Set SpanKind for HTTP and gRPC requests

plugin/ocgrpc/client.go

@@ -25,6 +25,9 @@ import (
 // traces. Use with gRPC clients only.
 type ClientHandler struct {
 	// StartOptions allows configuring the StartOptions used to create new spans.
+	//
+	// StartOptions.SpanKind will always be set to trace.SpanKindClient
+	// for spans started by this handler.
 	StartOptions trace.StartOptions
 }
 

plugin/ocgrpc/server.go

@@ -45,7 +45,11 @@ type ServerHandler struct {
 	// present on the inbound RPC but the SpanContext is not sampled. This
 	// ensures that each service has some opportunity to be traced. If you would
 	// like to not add any additional traces for this gRPC service, set:
+	//
 	//   StartOptions.Sampler = trace.ProbabilitySampler(0.0)
+	//
+	// StartOptions.SpanKind will always be set to trace.SpanKindServer
+	// for spans started by this handler.
 	StartOptions trace.StartOptions
 }
 

plugin/ocgrpc/trace_common.go

@@ -35,7 +35,10 @@ const traceContextKey = "grpc-trace-bin"
 // SpanContext added to the outgoing gRPC metadata.
 func (c *ClientHandler) traceTagRPC(ctx context.Context, rti *stats.RPCTagInfo) context.Context {
 	name := "Sent" + strings.Replace(rti.FullMethodName, "/", ".", -1)
-	span := trace.NewSpan(name, trace.FromContext(ctx), c.StartOptions) // span is ended by traceHandleRPC
+	span := trace.NewSpan(name, trace.FromContext(ctx), trace.StartOptions{
+		Sampler:  c.StartOptions.Sampler,
+		SpanKind: trace.SpanKindClient,
+	}) // span is ended by traceHandleRPC
 	ctx = trace.WithSpan(ctx, span)
 	traceContextBinary := propagation.Binary(span.SpanContext())
 	return metadata.AppendToOutgoingContext(ctx, traceContextKey, string(traceContextBinary))
@@ -48,6 +51,11 @@ func (c *ClientHandler) traceTagRPC(ctx context.Context, rti *stats.RPCTagInfo)
 //
 // It returns ctx, with the new trace span added.
 func (s *ServerHandler) traceTagRPC(ctx context.Context, rti *stats.RPCTagInfo) context.Context {
+	opts := trace.StartOptions{
+		Sampler:  s.StartOptions.Sampler,
+		SpanKind: trace.SpanKindServer,
+	}
+
 	md, _ := metadata.FromIncomingContext(ctx)
 	name := "Recv" + strings.Replace(rti.FullMethodName, "/", ".", -1)
 	traceContext := md[traceContextKey]
@@ -62,11 +70,11 @@ func (s *ServerHandler) traceTagRPC(ctx context.Context, rti *stats.RPCTagInfo)
 		traceContextBinary := []byte(traceContext[0])
 		parent, haveParent = propagation.FromBinary(traceContextBinary)
 		if haveParent && !s.IsPublicEndpoint {
-			span := trace.NewSpanWithRemoteParent(name, parent, s.StartOptions)
+			span := trace.NewSpanWithRemoteParent(name, parent, opts)
 			return trace.WithSpan(ctx, span)
 		}
 	}
-	span := trace.NewSpan(name, nil, s.StartOptions)
+	span := trace.NewSpan(name, nil, opts)
 	if haveParent {
 		span.AddLink(trace.Link{TraceID: parent.TraceID, SpanID: parent.SpanID, Type: trace.LinkTypeChild})
 	}

plugin/ochttp/client.go

@@ -38,6 +38,9 @@ type Transport struct {
 
 	// StartOptions are applied to the span started by this Transport around each
 	// request.
+	//
+	// StartOptions.SpanKind will always be set to trace.SpanKindClient
+	// for spans started by this transport.
 	StartOptions trace.StartOptions
 
 	// TODO: Implement tag propagation for HTTP.
@@ -52,9 +55,12 @@ func (t *Transport) RoundTrip(req *http.Request) (*http.Response, error) {
 		format = defaultFormat
 	}
 	rt = &traceTransport{
-		base:         rt,
-		format:       format,
-		startOptions: t.StartOptions,
+		base:   rt,
+		format: format,
+		startOptions: trace.StartOptions{
+			Sampler:  t.StartOptions.Sampler,
+			SpanKind: trace.SpanKindClient,
+		},
 	}
 	rt = statsTransport{base: rt}
 	return rt.RoundTrip(req)

plugin/ochttp/server.go

@@ -47,6 +47,9 @@ type Handler struct {
 
 	// StartOptions are applied to the span started by this Handler around each
 	// request.
+	//
+	// StartOptions.SpanKind will always be set to trace.SpanKindServer
+	// for spans started by this transport.
 	StartOptions trace.StartOptions
 
 	// IsPublicEndpoint should be set to true for publicly accessible HTTP(S)
@@ -71,15 +74,20 @@ func (h *Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 }
 
 func (h *Handler) startTrace(w http.ResponseWriter, r *http.Request) (*http.Request, func()) {
+	opts := trace.StartOptions{
+		Sampler:  h.StartOptions.Sampler,
+		SpanKind: trace.SpanKindServer,
+	}
+
 	name := spanNameFromURL("Recv", r.URL)
 	ctx := r.Context()
 	var span *trace.Span
 	sc, ok := h.extractSpanContext(r)
 	if ok && !h.IsPublicEndpoint {
-		span = trace.NewSpanWithRemoteParent(name, sc, h.StartOptions)
+		span = trace.NewSpanWithRemoteParent(name, sc, opts)
 		ctx = trace.WithSpan(ctx, span)
 	} else {
-		span = trace.NewSpan(name, nil, h.StartOptions)
+		span = trace.NewSpan(name, nil, opts)
 		if ok {
 			span.AddLink(trace.Link{
 				TraceID:    sc.TraceID,