add otel module based on uptrace-go

Signed-off-by: Adphi <philippe.adrien.nousse@gmail.com>

otel/otel.go

@@ -0,0 +1,122 @@
+package otel
+
+import (
+	"context"
+	"os"
+	"strings"
+	"sync/atomic"
+
+	"go.opentelemetry.io/otel"
+	"go.opentelemetry.io/otel/propagation"
+	sdktrace "go.opentelemetry.io/otel/sdk/trace"
+	"go.opentelemetry.io/otel/trace"
+
+	"go.linka.cloud/grpc-toolkit/logger"
+)
+
+var log = logger.StandardLogger().WithField("name", "otel")
+
+// Configure configures OpenTelemetry.
+// By default, it:
+//   - creates tracer provider;
+//   - registers span exporter;
+//   - sets tracecontext + baggage composite context propagator.
+//
+// You can use OTEL_DISABLED env var to completely skip otel configuration.
+func Configure(opts ...Option) {
+	if _, ok := os.LookupEnv("OTEL_DISABLED"); ok {
+		return
+	}
+
+	ctx := context.TODO()
+	conf := newConfig(opts)
+
+	if !conf.tracingEnabled && !conf.metricsEnabled && !conf.loggingEnabled {
+		return
+	}
+
+	if len(conf.dsn) == 0 {
+		log.Warn("no DSN provided (otel-go is disabled)")
+		return
+	}
+
+	dsn, err := ParseDSN(conf.dsn[0])
+	if err != nil {
+		log.Warnf("invalid DSN: %s (otel is disabled)", err)
+		return
+	}
+
+	if strings.HasSuffix(dsn.Host, ":4318") {
+		log.Warnf("otel-go uses OTLP/gRPC exporter, but got host %q", dsn.Host)
+	}
+
+	client := newClient(dsn)
+
+	configurePropagator(conf)
+	if conf.tracingEnabled {
+		client.tp = configureTracing(ctx, conf)
+	}
+	if conf.metricsEnabled {
+		client.mp = configureMetrics(ctx, conf)
+	}
+	if conf.loggingEnabled {
+		client.lp = configureLogging(ctx, conf)
+	}
+
+	atomicClient.Store(client)
+}
+
+func configurePropagator(conf *config) {
+	textMapPropagator := conf.textMapPropagator
+	if textMapPropagator == nil {
+		textMapPropagator = propagation.NewCompositeTextMapPropagator(
+			propagation.TraceContext{},
+			propagation.Baggage{},
+		)
+	}
+	otel.SetTextMapPropagator(textMapPropagator)
+}
+
+// ------------------------------------------------------------------------------
+
+var (
+	fallbackClient = newClient(&DSN{})
+	atomicClient   atomic.Value
+)
+
+func activeClient() *client {
+	v := atomicClient.Load()
+	if v == nil {
+		return fallbackClient
+	}
+	return v.(*client)
+}
+
+func TraceURL(span trace.Span) string {
+	return activeClient().TraceURL(span)
+}
+
+func ReportError(ctx context.Context, err error, opts ...trace.EventOption) {
+	activeClient().ReportError(ctx, err, opts...)
+}
+
+func ReportPanic(ctx context.Context, val any) {
+	activeClient().ReportPanic(ctx, val)
+}
+
+func Shutdown(ctx context.Context) error {
+	return activeClient().Shutdown(ctx)
+}
+
+func ForceFlush(ctx context.Context) error {
+	return activeClient().ForceFlush(ctx)
+}
+
+func TracerProvider() *sdktrace.TracerProvider {
+	return activeClient().tp
+}
+
+// SetLogger sets the logger to the given one.
+func SetLogger(logger logger.Logger) {
+	log = logger
+}