func initMetrics()

in pkg/otel_setup.go [143:201]
53 lines of code
10 McCabe index (conditional complexity)

func initMetrics() error {
	ctx := context.Background()
	// TODO: abstract the if-else
	var err error
	if testaccess.IsInTest() {
		metricsProvider = metric.NewMeterProvider(
			metric.WithReader(testaccess.ManualReader),
		)
	} else {
		if os.Getenv(metrics_exporter) == "none" {
			metricsProvider = noop.NewMeterProvider()
		} else if os.Getenv(metrics_exporter) == "console" {
			metricExporter, err = stdoutmetric.New()
			metricsProvider = metric.NewMeterProvider(
				metric.WithReader(metric.NewPeriodicReader(metricExporter)),
			)
		} else if os.Getenv(metrics_exporter) == "prometheus" {
			promExporter, err := prometheus.New()
			if err != nil {
				log.Fatalf("Failed to create prometheus metric exporter: %v", err)
			}
			metricsProvider = metric.NewMeterProvider(
				metric.WithReader(promExporter),
			)
			go serveMetrics()
		} else {
			if os.Getenv(report_protocol) == "grpc" || os.Getenv(trace_report_protocol) == "grpc" {
				metricExporter, err = otlpmetricgrpc.New(ctx)
				metricsProvider = metric.NewMeterProvider(
					metric.WithReader(metric.NewPeriodicReader(metricExporter)),
				)
			} else {
				metricExporter, err = otlpmetrichttp.New(ctx)
				metricsProvider = metric.NewMeterProvider(
					metric.WithReader(metric.NewPeriodicReader(metricExporter)),
				)
			}
		}
	}
	if err != nil {
		log.Fatalf("Failed to create metric exporter: %v", err)
	}
	if metricsProvider == nil {
		return errors.New("No MeterProvider is provided")
	}
	otel.SetMeterProvider(metricsProvider)
	m := metricsProvider.Meter("opentelemetry-global-meter")
	meter.SetMeter(m)
	// init http metrics
	http.InitHttpMetrics(m)
	// init rpc metrics
	rpc.InitRpcMetrics(m)
	// init db metrics
	db.InitDbMetrics(m)
	// nacos experimental metrics
	experimental.InitNacosExperimentalMetrics(m)
	// DefaultMinimumReadMemStatsInterval is 15 second
	return otelruntime.Start(otelruntime.WithMeterProvider(metricsProvider))
}