join.go

/*
Copyright 2018 The Kubernetes Authors.

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 kubefedctl

import (
	"context"
	goerrors "errors"
	"io"
	"reflect"
	"strings"
	"time"

	"github.com/golang/glog"
	"github.com/pkg/errors"

	fedv1a1 "github.com/kubernetes-sigs/federation-v2/pkg/apis/core/v1alpha1"
	genericclient "github.com/kubernetes-sigs/federation-v2/pkg/client/generic"
	"github.com/kubernetes-sigs/federation-v2/pkg/kubefedctl/options"
	"github.com/kubernetes-sigs/federation-v2/pkg/kubefedctl/util"
	"github.com/spf13/cobra"
	"github.com/spf13/pflag"
	corev1 "k8s.io/api/core/v1"
	rbacv1 "k8s.io/api/rbac/v1"
	apiextv1b1 "k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/v1beta1"
	apierrors "k8s.io/apimachinery/pkg/api/errors"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/util/wait"
	kubeclient "k8s.io/client-go/kubernetes"
	"k8s.io/client-go/rest"
	crv1a1 "k8s.io/cluster-registry/pkg/apis/clusterregistry/v1alpha1"
)

const (
	serviceAccountSecretTimeout = 30 * time.Second
)

var (
	join_long = `
		Join adds a cluster to a federation.

		Current context is assumed to be a Kubernetes cluster
		hosting the federation control plane. Please use the
		--host-cluster-context flag otherwise.`
	join_example = `
		# Join a cluster to a federation by specifying the
		# cluster name and the context name of the federation
		# control plane's host cluster. Cluster name must be
		# a valid RFC 1123 subdomain name. Cluster context
		# must be specified if the cluster name is different
		# than the cluster's context in the local kubeconfig.
		kubefedctl join foo --host-cluster-context=bar`

	// Policy rules allowing full access to resources in the cluster
	// or namespace.
	namespacedPolicyRules = []rbacv1.PolicyRule{
		{
			Verbs:     []string{rbacv1.VerbAll},
			APIGroups: []string{rbacv1.APIGroupAll},
			Resources: []string{rbacv1.ResourceAll},
		},
	}
	clusterPolicyRules = []rbacv1.PolicyRule{
		namespacedPolicyRules[0],
		{
			NonResourceURLs: []string{rbacv1.NonResourceAll},
			Verbs:           []string{"get"},
		},
	}
)

type joinFederation struct {
	options.GlobalSubcommandOptions
	options.CommonJoinOptions
	options.FederationConfigOptions
	joinFederationOptions
}

type joinFederationOptions struct {
	secretName      string
	addToRegistry   bool
	Scope           apiextv1b1.ResourceScope
	errorOnExisting bool
}

// Bind adds the join specific arguments to the flagset passed in as an
// argument.
func (o *joinFederationOptions) Bind(flags *pflag.FlagSet) {
	flags.StringVar(&o.secretName, "secret-name", "",
		"Name of the secret where the cluster's credentials will be stored in the host cluster. This name should be a valid RFC 1035 label. If unspecified, defaults to a generated name containing the cluster name.")
	flags.BoolVar(&o.addToRegistry, "add-to-registry", false,
		"Add the cluster to the cluster registry that is aggregated with the kubernetes API server running in the host cluster context.")
	flags.BoolVar(&o.errorOnExisting, "error-on-existing", false,
		"Whether the join operation will throw an error if it encounters existing artifacts with the same name as those it's trying to create. If false, the join operation will update existing artifacts to match its own specification.")
}

// NewCmdJoin defines the `join` command that joins a cluster to a
// federation.
func NewCmdJoin(cmdOut io.Writer, config util.FedConfig) *cobra.Command {
	opts := &joinFederation{}

	cmd := &cobra.Command{
		Use:     "join CLUSTER_NAME --host-cluster-context=HOST_CONTEXT",
		Short:   "Join a cluster to a federation",
		Long:    join_long,
		Example: join_example,
		Run: func(cmd *cobra.Command, args []string) {
			err := opts.Complete(args)
			if err != nil {
				glog.Fatalf("Error: %v", err)
			}

			err = opts.Run(cmdOut, config)
			if err != nil {
				glog.Fatalf("Error: %v", err)
			}
		},
	}

	flags := cmd.Flags()
	opts.GlobalSubcommandBind(flags)
	opts.CommonSubcommandBind(flags)
	opts.Bind(flags)

	return cmd
}

// Complete ensures that options are valid and marshals them if necessary.
func (j *joinFederation) Complete(args []string) error {
	err := j.SetName(args)
	if err != nil {
		return err
	}

