kyverno/pkg/webhookconfig/registration.go

package webhookconfig

import (
	"context"
	"encoding/json"
	"fmt"
	"reflect"
	"strings"
	"sync"
	"time"

	"github.com/go-logr/logr"
	kyvernoclient "github.com/kyverno/kyverno/pkg/client/clientset/versioned"
	kyvernoinformer "github.com/kyverno/kyverno/pkg/client/informers/externalversions/kyverno/v1"
	"github.com/kyverno/kyverno/pkg/config"
	client "github.com/kyverno/kyverno/pkg/dclient"
	"github.com/kyverno/kyverno/pkg/tls"
	"github.com/kyverno/kyverno/pkg/utils"
	"github.com/pkg/errors"
	admregapi "k8s.io/api/admissionregistration/v1"
	corev1 "k8s.io/api/core/v1"
	errorsapi "k8s.io/apimachinery/pkg/api/errors"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	adminformers "k8s.io/client-go/informers/admissionregistration/v1"
	informers "k8s.io/client-go/informers/apps/v1"
	"k8s.io/client-go/kubernetes"
	admlisters "k8s.io/client-go/listers/admissionregistration/v1"
	listers "k8s.io/client-go/listers/apps/v1"
	rest "k8s.io/client-go/rest"
)

const (
	kindMutating   string = "MutatingWebhookConfiguration"
	kindValidating string = "ValidatingWebhookConfiguration"
)

// Register manages webhook registration. There are five webhooks:
// 1. Policy Validation
// 2. Policy Mutation
// 3. Resource Validation
// 4. Resource Mutation
// 5. Webhook Status Mutation
type Register struct {
	// clients
	kubeClient   kubernetes.Interface
	clientConfig *rest.Config

	// listers
	mwcLister   admlisters.MutatingWebhookConfigurationLister
	vwcLister   admlisters.ValidatingWebhookConfigurationLister
	kDeplLister listers.DeploymentLister

	serverIP           string // when running outside a cluster
	timeoutSeconds     int32
	log                logr.Logger
	debug              bool
	autoUpdateWebhooks bool
	stopCh             <-chan struct{}

	UpdateWebhookChan    chan bool
	createDefaultWebhook chan string

	// manage implements methods to manage webhook configurations
	manage
}

// NewRegister creates new Register instance
func NewRegister(
	clientConfig *rest.Config,
	client client.Interface,
	kubeClient kubernetes.Interface,
	kyvernoClient kyvernoclient.Interface,
	mwcInformer adminformers.MutatingWebhookConfigurationInformer,
	vwcInformer adminformers.ValidatingWebhookConfigurationInformer,
	kDeplInformer informers.DeploymentInformer,
	pInformer kyvernoinformer.ClusterPolicyInformer,
	npInformer kyvernoinformer.PolicyInformer,
	serverIP string,
	webhookTimeout int32,
	debug bool,
	autoUpdateWebhooks bool,
	stopCh <-chan struct{},
	log logr.Logger) *Register {
	register := &Register{
		clientConfig:         clientConfig,
		kubeClient:           kubeClient,
		mwcLister:            mwcInformer.Lister(),
		vwcLister:            vwcInformer.Lister(),
		kDeplLister:          kDeplInformer.Lister(),
		serverIP:             serverIP,
		timeoutSeconds:       webhookTimeout,
		log:                  log.WithName("Register"),
		debug:                debug,
		autoUpdateWebhooks:   autoUpdateWebhooks,
		UpdateWebhookChan:    make(chan bool),
		createDefaultWebhook: make(chan string),
		stopCh:               stopCh,
	}

	register.manage = newWebhookConfigManager(client, kyvernoClient, pInformer, npInformer, mwcInformer, vwcInformer, serverIP, register.autoUpdateWebhooks, register.createDefaultWebhook, stopCh, log.WithName("WebhookConfigManager"))

