move PreFetchHook to WatcherConfig

lib/srv/discovery/common/watcher.go

@@ -63,6 +63,8 @@ type WatcherConfig struct {
 	DiscoveryGroup string
 	// Origin is used to specify what type of origin watcher's resources are
 	Origin string
+	// PreFetchHookFn is called before starting a new fetch cycle.
+	PreFetchHookFn func()
 }
 
 // CheckAndSetDefaults validates the config.
@@ -96,36 +98,19 @@ type Watcher struct {
 	ctx context.Context
 	// resourcesC is a channel where fetched resourcess are sent.
 	resourcesC chan (types.ResourcesWithLabels)
-	// preFetchHookFn is called before starting a new fetch cycle.
-	preFetchHookFn func()
-}
-
-// WatcherOption is a functional option for the Watcher.
-type WatcherOption func(*Watcher)
-
-// WithPreFetchHookFn sets a function that gets called before each new iteration.
-func WithPreFetchHookFn(f func()) WatcherOption {
-	return func(w *Watcher) {
-		w.preFetchHookFn = f
-	}
 }
 
 // NewWatcher returns a new instance of a common discovery watcher.
-func NewWatcher(ctx context.Context, config WatcherConfig, options ...WatcherOption) (*Watcher, error) {
+func NewWatcher(ctx context.Context, config WatcherConfig) (*Watcher, error) {
 	if err := config.CheckAndSetDefaults(); err != nil {
 		return nil, trace.Wrap(err)
 	}
-	watcher := &Watcher{
+
+	return &Watcher{
 		cfg:        config,
 		ctx:        ctx,
 		resourcesC: make(chan types.ResourcesWithLabels),
-	}
-
-	for _, opt := range options {
-		opt(watcher)
-	}
-
-	return watcher, nil
+	}, nil
 }
 
 // Start starts fetching cloud resources and sending them to the channel.
@@ -158,8 +143,8 @@ func (w *Watcher) Start() {
 
 // fetchAndSend fetches resources from all fetchers and sends them to the channel.
 func (w *Watcher) fetchAndSend() {
-	if w.preFetchHookFn != nil {
-		w.preFetchHookFn()
+	if w.cfg.PreFetchHookFn != nil {
+		w.cfg.PreFetchHookFn()
 	}
 
 	var (

lib/srv/discovery/common/watcher_test.go

@@ -69,10 +69,10 @@ func TestWatcher(t *testing.T) {
 			Interval:   time.Hour,
 			Clock:      clock,
 			Origin:     types.OriginCloud,
-		},
-		WithPreFetchHookFn(func() {
-			fetchIterations.Add(1)
-		}))
+			PreFetchHookFn: func() {
+				fetchIterations.Add(1)
+			},
+		})
 	require.NoError(t, err)
 	go watcher.Start()
 

lib/srv/discovery/database_watcher.go

@@ -73,10 +73,10 @@ func (s *Server) startDatabaseWatchers() error {
 			TriggerFetchC:  s.newDiscoveryConfigChangedSub(),
 			Origin:         types.OriginCloud,
 			Clock:          s.clock,
+			PreFetchHookFn: func() {
+				s.awsRDSResourcesStatus.reset()
+			},
 		},
-		common.WithPreFetchHookFn(func() {
-			s.awsRDSResourcesStatus.reset()
-		}),
 	)
 	if err != nil {
 		return trace.Wrap(err)

lib/srv/discovery/kube_integration_watcher.go

@@ -73,11 +73,10 @@ func (s *Server) startKubeIntegrationWatchers() error {
 		Interval:       s.PollInterval,
 		Origin:         types.OriginCloud,
 		TriggerFetchC:  s.newDiscoveryConfigChangedSub(),
-	},
-		common.WithPreFetchHookFn(func() {
+		PreFetchHookFn: func() {
 			s.awsEKSResourcesStatus.reset()
-		}),
-	)
+		},
+	})
 	if err != nil {
 		return trace.Wrap(err)
 	}