	if j.ClusterContext == "" {
		glog.V(2).Infof("Defaulting cluster context to joining cluster name %s", j.ClusterName)
		j.ClusterContext = j.ClusterName
	}

	if j.HostClusterName != "" && strings.ContainsAny(j.HostClusterName, ":/") {
		return goerrors.New("host-cluster-name may not contain \"/\" or \":\"")
	}

	if j.HostClusterName == "" && strings.ContainsAny(j.HostClusterContext, ":/") {
		glog.Fatal("host-cluster-name must be set if the name of the host cluster context contains one of \":\" or \"/\"")
	}

	glog.V(2).Infof("Args and flags: name %s, host: %s, host-system-namespace: %s, kubeconfig: %s, cluster-context: %s, secret-name: %s, dry-run: %v",
		j.ClusterName, j.HostClusterContext, j.FederationNamespace, j.Kubeconfig, j.ClusterContext,
		j.secretName, j.DryRun)

	return nil
}

// Run is the implementation of the `join federation` command.
func (j *joinFederation) Run(cmdOut io.Writer, config util.FedConfig) error {
	hostConfig, err := config.HostConfig(j.HostClusterContext, j.Kubeconfig)
	if err != nil {
		// TODO(font): Return new error with this same text so it can be output
		// by caller.
		glog.V(2).Infof("Failed to get host cluster config: %v", err)
		return err
	}

	j.Scope, j.ClusterNamespace, err = options.GetOptionsFromFederationConfig(hostConfig, j.FederationNamespace)
	if err != nil {
		return err
	}

	clusterConfig, err := config.ClusterConfig(j.ClusterContext, j.Kubeconfig)
	if err != nil {
		glog.V(2).Infof("Failed to get joining cluster config: %v", err)
		return err
	}

	hostClusterName := j.HostClusterContext
	if j.HostClusterName != "" {
		hostClusterName = j.HostClusterName
	}

	return JoinCluster(hostConfig, clusterConfig, j.FederationNamespace, j.ClusterNamespace,
		hostClusterName, j.ClusterName, j.secretName, j.addToRegistry, j.Scope, j.DryRun, j.errorOnExisting)
}

// JoinCluster performs all the necessary steps to join a cluster to the
// federation provided the required set of parameters are passed in.
func JoinCluster(hostConfig, clusterConfig *rest.Config, federationNamespace, clusterNamespace,
	hostClusterName, joiningClusterName, secretName string, addToRegistry bool, Scope apiextv1b1.ResourceScope, dryRun, errorOnExisting bool) error {
	hostClientset, err := util.HostClientset(hostConfig)
	if err != nil {
		glog.V(2).Infof("Failed to get host cluster clientset: %v", err)
		return err
	}

	clusterClientset, err := util.ClusterClientset(clusterConfig)
	if err != nil {
		glog.V(2).Infof("Failed to get joining cluster clientset: %v", err)
		return err
	}

	client, err := genericclient.New(hostConfig)
	if err != nil {
		glog.V(2).Infof("Failed to get federation clientset: %v", err)
		return err
	}

	glog.V(2).Infof("Performing preflight checks.")
	err = performPreflightChecks(clusterClientset, joiningClusterName, hostClusterName, federationNamespace, errorOnExisting)
	if err != nil {
		return err
	}

	if addToRegistry {
		err = addToClusterRegistry(hostConfig, clusterNamespace, clusterConfig.Host, joiningClusterName, dryRun, errorOnExisting)
		if err != nil {
			return err
		}
	} else {
		// TODO(font): If cluster exists in clusterregistry, grab the
		// ServerAddress from the KubernetesAPIEndpoints to create a
		// clusterClientset from it.
		err = verifyExistsInClusterRegistry(hostConfig, clusterNamespace, joiningClusterName)
		if err != nil {
			return err
		}
	}

	glog.V(2).Infof("Creating %s namespace in joining cluster", federationNamespace)
	_, err = createFederationNamespace(clusterClientset, federationNamespace,
		joiningClusterName, dryRun)
	if err != nil {
		glog.V(2).Infof("Error creating %s namespace in joining cluster: %v",
			federationNamespace, err)
		return err
	}
	glog.V(2).Infof("Created %s namespace in joining cluster", federationNamespace)