	return register
}

// Register clean up the old webhooks and re-creates admission webhooks configs on cluster
func (wrc *Register) Register() error {
	logger := wrc.log
	if wrc.serverIP != "" {
		logger.Info("Registering webhook", "url", fmt.Sprintf("https://%s", wrc.serverIP))
	}
	if !wrc.debug {
		if err := wrc.checkEndpoint(); err != nil {
			return err
		}
	}

	caData := wrc.readCaData()
	if caData == nil {
		return errors.New("Unable to extract CA data from configuration")
	}

	errors := make([]string, 0)
	if err := wrc.createVerifyMutatingWebhookConfiguration(caData); err != nil {
		errors = append(errors, err.Error())
	}

	if err := wrc.createPolicyValidatingWebhookConfiguration(caData); err != nil {
		errors = append(errors, err.Error())
	}

	if err := wrc.createPolicyMutatingWebhookConfiguration(caData); err != nil {
		errors = append(errors, err.Error())
	}

	if err := wrc.createResourceValidatingWebhookConfiguration(caData); err != nil {
		errors = append(errors, err.Error())
	}

	if err := wrc.createResourceMutatingWebhookConfiguration(caData); err != nil {
		errors = append(errors, err.Error())
	}

	if len(errors) > 0 {
		return fmt.Errorf("%s", strings.Join(errors, ","))
	}

	go wrc.manage.start()
	return nil
}

// Check returns an error if any of the webhooks are not configured
func (wrc *Register) Check() error {
	if _, err := wrc.mwcLister.Get(wrc.getVerifyWebhookMutatingWebhookName()); err != nil {
		return err
	}

	if _, err := wrc.mwcLister.Get(getResourceMutatingWebhookConfigName(wrc.serverIP)); err != nil {
		return err
	}

	if _, err := wrc.vwcLister.Get(getResourceValidatingWebhookConfigName(wrc.serverIP)); err != nil {
		return err
	}

	if _, err := wrc.mwcLister.Get(getPolicyMutatingWebhookConfigurationName(wrc.serverIP)); err != nil {
		return err
	}

	if _, err := wrc.vwcLister.Get(getPolicyValidatingWebhookConfigurationName(wrc.serverIP)); err != nil {
		return err
	}

	return nil
}

// Remove removes all webhook configurations
func (wrc *Register) Remove(cleanUp chan<- struct{}) {
	defer close(cleanUp)

	// delete Lease object to let init container do the cleanup
	err := wrc.kubeClient.CoordinationV1().Leases(config.KyvernoNamespace).Delete(context.TODO(), "kyvernopre-lock", metav1.DeleteOptions{})
	if err != nil && errorsapi.IsNotFound(err) {
		wrc.log.WithName("cleanup").Error(err, "failed to clean up Lease lock")
	}

	if !wrc.cleanupKyvernoResource() {
		return
	}

	wrc.removeWebhookConfigurations()
	wrc.removeSecrets()
}

// UpdateWebhookConfigurations updates resource webhook configurations dynamically
// based on the UPDATEs of Kyverno ConfigMap defined in INIT_CONFIG env
//
// it currently updates namespaceSelector only, can be extend to update other fields
// +deprecated
func (wrc *Register) UpdateWebhookConfigurations(configHandler config.Interface) {
	logger := wrc.log.WithName("UpdateWebhookConfigurations")
	for {
		<-wrc.UpdateWebhookChan
		logger.V(4).Info("received the signal to update webhook configurations")

		webhookCfgs := configHandler.GetWebhooks()
		webhookCfg := config.WebhookConfig{}
		if len(webhookCfgs) > 0 {
			webhookCfg = webhookCfgs[0]
		}

		retry := false
		if err := wrc.updateResourceMutatingWebhookConfiguration(webhookCfg); err != nil {
			logger.Error(err, "unable to update mutatingWebhookConfigurations", "name", getResourceMutatingWebhookConfigName(wrc.serverIP))
			retry = true
		}

