/
admission.go
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/
admission.go
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// SPDX-FileCopyrightText: 2024 SAP SE or an SAP affiliate company and Gardener contributors
//
// SPDX-License-Identifier: Apache-2.0
package dns
import (
"context"
"errors"
"fmt"
"io"
"reflect"
"sort"
"strconv"
"strings"
apierrors "k8s.io/apimachinery/pkg/api/errors"
"k8s.io/apimachinery/pkg/labels"
"k8s.io/apimachinery/pkg/util/validation/field"
"k8s.io/apiserver/pkg/admission"
kubeinformers "k8s.io/client-go/informers"
kubecorev1listers "k8s.io/client-go/listers/core/v1"
"k8s.io/utils/ptr"
"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"
gardencoreinformers "github.com/gardener/gardener/pkg/client/core/informers/externalversions"
gardencorev1beta1listers "github.com/gardener/gardener/pkg/client/core/listers/core/v1beta1"
"github.com/gardener/gardener/pkg/utils"
gardenerutils "github.com/gardener/gardener/pkg/utils/gardener"
plugin "github.com/gardener/gardener/plugin/pkg"
admissionutils "github.com/gardener/gardener/plugin/pkg/utils"
)
// Register registers a plugin.
func Register(plugins *admission.Plugins) {
plugins.Register(plugin.PluginNameShootDNS, func(_ io.Reader) (admission.Interface, error) {
return New()
})
}
// DNS contains listers and admission handler.
type DNS struct {
*admission.Handler
secretLister kubecorev1listers.SecretLister
projectLister gardencorev1beta1listers.ProjectLister
seedLister gardencorev1beta1listers.SeedLister
readyFunc admission.ReadyFunc
}
var (
_ = admissioninitializer.WantsCoreInformerFactory(&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)
}
// SetCoreInformerFactory gets Lister from SharedInformerFactory.
func (d *DNS) SetCoreInformerFactory(f gardencoreinformers.SharedInformerFactory) {
projectInformer := f.Core().V1beta1().Projects()
d.projectLister = projectInformer.Lister()
seedInformer := f.Core().V1beta1().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(_ context.Context, a admission.Attributes, _ 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 all subresources, except for binding
// Binding subresource is required because there are fields being set in the shoot
// when it is scheduled and we want this plugin to be triggered.
if a.GetSubresource() != "" && a.GetSubresource() != "binding" {
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(a, shoot, defaultDomains); err != nil {
return err
}
switch a.GetOperation() {
case admission.Create:
// If shoot uses default domain, validate domain even though shoot can be assigned to seed
// having dns disabled later on
if isShootDomainSet(shoot) && !helper.ShootUsesUnmanagedDNS(shoot) {
if err := checkDefaultDomainFormat(a, shoot, d.projectLister, defaultDomains); err != nil {
return err
}
}
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")
}
// Only validate domain on updates if the shoot's domain was not set previously and is being currently set.
// This is necessary to avoid reconciliation errors for older shoots that already use a domain with an incorrect format.
// There is also a possibility that an old shoot had an invalid domain, but was never assigned to a seed. This is why we check
// if the shoot was previously not assigned to a seed and if the shoot's domain is invalid, the update is denied so that the invalid
// domain does not get created.
if (oldShoot.Spec.SeedName == nil || !isShootDomainSet(oldShoot)) && isShootDomainSet(shoot) && !helper.ShootUsesUnmanagedDNS(shoot) {
if err := checkDefaultDomainFormat(a, shoot, d.projectLister, defaultDomains); err != nil {
return err
}
}
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 = ptr.To(true)
break
}
}
}
}
if shoot.Spec.SeedName == nil {
return nil
}
if oldShoot.Spec.SeedName != nil && shoot.Spec.DNS != nil {
return checkFunctionlessDNSProviders(a, shoot)
}
}
specPath := field.NewPath("spec")
// Generate a Shoot domain if none is configured.
if !helper.ShootUsesUnmanagedDNS(shoot) {
if err := assignDefaultDomainIfNeeded(shoot, d.projectLister, defaultDomains); err != nil {
return err
}
if !isShootDomainSet(shoot) {
fieldErr := field.Required(specPath.Child("DNS"), fmt.Sprintf("shoot domain field .spec.dns.domain must be set if provider != %s", core.DNSUnmanaged))
return apierrors.NewInvalid(a.GetKind().GroupKind(), shoot.Name, field.ErrorList{fieldErr})
}
}
if shoot.Spec.DNS != nil {
if err := setPrimaryDNSProvider(a, shoot, defaultDomains); err != nil {
return err
}
if err := checkFunctionlessDNSProviders(a, shoot); err != nil {
return err
}
}
return nil
}
// checkFunctionlessDNSProviders returns an error if a non-primary provider isn't configured correctly.