	// Create a service account and use its credentials.
	glog.V(2).Info("Creating cluster credentials secret")

	secret, err := createRBACSecret(hostClientset, clusterClientset,
		federationNamespace, joiningClusterName, hostClusterName,
		secretName, Scope, dryRun, errorOnExisting)
	if err != nil {
		glog.V(2).Infof("Could not create cluster credentials secret: %v", err)
		return err
	}

	glog.V(2).Info("Cluster credentials secret created")

	glog.V(2).Info("Creating federated cluster resource")

	_, err = createFederatedCluster(client, joiningClusterName, secret.Name,
		federationNamespace, dryRun, errorOnExisting)
	if err != nil {
		glog.V(2).Infof("Failed to create federated cluster resource: %v", err)
		return err
	}

	glog.V(2).Info("Created federated cluster resource")
	return nil
}

// performPreflightChecks checks that the host and joining clusters are in
// a consistent state.
func performPreflightChecks(clusterClientset kubeclient.Interface, name, hostClusterName,
	federationNamespace string, errorOnExisting bool) error {
	// Make sure there is no existing service account in the joining cluster.
	saName := util.ClusterServiceAccountName(name, hostClusterName)
	_, err := clusterClientset.CoreV1().ServiceAccounts(federationNamespace).Get(saName,
		metav1.GetOptions{})

	switch {
	case apierrors.IsNotFound(err):
		return nil
	case err != nil:
		return err
	case errorOnExisting:
		return errors.Errorf("service account: %s already exists in joining cluster: %s", saName, name)
	default:
		glog.V(2).Infof("Service account %s already exists in joining cluster %s", saName, name)
		return nil
	}
}

// addToClusterRegistry handles adding the cluster to the cluster registry and
// reports progress.
func addToClusterRegistry(hostConfig *rest.Config, clusterNamespace, host, joiningClusterName string,
	dryRun, errorOnExisting bool) error {
	// Get the cluster registry clientset using the host cluster config.
	client, err := util.ClusterRegistryClientset(hostConfig)
	if err != nil {
		glog.V(2).Infof("Failed to get cluster registry clientset: %v", err)
		return err
	}

	glog.V(2).Infof("Registering cluster: %s with the cluster registry.", joiningClusterName)

	err = registerCluster(client, clusterNamespace, host, joiningClusterName, dryRun, errorOnExisting)
	if err != nil {
		glog.V(2).Infof("Could not register cluster: %s with the cluster registry: %v",
			joiningClusterName, err)
		return err
	}

	glog.V(2).Infof("Registered cluster: %s with the cluster registry.", joiningClusterName)
	return nil
}

// verifyExistsInClusterRegistry verifies that the given joining cluster name exists
// in the cluster registry.
func verifyExistsInClusterRegistry(hostConfig *rest.Config, clusterNamespace, joiningClusterName string) error {
	client, err := util.ClusterRegistryClientset(hostConfig)
	if err != nil {
		glog.V(2).Infof("Failed to get cluster registry clientset: %v", err)
		return err
	}

	glog.V(2).Infof("Verifying cluster: %s exists in the cluster registry.",
		joiningClusterName)

	cluster := &crv1a1.Cluster{}
	err = client.Get(context.TODO(), cluster, clusterNamespace, joiningClusterName)
	if err != nil {
		if apierrors.IsNotFound(err) {
			return errors.Errorf("Cluster %s does not exist in the cluster registry.",
				joiningClusterName)
		}

		glog.V(2).Infof("Could not retrieve cluster %s from the cluster registry: %v",
			joiningClusterName, err)
		return err
	}

	glog.V(2).Infof("Verified cluster %s exists in the cluster registry.", joiningClusterName)
	return nil
}

// registerCluster registers a cluster with the cluster registry.
// TODO: save off service account authinfo for cluster.
func registerCluster(client genericclient.Client, clusterNamespace, host, joiningClusterName string,
	dryRun, errorOnExisting bool) error {
	cluster := &crv1a1.Cluster{
		ObjectMeta: metav1.ObjectMeta{
			Namespace: clusterNamespace,
			Name:      joiningClusterName,
		},
		Spec: crv1a1.ClusterSpec{
			KubernetesAPIEndpoints: crv1a1.KubernetesAPIEndpoints{
				ServerEndpoints: []crv1a1.ServerAddressByClientCIDR{
					{
						ClientCIDR:    "0.0.0.0/0",
						ServerAddress: host,
					},
				},
			},
		},
	}

	if dryRun {
		return nil
	}

	existingCluster := &crv1a1.Cluster{}
	err := client.Get(context.TODO(), existingCluster, clusterNamespace, cluster.Name)
	switch {
	case err != nil && !apierrors.IsNotFound(err):
		glog.V(2).Infof("Cannot retrieve cluster registry cluster %s due to %v", cluster.Name, err)
		return err
	case err == nil && errorOnExisting:
		return errors.Errorf("cluster registry cluster %s already exists", cluster.Name)
	case err == nil:
		existingCluster.Spec = cluster.Spec
		glog.V(2).Infof("Updating existing cluster registry cluster %s", cluster.Name)
		return client.Update(context.TODO(), existingCluster)
	default:
		glog.V(2).Infof("Creating cluster registry cluster %s", cluster.Name)
		return client.Create(context.TODO(), cluster)
	}
}