		if err := wrc.updateResourceValidatingWebhookConfiguration(webhookCfg); err != nil {
			logger.Error(err, "unable to update validatingWebhookConfigurations", "name", getResourceValidatingWebhookConfigName(wrc.serverIP))
			retry = true
		}

		if retry {
			go func() {
				time.Sleep(1 * time.Second)
				wrc.UpdateWebhookChan <- true
			}()
		}
	}
}

func (wrc *Register) ValidateWebhookConfigurations(namespace, name string) error {
	logger := wrc.log.WithName("ValidateWebhookConfigurations")
	cm, err := wrc.kubeClient.CoreV1().ConfigMaps(namespace).Get(context.TODO(), name, metav1.GetOptions{})
	if err != nil {
		logger.Error(err, "unable to fetch ConfigMap", "namespace", namespace, "name", name)
		return nil
	}
	webhooks, ok := cm.Data["webhooks"]
	if !ok {
		logger.V(4).Info("webhook configurations not defined")
		return nil
	}
	webhookCfgs := make([]config.WebhookConfig, 0, 10)
	return json.Unmarshal([]byte(webhooks), &webhookCfgs)
}

// cleanupKyvernoResource returns true if Kyverno is terminating
func (wrc *Register) cleanupKyvernoResource() bool {
	logger := wrc.log.WithName("cleanupKyvernoResource")
	deploy, err := wrc.kubeClient.AppsV1().Deployments(config.KyvernoNamespace).Get(context.TODO(), config.KyvernoDeploymentName, metav1.GetOptions{})
	if err != nil {
		if errorsapi.IsNotFound(err) {
			logger.Info("Kyverno deployment not found, cleanup Kyverno resources")
			return true
		}
		logger.Error(err, "failed to get deployment, not cleaning up kyverno resources")
		return false
	}
	if deploy.GetDeletionTimestamp() != nil {
		logger.Info("Kyverno is terminating, cleanup Kyverno resources")
		return true
	}
	if deploy.Spec.Replicas != nil && *deploy.Spec.Replicas == 0 {
		logger.Info("Kyverno is scaled to zero, cleanup Kyverno resources")
		return true
	}
	logger.Info("updating Kyverno Pod, won't clean up Kyverno resources")
	return false
}

func (wrc *Register) createResourceMutatingWebhookConfiguration(caData []byte) error {
	var config *admregapi.MutatingWebhookConfiguration

	if wrc.serverIP != "" {
		config = wrc.constructDefaultDebugMutatingWebhookConfig(caData)
	} else {
		config = wrc.constructDefaultMutatingWebhookConfig(caData)
	}

	logger := wrc.log.WithValues("kind", kindMutating, "name", config.Name)

	_, err := wrc.kubeClient.AdmissionregistrationV1().MutatingWebhookConfigurations().Create(context.TODO(), config, metav1.CreateOptions{})
	if errorsapi.IsAlreadyExists(err) {
		logger.V(6).Info("resource mutating webhook configuration already exists", "name", config.Name)
		err = wrc.updateMutatingWebhookConfiguration(config)
		if err != nil {
			return err
		}
		return nil
	}
	if err != nil {
		logger.Error(err, "failed to create resource mutating webhook configuration", "name", config.Name)
		return err
	}

	logger.Info("created webhook")
	return nil
}

func (wrc *Register) createResourceValidatingWebhookConfiguration(caData []byte) error {
	var config *admregapi.ValidatingWebhookConfiguration

	if wrc.serverIP != "" {
		config = wrc.constructDefaultDebugValidatingWebhookConfig(caData)
	} else {
		config = wrc.constructDefaultValidatingWebhookConfig(caData)
	}

	logger := wrc.log.WithValues("kind", kindValidating, "name", config.Name)

