Keep the entrypoint UUID out of webhooker's own logs (closes #531)

On the receiver route the access log and the per-entrypoint 429 line
name the route pattern whatever the status. The received line names
the entrypoint and webhook IDs, and the unknown-entrypoint line logs
no path. The pattern is middleware.ReceiverRoute, which routes.go
registers the receiver with.

The README says the proxy's access log holds the UUID and must be
protected like the URL, and its access-log, rate-limit, Sentry and
log-size passages now match the code.

Model: opus-5-5

internal/handlers/webhook_test.go

@@ -12,12 +12,15 @@ import (
 	"testing"
 
 	"github.com/go-chi/chi"
+	"github.com/google/uuid"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
+	"gorm.io/gorm/clause"
 	"sneak.berlin/go/webhooker/internal/config"
 	"sneak.berlin/go/webhooker/internal/database"
 	"sneak.berlin/go/webhooker/internal/handlers"
 	"sneak.berlin/go/webhooker/internal/middleware"
+	"sneak.berlin/go/webhooker/internal/middleware/middlewaretest"
 )
 
 // TestHandleWebhook_LogsClientNextToThePeer checks that the
@@ -99,6 +102,87 @@ func TestHandleWebhook_LogsClientNextToThePeer(t *testing.T) {
 	}
 }
 
+// TestHandleWebhook_LogsNoEntrypointUUID sends an accepted event, a
+// request over the receiver rate limit and a request for an unknown
+// UUID through the receiver as routes.go mounts it, and checks that
+// nothing logged, at any level, carries either UUID.
+func TestHandleWebhook_LogsNoEntrypointUUID(t *testing.T) {
+	t.Parallel()
+
+	var (
+		h  *handlers.Handlers
+		db *database.Database
+	)
+
+	cfg := &config.Config{DataDir: t.TempDir(), ReceiverRateLimit: 1}
+
+	app := newTestAppWithConfig(t, cfg, &h, &db)
+	app.RequireStart()
+
+	t.Cleanup(app.RequireStop)
+
+	buf := new(bytes.Buffer)
+	log := slog.New(slog.NewJSONHandler(
+		buf, &slog.HandlerOptions{Level: slog.LevelDebug},
+	))
+	h.SetLogForTest(log)
+	mw := middlewaretest.New(t, log, cfg, nil)
+
+	webhook := seedWebhook(t, db)
+	entrypoint := &database.Entrypoint{
+		WebhookID: webhook.ID,
+		Path:      uuid.New().String(),
+		Active:    true,
+	}
+	require.NoError(t, db.DB().Omit(clause.Associations).
+		Create(entrypoint).Error)
+
+	unknownUUID := uuid.New().String()
+
+	router := chi.NewRouter()
+	router.Use(mw.Logging())
+	router.With(mw.ReceiverRateLimit()).HandleFunc(
+		middleware.ReceiverRoute, h.HandleWebhook(),
+	)
+
+	// In order: the limit is one request per minute per path, so the
+	// second request for the known UUID is the rejected one.
+	for _, step := range []struct {
+		entrypointUUID string
+		wantStatus     int
+	}{
+		{entrypoint.Path, http.StatusOK},
+		{entrypoint.Path, http.StatusTooManyRequests},
+		{unknownUUID, http.StatusNotFound},
+	} {
+		req := httptest.NewRequestWithContext(
+			context.Background(), http.MethodPost,
+			"/h/"+step.entrypointUUID, strings.NewReader("{}"),
+		)
+		w := httptest.NewRecorder()
+		router.ServeHTTP(w, req)
+
+		require.Equal(t, step.wantStatus, w.Code)
+	}
+
+	// The lines this test is about were all written, so the checks
+	// below are not passing on an empty log.
+	for _, msg := range []string{
+		"webhook request received",
+		"webhook receiver rate limit exceeded",
+		"entrypoint not found",
+	} {
+		assert.Contains(t, buf.String(), `"msg":"`+msg+`"`)
+	}
+
+	assert.NotContains(t, buf.String(), entrypoint.Path)
+	assert.NotContains(t, buf.String(), unknownUUID)
+
+	line := receivedLine(t, buf)
+	assert.Equal(t, entrypoint.ID, line["entrypoint_id"])
+	assert.Equal(t, webhook.ID, line["webhook_id"])
+}
+
 // receivedLine returns the one "webhook request received" line in the
 // captured JSON log.
 func receivedLine(t *testing.T, buf *bytes.Buffer) map[string]any {