// createFederatedCluster creates a federated cluster resource that associates
// the cluster and secret.
func createFederatedCluster(client genericclient.Client, joiningClusterName,
	secretName, federationNamespace string, dryRun, errorOnExisting bool) (*fedv1a1.FederatedCluster, error) {
	fedCluster := &fedv1a1.FederatedCluster{
		ObjectMeta: metav1.ObjectMeta{
			Namespace: federationNamespace,
			Name:      joiningClusterName,
		},
		Spec: fedv1a1.FederatedClusterSpec{
			ClusterRef: fedv1a1.LocalClusterReference{
				Name: joiningClusterName,
			},
			SecretRef: &fedv1a1.LocalSecretReference{
				Name: secretName,
			},
		},
	}

	if dryRun {
		return fedCluster, nil
	}

	existingFedCluster := &fedv1a1.FederatedCluster{}
	err := client.Get(context.TODO(), existingFedCluster, federationNamespace, joiningClusterName)
	switch {
	case err != nil && !apierrors.IsNotFound(err):
		glog.V(2).Infof("Could not retrieve federated cluster %s due to %v", joiningClusterName, err)
		return nil, err
	case err == nil && errorOnExisting:
		return nil, errors.Errorf("federated cluster %s already exists in host cluster", joiningClusterName)
	case err == nil:
		existingFedCluster.Spec = fedCluster.Spec
		err = client.Update(context.TODO(), existingFedCluster)
		if err != nil {
			glog.V(2).Infof("Could not update federated cluster %s due to %v", fedCluster.Name, err)
			return nil, err
		}
		return existingFedCluster, nil
	default:
		err = client.Create(context.TODO(), fedCluster)
		if err != nil {
			glog.V(2).Infof("Could not create federated cluster %s due to %v", fedCluster.Name, err)
			return nil, err
		}
		return fedCluster, nil
	}
}

// createFederationNamespace creates the federation namespace in the cluster
// associated with clusterClientset, if it doesn't already exist.
func createFederationNamespace(clusterClientset kubeclient.Interface, federationNamespace,
	joiningClusterName string, dryRun bool) (*corev1.Namespace, error) {
	federationNS := &corev1.Namespace{
		ObjectMeta: metav1.ObjectMeta{
			Name: federationNamespace,
		},
	}

	if dryRun {
		return federationNS, nil
	}

	_, err := clusterClientset.CoreV1().Namespaces().Get(federationNamespace, metav1.GetOptions{})
	if err != nil && !apierrors.IsNotFound(err) {
		glog.V(2).Infof("Could not get %s namespace: %v", federationNamespace, err)
		return nil, err
	}

	if err == nil {
		glog.V(2).Infof("Already existing %s namespace", federationNamespace)
		return federationNS, nil
	}

	// Not found, so create.
	_, err = clusterClientset.CoreV1().Namespaces().Create(federationNS)
	if err != nil && !apierrors.IsAlreadyExists(err) {
		glog.V(2).Infof("Could not create %s namespace: %v", federationNamespace, err)
		return nil, err
	}
	return federationNS, nil
}

// createRBACSecret creates a secret in the joining cluster using a service
// account, and populate that secret into the host cluster to allow it to
// access the joining cluster.
func createRBACSecret(hostClusterClientset, joiningClusterClientset kubeclient.Interface,
	namespace, joiningClusterName, hostClusterName,
	secretName string, Scope apiextv1b1.ResourceScope, dryRun, errorOnExisting bool) (*corev1.Secret, error) {

	glog.V(2).Infof("Creating service account in joining cluster: %s", joiningClusterName)

	saName, err := createServiceAccount(joiningClusterClientset, namespace,
		joiningClusterName, hostClusterName, dryRun, errorOnExisting)
	if err != nil {
		glog.V(2).Infof("Error creating service account: %s in joining cluster: %s due to: %v",
			saName, joiningClusterName, err)
		return nil, err
	}

	glog.V(2).Infof("Created service account: %s in joining cluster: %s", saName, joiningClusterName)

