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

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

internal/tracing/options.go

@@ -0,0 +1,48 @@
+package tracing
+
+import (
+	"go.opentelemetry.io/otel"
+	"go.opentelemetry.io/otel/trace"
+)
+
+// tracerName is the instrumentation scope for every span this module emits.
+const tracerName = "gitea.home.hrajfrisbee.cz/kacerr/egress-proxies-operator"
+
+type options struct {
+	tp trace.TracerProvider
+}
+
+// Option configures the tracing decorators. The zero configuration uses the
+// global TracerProvider installed by Setup; tests inject their own recorder
+// via WithTracerProvider so they can run in parallel without touching
+// process-global state.
+type Option func(*options)
+
+// WithTracerProvider overrides the global TracerProvider.
+func WithTracerProvider(tp trace.TracerProvider) Option {
+	return func(o *options) { o.tp = tp }
+}
+
+func newOptions(opts []Option) options {
+	var o options
+	for _, opt := range opts {
+		opt(&o)
+	}
+	return o
+}
+
+// Tracer resolves a tracer from the given options, for decorators outside
+// this package (provider.WithTracing).
+func Tracer(opts ...Option) trace.Tracer {
+	return newOptions(opts).tracer()
+}
+
+// tracer resolves the configured tracer. The global path goes through
+// otel.Tracer, which delegates to whatever provider Setup installs later —
+// construction order between decorators and Setup does not matter.
+func (o options) tracer() trace.Tracer {
+	if o.tp != nil {
+		return o.tp.Tracer(tracerName)
+	}
+	return otel.Tracer(tracerName)
+}