done

core/metrics/multiexporter.go

@@ -0,0 +1,46 @@
+package metrics
+
+import (
+	"context"
+	"fmt"
+
+	"go.opentelemetry.io/otel/exporters/otlp/otlptrace"
+	tracesdk "go.opentelemetry.io/otel/sdk/trace"
+)
+
+type multiExporter struct {
+	exporters []*otlptrace.Exporter
+}
+
+// NewMultiExporter creates a new multi exporter that forwards spans to multiple OTLP trace exporters.
+// It takes in one or more otlptrace.Exporter instances and ensures that spans are sent to all of them.
+// This is useful when you need to send trace data to multiple backends or endpoints.
+func NewMultiExporter(exporters ...*otlptrace.Exporter) tracesdk.SpanExporter {
+	return &multiExporter{
+		exporters: exporters,
+	}
+}
+
+// ExportSpans exports a batch of spans.
+func (m *multiExporter) ExportSpans(ctx context.Context, ss []tracesdk.ReadOnlySpan) error {
+	for _, exporter := range m.exporters {
+		err := exporter.ExportSpans(ctx, ss)
+		if err != nil {
+			return fmt.Errorf("could not export spans: %w", err)
+		}
+	}
+	return nil
+}
+
+// Shutdown notifies the exporter of a pending halt to operations.
+func (m *multiExporter) Shutdown(ctx context.Context) error {
+	for _, exporter := range m.exporters {
+		err := exporter.Shutdown(ctx)
+		if err != nil {
+			return fmt.Errorf("could not stop exporter: %w", err)
+		}
+	}
+	return nil
+}
+
+var _ tracesdk.SpanExporter = &multiExporter{}

core/metrics/otlp.go

@@ -28,6 +28,7 @@ func NewOTLPMetricsHandler(buildInfo config.BuildInfo) Handler {
 }
 
 func (n *otlpHandler) Start(ctx context.Context) (err error) {
+	// TODO: generalize this to allow for more than two exporters.
 	client, err := buildClientFromTransport(transportFromString(core.GetEnv(otlpTransportEnv, otlpTransportGRPC.String())))
 	if err != nil {
 		return fmt.Errorf("could not create client: %w", err)
@@ -48,18 +49,15 @@ func (n *otlpHandler) Start(ctx context.Context) (err error) {
 		return fmt.Errorf("failed to create secondary otlp exporter: %w", err)
 	}
 
+	multiExporter := NewMultiExporter(exporter, secondaryExporter)
+
 	n.baseHandler = newBaseHandler(
 		n.buildInfo,
 		tracesdk.WithBatcher(
-			exporter,
+			multiExporter,
 			tracesdk.WithMaxQueueSize(defaultMaxQueueSize),
 			tracesdk.WithMaxExportBatchSize(defaultMaxExportBatch),
 		),
-		tracesdk.WithBatcher(
-			secondaryExporter,
-			tracesdk.WithMaxQueueSize(defaultMaxQueueSize),
-			tracesdk.WithMaxExportBatchSize(metricsPortDefault),
-		),
 		tracesdk.WithSampler(tracesdk.AlwaysSample()),
 	)