	_, err := wrc.kubeClient.AdmissionregistrationV1().ValidatingWebhookConfigurations().Create(context.TODO(), config, metav1.CreateOptions{})
	if errorsapi.IsAlreadyExists(err) {
		logger.V(6).Info("resource validating webhook configuration already exists", "name", config.Name)
		err = wrc.updateValidatingWebhookConfiguration(config)
		if err != nil {
			return err
		}
		return nil
	}

	if err != nil {
		logger.Error(err, "failed to create resource")
		return err
	}

	logger.Info("created webhook")
	return nil
}

//registerPolicyValidatingWebhookConfiguration create a Validating webhook configuration for Policy CRD
func (wrc *Register) createPolicyValidatingWebhookConfiguration(caData []byte) error {
	var config *admregapi.ValidatingWebhookConfiguration

	if wrc.serverIP != "" {
		config = wrc.constructDebugPolicyValidatingWebhookConfig(caData)
	} else {
		config = wrc.constructPolicyValidatingWebhookConfig(caData)
	}

	if _, err := wrc.kubeClient.AdmissionregistrationV1().ValidatingWebhookConfigurations().Create(context.TODO(), config, metav1.CreateOptions{}); err != nil {
		if errorsapi.IsAlreadyExists(err) {
			wrc.log.V(6).Info("webhook already exists", "kind", kindValidating, "name", config.Name)
			err = wrc.updateValidatingWebhookConfiguration(config)
			if err != nil {
				return err
			}
			return nil
		}

		return err
	}

	wrc.log.Info("created webhook", "kind", kindValidating, "name", config.Name)
	return nil
}

func (wrc *Register) createPolicyMutatingWebhookConfiguration(caData []byte) error {
	var config *admregapi.MutatingWebhookConfiguration

	if wrc.serverIP != "" {
		config = wrc.constructDebugPolicyMutatingWebhookConfig(caData)
	} else {
		config = wrc.constructPolicyMutatingWebhookConfig(caData)
	}

	if _, err := wrc.kubeClient.AdmissionregistrationV1().MutatingWebhookConfigurations().Create(context.TODO(), config, metav1.CreateOptions{}); err != nil {
		if errorsapi.IsAlreadyExists(err) {
			wrc.log.V(6).Info("webhook already exists", "kind", kindMutating, "name", config.Name)
			err = wrc.updateMutatingWebhookConfiguration(config)
			if err != nil {
				return err
			}
			return nil
		}

		return err
	}

	wrc.log.Info("created webhook", "kind", kindMutating, "name", config.Name)
	return nil
}

func (wrc *Register) createVerifyMutatingWebhookConfiguration(caData []byte) error {
	var config *admregapi.MutatingWebhookConfiguration

	if wrc.serverIP != "" {
		config = wrc.constructDebugVerifyMutatingWebhookConfig(caData)
	} else {
		config = wrc.constructVerifyMutatingWebhookConfig(caData)
	}

	if _, err := wrc.kubeClient.AdmissionregistrationV1().MutatingWebhookConfigurations().Create(context.TODO(), config, metav1.CreateOptions{}); err != nil {
		if errorsapi.IsAlreadyExists(err) {
			wrc.log.V(6).Info("webhook already exists", "kind", kindMutating, "name", config.Name)
			err = wrc.updateMutatingWebhookConfiguration(config)
			if err != nil {
				return err
			}
			return nil
		}

		return err
	}

	wrc.log.Info("created webhook", "kind", kindMutating, "name", config.Name)
	return nil
}

func (wrc *Register) removeWebhookConfigurations() {
	startTime := time.Now()
	wrc.log.V(3).Info("deleting all webhook configurations")
	defer func() {
		wrc.log.V(4).Info("removed webhook configurations", "processingTime", time.Since(startTime).String())
	}()

	var wg sync.WaitGroup
	wg.Add(5)

	go wrc.removeResourceMutatingWebhookConfiguration(&wg)
	go wrc.removeResourceValidatingWebhookConfiguration(&wg)
	go wrc.removePolicyMutatingWebhookConfiguration(&wg)
	go wrc.removePolicyValidatingWebhookConfiguration(&wg)
	go wrc.removeVerifyWebhookMutatingWebhookConfig(&wg)

