/otel"
+	"go.opentelemetry.io/otel/attribute"
+	"go.opentelemetry.io/otel/codes"
+	"go.opentelemetry.io/otel/propagation"
+	"go.opentelemetry.io/otel/trace"
+)
+
+// Tracer is otel span tracer
+type Tracer struct {
+	tracer trace.Tracer
+	kind   trace.SpanKind
+}
+
+// NewTracer create tracer instance
+func NewTracer(kind trace.SpanKind, opts ...Option) *Tracer {
+	options := options{}
+	for _, o := range opts {
+		o(&options)
+	}
+	if options.TracerProvider != nil {
+		otel.SetTracerProvider(options.TracerProvider)
+	}
+	if options.Propagators != nil {
+		otel.SetTextMapPropagator(options.Propagators)
+	} else {
+		otel.SetTextMapPropagator(propagation.NewCompositeTextMapPropagator(propagation.Baggage{}, propagation.TraceContext{}))
+	}
+	var name string
+	if kind == trace.SpanKindServer {
+		name = "server"
+	} else if kind == trace.SpanKindClient {
+		name = "client"
+	} else {
+		panic(fmt.Sprintf("unsupported span kind: %v", kind))
+	}
+	tracer := otel.Tracer(name)
+	return &Tracer{tracer: tracer, kind: kind}
+}
+
+// Start start tracing span
+func (t *Tracer) Start(ctx context.Context, component string, operation string, carrier propagation.TextMapCarrier) (context.Context, trace.Span) {
+	if t.kind == trace.SpanKindServer {
+		ctx = otel.GetTextMapPropagator().Extract(ctx, carrier)
+	}
+	ctx, span := t.tracer.Start(ctx,
+		operation,
+		trace.WithAttributes(attribute.String("component", component)),
+		trace.WithSpanKind(t.kind),
+	)
+	if t.kind == trace.SpanKindClient {
+		otel.GetTextMapPropagator().Inject(ctx, carrier)
+	}
+	return ctx, span
+}
+
+// End finish tracing span
+func (t *Tracer) End(ctx context.Context, span trace.Span, err error) {
+	if err != nil {
+		span.RecordError(err)
+		span.SetAttributes(
+			attribute.String("event", "error"),
+			attribute.String("message", err.Error()),
+		)
+		span.SetStatus(codes.Error, err.Error())
+	} else {
+		span.SetStatus(codes.Ok, "OK")
+	}
+	span.End()
+}

middleware/tracing/tracing.go

@@ -7,8 +7,6 @@ import (
 	"github.com/go-kratos/kratos/v2/transport/grpc"
 	"github.com/go-kratos/kratos/v2/transport/http"
 	"go.opentelemetry.io/otel"
-	"go.opentelemetry.io/otel/attribute"
-	"go.opentelemetry.io/otel/codes"
 	"go.opentelemetry.io/otel/propagation"
 	"go.opentelemetry.io/otel/trace"
 	"google.golang.org/grpc/metadata"
@@ -34,80 +32,36 @@ func WithTracerProvider(provider trace.TracerProvider) Option {
 	}
 }
 
