/
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 dns
import (
"context"
"errors"
"fmt"
"io"
"reflect"
"strings"
"github.com/gardener/gardener/pkg/apis/core"
"github.com/gardener/gardener/pkg/apis/core/helper"
v1beta1constants "github.com/gardener/gardener/pkg/apis/core/v1beta1/constants"
admissioninitializer "github.com/gardener/gardener/pkg/apiserver/admission/initializer"
coreinformers "github.com/gardener/gardener/pkg/client/core/informers/internalversion"
corelisters "github.com/gardener/gardener/pkg/client/core/listers/core/internalversion"
"github.com/gardener/gardener/pkg/operation/common"
gardenerutils "github.com/gardener/gardener/pkg/utils"
admissionutils "github.com/gardener/gardener/plugin/pkg/utils"
corev1 "k8s.io/api/core/v1"
apierrors "k8s.io/apimachinery/pkg/api/errors"
"k8s.io/apimachinery/pkg/labels"
"k8s.io/apiserver/pkg/admission"
kubeinformers "k8s.io/client-go/informers"
kubecorev1listers "k8s.io/client-go/listers/core/v1"
"k8s.io/utils/pointer"
)
const (
// PluginName is the name of this admission plugin.
PluginName = "ShootDNS"
)
// Register registers a plugin.
func Register(plugins *admission.Plugins) {
plugins.Register(PluginName, func(config io.Reader) (admission.Interface, error) {
return New()
})
}
// DNS contains listers and and admission handler.
type DNS struct {
*admission.Handler
secretLister kubecorev1listers.SecretLister
projectLister corelisters.ProjectLister
seedLister corelisters.SeedLister
readyFunc admission.ReadyFunc
}
var (
_ = admissioninitializer.WantsInternalCoreInformerFactory(&DNS{})
_ = admissioninitializer.WantsKubeInformerFactory(&DNS{})
readyFuncs = []admission.ReadyFunc{}
)
// New creates a new DNS admission plugin.
func New() (*DNS, error) {
return &DNS{
Handler: admission.NewHandler(admission.Create, admission.Update),
}, nil
}
// AssignReadyFunc assigns the ready function to the admission handler.
func (d *DNS) AssignReadyFunc(f admission.ReadyFunc) {
d.readyFunc = f
d.SetReadyFunc(f)
}
// SetInternalCoreInformerFactory gets Lister from SharedInformerFactory.
func (d *DNS) SetInternalCoreInformerFactory(f coreinformers.SharedInformerFactory) {
projectInformer := f.Core().InternalVersion().Projects()
d.projectLister = projectInformer.Lister()
seedInformer := f.Core().InternalVersion().Seeds()
d.seedLister = seedInformer.Lister()
readyFuncs = append(readyFuncs, projectInformer.Informer().HasSynced, seedInformer.Informer().HasSynced)
}
// SetKubeInformerFactory gets Lister from SharedInformerFactory.
func (d *DNS) 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 *DNS) ValidateInitialization() error {
if d.secretLister == nil {
return errors.New("missing secret lister")
}
if d.projectLister == nil {
return errors.New("missing project lister")
}
if d.seedLister == nil {
return errors.New("missing seed lister")
}
return nil
}
var _ admission.MutationInterface = &DNS{}
// Admit tries to determine a DNS hosted zone for the Shoot's external domain.
func (d *DNS) Admit(ctx context.Context, a admission.Attributes, o admission.ObjectInterfaces) 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() != core.Kind("Shoot") {
return nil
}
// Ignore updates to shoot status or other subresources
if a.GetSubresource() != "" {
return nil
}
shoot, ok := a.GetObject().(*core.Shoot)
if !ok {
return apierrors.NewBadRequest("could not convert resource into Shoot object")
}
defaultDomains, err := getDefaultDomains(d.secretLister)
if err != nil {
return fmt.Errorf("error retrieving default domains: %s", err)
}
if err := checkPrimaryDNSProvider(shoot.Spec.DNS, defaultDomains); err != nil {
return err
}
// If a shoot is newly created and not yet assigned to a seed we do nothing. We need to know the seed
// in order to check whether it's tainted to not use DNS.
