tracing: support for shutting down the trace provider

tracing/tracing.go

@@ -19,6 +19,8 @@ import (
 
 // https://github.com/open-telemetry/opentelemetry-go/blob/main/exporters/otlp/otlptrace/otlptracehttp/example_test.go
 
+type TpShutdownFunc func(ctx context.Context) error
+
 func Tracer() trace.Tracer {
 	traceProvider := otel.GetTracerProvider()
 	return traceProvider.Tracer("ntppool-tracer")
@@ -29,7 +31,11 @@ type TracerConfig struct {
 	Environment string
 }
 
-func InitTracer(ctx context.Context, cfg *TracerConfig) error {
+var emptyTpShutdownFunc = func(_ context.Context) error {
+	return nil
+}
+
+func InitTracer(ctx context.Context, cfg *TracerConfig) (TpShutdownFunc, error) {
 
 	log := logger.Setup()
 
@@ -43,10 +49,14 @@ func InitTracer(ctx context.Context, cfg *TracerConfig) error {
 	}
 
 	if err != nil {
-		return err
+		return emptyTpShutdownFunc, err
+	}
+
+	if exporter == nil {
+		log.Warn("tracing not configured")
+		return emptyTpShutdownFunc, nil
 	}
 
-	if exporter != nil {
 	tp := otelsdktrace.NewTracerProvider(
 		otelsdktrace.WithSampler(otelsdktrace.AlwaysSample()),
 		otelsdktrace.WithBatcher(exporter),
@@ -55,11 +65,8 @@ func InitTracer(ctx context.Context, cfg *TracerConfig) error {
 
 	otel.SetTracerProvider(tp)
 	otel.SetTextMapPropagator(propagation.NewCompositeTextMapPropagator(propagation.TraceContext{}, propagation.Baggage{}))
-	} else {
-		log.Warn("tracing not configured")
-	}
 
-	return nil
+	return tp.Shutdown, nil
 }
 
 func newOLTPExporter(ctx context.Context) (otelsdktrace.SpanExporter, error) {