test(webhook): assert async conversion span shares server trace id

pkg/modules/webhook/middleware_trace_test.go

@@ -0,0 +1,86 @@
+package webhook
+
+import (
+	"context"
+	"testing"
+	"time"
+
+	"go.opentelemetry.io/otel"
+	sdktrace "go.opentelemetry.io/otel/sdk/trace"
+	"go.opentelemetry.io/otel/sdk/trace/tracetest"
+	"go.opentelemetry.io/otel/trace"
+
+	"github.com/gotenberg/gotenberg/v8/pkg/gotenberg"
+	"github.com/gotenberg/gotenberg/v8/pkg/modules/api"
+)
+
+// TestDetachAsyncContext_TraceContinuity asserts that an asynchronous webhook
+// conversion stays in the inbound request's trace: the worker-root
+// webhook.Async span and the downstream conversion span share the server
+// span's trace id, and webhook.Async links back to the server span.
+func TestDetachAsyncContext_TraceContinuity(t *testing.T) {
+	recorder := tracetest.NewSpanRecorder()
+	provider := sdktrace.NewTracerProvider(sdktrace.WithSpanProcessor(recorder))
+
+	previous := otel.GetTracerProvider()
+	otel.SetTracerProvider(provider)
+	t.Cleanup(func() { otel.SetTracerProvider(previous) })
+
+	serverCtx, serverSpan := provider.Tracer("test").Start(
+		context.Background(),
+		"POST /forms/chromium/convert/html",
+		trace.WithSpanKind(trace.SpanKindServer),
+	)
+	serverSpanCtx := serverSpan.SpanContext()
+
+	reqCtx, reqCancel := context.WithDeadline(serverCtx, time.Now().Add(time.Hour))
+	defer reqCancel()
+
+	ctx := &api.Context{Context: reqCtx}
+	cancel := detachAsyncContext(ctx, func() {})
+
+	// Simulate a downstream conversion span using the detached context, as the
+	// chromium/libreoffice engines would.
+	_, conversionSpan := gotenberg.Tracer().Start(ctx.Context, "chromium.Pdf", trace.WithSpanKind(trace.SpanKindClient))
+	conversionSpan.End()
+
+	// The server span ends when the synchronous handler returns, before the
+	// asynchronous worker finishes.
+	serverSpan.End()
+	cancel()
+
+	var asyncSpan, conversion sdktrace.ReadOnlySpan
+	for _, s := range recorder.Ended() {
+		switch s.Name() {
+		case "webhook.Async":
+			asyncSpan = s
+		case "chromium.Pdf":
+			conversion = s
+		}
+	}
+
+	if asyncSpan == nil {
+		t.Fatal("expected a webhook.Async span to be recorded")
+	}
+	if conversion == nil {
+		t.Fatal("expected a chromium.Pdf span to be recorded")
+	}
+
+	if conversion.SpanContext().TraceID() != serverSpanCtx.TraceID() {
+		t.Errorf("conversion span trace id = %s, want %s", conversion.SpanContext().TraceID(), serverSpanCtx.TraceID())
+	}
+	if asyncSpan.SpanContext().TraceID() != serverSpanCtx.TraceID() {
+		t.Errorf("webhook.Async trace id = %s, want %s", asyncSpan.SpanContext().TraceID(), serverSpanCtx.TraceID())
+	}
+	if conversion.Parent().SpanID() != asyncSpan.SpanContext().SpanID() {
+		t.Errorf("conversion span parent = %s, want webhook.Async %s", conversion.Parent().SpanID(), asyncSpan.SpanContext().SpanID())
+	}
+
+	links := asyncSpan.Links()
+	if len(links) != 1 {
+		t.Fatalf("expected webhook.Async to have 1 link, got %d", len(links))
+	}
+	if links[0].SpanContext.SpanID() != serverSpanCtx.SpanID() {
+		t.Errorf("webhook.Async link span id = %s, want %s", links[0].SpanContext.SpanID(), serverSpanCtx.SpanID())
+	}
+}