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

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

internal/tracing/http_test.go

@@ -0,0 +1,82 @@
+package tracing
+
+import (
+	"context"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+
+	sdktrace "go.opentelemetry.io/otel/sdk/trace"
+	"go.opentelemetry.io/otel/sdk/trace/tracetest"
+	logf "sigs.k8s.io/controller-runtime/pkg/log"
+)
+
+const sampleTraceparent = "00-4bf92f3577b34da6a3ce929d0e0e4736-00f067aa0ba902b7-01"
+
+func TestHTTPMiddleware(t *testing.T) {
+	t.Parallel()
+
+	newServer := func(lines *[]string, tp *sdktrace.TracerProvider) http.Handler {
+		mux := http.NewServeMux()
+		handler := func(w http.ResponseWriter, r *http.Request) {
+			logf.FromContext(r.Context()).Info("handling")
+			w.WriteHeader(http.StatusOK)
+		}
+		mux.HandleFunc("GET /healthz", handler)
+		mux.HandleFunc("GET /v1/things/{id}", handler)
+		return HTTPMiddleware("discovery", captureLogger(lines), WithTracerProvider(tp))(mux)
+	}
+
+	t.Run("route span, enriched handler logs, traceparent continuation", func(t *testing.T) {
+		t.Parallel()
+		sr := tracetest.NewSpanRecorder()
+		tp := sdktrace.NewTracerProvider(sdktrace.WithSpanProcessor(sr))
+		t.Cleanup(func() { _ = tp.Shutdown(context.Background()) })
+
+		var lines []string
+		rec := httptest.NewRecorder()
+		req := httptest.NewRequest(http.MethodGet, "/v1/things/42", nil)
+		req.Header.Set("traceparent", sampleTraceparent)
+		newServer(&lines, tp).ServeHTTP(rec, req)
+
+		ended := sr.Ended()
+		if len(ended) != 1 {
+			t.Fatalf("got %d spans, want 1", len(ended))
+		}
+		if got := ended[0].Name(); got != "GET /v1/things/{id}" {
+			t.Errorf("span name = %q, want route pattern", got)
+		}
+		wantTrace := "4bf92f3577b34da6a3ce929d0e0e4736"
+		if got := ended[0].SpanContext().TraceID().String(); got != wantTrace {
+			t.Errorf("span traceID = %s, want continuation of client trace %s", got, wantTrace)
+		}
+		if len(lines) != 1 {
+			t.Fatalf("got %d log lines, want 1: %v", len(lines), lines)
+		}
+		if n := strings.Count(lines[0], `"traceID"`); n != 1 {
+			t.Errorf("traceID appears %d times, want 1: %s", n, lines[0])
+		}
+		if !strings.Contains(lines[0], wantTrace) {
+			t.Errorf("handler log missing traceID %s: %s", wantTrace, lines[0])
+		}
+	})
+
+	t.Run("healthz is not traced but still gets a logger", func(t *testing.T) {
+		t.Parallel()
+		sr := tracetest.NewSpanRecorder()
+		tp := sdktrace.NewTracerProvider(sdktrace.WithSpanProcessor(sr))
+		t.Cleanup(func() { _ = tp.Shutdown(context.Background()) })
+
+		var lines []string
+		rec := httptest.NewRecorder()
+		newServer(&lines, tp).ServeHTTP(rec, httptest.NewRequest(http.MethodGet, "/healthz", nil))
+
+		if len(sr.Ended()) != 0 {
+			t.Fatalf("healthz produced %d spans, want 0", len(sr.Ended()))
+		}
+		if len(lines) != 1 || strings.Contains(lines[0], "traceID") {
+			t.Fatalf("want one unenriched log line, got %v", lines)
+		}
+	})
+}