otelgrpc: add custom attributes to the stats handler (#5133)

Fixes
#3894

Co-authored-by: Damien Mathieu <[email protected]>

CHANGELOG.md

@@ -25,6 +25,7 @@ The next release will require at least [Go 1.22].
 - Add `WithGinFilter` filter parameter in `go.opentelemetry.io/contrib/instrumentation/github.com/gin-gonic/gin/otelgin` to allow filtering requests with `*gin.Context`. (#5743)
 - Support [Go 1.23]. (#6017)
 - Add the `WithMetricsAttributesFn` option to allow setting dynamic, per-request metric attributes in `go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp`. (#5876)
+- Add the `WithSpanAttributes` and `WithMetricAttributes` methods to set custom attributes to the stats handler in `go.opentelemetry.io/contrib/instrumentation/google.golang.org/grpc/otelgrpc`. (#5133)
 
 ### Removed
 

instrumentation/google.golang.org/grpc/otelgrpc/config.go

@@ -42,6 +42,8 @@ type config struct {
 	TracerProvider    trace.TracerProvider
 	MeterProvider     metric.MeterProvider
 	SpanStartOptions  []trace.SpanStartOption
+	SpanAttributes    []attribute.KeyValue
+	MetricAttributes  []attribute.KeyValue
 
 	ReceivedEvent bool
 	SentEvent     bool
@@ -257,3 +259,29 @@ func (o spanStartOption) apply(c *config) {
 func WithSpanOptions(opts ...trace.SpanStartOption) Option {
 	return spanStartOption{opts}
 }
+
+type spanAttributesOption struct{ a []attribute.KeyValue }
+
+func (o spanAttributesOption) apply(c *config) {
+	if o.a != nil {
+		c.SpanAttributes = o.a
+	}
+}
+
+// WithSpanAttributes returns an Option to add custom attributes to the spans.
+func WithSpanAttributes(a ...attribute.KeyValue) Option {
+	return spanAttributesOption{a: a}
+}
+
+type metricAttributesOption struct{ a []attribute.KeyValue }
+
+func (o metricAttributesOption) apply(c *config) {
+	if o.a != nil {
+		c.MetricAttributes = o.a
+	}
+}
+
+// WithMetricAttributes returns an Option to add custom attributes to the metrics.
+func WithMetricAttributes(a ...attribute.KeyValue) Option {
+	return metricAttributesOption{a: a}
+}

instrumentation/google.golang.org/grpc/otelgrpc/stats_handler.go

@@ -62,11 +62,11 @@ func (h *serverHandler) TagRPC(ctx context.Context, info *stats.RPCTagInfo) cont
 		trace.ContextWithRemoteSpanContext(ctx, trace.SpanContextFromContext(ctx)),
 		name,
 		trace.WithSpanKind(trace.SpanKindServer),
-		trace.WithAttributes(attrs...),
+		trace.WithAttributes(append(attrs, h.config.SpanAttributes...)...),
 	)
 
 	gctx := gRPCContext{
-		metricAttrs: attrs,
+		metricAttrs: append(attrs, h.config.MetricAttributes...),
 		record:      true,
 	}
 	if h.config.Filter != nil {
@@ -102,11 +102,11 @@ func (h *clientHandler) TagRPC(ctx context.Context, info *stats.RPCTagInfo) cont
 		ctx,
 		name,
 		trace.WithSpanKind(trace.SpanKindClient),
-		trace.WithAttributes(attrs...),
+		trace.WithAttributes(append(attrs, h.config.SpanAttributes...)...),
 	)
 
 	gctx := gRPCContext{
-		metricAttrs: attrs,
+		metricAttrs: append(attrs, h.config.MetricAttributes...),
 		record:      true,
 	}
 	if h.config.Filter != nil {