test otel

cmd/cart/otel.go

@@ -0,0 +1,122 @@
+package main
+
+import (
+	"context"
+	"errors"
+	"time"
+
+	"go.opentelemetry.io/otel"
+	"go.opentelemetry.io/otel/exporters/stdout/stdoutlog"
+	"go.opentelemetry.io/otel/exporters/stdout/stdoutmetric"
+	"go.opentelemetry.io/otel/exporters/stdout/stdouttrace"
+	"go.opentelemetry.io/otel/log/global"
+	"go.opentelemetry.io/otel/propagation"
+	"go.opentelemetry.io/otel/sdk/log"
+	"go.opentelemetry.io/otel/sdk/metric"
+	"go.opentelemetry.io/otel/sdk/trace"
+)
+
+// setupOTelSDK bootstraps the OpenTelemetry pipeline.
+// If it does not return an error, make sure to call shutdown for proper cleanup.
+func setupOTelSDK(ctx context.Context) (func(context.Context) error, error) {
+	var shutdownFuncs []func(context.Context) error
+	var err error
+
+	// shutdown calls cleanup functions registered via shutdownFuncs.
+	// The errors from the calls are joined.
+	// Each registered cleanup will be invoked once.
+	shutdown := func(ctx context.Context) error {
+		var err error
+		for _, fn := range shutdownFuncs {
+			err = errors.Join(err, fn(ctx))
+		}
+		shutdownFuncs = nil
+		return err
+	}
+
+	// handleErr calls shutdown for cleanup and makes sure that all errors are returned.
+	handleErr := func(inErr error) {
+		err = errors.Join(inErr, shutdown(ctx))
+	}
+
+	// Set up propagator.
+	prop := newPropagator()
+	otel.SetTextMapPropagator(prop)
+
+	// Set up trace provider.
+	tracerProvider, err := newTracerProvider()
+	if err != nil {
+		handleErr(err)
+		return shutdown, err
+	}
+	shutdownFuncs = append(shutdownFuncs, tracerProvider.Shutdown)
+	otel.SetTracerProvider(tracerProvider)
+
+	// Set up meter provider.
+	meterProvider, err := newMeterProvider()
+	if err != nil {
+		handleErr(err)
+		return shutdown, err
+	}
+	shutdownFuncs = append(shutdownFuncs, meterProvider.Shutdown)
+	otel.SetMeterProvider(meterProvider)
+
+	// Set up logger provider.
+	loggerProvider, err := newLoggerProvider()
+	if err != nil {
+		handleErr(err)
+		return shutdown, err
+	}
+	shutdownFuncs = append(shutdownFuncs, loggerProvider.Shutdown)
+	global.SetLoggerProvider(loggerProvider)
+
+	return shutdown, err
+}
+
+func newPropagator() propagation.TextMapPropagator {
+	return propagation.NewCompositeTextMapPropagator(
+		propagation.TraceContext{},
+		propagation.Baggage{},
+	)
+}
+
+func newTracerProvider() (*trace.TracerProvider, error) {
+	traceExporter, err := stdouttrace.New(
+		stdouttrace.WithPrettyPrint())
+	if err != nil {
+		return nil, err
+	}
+
+	tracerProvider := trace.NewTracerProvider(
+		trace.WithBatcher(traceExporter,
+			// Default is 5s. Set to 1s for demonstrative purposes.
+			trace.WithBatchTimeout(time.Second)),
+	)
+	return tracerProvider, nil
+}
+
+func newMeterProvider() (*metric.MeterProvider, error) {
+	metricExporter, err := stdoutmetric.New()
+	if err != nil {
+		return nil, err
+	}
+
+	meterProvider := metric.NewMeterProvider(
+		metric.WithReader(metric.NewPeriodicReader(metricExporter,
+			// Default is 1m. Set to 3s for demonstrative purposes.
+			metric.WithInterval(3*time.Second))),
+	)
+	return meterProvider, nil
+}
+
+func newLoggerProvider() (*log.LoggerProvider, error) {
+	logExporter, err := stdoutlog.New()
+	if err != nil {
+		return nil, err
+	}
+
+	loggerProvider := log.NewLoggerProvider(
+		log.WithProcessor(log.NewBatchProcessor(logExporter)),
+	)
+	return loggerProvider, nil
+}