Add tracing package with sharable code that configures tracing provider

The tracing package contains sharable common code that configure tracing
provider. The package then can be vendored into other projects/components
that need to set up OpenTelemetry tracing.

Signed-off-by: Vu Dinh <vudinh@outlook.com>

Author: dinhxuanvu

pkg/tracing/otlp_sdk.go

@@ -0,0 +1,104 @@
+package tracing
+
+import (
+	"context"
+	"time"
+
+	"go.opentelemetry.io/contrib/exporters/autoexport"
+	"go.opentelemetry.io/otel"
+	"go.opentelemetry.io/otel/attribute"
+	"go.opentelemetry.io/otel/propagation"
+	"go.opentelemetry.io/otel/sdk/resource"
+	tracesdk "go.opentelemetry.io/otel/sdk/trace"
+
+	"github.com/go-logr/logr"
+	errors "github.com/zgalor/weberr"
+)
+
+// ConfigureOpenTelemetryTracer configures the global OpenTelemetry trace
+// provider and propagator for baggages and trace context.
+//
+// The function uses the following environment variables for the tracer
+// configuration:
+//   - `OTEL_TRACES_EXPORTER`, either `otlp` to send traces to an OTLP endpoint or `console`.
+//   - `OTEL_EXPORTER_OTLP_TRACES_PROTOCOL`, either `grpc` or `http`.
+//   - `OTEL_EXPORTER_OTLP_TRACES_ENDPOINT`, endpoint where to send the OTLP
+//     traces (e.g. `https://localhost:4318/v1/traces`).
+//
+// See
+// https://pkg.go.dev/go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp
+// for the list of all supported variables.
+//
+// An error is returned if an environment value is set to an unhandled value.
+//
+// If no environment variable are set, a no-op tracer is setup.
+func ConfigureOpenTelemetryTracer(ctx context.Context, logger logr.Logger, resourceAttrs ...attribute.KeyValue) (func(context.Context) error, error) {
+	logger.Info("initializing OpenTelemetry tracer...")
+
+	exp, err := autoexport.NewSpanExporter(ctx, autoexport.WithFallbackSpanExporter(newNoopFactory))
+	if err != nil {
+		return nil, errors.Errorf("failed to create OTEL exporter: %s", err)
+	}
+
+	var isNoop bool
+	if _, isNoop = exp.(*noopSpanExporter); !isNoop || autoexport.IsNoneSpanExporter(exp) {
+		isNoop = true
+	}
+	logger.Info("initializing OpenTelemetry tracer:", "isNoop", isNoop)
+
+	opts := []resource.Option{resource.WithHost()}
+	if len(resourceAttrs) > 0 {
+		opts = append(opts, resource.WithAttributes(resourceAttrs...))
+	}
+	resources, err := resource.New(ctx, opts...)
+	if err != nil {
+		return nil, errors.Errorf("failed to initialize trace resources: %s", err)
+	}
+
+	tp := tracesdk.NewTracerProvider(
+		tracesdk.WithBatcher(exp),
+		tracesdk.WithResource(resources),
+	)
+	otel.SetTracerProvider(tp)
+
+	shutdown := func(ctx context.Context) error {
+		ctx, cancel := context.WithTimeout(ctx, 5*time.Second)
+		defer cancel()
+		return tp.Shutdown(ctx)
+	}
+
+	propagator := propagation.NewCompositeTextMapPropagator(propagation.Baggage{}, propagation.TraceContext{})
+	otel.SetTextMapPropagator(propagator)
+
+	otel.SetErrorHandler(otelErrorHandlerFunc(func(err error) {
+		logger.Error(err, "OpenTelemetry.ErrorHandler: %v", err.Error())
+	}))
+
+	return shutdown, nil
+}
+
+type otelErrorHandlerFunc func(error)
+
+// Handle implements otel.ErrorHandler
+func (f otelErrorHandlerFunc) Handle(err error) {
+	f(err)
+}
+
+func newNoopFactory(_ context.Context) (tracesdk.SpanExporter, error) {
+	return &noopSpanExporter{}, nil
+}
+
+var _ tracesdk.SpanExporter = noopSpanExporter{}
+
+// noopSpanExporter is an implementation of trace.SpanExporter that performs no operations.
+type noopSpanExporter struct{}
+
+// ExportSpans is part of trace.SpanExporter interface.
+func (e noopSpanExporter) ExportSpans(ctx context.Context, spans []tracesdk.ReadOnlySpan) error {
+	return nil
+}
+
+// Shutdown is part of trace.SpanExporter interface.
+func (e noopSpanExporter) Shutdown(ctx context.Context) error {
+	return nil
+}