fixup tracer span labels

Signed-off-by: Vasiliy Tolstov <v.tolstov@unistack.org>

tracer.go

@@ -7,9 +7,9 @@ import (
 	"unicode/utf8"
 
 	"github.com/twmb/franz-go/pkg/kgo"
-	"go.unistack.org/micro/v3/tracer"
 	"go.opentelemetry.io/otel/attribute"
 	semconv "go.opentelemetry.io/otel/semconv/v1.18.0"
+	"go.unistack.org/micro/v3/tracer"
 )
 
 type hookTracer struct {
@@ -71,12 +71,8 @@ func (m *hookTracer) OnProduceRecordBuffered(r *kgo.Record) {
 	if m.clientID != "" {
 		attrs = append(attrs, semconv.MessagingKafkaClientIDKey.String(m.clientID))
 	}
-	ifattrs := make([]interface{}, 0, len(attrs))
-	for _, attr := range attrs {
-		ifattrs = append(ifattrs, attr)
-	}
 	opts := []tracer.SpanOption{
-		tracer.WithSpanLabels(ifattrs...),
+		tracer.WithSpanLabels(otel2Micro(attrs...)),
 		tracer.WithSpanKind(tracer.SpanKindProducer),
 	}
 	// Start the "publish" span.
@@ -129,12 +125,8 @@ func (m *hookTracer) OnFetchRecordBuffered(r *kgo.Record) {
 	if m.group != "" {
 		attrs = append(attrs, semconv.MessagingKafkaConsumerGroupKey.String(m.group))
 	}
-	ifattrs := make([]interface{}, 0, len(attrs))
-	for _, attr := range attrs {
-		ifattrs = append(ifattrs, attr)
-	}
 	opts := []tracer.SpanOption{
-		tracer.WithSpanLabels(ifattrs...),
+		tracer.WithSpanLabels(otel2Micro(attrs...)),
 		tracer.WithSpanKind(tracer.SpanKindConsumer),
 	}
 
@@ -177,10 +169,6 @@ func (m *hookTracer) WithProcessSpan(r *kgo.Record) (context.Context, tracer.Spa
 		semconv.MessagingKafkaMessageOffset(int(r.Offset)),
 	}
 	attrs = maybeKeyAttr(attrs, r)
-	ifattrs := make([]interface{}, 0, len(attrs))
-	for _, attr := range attrs {
-		ifattrs = append(ifattrs, attr)
-	}
 	if m.clientID != "" {
 		attrs = append(attrs, semconv.MessagingKafkaClientIDKey.String(m.clientID))
 	}
@@ -188,7 +176,7 @@ func (m *hookTracer) WithProcessSpan(r *kgo.Record) (context.Context, tracer.Spa
 		attrs = append(attrs, semconv.MessagingKafkaConsumerGroupKey.String(m.group))
 	}
 	opts := []tracer.SpanOption{
-		tracer.WithSpanLabels(ifattrs...),
+		tracer.WithSpanLabels(otel2Micro(attrs...)),
 		tracer.WithSpanKind(tracer.SpanKindConsumer),
 	}
 
@@ -210,3 +198,11 @@ func maybeKeyAttr(attrs []attribute.KeyValue, r *kgo.Record) []attribute.KeyValu
 	keykey = string(r.Key)
 	return append(attrs, semconv.MessagingKafkaMessageKeyKey.String(keykey))
 }
+
+func otel2Micro(attrs ...attribute.KeyValue) []interface{} {
+	ret := make([]interface{}, 0, len(attrs))
+	for _, a := range attrs {
+		ret = append(ret, a.Key, a.Value)
+	}
+	return ret
+}