	wg.Wait()
}

func (wrc *Register) removePolicyMutatingWebhookConfiguration(wg *sync.WaitGroup) {
	defer wg.Done()

	mutatingConfig := getPolicyMutatingWebhookConfigurationName(wrc.serverIP)

	logger := wrc.log.WithValues("kind", kindMutating, "name", mutatingConfig)

	if _, err := wrc.mwcLister.Get(mutatingConfig); err != nil && errorsapi.IsNotFound(err) {
		logger.V(4).Info("webhook not found")
		return
	}

	err := wrc.kubeClient.AdmissionregistrationV1().MutatingWebhookConfigurations().Delete(context.TODO(), mutatingConfig, metav1.DeleteOptions{})
	if errorsapi.IsNotFound(err) {
		logger.V(5).Info("policy mutating webhook configuration not found")
		return
	}

	if err != nil {
		logger.Error(err, "failed to delete policy mutating webhook configuration")
		return
	}

	logger.Info("webhook configuration deleted")
}

func getPolicyMutatingWebhookConfigurationName(serverIP string) string {
	var mutatingConfig string
	if serverIP != "" {
		mutatingConfig = config.PolicyMutatingWebhookConfigurationDebugName
	} else {
		mutatingConfig = config.PolicyMutatingWebhookConfigurationName
	}
	return mutatingConfig
}

func (wrc *Register) removePolicyValidatingWebhookConfiguration(wg *sync.WaitGroup) {
	defer wg.Done()

	validatingConfig := getPolicyValidatingWebhookConfigurationName(wrc.serverIP)

	logger := wrc.log.WithValues("kind", kindValidating, "name", validatingConfig)
	if _, err := wrc.vwcLister.Get(validatingConfig); err != nil && errorsapi.IsNotFound(err) {
		logger.V(4).Info("webhook not found")
		return
	}

	logger.V(4).Info("removing validating webhook configuration")
	err := wrc.kubeClient.AdmissionregistrationV1().ValidatingWebhookConfigurations().Delete(context.TODO(), validatingConfig, metav1.DeleteOptions{})
	if errorsapi.IsNotFound(err) {
		logger.V(5).Info("policy validating webhook configuration not found")
		return
	}

	if err != nil {
		logger.Error(err, "failed to delete policy validating webhook configuration")
		return
	}

	logger.Info("webhook configuration deleted")
}

func getPolicyValidatingWebhookConfigurationName(serverIP string) string {
	var validatingConfig string
	if serverIP != "" {
		validatingConfig = config.PolicyValidatingWebhookConfigurationDebugName
	} else {
		validatingConfig = config.PolicyValidatingWebhookConfigurationName
	}
	return validatingConfig
}

func (wrc *Register) constructVerifyMutatingWebhookConfig(caData []byte) *admregapi.MutatingWebhookConfiguration {
	genWebHook := generateMutatingWebhook(
		config.VerifyMutatingWebhookName,
		config.VerifyMutatingWebhookServicePath,
		caData,
		true,
		wrc.timeoutSeconds,
		admregapi.Rule{
			Resources:   []string{"leases"},
			APIGroups:   []string{"coordination.k8s.io"},
			APIVersions: []string{"v1"},
		},
		[]admregapi.OperationType{admregapi.Update},
		admregapi.Ignore,
	)

	genWebHook.ObjectSelector = &metav1.LabelSelector{
		MatchLabels: map[string]string{
			"app.kubernetes.io/name": "kyverno",
		},
	}
	return &admregapi.MutatingWebhookConfiguration{
		ObjectMeta: metav1.ObjectMeta{
			Name: config.VerifyMutatingWebhookConfigurationName,
			OwnerReferences: []metav1.OwnerReference{
				wrc.constructOwner(),
			},
		},
		Webhooks: []admregapi.MutatingWebhook{
			genWebHook,
		},
	}
}