	if Scope == apiextv1b1.NamespaceScoped {
		glog.V(2).Infof("Creating role and binding for service account: %s in joining cluster: %s", saName, joiningClusterName)

		err = createRoleAndBinding(joiningClusterClientset, saName, namespace, joiningClusterName, dryRun, errorOnExisting)
		if err != nil {
			glog.V(2).Infof("Error creating role and binding for service account: %s in joining cluster: %s due to: %v", saName, joiningClusterName, err)
			return nil, err
		}

		glog.V(2).Infof("Created role and binding for service account: %s in joining cluster: %s",
			saName, joiningClusterName)

		glog.V(2).Infof("Creating health check cluster role and binding for service account: %s in joining cluster: %s", saName, joiningClusterName)

		err = createHealthCheckClusterRoleAndBinding(joiningClusterClientset, saName, namespace, joiningClusterName,
			dryRun, errorOnExisting)
		if err != nil {
			glog.V(2).Infof("Error creating health check cluster role and binding for service account: %s in joining cluster: %s due to: %v",
				saName, joiningClusterName, err)
			return nil, err
		}

		glog.V(2).Infof("Created health check cluster role and binding for service account: %s in joining cluster: %s",
			saName, joiningClusterName)

	} else {
		glog.V(2).Infof("Creating cluster role and binding for service account: %s in joining cluster: %s", saName, joiningClusterName)

		err = createClusterRoleAndBinding(joiningClusterClientset, saName, namespace, joiningClusterName, dryRun, errorOnExisting)
		if err != nil {
			glog.V(2).Infof("Error creating cluster role and binding for service account: %s in joining cluster: %s due to: %v",
				saName, joiningClusterName, err)
			return nil, err
		}

		glog.V(2).Infof("Created cluster role and binding for service account: %s in joining cluster: %s",
			saName, joiningClusterName)
	}

	glog.V(2).Infof("Creating secret in host cluster: %s", hostClusterName)

	secret, err := populateSecretInHostCluster(joiningClusterClientset, hostClusterClientset,
		saName, namespace, joiningClusterName, secretName, dryRun)
	if err != nil {
		glog.V(2).Infof("Error creating secret in host cluster: %s due to: %v", hostClusterName, err)
		return nil, err
	}

	glog.V(2).Infof("Created secret in host cluster: %s", hostClusterName)

	return secret, nil
}

// createServiceAccount creates a service account in the cluster associated
// with clusterClientset with credentials that will be used by the host cluster
// to access its API server.
func createServiceAccount(clusterClientset kubeclient.Interface, namespace,
	joiningClusterName, hostClusterName string, dryRun, errorOnExisting bool) (string, error) {
	saName := util.ClusterServiceAccountName(joiningClusterName, hostClusterName)
	sa := &corev1.ServiceAccount{
		ObjectMeta: metav1.ObjectMeta{
			Name:      saName,
			Namespace: namespace,
		},
	}

	if dryRun {
		return saName, nil
	}

	// Create a new service account.
	_, err := clusterClientset.CoreV1().ServiceAccounts(namespace).Create(sa)
	switch {
	case apierrors.IsAlreadyExists(err) && errorOnExisting:
		glog.V(2).Infof("Service account %s/%s already exists in target cluster %s", namespace, saName, joiningClusterName)
		return "", err
	case err != nil && !apierrors.IsAlreadyExists(err):
		glog.V(2).Infof("Could not create service account %s/%s in target cluster %s due to: %v", namespace, saName, joiningClusterName, err)
		return "", err
	default:
		return saName, nil
	}
}

func bindingSubjects(saName, namespace string) []rbacv1.Subject {
	return []rbacv1.Subject{
		{
			Kind:      rbacv1.ServiceAccountKind,
			Name:      saName,
			Namespace: namespace,
		},
	}
}

// createClusterRoleAndBinding creates an RBAC cluster role and
// binding that allows the service account identified by saName to
// access all resources in all namespaces in the cluster associated
// with clientset.
func createClusterRoleAndBinding(clientset kubeclient.Interface, saName, namespace, clusterName string, dryRun, errorOnExisting bool) error {
	if dryRun {
		return nil
	}

	roleName := util.RoleName(saName)

