rebase: bump sigs.k8s.io/controller-runtime

Bumps the k8s-dependencies group with 1 update: [sigs.k8s.io/controller-runtime](https://github.com/kubernetes-sigs/controller-runtime).


Updates `sigs.k8s.io/controller-runtime` from 0.19.3 to 0.19.4
- [Release notes](https://github.com/kubernetes-sigs/controller-runtime/releases)
- [Changelog](https://github.com/kubernetes-sigs/controller-runtime/blob/main/RELEASE.md)
- [Commits](https://github.com/kubernetes-sigs/controller-runtime/compare/v0.19.3...v0.19.4)

---
updated-dependencies:
- dependency-name: sigs.k8s.io/controller-runtime
  dependency-type: direct:production
  update-type: version-update:semver-patch
  dependency-group: k8s-dependencies
...

Signed-off-by: dependabot[bot] <support@github.com>

vendor/sigs.k8s.io/controller-runtime/pkg/certwatcher/certwatcher.go

@@ -20,10 +20,15 @@ import (
 	"bytes"
 	"context"
 	"crypto/tls"
+	"fmt"
 	"os"
 	"sync"
 	"time"
 
+	"github.com/fsnotify/fsnotify"
+	kerrors "k8s.io/apimachinery/pkg/util/errors"
+	"k8s.io/apimachinery/pkg/util/sets"
+	"k8s.io/apimachinery/pkg/util/wait"
 	"sigs.k8s.io/controller-runtime/pkg/certwatcher/metrics"
 	logf "sigs.k8s.io/controller-runtime/pkg/internal/log"
 )
@@ -40,6 +45,7 @@ type CertWatcher struct {
 	sync.RWMutex
 
 	currentCert *tls.Certificate
+	watcher     *fsnotify.Watcher
 	interval    time.Duration
 
 	certPath string
@@ -53,13 +59,25 @@ type CertWatcher struct {
 
 // New returns a new CertWatcher watching the given certificate and key.
 func New(certPath, keyPath string) (*CertWatcher, error) {
+	var err error
+
 	cw := &CertWatcher{
 		certPath: certPath,
 		keyPath:  keyPath,
 		interval: defaultWatchInterval,
 	}
 
-	return cw, cw.ReadCertificate()
+	// Initial read of certificate and key.
+	if err := cw.ReadCertificate(); err != nil {
+		return nil, err
+	}
+
+	cw.watcher, err = fsnotify.NewWatcher()
+	if err != nil {
+		return nil, err
+	}
+
+	return cw, nil
 }
 
 // WithWatchInterval sets the watch interval and returns the CertWatcher pointer
@@ -88,14 +106,35 @@ func (cw *CertWatcher) GetCertificate(_ *tls.ClientHelloInfo) (*tls.Certificate,
 
 // Start starts the watch on the certificate and key files.
 func (cw *CertWatcher) Start(ctx context.Context) error {
+	files := sets.New(cw.certPath, cw.keyPath)
+
+	{
+		var watchErr error
+		if err := wait.PollUntilContextTimeout(ctx, 1*time.Second, 10*time.Second, true, func(ctx context.Context) (done bool, err error) {
+			for _, f := range files.UnsortedList() {
+				if err := cw.watcher.Add(f); err != nil {
+					watchErr = err
+					return false, nil //nolint:nilerr // We want to keep trying.
+				}
+				// We've added the watch, remove it from the set.
+				files.Delete(f)
+			}
+			return true, nil
+		}); err != nil {
+			return fmt.Errorf("failed to add watches: %w", kerrors.NewAggregate([]error{err, watchErr}))
+		}
+	}
+
+	go cw.Watch()
+
 	ticker := time.NewTicker(cw.interval)
 	defer ticker.Stop()
 
-	log.Info("Starting certificate watcher")
+	log.Info("Starting certificate poll+watcher", "interval", cw.interval)
 	for {
 		select {
 		case <-ctx.Done():
-			return nil
+			return cw.watcher.Close()
 		case <-ticker.C:
 			if err := cw.ReadCertificate(); err != nil {
 				log.Error(err, "failed read certificate")
@@ -104,11 +143,26 @@ func (cw *CertWatcher) Start(ctx context.Context) error {
 	}
 }
 
-// Watch used to read events from the watcher's channel and reacts to changes,
-// it has currently no function and it's left here for backward compatibility until a future release.
-//
-// Deprecated: fsnotify has been removed and Start() is now polling instead.
+// Watch reads events from the watcher's channel and reacts to changes.
 func (cw *CertWatcher) Watch() {
+	for {
+		select {
+		case event, ok := <-cw.watcher.Events:
+			// Channel is closed.
+			if !ok {
+				return
+			}
+
+			cw.handleEvent(event)
+		case err, ok := <-cw.watcher.Errors:
+			// Channel is closed.
+			if !ok {
+				return
+			}
+
+			log.Error(err, "certificate watch error")
+		}
+	}
 }
 
 // updateCachedCertificate checks if the new certificate differs from the cache,
@@ -166,3 +220,23 @@ func (cw *CertWatcher) ReadCertificate() error {
 	}
 	return nil
 }
+
+func (cw *CertWatcher) handleEvent(event fsnotify.Event) {
+	// Only care about events which may modify the contents of the file.
+	switch {
+	case event.Op.Has(fsnotify.Write):
+	case event.Op.Has(fsnotify.Create):
+	case event.Op.Has(fsnotify.Chmod), event.Op.Has(fsnotify.Remove):
+		// If the file was removed or renamed, re-add the watch to the previous name
+		if err := cw.watcher.Add(event.Name); err != nil {
+			log.Error(err, "error re-watching file")
+		}
+	default:
+		return
+	}
+
+	log.V(1).Info("certificate event", "event", event)
+	if err := cw.ReadCertificate(); err != nil {
+		log.Error(err, "error re-reading certificate")
+	}
+}