func (wrc *Register) constructDebugVerifyMutatingWebhookConfig(caData []byte) *admregapi.MutatingWebhookConfiguration {
	logger := wrc.log
	url := fmt.Sprintf("https://%s%s", wrc.serverIP, config.VerifyMutatingWebhookServicePath)
	logger.V(4).Info("Debug VerifyMutatingWebhookConfig is registered with url", "url", url)
	genWebHook := generateDebugMutatingWebhook(
		config.VerifyMutatingWebhookName,
		url,
		caData,
		true,
		wrc.timeoutSeconds,
		admregapi.Rule{
			Resources:   []string{"leases"},
			APIGroups:   []string{"coordination.k8s.io"},
			APIVersions: []string{"v1"},
		},
		[]admregapi.OperationType{admregapi.Update},
		admregapi.Ignore,
	)
	genWebHook.ObjectSelector = &metav1.LabelSelector{
		MatchLabels: map[string]string{
			"app.kubernetes.io/name": "kyverno",
		},
	}
	return &admregapi.MutatingWebhookConfiguration{
		ObjectMeta: metav1.ObjectMeta{
			Name: config.VerifyMutatingWebhookConfigurationDebugName,
		},
		Webhooks: []admregapi.MutatingWebhook{
			genWebHook,
		},
	}
}

func (wrc *Register) removeVerifyWebhookMutatingWebhookConfig(wg *sync.WaitGroup) {
	defer wg.Done()

	var err error
	mutatingConfig := wrc.getVerifyWebhookMutatingWebhookName()
	logger := wrc.log.WithValues("kind", kindMutating, "name", mutatingConfig)

	if _, err := wrc.mwcLister.Get(mutatingConfig); err != nil && errorsapi.IsNotFound(err) {
		logger.V(4).Info("webhook not found")
		return
	}

	err = wrc.kubeClient.AdmissionregistrationV1().MutatingWebhookConfigurations().Delete(context.TODO(), mutatingConfig, metav1.DeleteOptions{})
	if errorsapi.IsNotFound(err) {
		logger.V(5).Info("verify webhook configuration not found")
		return
	}

	if err != nil {
		logger.Error(err, "failed to delete verify webhook configuration")
		return
	}

	logger.Info("webhook configuration deleted")
}

func (wrc *Register) getVerifyWebhookMutatingWebhookName() string {
	var mutatingConfig string
	if wrc.serverIP != "" {
		mutatingConfig = config.VerifyMutatingWebhookConfigurationDebugName
	} else {
		mutatingConfig = config.VerifyMutatingWebhookConfigurationName
	}
	return mutatingConfig
}

// GetWebhookTimeOut returns the value of webhook timeout
func (wrc *Register) GetWebhookTimeOut() time.Duration {
	return time.Duration(wrc.timeoutSeconds)
}

// removeSecrets removes Kyverno managed secrets
func (wrc *Register) removeSecrets() {
	selector := &metav1.LabelSelector{
		MatchLabels: map[string]string{
			tls.ManagedByLabel: "kyverno",
		},
	}
	if err := wrc.kubeClient.CoreV1().Secrets(config.KyvernoNamespace).DeleteCollection(context.TODO(), metav1.DeleteOptions{}, metav1.ListOptions{LabelSelector: metav1.FormatLabelSelector(selector)}); err != nil {
		wrc.log.Error(err, "failed to clean up Kyverno managed secrets")
		return
	}
}