	role := &rbacv1.ClusterRole{
		ObjectMeta: metav1.ObjectMeta{
			Name: roleName,
		},
		Rules: clusterPolicyRules,
	}
	existingRole, err := clientset.RbacV1().ClusterRoles().Get(roleName, metav1.GetOptions{})
	switch {
	case err != nil && !apierrors.IsNotFound(err):
		glog.V(2).Infof("Could not get cluster role for service account %s in joining cluster %s due to %v",
			saName, clusterName, err)
		return err
	case err == nil && errorOnExisting:
		return errors.Errorf("cluster role for service account %s in joining cluster %s already exists", saName, clusterName)
	case err == nil:
		existingRole.Rules = role.Rules
		_, err := clientset.RbacV1().ClusterRoles().Update(existingRole)
		if err != nil {
			glog.V(2).Infof("Could not update cluster role for service account: %s in joining cluster: %s due to: %v",
				saName, clusterName, err)
			return err
		}
	default: // role was not found
		_, err := clientset.RbacV1().ClusterRoles().Create(role)
		if err != nil {
			glog.V(2).Infof("Could not create cluster role for service account: %s in joining cluster: %s due to: %v",
				saName, clusterName, err)
			return err
		}
	}

	// TODO: This should limit its access to only necessary resources.
	binding := &rbacv1.ClusterRoleBinding{
		ObjectMeta: metav1.ObjectMeta{
			Name: roleName,
		},
		Subjects: bindingSubjects(saName, namespace),
		RoleRef: rbacv1.RoleRef{
			APIGroup: rbacv1.GroupName,
			Kind:     "ClusterRole",
			Name:     roleName,
		},
	}
	existingBinding, err := clientset.RbacV1().ClusterRoleBindings().Get(binding.Name, metav1.GetOptions{})
	switch {
	case err != nil && !apierrors.IsNotFound(err):
		glog.V(2).Infof("Could not get cluster role binding for service account %s in joining cluster %s due to %v",
			saName, clusterName, err)
		return err
	case err == nil && errorOnExisting:
		return errors.Errorf("cluster role binding for service account %s in joining cluster %s already exists", saName, clusterName)
	case err == nil:
		// The roleRef cannot be updated, therefore if the existing roleRef is different, the existing rolebinding
		// must be deleted and recreated with the correct roleRef
		if !reflect.DeepEqual(existingBinding.RoleRef, binding.RoleRef) {
			err = clientset.RbacV1().ClusterRoleBindings().Delete(existingBinding.Name, &metav1.DeleteOptions{})
			if err != nil {
				glog.V(2).Infof("Could not delete existing cluster role binding for service account %s in joining cluster %s due to: %v",
					saName, clusterName, err)
				return err
			}
			_, err = clientset.RbacV1().ClusterRoleBindings().Create(binding)
			if err != nil {
				glog.V(2).Infof("Could not create cluster role binding for service account: %s in joining cluster: %s due to: %v",
					saName, clusterName, err)
				return err
			}
		} else {
			existingBinding.Subjects = binding.Subjects
			_, err := clientset.RbacV1().ClusterRoleBindings().Update(existingBinding)
			if err != nil {
				glog.V(2).Infof("Could not update cluster role binding for service account: %s in joining cluster: %s due to: %v",
					saName, clusterName, err)
				return err
			}
		}
	default:
		_, err = clientset.RbacV1().ClusterRoleBindings().Create(binding)
		if err != nil {
			glog.V(2).Infof("Could not create cluster role binding for service account: %s in joining cluster: %s due to: %v",
				saName, clusterName, err)
			return err
		}
	}
	return nil
}

// createRoleAndBinding creates an RBAC role and binding
// that allows the service account identified by saName to access all
// resources in the specified namespace.
func createRoleAndBinding(clientset kubeclient.Interface, saName, namespace, clusterName string, dryRun, errorOnExisting bool) error {
	if dryRun {
		return nil
	}

	roleName := util.RoleName(saName)

	role := &rbacv1.Role{
		ObjectMeta: metav1.ObjectMeta{
			Name: roleName,
		},
		Rules: namespacedPolicyRules,
	}
	existingRole, err := clientset.RbacV1().Roles(namespace).Get(roleName, metav1.GetOptions{})
	switch {
	case err != nil && !apierrors.IsNotFound(err):
		glog.V(2).Infof("Could not retrieve role for service account %s in joining cluster %s due to %v", saName, clusterName, err)
		return err
	case errorOnExisting && err == nil:
		return errors.Errorf("role for service account %s in joining cluster %s already exists", saName, clusterName)
	case err == nil:
		existingRole.Rules = role.Rules
		_, err = clientset.RbacV1().Roles(namespace).Update(existingRole)
		if err != nil {
			glog.V(2).Infof("Could not update role for service account: %s in joining cluster: %s due to: %v",
				saName, clusterName, err)
			return err
		}
	default:
		_, err := clientset.RbacV1().Roles(namespace).Create(role)
		if err != nil {
			glog.V(2).Infof("Could not create role for service account: %s in joining cluster: %s due to: %v",
				saName, clusterName, err)
			return err
		}
	}

