[receiver/datadog] Use _dd.base_service when available

Without this, internal spans such as postgresql queries have a service.name set
to postgresql.

Author: xiu

receiver/datadogreceiver/internal/translator/traces_translator.go

@@ -103,6 +103,11 @@ func ToTraces(payload *pb.TracerPayload, req *http.Request) ptrace.Traces {
 
 	for _, trace := range traces {
 		for _, span := range trace {
+			// Restore base service name as the service name.
+			// Without this, internal spans such as postgresql queries have a service.name set to postgresql
+			if val, ok := span.Meta["_dd.base_service"]; ok {
+				span.Service = val
+			}
 			slice, exist := groupByService[span.Service]
 			if !exist {
 				slice = ptrace.NewSpanSlice()

receiver/datadogreceiver/internal/translator/traces_translator_test.go

@@ -221,3 +221,39 @@ func TestUpsertHeadersAttributes(t *testing.T) {
 	assert.True(t, ok)
 	assert.Equal(t, "dotnet", val.Str())
 }
+
+func TestToTracesServiceName(t *testing.T) {
+	expectedServiceName := "my-service"
+	spans := []pb.Span{
+		{
+			TraceID:  2133000431340558749,
+			SpanID:   2133000431340558749,
+			ParentID: 2133000431340558749,
+			Name:     "postgresql",
+			Meta: map[string]string{
+				"_dd.base_service": expectedServiceName,
+			},
+		},
+		{
+			TraceID:  2133000431340558749,
+			SpanID:   2133000431340558750,
+			ParentID: 2133000431340558750,
+			Name:     "postgresql",
+			Meta: map[string]string{
+				"_dd.base_service": expectedServiceName,
+			},
+		},
+	}
+	payload := &pb.TracerPayload{
+		Chunks: traceChunksFromSpans(spans),
+	}
+	req := &http.Request{
+		Header: http.Header{},
+	}
+
+	traces := ToTraces(payload, req)
+	for _, rs := range traces.ResourceSpans().All() {
+		actualServiceName, _ := rs.Resource().Attributes().Get(semconv.AttributeServiceName)
+		assert.Equal(t, expectedServiceName, actualServiceName.AsString())
+	}
+}