switch a.GetOperation() {
case admission.Create:
if shoot.Spec.SeedName == nil {
return nil
}
case admission.Update:
oldShoot, ok := a.GetOldObject().(*core.Shoot)
if !ok {
return apierrors.NewBadRequest("could not convert old resource into Shoot object")
}
if oldShoot.Spec.DNS != nil && shoot.Spec.DNS != nil {
oldPrimaryProvider := helper.FindPrimaryDNSProvider(oldShoot.Spec.DNS.Providers)
primaryProvider := helper.FindPrimaryDNSProvider(shoot.Spec.DNS.Providers)
if oldPrimaryProvider != nil && primaryProvider == nil {
// Since it was possible to apply shoots w/o a primary provider before, we have to re-add it here.
for i, provider := range shoot.Spec.DNS.Providers {
if reflect.DeepEqual(provider.Type, oldPrimaryProvider.Type) && reflect.DeepEqual(provider.SecretName, oldPrimaryProvider.SecretName) {
shoot.Spec.DNS.Providers[i].Primary = pointer.BoolPtr(true)
}
}
}
}
if shoot.Spec.SeedName == nil {
return nil
}
if oldShoot.Spec.SeedName != nil {
return nil
}
}
dnsDisabled, err := seedDisablesDNS(d.seedLister, *shoot.Spec.SeedName)
if err != nil {
return apierrors.NewBadRequest(fmt.Sprintf("could not get referenced seed: %+v", err.Error()))
}
if dnsDisabled {
if shoot.Spec.DNS != nil {
return apierrors.NewBadRequest("shoot's .spec.dns section must be nil if seed with disabled DNS is chosen")
}
return nil
}
// Generate a Shoot domain if none is configured (at this point in time we know that the chosen seed does
// not disable DNS.
if !helper.ShootUsesUnmanagedDNS(shoot) {
if err := assignDefaultDomainIfNeeded(shoot, d.projectLister, defaultDomains); err != nil {
return err
}
if shoot.Spec.DNS == nil || shoot.Spec.DNS.Domain == nil {
return apierrors.NewBadRequest(fmt.Sprintf("shoot domain field .spec.dns.domain must be set if provider != %s and assigned to a seed which does not disable DNS", core.DNSUnmanaged))
}
}
if err := managePrimaryDNSProvider(shoot.Spec.DNS, defaultDomains); err != nil {
return err
}
return nil
}
func checkPrimaryDNSProvider(dns *core.DNS, defaultDomains []string) error {
if dns == nil || dns.Domain == nil || len(dns.Providers) == 0 {
return nil
}
var defaultDomain = isDefaultDomain(*dns.Domain, defaultDomains)
if defaultDomain {
primary := helper.FindPrimaryDNSProvider(dns.Providers)
if primary != nil {
return apierrors.NewBadRequest("primary dns provider must not be set when default domain is used")
}
}
return nil
}
func isDefaultDomain(domain string, defaultDomains []string) bool {
for _, defaultDomain := range defaultDomains {
if strings.HasSuffix(domain, "."+defaultDomain) {
return true
}
}
return false
}
func managePrimaryDNSProvider(dns *core.DNS, defaultDomains []string) error {
if dns == nil {
return nil
}
if err := checkPrimaryDNSProvider(dns, defaultDomains); err != nil {
return err
}
if dns.Domain != nil && isDefaultDomain(*dns.Domain, defaultDomains) {
return nil
}
primary := helper.FindPrimaryDNSProvider(dns.Providers)
if primary == nil && len(dns.Providers) > 0 {
dns.Providers[0].Primary = pointer.BoolPtr(true)
}
return nil
}
func seedDisablesDNS(seedLister corelisters.SeedLister, seedName string) (bool, error) {
seed, err := seedLister.Get(seedName)
if err != nil {
return false, err
}
return !seed.Spec.Settings.ShootDNS.Enabled, nil
}
// assignDefaultDomainIfNeeded generates a domain <shoot-name>.<project-name>.<default-domain>
// and sets it in the shoot resource in the `spec.dns.domain` field.