func (wrc *Register) checkEndpoint() error {
	endpoint, err := wrc.kubeClient.CoreV1().Endpoints(config.KyvernoNamespace).Get(context.TODO(), config.KyvernoServiceName, metav1.GetOptions{})
	if err != nil {
		return fmt.Errorf("failed to get endpoint %s/%s: %v", config.KyvernoNamespace, config.KyvernoServiceName, err)
	}
	selector := &metav1.LabelSelector{
		MatchLabels: map[string]string{
			"app.kubernetes.io/name": "kyverno",
		},
	}
	pods, err := wrc.kubeClient.CoreV1().Pods(config.KyvernoNamespace).List(context.TODO(), metav1.ListOptions{LabelSelector: metav1.FormatLabelSelector(selector)})
	if err != nil {
		return fmt.Errorf("failed to list Kyverno Pod: %v", err)
	}
	ips, errs := getHealthyPodsIP(pods.Items)
	if len(errs) != 0 {
		return fmt.Errorf("error getting pod's IP: %v", errs)
	}
	if len(ips) == 0 {
		return fmt.Errorf("pod is not assigned to any node yet")
	}
	for _, subset := range endpoint.Subsets {
		if len(subset.Addresses) == 0 {
			continue
		}
		for _, addr := range subset.Addresses {
			if utils.ContainsString(ips, addr.IP) {
				wrc.log.Info("Endpoint ready", "ns", config.KyvernoNamespace, "name", config.KyvernoServiceName)
				return nil
			}
		}
	}
	err = fmt.Errorf("endpoint not ready")
	wrc.log.V(3).Info(err.Error(), "ns", config.KyvernoNamespace, "name", config.KyvernoServiceName)
	return err
}

func getHealthyPodsIP(pods []corev1.Pod) (ips []string, errs []error) {
	for _, pod := range pods {
		if pod.Status.Phase != "Running" {
			continue
		}
		ips = append(ips, pod.Status.PodIP)
	}
	return
}

func (wrc *Register) updateResourceValidatingWebhookConfiguration(webhookCfg config.WebhookConfig) error {
	resource, err := wrc.vwcLister.Get(getResourceValidatingWebhookConfigName(wrc.serverIP))
	if err != nil {
		return errors.Wrapf(err, "unable to get validatingWebhookConfigurations")
	}
	copy := resource.DeepCopy()
	for i := range copy.Webhooks {
		copy.Webhooks[i].ObjectSelector = webhookCfg.ObjectSelector
		copy.Webhooks[i].NamespaceSelector = webhookCfg.NamespaceSelector
	}
	if reflect.DeepEqual(resource.Webhooks, copy.Webhooks) {
		wrc.log.V(4).Info("namespaceSelector unchanged, skip updating validatingWebhookConfigurations")
		return nil
	}
	if _, err := wrc.kubeClient.AdmissionregistrationV1().ValidatingWebhookConfigurations().Update(context.TODO(), copy, metav1.UpdateOptions{}); err != nil {
		return err
	}
	wrc.log.V(3).Info("successfully updated validatingWebhookConfigurations", "name", getResourceMutatingWebhookConfigName(wrc.serverIP))
	return nil
}

func (wrc *Register) updateResourceMutatingWebhookConfiguration(webhookCfg config.WebhookConfig) error {
	resource, err := wrc.mwcLister.Get(getResourceMutatingWebhookConfigName(wrc.serverIP))
	if err != nil {
		return errors.Wrapf(err, "unable to get mutatingWebhookConfigurations")
	}
	copy := resource.DeepCopy()
	for i := range copy.Webhooks {
		copy.Webhooks[i].ObjectSelector = webhookCfg.ObjectSelector
		copy.Webhooks[i].NamespaceSelector = webhookCfg.NamespaceSelector
	}
	if reflect.DeepEqual(resource.Webhooks, copy.Webhooks) {
		wrc.log.V(4).Info("namespaceSelector unchanged, skip updating mutatingWebhookConfigurations")
		return nil
	}
	if _, err := wrc.kubeClient.AdmissionregistrationV1().MutatingWebhookConfigurations().Update(context.TODO(), copy, metav1.UpdateOptions{}); err != nil {
		return err
	}
	wrc.log.V(3).Info("successfully updated mutatingWebhookConfigurations", "name", getResourceMutatingWebhookConfigName(wrc.serverIP))
	return nil
}