func checkFunctionlessDNSProviders(a admission.Attributes, shoot *core.Shoot) error {
dns := shoot.Spec.DNS
for _, provider := range dns.Providers {
if !ptr.Deref(provider.Primary, false) && (provider.Type == nil || provider.SecretName == nil) {
fieldErr := field.Required(field.NewPath("spec", "dns", "providers"), "non-primary DNS providers in .spec.dns.providers must specify a `type` and `secretName`")
return apierrors.NewInvalid(a.GetKind().GroupKind(), shoot.Name, field.ErrorList{fieldErr})
}
}
return nil
}
// checkPrimaryDNSProvider checks if the shoot uses a default domain and returns an error
// if a primary provider is used at the same time.
func checkPrimaryDNSProvider(a admission.Attributes, shoot *core.Shoot, defaultDomains []string) error {
dns := shoot.Spec.DNS
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 {
fieldErr := field.Invalid(field.NewPath("spec", "dns"), shoot.Name, "primary dns provider must not be set when default domain is used")
return apierrors.NewInvalid(a.GetKind().GroupKind(), shoot.Name, field.ErrorList{fieldErr})
}
}
return nil
}
func isShootDomainSet(shoot *core.Shoot) bool {
return shoot.Spec.DNS != nil && shoot.Spec.DNS.Domain != nil
}
func isDefaultDomain(domain string, defaultDomains []string) bool {
for _, defaultDomain := range defaultDomains {
if strings.HasSuffix(domain, "."+defaultDomain) {
return true
}
}
return false
}
func setPrimaryDNSProvider(a admission.Attributes, shoot *core.Shoot, defaultDomains []string) error {
dns := shoot.Spec.DNS
if dns == nil {
return nil
}
if err := checkPrimaryDNSProvider(a, shoot, 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 = ptr.To(true)
}
return 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 gardencorev1beta1listers.ProjectLister, defaultDomains []string) error {
project, err := admissionutils.ProjectForNamespaceFromLister(projectLister, shoot.Namespace)
if err != nil {
return apierrors.NewInternalError(err)
}
if shoot.Spec.DNS == nil {
shoot.Spec.DNS = &core.DNS{}
}
if len(defaultDomains) > 0 && shoot.Spec.DNS.Domain == nil {
domain := defaultDomains[0]
shootDNSName := shoot.Name
if len(shoot.Name) == 0 && len(shoot.GenerateName) > 0 {
shootDNSName, err = utils.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
}
func checkDefaultDomainFormat(a admission.Attributes, shoot *core.Shoot, projectLister gardencorev1beta1listers.ProjectLister, defaultDomains []string) error {
project, err := admissionutils.ProjectForNamespaceFromLister(projectLister, shoot.Namespace)
if err != nil {
return apierrors.NewInternalError(err)
}
shootDomain := shoot.Spec.DNS.Domain
for _, domain := range defaultDomains {
if 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)) {
fieldErr := field.Invalid(field.NewPath("spec", "dns"), shoot.Name, "shoot with 'metadata.generateName' uses a default domain but does not match expected scheme: <random-subdomain>.<project-name>.<default-domain>")
return apierrors.NewInvalid(a.GetKind().GroupKind(), shoot.Name, field.ErrorList{fieldErr})
}
return nil
}
if *shootDomain != fmt.Sprintf("%s.%s.%s", shoot.Name, project.Name, domain) {
fieldErr := field.Invalid(field.NewPath("spec", "dns"), shoot.Name, "shoot uses a default domain but does not match expected scheme: <shoot-name>.<project-name>.<default-domain>")
return apierrors.NewInvalid(a.GetKind().GroupKind(), shoot.Name, field.ErrorList{fieldErr})
}
return nil
}
}
return nil
}
func getDefaultDomains(secretLister kubecorev1listers.SecretLister) ([]string, error) {
selector, err := labels.Parse(fmt.Sprintf("%s=%s", v1beta1constants.GardenRole, v1beta1constants.GardenRoleDefaultDomain))
if err != nil {
return nil, apierrors.NewInternalError(err)
}
domainSecrets, err := secretLister.Secrets(v1beta1constants.GardenNamespace).List(selector)
if err != nil {
return nil, apierrors.NewInternalError(err)
}
// sort domainSecrets with DNSDefaultDomainPriority to get the domain with the highest priority in first place
sort.SliceStable(domainSecrets, func(i, j int) bool {
iAnnotations := domainSecrets[i].GetAnnotations()
jAnnotations := domainSecrets[j].GetAnnotations()
var iPriority, jPriority int
if iAnnotations != nil {
if domainPriority, ok := iAnnotations[gardenerutils.DNSDefaultDomainPriority]; ok {
iPriority, err = strconv.Atoi(domainPriority)
if err != nil {
iPriority = 0
}
}
}
if jAnnotations != nil {
if domainPriority, ok := jAnnotations[gardenerutils.DNSDefaultDomainPriority]; ok {
jPriority, err = strconv.Atoi(domainPriority)
if err != nil {
jPriority = 0
}
}
}
return iPriority > jPriority
})
var defaultDomains []string
for _, domainSecret := range domainSecrets {
_, domain, _, err := gardenerutils.GetDomainInfoFromAnnotations(domainSecret.GetAnnotations())
if err != nil {
return nil, err
}
defaultDomains = append(defaultDomains, domain)
}
return defaultDomains, nil
}