// If for any reason no domain can be generated, no domain is assigned to the Shoot.
func assignDefaultDomainIfNeeded(shoot *core.Shoot, projectLister corelisters.ProjectLister, defaultDomains []string) error {
project, err := admissionutils.GetProject(shoot.Namespace, projectLister)
if err != nil {
return apierrors.NewInternalError(err)
}
var shootDomain *string
if shoot.Spec.DNS != nil {
shootDomain = shoot.Spec.DNS.Domain
}
for _, domain := range defaultDomains {
if shootDomain != nil && strings.HasSuffix(*shootDomain, "."+domain) {
// Check that the specified domain matches the pattern for default domains, especially in order
// to prevent shoots from "stealing" domain names for shoots in other projects
if len(shoot.GenerateName) > 0 && (len(shoot.Name) == 0 || strings.HasPrefix(shoot.Name, shoot.GenerateName)) {
// Case where shoot name is generated or to be generated
if !strings.HasSuffix(*shootDomain, fmt.Sprintf(".%s.%s", project.Name, domain)) {
return apierrors.NewBadRequest("shoot with 'metadata.generateName' uses a default domain but does not match expected scheme: <random-subdomain>.<project-name>.<default-domain>")
}
return nil
}
if *shootDomain != fmt.Sprintf("%s.%s.%s", shoot.Name, project.Name, domain) {
return apierrors.NewBadRequest("shoot uses a default domain but does not match expected scheme: <shoot-name>.<project-name>.<default-domain>")
}
return nil
}
// Shoot did not specify a domain, assign default domain and set provider to nil
if shootDomain == nil {
if shoot.Spec.DNS == nil {
shoot.Spec.DNS = &core.DNS{}
}
shootDNSName := shoot.Name
if len(shoot.Name) == 0 && len(shoot.GenerateName) > 0 {
shootDNSName, err = gardenerutils.GenerateRandomStringFromCharset(len(shoot.GenerateName)+5, "0123456789abcdefghijklmnopqrstuvwxyz")
if err != nil {
return apierrors.NewInternalError(err)
}
}
generatedDomain := fmt.Sprintf("%s.%s.%s", shootDNSName, project.Name, domain)
shoot.Spec.DNS.Domain = &generatedDomain
return nil
}
}
return nil
}
func getDefaultDomains(secretLister kubecorev1listers.SecretLister) ([]string, error) {
var domainSecrets []*corev1.Secret
deprecatedSelector, err := labels.Parse(fmt.Sprintf("%s=%s", v1beta1constants.DeprecatedGardenRole, common.GardenRoleDefaultDomain))
if err != nil {
return nil, apierrors.NewInternalError(err)
}
secrets, err := secretLister.Secrets(v1beta1constants.GardenNamespace).List(deprecatedSelector)
if err != nil {
return nil, apierrors.NewInternalError(err)
}
domainSecrets = append(domainSecrets, secrets...)
selector, err := labels.Parse(fmt.Sprintf("%s=%s", v1beta1constants.GardenRole, common.GardenRoleDefaultDomain))
if err != nil {
return nil, apierrors.NewInternalError(err)
}
secrets, err = secretLister.Secrets(v1beta1constants.GardenNamespace).List(selector)
if err != nil {
return nil, apierrors.NewInternalError(err)
}
domainSecrets = append(domainSecrets, secrets...)
var defaultDomains []string
for _, domainSecret := range domainSecrets {
_, domain, _, _, err := common.GetDomainInfoFromAnnotations(domainSecret.GetAnnotations())
if err != nil {
return nil, err
}
defaultDomains = append(defaultDomains, domain)
}
return defaultDomains, nil
}