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admission.go
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admission.go
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// Copyright (c) 2018 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 dnshostedzone
import (
"errors"
"fmt"
"io"
"strings"
"github.com/gardener/gardener/pkg/apis/garden"
admissioninitializer "github.com/gardener/gardener/pkg/apiserver/admission/initializer"
gardeninformers "github.com/gardener/gardener/pkg/client/garden/informers/internalversion"
gardenlisters "github.com/gardener/gardener/pkg/client/garden/listers/garden/internalversion"
"github.com/gardener/gardener/pkg/operation/cloudbotanist/awsbotanist"
"github.com/gardener/gardener/pkg/operation/cloudbotanist/gcpbotanist"
"github.com/gardener/gardener/pkg/operation/cloudbotanist/openstackbotanist"
"github.com/gardener/gardener/pkg/operation/common"
admissionutils "github.com/gardener/gardener/plugin/pkg/utils"
corev1 "k8s.io/api/core/v1"
apierrors "k8s.io/apimachinery/pkg/api/errors"
metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
"k8s.io/apimachinery/pkg/labels"
"k8s.io/apiserver/pkg/admission"
kubeinformers "k8s.io/client-go/informers"
kubecorev1listers "k8s.io/client-go/listers/core/v1"
)
const (
// PluginName is the name of this admission plugin.
PluginName = "ShootDNSHostedZone"
)
// Register registers a plugin.
func Register(plugins *admission.Plugins) {
plugins.Register(PluginName, func(config io.Reader) (admission.Interface, error) {
return New()
})
}
// DNSHostedZone contains listers and and admission handler.
type DNSHostedZone struct {
*admission.Handler
secretLister kubecorev1listers.SecretLister
secretBindingLister gardenlisters.SecretBindingLister
projectLister gardenlisters.ProjectLister
readyFunc admission.ReadyFunc
}
var (
_ = admissioninitializer.WantsInternalGardenInformerFactory(&DNSHostedZone{})
_ = admissioninitializer.WantsKubeInformerFactory(&DNSHostedZone{})
readyFuncs = []admission.ReadyFunc{}
)
// New creates a new DNSHostedZone admission plugin.
func New() (*DNSHostedZone, error) {
return &DNSHostedZone{
Handler: admission.NewHandler(admission.Create, admission.Update),
}, nil
}
// AssignReadyFunc assigns the ready function to the admission handler.
func (d *DNSHostedZone) AssignReadyFunc(f admission.ReadyFunc) {
d.readyFunc = f
d.SetReadyFunc(f)
}
// SetInternalGardenInformerFactory gets Lister from SharedInformerFactory.
func (d *DNSHostedZone) SetInternalGardenInformerFactory(f gardeninformers.SharedInformerFactory) {
secretBindingInformer := f.Garden().InternalVersion().SecretBindings()
d.secretBindingLister = secretBindingInformer.Lister()
projectInformer := f.Garden().InternalVersion().Projects()
d.projectLister = projectInformer.Lister()
readyFuncs = append(
readyFuncs, secretBindingInformer.Informer().HasSynced, projectInformer.Informer().HasSynced,
)
}
// SetKubeInformerFactory gets Lister from SharedInformerFactory.
func (d *DNSHostedZone) SetKubeInformerFactory(f kubeinformers.SharedInformerFactory) {
secretInformer := f.Core().V1().Secrets()
d.secretLister = secretInformer.Lister()
readyFuncs = append(readyFuncs, secretInformer.Informer().HasSynced)
}
// ValidateInitialization checks whether the plugin was correctly initialized.
func (d *DNSHostedZone) ValidateInitialization() error {
if d.secretLister == nil {
return errors.New("missing secret lister")
}
if d.secretBindingLister == nil {
return errors.New("missing secret binding lister")
}
return nil
}
// Admit tries to determine a DNS hosted zone for the Shoot's external domain.
func (d *DNSHostedZone) Admit(a admission.Attributes) error {
// Wait until the caches have been synced
if d.readyFunc == nil {
d.AssignReadyFunc(func() bool {
for _, readyFunc := range readyFuncs {
if !readyFunc() {
return false
}
}
return true
})
}
if !d.WaitForReady() {
return admission.NewForbidden(a, errors.New("not yet ready to handle request"))
}
// Ignore all kinds other than Shoot
if a.GetKind().GroupKind() != garden.Kind("Shoot") {
return nil
}
shoot, ok := a.GetObject().(*garden.Shoot)
if !ok {
return apierrors.NewBadRequest("could not convert resource into Shoot object")
}
// If the Shoot manifest specifies the 'unmanaged' DNS provider, then we do nothing.
