start reworking exporters to be more composable

pkg/combined_exporter/combined_exporter.go

@@ -0,0 +1,40 @@
+package combined_exporter
+
+import (
+	"context"
+	"fmt"
+	"go.opentelemetry.io/otel/sdk/trace"
+)
+
+type Exporter struct {
+	exporters []trace.SpanExporter
+}
+
+func NewExporter(exporters ...trace.SpanExporter) trace.SpanExporter {
+	return &Exporter{
+		exporters: exporters,
+	}
+}
+
+// Implements [trace.SpanExporter]
+func (e *Exporter) ExportSpans(ctx context.Context, spans []trace.ReadOnlySpan) error {
+	for _, exp := range e.exporters {
+		exp.ExportSpans(ctx, spans)
+	}
+	return nil
+}
+
+// Implements [trace.SpanExporter]
+func (e *Exporter) Shutdown(ctx context.Context) error {
+	var errs []error
+	for _, exp := range e.exporters {
+		err := exp.Shutdown(ctx)
+		if err != nil {
+			errs = append(errs, err)
+		}
+	}
+	if len(errs) > 0 {
+		return fmt.Errorf("multiple erros have occured: %#v", errs)
+	}
+	return nil
+}