Add internal/tracing: env-gated OTel setup, span/log helpers, decorators

Co-Authored-By: Claude <noreply@anthropic.com>

internal/tracing/reconciler.go

@@ -0,0 +1,52 @@
+package tracing
+
+import (
+	"context"
+
+	"go.opentelemetry.io/otel/attribute"
+	"go.opentelemetry.io/otel/codes"
+	"go.opentelemetry.io/otel/trace"
+	"sigs.k8s.io/controller-runtime/pkg/controller"
+	"sigs.k8s.io/controller-runtime/pkg/reconcile"
+)
+
+// NewReconciler wraps inner so every reconcile runs in a root span named
+// "Reconcile <kind>" and every log line under it carries the trace context.
+// Reconciles are triggered by watch events with no incoming trace to
+// continue, so each one starts a new trace.
+func NewReconciler(kind string, inner reconcile.Reconciler, opts ...Option) reconcile.Reconciler {
+	return &tracedReconciler{
+		spanName: "Reconcile " + kind,
+		inner:    inner,
+		tracer:   newOptions(opts).tracer(),
+	}
+}
+
+type tracedReconciler struct {
+	spanName string
+	inner    reconcile.Reconciler
+	tracer   trace.Tracer
+}
+
+func (t *tracedReconciler) Reconcile(ctx context.Context, req reconcile.Request) (reconcile.Result, error) {
+	ctx, span := StartSpan(ctx, t.tracer, t.spanName,
+		trace.WithAttributes(
+			attribute.String("k8s.namespace.name", req.Namespace),
+			attribute.String("k8s.object.name", req.Name),
+		))
+	defer span.End()
+	if id := controller.ReconcileIDFromContext(ctx); id != "" {
+		span.SetAttributes(attribute.String("reconcile.id", string(id)))
+	}
+
+	res, err := t.inner.Reconcile(ctx, req)
+	if err != nil {
+		span.SetStatus(codes.Error, err.Error())
+		return res, err
+	}
+	span.SetStatus(codes.Ok, "")
+	if res.RequeueAfter > 0 {
+		span.SetAttributes(attribute.Int64("reconcile.requeue_after_ms", res.RequeueAfter.Milliseconds()))
+	}
+	return res, nil
+}