if shoot.Spec.DNS.Provider == garden.DNSUnmanaged {
return nil
}
// Alicloud DNS needs no HostedZoneID, no need to do check by now
// As about credentials needed by shoot DNS, they are checked in operation/botanist/dns.go
if shoot.Spec.DNS.Provider == garden.DNSAlicloud {
return nil
}
// Generate a Shoot domain if none is configured.
if shoot.Spec.DNS.Domain == nil {
assignDefaultDomain(shoot, d.projectLister, d.secretLister)
}
// Checks on Hosted Zone ID can only be done if the Shoot manifest has a domain.
if shoot.Spec.DNS.Domain == nil {
return apierrors.NewBadRequest("shoot domain field .spec.dns.domain must be set if provider != unmanaged")
}
// If the Shoot manifest specifies a Hosted Zone ID then we check whether it is an ID of a default domain.
// If not, we must ensure that the cloud provider secret provided by the user contains credentials for the
// respective DNS provider.
if shoot.Spec.DNS.HostedZoneID != nil {
if err := verifyHostedZoneID(shoot, d.secretBindingLister, d.secretLister); err != nil {
return admission.NewForbidden(a, err)
}
return nil
}
hostedZoneID, err := determineHostedZoneID(shoot, d.secretLister)
if err != nil {
return admission.NewForbidden(a, err)
}
shoot.Spec.DNS.HostedZoneID = &hostedZoneID
return nil
}
// assignDefaultDomain generates a domain <Shoot_Name>.<Project_Name>.<Default_Domain>
// and sets it in the Shoot manifest `spec.dns.domain` as well as the hostedZoneID.
// If for any reason no domain can be generated, no domain is assigned to the Shoot.
func assignDefaultDomain(shoot *garden.Shoot, projectLister gardenlisters.ProjectLister, secretLister kubecorev1listers.SecretLister) {
secrets, err := getDefaultDomainSecrets(secretLister)
if err != nil {
return
}
project, err := admissionutils.GetProject(shoot, projectLister)
if err != nil {
return
}
var (
defaultDomain string
zoneID string
)
for _, secret := range secrets {
if shoot.Spec.DNS.Provider == garden.DNSProvider(secret.Annotations[common.DNSProvider]) {
defaultDomain = secret.Annotations[common.DNSDomain]
zoneID = secret.Annotations[common.DNSHostedZoneID]
break
}
}
if len(defaultDomain) > 0 && len(zoneID) > 0 && project != nil {
generatedDomain := fmt.Sprintf("%s.%s.%s", shoot.Name, project.Name, defaultDomain)
shoot.Spec.DNS.Domain = &generatedDomain
shoot.Spec.DNS.HostedZoneID = &zoneID
}
}
// verifyHostedZoneID verifies that the cloud provider secret for the Shoot cluster contains credentials for the
// respective DNS provider.
func verifyHostedZoneID(shoot *garden.Shoot, secretBindingLister gardenlisters.SecretBindingLister, secretLister kubecorev1listers.SecretLister) error {
secrets, err := getDefaultDomainSecrets(secretLister)
if err != nil {
return err
}
// If the dns domain matches a default domain then the specified hosted zone id must also match.
for _, secret := range secrets {
if strings.HasSuffix(*(shoot.Spec.DNS.Domain), secret.Annotations[common.DNSDomain]) && shoot.Spec.DNS.Provider == garden.DNSProvider(secret.Annotations[common.DNSProvider]) {
if *shoot.Spec.DNS.HostedZoneID == secret.Annotations[common.DNSHostedZoneID] {
return nil
}
return errors.New("specified dns domain matches a default domain but the specified hosted zone id is incorrect")
}
}
// If the hosted zone id does not match a default domain then either the cloud provider secret must contain valid
// credentials for the respective DNS provider, or the spec.dns section must contain a field 'secretName' which is
// a reference to a secret containing the needed credentials.
