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

@@ -34,6 +34,7 @@ const traceContextKey = "grpc-trace-bin"
 // It returns ctx with the new trace span added and a serialization of the
 // SpanContext added to the outgoing gRPC metadata.
 func (c *ClientHandler) traceTagRPC(ctx context.Context, rti *stats.RPCTagInfo) context.Context {
+	c.StartOptions.SpanKind = trace.SpanKindClient
 	name := "Sent" + strings.Replace(rti.FullMethodName, "/", ".", -1)
 	span := trace.NewSpan(name, trace.FromContext(ctx), c.StartOptions) // span is ended by traceHandleRPC
 	ctx = trace.WithSpan(ctx, span)
@@ -48,6 +49,7 @@ 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 {
+	s.StartOptions.SpanKind = trace.SpanKindServer
 	md, _ := metadata.FromIncomingContext(ctx)
 	name := "Recv" + strings.Replace(rti.FullMethodName, "/", ".", -1)
 	traceContext := md[traceContextKey]

plugin/ochttp/client.go

@@ -38,13 +38,17 @@ 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.
 }
 
 // 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) {
+	t.StartOptions.SpanKind = trace.SpanKindClient
 	rt := t.base()
 	// TODO: remove excessive nesting of http.RoundTrippers here.
 	format := t.Propagation

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)
@@ -71,6 +74,7 @@ func (h *Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 }
 
 func (h *Handler) startTrace(w http.ResponseWriter, r *http.Request) (*http.Request, func()) {
+	h.StartOptions.SpanKind = trace.SpanKindServer
 	name := spanNameFromURL("Recv", r.URL)
 	ctx := r.Context()
 	var span *trace.Span