// updateMutatingWebhookConfiguration updates an existing MutatingWebhookConfiguration with the rules provided by
// the targetConfig. If the targetConfig doesn't provide any rules, the existing rules will be preserved.
func (wrc *Register) updateMutatingWebhookConfiguration(targetConfig *admregapi.MutatingWebhookConfiguration) error {
	// Fetch the existing webhook.
	currentConfiguration, err := wrc.mwcLister.Get(targetConfig.Name)
	if err != nil {
		return fmt.Errorf("failed to get %s %s: %v", kindMutating, targetConfig.Name, err)
	}
	// Create a map of the target webhooks.
	targetWebhooksMap := make(map[string]admregapi.MutatingWebhook)
	for _, w := range targetConfig.Webhooks {
		targetWebhooksMap[w.Name] = w
	}
	// Update the webhooks.
	newWebhooks := make([]admregapi.MutatingWebhook, 0)
	for _, w := range currentConfiguration.Webhooks {
		target, exist := targetWebhooksMap[w.Name]
		if !exist {
			continue
		}
		delete(targetWebhooksMap, w.Name)
		// Update the webhook configuration
		w.ClientConfig.URL = target.ClientConfig.URL
		w.ClientConfig.Service = target.ClientConfig.Service
		w.ClientConfig.CABundle = target.ClientConfig.CABundle
		if target.Rules != nil {
			// If the target webhook has rule definitions override the current.
			w.Rules = target.Rules
		}
		newWebhooks = append(newWebhooks, w)
	}
	// Check if there are additional webhooks defined and add them.
	for _, w := range targetWebhooksMap {
		newWebhooks = append(newWebhooks, w)
	}
	// Update the current configuration.
	currentConfiguration.Webhooks = newWebhooks
	if _, err := wrc.kubeClient.AdmissionregistrationV1().MutatingWebhookConfigurations().Update(context.TODO(), currentConfiguration, metav1.UpdateOptions{}); err != nil {
		return err
	}
	wrc.log.V(3).Info("successfully updated mutatingWebhookConfigurations", "name", targetConfig.Name)
	return nil
}

// updateValidatingWebhookConfiguration updates an existing ValidatingWebhookConfiguration with the rules provided by
// the targetConfig. If the targetConfig doesn't provide any rules, the existing rules will be preserved.
func (wrc *Register) updateValidatingWebhookConfiguration(targetConfig *admregapi.ValidatingWebhookConfiguration) error {
	// Fetch the existing webhook.
	currentConfiguration, err := wrc.vwcLister.Get(targetConfig.Name)
	if err != nil {
		return fmt.Errorf("failed to get %s %s: %v", kindValidating, targetConfig.Name, err)
	}
	// Create a map of the target webhooks.
	targetWebhooksMap := make(map[string]admregapi.ValidatingWebhook)
	for _, w := range targetConfig.Webhooks {
		targetWebhooksMap[w.Name] = w
	}
	// Update the webhooks.
	newWebhooks := make([]admregapi.ValidatingWebhook, 0)
	for _, w := range currentConfiguration.Webhooks {
		target, exist := targetWebhooksMap[w.Name]
		if !exist {
			continue
		}
		delete(targetWebhooksMap, w.Name)
		// Update the webhook configuration
		w.ClientConfig.URL = target.ClientConfig.URL
		w.ClientConfig.Service = target.ClientConfig.Service
		w.ClientConfig.CABundle = target.ClientConfig.CABundle
		if target.Rules != nil {
			// If the target webhook has rule definitions override the current.
			w.Rules = target.Rules
		}
		newWebhooks = append(newWebhooks, w)
	}
	// Check if there are additional webhooks defined and add them.
	for _, w := range targetWebhooksMap {
		newWebhooks = append(newWebhooks, w)
	}
	// Update the current configuration.
	currentConfiguration.Webhooks = newWebhooks
	if _, err := wrc.kubeClient.AdmissionregistrationV1().ValidatingWebhookConfigurations().Update(context.TODO(), currentConfiguration, metav1.UpdateOptions{}); err != nil {
		return err
	}
	wrc.log.V(3).Info("successfully updated validatingWebhookConfigurations", "name", targetConfig.Name)
	return nil
}