var credentials *corev1.Secret
if shoot.Spec.DNS.SecretName != nil {
referencedSecret, err := secretLister.Secrets(shoot.Namespace).Get(*shoot.Spec.DNS.SecretName)
if err != nil {
return err
}
credentials = referencedSecret
} else {
cloudProviderSecret, err := getCloudProviderSecret(shoot, secretBindingLister, secretLister)
if err != nil {
return err
}
credentials = cloudProviderSecret
}
switch shoot.Spec.DNS.Provider {
case garden.DNSAWSRoute53:
_, accessKeyFound := credentials.Data[awsbotanist.AccessKeyID]
_, secretKeyFound := credentials.Data[awsbotanist.SecretAccessKey]
if !accessKeyFound || !secretKeyFound {
return fmt.Errorf("specifying the `.spec.dns.hostedZoneID` field is only possible if the cloud provider secret or the secret referenced in .spec.dns.secretName contains credentials for AWS Route53 (%s and %s)", awsbotanist.AccessKeyID, awsbotanist.SecretAccessKey)
}
case garden.DNSGoogleCloudDNS:
_, serviceAccountJSONFound := credentials.Data[gcpbotanist.ServiceAccountJSON]
if !serviceAccountJSONFound {
return fmt.Errorf("specifying the `.spec.dns.hostedZoneID` field is only possible if the cloud provider secret or the secret referenced in .spec.dns.secretName contains credentials for Google CloudDNS (%s)", gcpbotanist.ServiceAccountJSON)
}
case garden.DNSOpenstackDesignate:
_, authURLFound := credentials.Data[openstackbotanist.AuthURL]
_, domainNameFound := credentials.Data[openstackbotanist.DomainName]
_, tenantNameFound := credentials.Data[openstackbotanist.TenantName]
_, usernameFound := credentials.Data[openstackbotanist.UserName]
_, userDomainNameFound := credentials.Data[openstackbotanist.UserDomainName]
_, passwordFound := credentials.Data[openstackbotanist.Password]
if !authURLFound || !domainNameFound || !tenantNameFound || !usernameFound || !userDomainNameFound || !passwordFound {
return fmt.Errorf("specifying the `.spec.dns.hostedZoneID` field is only possible if the cloud provider secret or the secret referenced in .spec.dns.secretName contains credentials for Designate (%s, %s, %s, %s, %s and %s)", openstackbotanist.AuthURL, openstackbotanist.DomainName, openstackbotanist.TenantName, openstackbotanist.UserName, openstackbotanist.UserDomainName, openstackbotanist.Password)
}
}
return nil
}
// determineHostedZoneID reads the default domain secrets and compare their annotations with the specified Shoot
// domain. If both fit, it will return the Hosted Zone of the respective default domain.
func determineHostedZoneID(shoot *garden.Shoot, secretLister kubecorev1listers.SecretLister) (string, error) {
secrets, err := getDefaultDomainSecrets(secretLister)
if err != nil {
return "", err
}
if len(secrets) == 0 {
return "", apierrors.NewInternalError(errors.New("failed to determine a DNS hosted zone: no default domain secrets found"))
}
for _, secret := range secrets {
if strings.HasSuffix(*(shoot.Spec.DNS.Domain), secret.Annotations[common.DNSDomain]) && shoot.Spec.DNS.Provider == garden.DNSProvider(secret.Annotations[common.DNSProvider]) {
return secret.Annotations[common.DNSHostedZoneID], nil
}
}
return "", apierrors.NewInternalError(errors.New("failed to determine a hosted zone id for the given domain (no default domain secret matches)"))
}
// getDefaultDomainSecrets filters the secrets in the Garden namespace for default domain secrets.
func getDefaultDomainSecrets(secretLister kubecorev1listers.SecretLister) ([]corev1.Secret, error) {
defaultDomainSecrets := []corev1.Secret{}
selector, err := labels.Parse(fmt.Sprintf("%s=%s", common.GardenRole, common.GardenRoleDefaultDomain))
if err != nil {
return nil, err
}
secrets, err := secretLister.Secrets(common.GardenNamespace).List(selector)
if err != nil {
return nil, err
}
for _, secret := range secrets {
metadata := secret.ObjectMeta
if !metav1.HasAnnotation(metadata, common.DNSHostedZoneID) || !metav1.HasAnnotation(metadata, common.DNSProvider) || !metav1.HasAnnotation(metadata, common.DNSDomain) {
continue
}
defaultDomainSecrets = append(defaultDomainSecrets, *secret)
}
return defaultDomainSecrets, nil
}
// getCloudProviderSecret reads the cloud provider secret specified by the binding referenced in the Shoot manifest.
func getCloudProviderSecret(shoot *garden.Shoot, secretBindingLister gardenlisters.SecretBindingLister, secretLister kubecorev1listers.SecretLister) (*corev1.Secret, error) {
binding, err := secretBindingLister.SecretBindings(shoot.Namespace).Get(shoot.Spec.Cloud.SecretBindingRef.Name)
if err != nil {
return nil, err
}
return secretLister.Secrets(binding.SecretRef.Namespace).Get(binding.SecretRef.Name)
}