-type MetadataCarrier struct {
-	md *metadata.MD
-}
-
-var _ propagation.TextMapCarrier = &MetadataCarrier{}
-
-func (mc MetadataCarrier) Get(key string) string {
-	values := mc.md.Get(key)
-	if len(values) == 0 {
-		return ""
-	}
-	return values[0]
-}
-
-func (mc MetadataCarrier) Set(key string, value string) {
-	mc.md.Set(key, value)
-}
-
-func (mc MetadataCarrier) Keys() []string {
-	keys := make([]string, 0, mc.md.Len())
-	for key := range *mc.md {
-		keys = append(keys, key)
-	}
-	return keys
-}
-
 // Server returns a new server middleware for OpenTelemetry.
 func Server(opts ...Option) middleware.Middleware {
-	options := options{}
+	tracer := NewTracer(trace.SpanKindServer, opts...)
-	for _, o := range opts {
+
-		o(&options)
-	}
-	if options.TracerProvider != nil {
-		otel.SetTracerProvider(options.TracerProvider)
-	}
-	if options.Propagators != nil {
-		otel.SetTextMapPropagator(options.Propagators)
-	}
-	tracer := otel.Tracer("server")
 	return func(handler middleware.Handler) middleware.Handler {
 		return func(ctx context.Context, req interface{}) (reply interface{}, err error) {
 			var (
 				component string
 				operation string
+				carrier   propagation.TextMapCarrier
 			)
 			if info, ok := http.FromServerContext(ctx); ok {
 				// HTTP span
 				component = "HTTP"
 				operation = info.Request.RequestURI
+				carrier = propagation.HeaderCarrier(info.Request.Header)
 				ctx = otel.GetTextMapPropagator().Extract(ctx, propagation.HeaderCarrier(info.Request.Header))
 			} else if info, ok := grpc.FromServerContext(ctx); ok {
 				// gRPC span
 				component = "gRPC"
 				operation = info.FullMethod
 				if md, ok := metadata.FromIncomingContext(ctx); ok {
-					ctx = otel.GetTextMapPropagator().Extract(ctx, MetadataCarrier{md: &md})
+					carrier = MetadataCarrier(md)
 				}
 			}
-			ctx, span := tracer.Start(ctx,
+			ctx, span := tracer.Start(ctx, component, operation, carrier)
-				operation,
+			defer tracer.End(ctx, span, err)
-				trace.WithAttributes(attribute.String("component", component)),
+
-				trace.WithSpanKind(trace.SpanKindServer),
+			reply, err = handler(ctx, req)
-			)
+
-			defer span.End()
-			if reply, err = handler(ctx, req); err != nil {
-				span.RecordError(err)
-				span.SetAttributes(
-					attribute.String("event", "error"),
-					attribute.String("message", err.Error()),
-				)
-				span.SetStatus(codes.Error, err.Error())
-			} else {
-				span.SetStatus(codes.Ok, "OK")
-			}
 			return
 		}
 	}
@@ -115,17 +69,8 @@ func Server(opts ...Option) middleware.Middleware {
 
 // Client returns a new client middleware for OpenTelemetry.
 func Client(opts ...Option) middleware.Middleware {
-	options := options{}
+	tracer := NewTracer(trace.SpanKindClient, opts...)
-	for _, o := range opts {
+
-		o(&options)
-	}
-	if options.TracerProvider != nil {
-		otel.SetTracerProvider(options.TracerProvider)
-	}
-	if options.Propagators != nil {
-		otel.SetTextMapPropagator(options.Propagators)
-	}
-	tracer := otel.Tracer("client")
 	return func(handler middleware.Handler) middleware.Handler {
 		return func(ctx context.Context, req interface{}) (reply interface{}, err error) {
 			var (
@@ -146,26 +91,14 @@ func Client(opts ...Option) middleware.Middleware {
 				if !ok {
 					md = metadata.Pairs()
 				}
-				carrier = MetadataCarrier{md: &md}
+				carrier = MetadataCarrier(md)
 				ctx = metadata.NewOutgoingContext(ctx, md)
 			}
-			ctx, span := tracer.Start(ctx,
+			ctx, span := tracer.Start(ctx, component, operation, carrier)
-				operation,
+			defer tracer.End(ctx, span, err)
-				trace.WithAttributes(attribute.String("component", component)),
+
-				trace.WithSpanKind(trace.SpanKindClient),
+			reply, err = handler(ctx, req)
-			)
+
-			defer span.End()
-			otel.GetTextMapPropagator().Inject(ctx, carrier)
-			if reply, err = handler(ctx, req); err != nil {
-				span.RecordError(err)
-				span.SetAttributes(
-					attribute.String("event", "error"),
-					attribute.String("message", err.Error()),
-				)
-				span.SetStatus(codes.Error, err.Error())
-			} else {
-				span.SetStatus(codes.Ok, "OK")
-			}
 			return
 		}
 	}