You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: waiter.go
    path of file: ./repos/gardener/pkg/component/kubernetes/controllermanager
    
    the code of the file until where you have to start completion: // Copyright 2020 SAP SE or an SAP affiliate company. All rights reserved. This file is licensed under the Apache Software License, v. 2 except as noted otherwise in the LICENSE file
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package controllermanager

import (
	"context"
	"fmt"
	"time"

	appsv1 "k8s.io/api/apps/v1"
	corev1 "k8s.io/api/core/v1"
	apierrors "k8s.io/apimachinery/pkg/api/errors"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/client-go/tools/leaderelection/resourcelock"
	"sigs.k8s.io/controller-runtime/pkg/client"

	v1beta1constants "github.com/gardener/gardener/pkg/apis/core/v1beta1/constants"
	kubernetesutils "github.com/gardener/gardener/pkg/utils/kubernetes"
	"github.com/gardener/gardener/pkg/utils/kubernetes/health"
	"github.com/gardener/gardener/pkg/utils/managedresources"
	"github.com/gardener/gardener/pkg/utils/retry"
)

var (
	// IntervalWaitForDeployment is the interval used while waiting for the Deployments to become healthy or
    
func (k *kubeControllerManager) WaitForControllerToBeActive(ctx context.Context) error {
	const (
		pollInterval = 5 * time.Second
		pollTimeout  = 90 * time.Second
	)

	// Check whether the kube-controller-manager deployment exists
	if err := k.seedClient.Client().Get(ctx, kubernetesutils.Key(k.namespace, v1beta1constants.DeploymentNameKubeControllerManager), &appsv1.Deployment{}); err != nil {
		if apierrors.IsNotFound(err) {
			return fmt.Errorf("kube controller manager deployment not found: %w", err)
		}
		return err
	}

	return retry.UntilTimeout(ctx, pollInterval, pollTimeout, func(ctx context.Context) (done bool, err error) {
		podList := &corev1.PodList{}
		err = k.seedClient.Client().List(ctx, podList,
			client.InNamespace(k.namespace),
			client.MatchingLabels(map[string]string{
				v1beta1constants.LabelApp:  v1beta1constants.LabelKubernetes,
				v1beta1constants.LabelRole: LabelRole,
			}))
		if err != nil {
			return retry.SevereError(fmt.Errorf("could not check whether controller %s is active: %w", v1beta1constants.DeploymentNameKubeControllerManager, err))
		}

		// Check that one replica of the controller exists.
		if len(podList.Items) < 1 {
			k.log.Info("Waiting for kube-controller-manager to have at least one replica")
			return retry.MinorError(fmt.Errorf("controller %s is not active", v1beta1constants.DeploymentNameKubeControllerManager))
		}

		// Check that the existing replicas are not getting deleted.
		for _, pod := range podList.Items {
			if pod.DeletionTimestamp != nil {
				k.log.Info("Waiting for a new replica of kube-controller-manager")
				return retry.MinorError(fmt.Errorf("controller %s is not active", v1beta1constants.DeploymentNameKubeControllerManager))
			}
		}

		// Check if the controller is active by reading its leader election record.
		lock := resourcelock.LeasesResourceLock

		leaderElectionRecord, err := kubernetesutils.ReadLeaderElectionRecord(ctx, k.shootClient, lock, metav1.NamespaceSystem, v1beta1constants.DeploymentNameKubeControllerManager)
		if err != nil {
			return retry.SevereError(fmt.Errorf("could not check whether controller %s is active: %w", v1beta1constants.DeploymentNameKubeControllerManager, err))
		}

		lastRenew := metav1.Now().UTC().Sub(leaderElectionRecord.RenewTime.Time.UTC())
		defaultRenewalTime := 2 * time.Second
		if lastRenew <= defaultRenewalTime*2 {
			return retry.Ok()
		}

		k.log.Info("Waiting for kube-controller-manager to be active")
		return retry.MinorError(fmt.Errorf("controller %s is not active", v1beta1constants.DeploymentNameKubeControllerManager))
	})
}