	binding := &rbacv1.RoleBinding{
		ObjectMeta: metav1.ObjectMeta{
			Name: roleName,
		},
		Subjects: bindingSubjects(saName, namespace),
		RoleRef: rbacv1.RoleRef{
			APIGroup: rbacv1.GroupName,
			Kind:     "Role",
			Name:     roleName,
		},
	}

	existingBinding, err := clientset.RbacV1().RoleBindings(namespace).Get(binding.Name, metav1.GetOptions{})
	switch {
	case err != nil && !apierrors.IsNotFound(err):
		glog.V(2).Infof("Could not retrieve role binding for service account %s in joining cluster %s due to: %v",
			saName, clusterName, err)
		return err
	case err == nil && errorOnExisting:
		return errors.Errorf("role binding for service account %s in joining cluster %s already exists", saName, clusterName)
	case err == nil:
		// The roleRef cannot be updated, therefore if the existing roleRef is different, the existing rolebinding
		// must be deleted and recreated with the correct roleRef
		if !reflect.DeepEqual(existingBinding.RoleRef, binding.RoleRef) {
			err = clientset.RbacV1().RoleBindings(namespace).Delete(existingBinding.Name, &metav1.DeleteOptions{})
			if err != nil {
				glog.V(2).Infof("Could not delete existing role binding for service account %s in joining cluster %s due to: %v",
					saName, clusterName, err)
				return err
			}
			_, err = clientset.RbacV1().RoleBindings(namespace).Create(binding)
			if err != nil {
				glog.V(2).Infof("Could not create role binding for service account: %s in joining cluster: %s due to: %v",
					saName, clusterName, err)
				return err
			}
		} else {
			existingBinding.Subjects = binding.Subjects
			_, err = clientset.RbacV1().RoleBindings(namespace).Update(existingBinding)
			if err != nil {
				glog.V(2).Infof("Could not update role binding for service account %s in joining cluster %s due to: %v",
					saName, clusterName, err)
				return err
			}
		}
	default:
		_, err = clientset.RbacV1().RoleBindings(namespace).Create(binding)
		if err != nil {
			glog.V(2).Infof("Could not create role binding for service account: %s in joining cluster: %s due to: %v",
				saName, clusterName, err)
			return err
		}
	}

	return nil
}

// createHealthCheckClusterRoleAndBinding creates an RBAC cluster role and
// binding that allows the service account identified by saName to
// access the health check path of the cluster.
func createHealthCheckClusterRoleAndBinding(clientset kubeclient.Interface, saName, namespace, clusterName string, dryRun, errorOnExisting bool) error {
	if dryRun {
		return nil
	}

	roleName := util.HealthCheckRoleName(saName, namespace)

	role := &rbacv1.ClusterRole{
		ObjectMeta: metav1.ObjectMeta{
			Name: roleName,
		},
		Rules: []rbacv1.PolicyRule{
			{
				Verbs:           []string{"Get"},
				NonResourceURLs: []string{"/healthz"},
			},
			// The cluster client expects to be able to list nodes to retrieve zone and region details.
			// TODO(marun) Consider making zone/region retrieval optional
			{
				Verbs:     []string{"list"},
				APIGroups: []string{""},
				Resources: []string{"nodes"},
			},
		},
	}
	existingRole, err := clientset.RbacV1().ClusterRoles().Get(role.Name, metav1.GetOptions{})
	switch {
	case err != nil && !apierrors.IsNotFound(err):
		glog.V(2).Infof("Could not get health check cluster role for service account %s in joining cluster %s due to %v",
			saName, clusterName, err)
		return err
	case err == nil && errorOnExisting:
		return errors.Errorf("health check cluster role for service account %s in joining cluster %s already exists", saName, clusterName)
	case err == nil:
		existingRole.Rules = role.Rules
		_, err := clientset.RbacV1().ClusterRoles().Update(existingRole)
		if err != nil {
			glog.V(2).Infof("Could not update health check cluster role for service account: %s in joining cluster: %s due to: %v",
				saName, clusterName, err)
			return err
		}
	default: // role was not found
		_, err := clientset.RbacV1().ClusterRoles().Create(role)
		if err != nil {
			glog.V(2).Infof("Could not create health check cluster role for service account: %s in joining cluster: %s due to: %v",
				saName, clusterName, err)
			return err
		}
	}

	binding := &rbacv1.ClusterRoleBinding{
		ObjectMeta: metav1.ObjectMeta{
			Name: roleName,
		},
		Subjects: bindingSubjects(saName, namespace),
		RoleRef: rbacv1.RoleRef{
			APIGroup: rbacv1.GroupName,
			Kind:     "ClusterRole",
			Name:     roleName,
		},
	}
	existingBinding, err := clientset.RbacV1().ClusterRoleBindings().Get(binding.Name, metav1.GetOptions{})
	switch {
	case err != nil && !apierrors.IsNotFound(err):
		glog.V(2).Infof("Could not get health check cluster role binding for service account %s in joining cluster %s due to %v",
			saName, clusterName, err)
		return err
	case err == nil && errorOnExisting:
		return errors.Errorf("health check cluster role binding for service account %s in joining cluster %s already exists", saName, clusterName)
	case err == nil:
		// The roleRef cannot be updated, therefore if the existing roleRef is different, the existing rolebinding
		// must be deleted and recreated with the correct roleRef
		if !reflect.DeepEqual(existingBinding.RoleRef, binding.RoleRef) {
			err = clientset.RbacV1().ClusterRoleBindings().Delete(existingBinding.Name, &metav1.DeleteOptions{})
			if err != nil {
				glog.V(2).Infof("Could not delete existing health check cluster role binding for service account %s in joining cluster %s due to: %v",
					saName, clusterName, err)
				return err
			}
			_, err = clientset.RbacV1().ClusterRoleBindings().Create(binding)
			if err != nil {
				glog.V(2).Infof("Could not create health check cluster role binding for service account: %s in joining cluster: %s due to: %v",
					saName, clusterName, err)
				return err
			}
		} else {
			existingBinding.Subjects = binding.Subjects
			_, err := clientset.RbacV1().ClusterRoleBindings().Update(existingBinding)
			if err != nil {
				glog.V(2).Infof("Could not update health check cluster role binding for service account: %s in joining cluster: %s due to: %v",
					saName, clusterName, err)
				return err
			}
		}
	default:
		_, err = clientset.RbacV1().ClusterRoleBindings().Create(binding)
		if err != nil {
			glog.V(2).Infof("Could not create health check cluster role binding for service account: %s in joining cluster: %s due to: %v",
				saName, clusterName, err)
			return err
		}
	}
	return nil
}

// populateSecretInHostCluster copies the service account secret for saName
// from the cluster referenced by clusterClientset to the client referenced by
// hostClientset, putting it in a secret named secretName in the provided
// namespace.
func populateSecretInHostCluster(clusterClientset, hostClientset kubeclient.Interface,
	saName, namespace, joiningClusterName, secretName string,
	dryRun bool) (*corev1.Secret, error) {
	if dryRun {
		dryRunSecret := &corev1.Secret{}
		dryRunSecret.Name = secretName
		return dryRunSecret, nil
	}

	// Get the secret from the joining cluster.
	var secret *corev1.Secret
	err := wait.PollImmediate(1*time.Second, serviceAccountSecretTimeout, func() (bool, error) {
		sa, err := clusterClientset.CoreV1().ServiceAccounts(namespace).Get(saName,
			metav1.GetOptions{})
		if err != nil {
			return false, nil
		}

		for _, objReference := range sa.Secrets {
			saSecretName := objReference.Name
			var err error
			secret, err = clusterClientset.CoreV1().Secrets(namespace).Get(saSecretName,
				metav1.GetOptions{})
			if err != nil {
				return false, nil
			}
			if secret.Type == corev1.SecretTypeServiceAccountToken {
				glog.V(2).Infof("Using secret named: %s", secret.Name)
				return true, nil
			}
		}
		return false, nil
	})

	if err != nil {
		glog.V(2).Infof("Could not get service account secret from joining cluster: %v", err)
		return nil, err
	}

	// Create a parallel secret in the host cluster.
	v1Secret := corev1.Secret{
		ObjectMeta: metav1.ObjectMeta{
			Namespace: namespace,
		},
		Data: secret.Data,
	}

	if secretName == "" {
		v1Secret.GenerateName = joiningClusterName + "-"
	} else {
		v1Secret.Name = secretName
	}

	v1SecretResult, err := hostClientset.CoreV1().Secrets(namespace).Create(&v1Secret)
	if err != nil {
		glog.V(2).Infof("Could not create secret in host cluster: %v", err)
		return nil, err
	}

	glog.V(2).Infof("Created secret in host cluster named: %s", v1SecretResult.Name)
	return v1SecretResult, nil
}