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Add a mutating webhook for adding extension labels
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shafeeqes committed Feb 22, 2022
1 parent e2ef57a commit b4e57a0
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6 changes: 6 additions & 0 deletions docs/concepts/apiserver_admission_plugins.md
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Expand Up @@ -54,6 +54,12 @@ This admission controller reacts on `CREATE` and `UPDATE` operations for `Backup
For all the various extension types in the specifications of these objects, it validates whether there exists a `ControllerRegistration` in the system that is primarily responsible for the stated extension type(s).
This prevents misconfigurations that would otherwise allow users to create such resources with extension types that don't exist in the cluster, effectively leading to failing reconciliation loops.

## `ExtensionLabels`

_(enabled by default)_

This admission controller reacts on `CREATE` and `UPDATE` operations for `BackupBucket`s, `BackupEntry`s, `CloudProfile`s, `Seed`s and `Shoot`s. For all the various extension types in the specifications of these objects, it adds a corresponding label in the resource. This would allow the extension admission webhooks to filter out the resources they are responsible for and ignore all others.

## `PlantValidator`

_(enabled by default)_
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13 changes: 13 additions & 0 deletions pkg/apis/core/v1beta1/constants/types_constants.go
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Expand Up @@ -287,6 +287,19 @@ const (
// LabelMonitoring is a constant for a label for monitoring stack configurations
LabelMonitoring = "monitoring"

// LabelExtensionTypePrefix is used to prefix extension label for extension types.
LabelExtensionTypePrefix = "extensions.extensions.gardener.cloud/"
// LabelExtensionProviderPrefix is used to prefix extension label for cloud provider types.
LabelExtensionProviderPrefix = "provider.extensions.gardener.cloud/"
// LabelExtensionDNSRecordPrefix is used to prefix extension label for DNS types.
LabelExtensionDNSRecordPrefix = "dnsrecord.extensions.gardener.cloud/"
// LabelExtensionNetworkingPrefix is used to prefix extension label for networking plugin types.
LabelExtensionNetworkingPrefix = "networking.extensions.gardener.cloud/"
// LabelExtensionOperatingSystemConfigPrefix is used to prefix extension label for OperatingSystemConfig types.
LabelExtensionOperatingSystemConfigPrefix = "operatingsystemconfig.extensions.gardener.cloud/"
// LabelExtensionContainerRuntimePrefix is used to prefix extension label for ContainerRuntime types.
LabelExtensionContainerRuntimePrefix = "containerruntime.extensions.gardener.cloud/"

// LabelNetworkPolicyToBlockedCIDRs allows Egress from pods labeled with 'networking.gardener.cloud/to-blocked-cidrs=allowed'.
LabelNetworkPolicyToBlockedCIDRs = "networking.gardener.cloud/to-blocked-cidrs"
// LabelNetworkPolicyToDNS allows Egress from pods labeled with 'networking.gardener.cloud/to-dns=allowed' to DNS running in 'kube-system'.
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4 changes: 4 additions & 0 deletions pkg/apiserver/plugins.go
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Expand Up @@ -19,6 +19,7 @@ import (
controllerregistrationresources "github.com/gardener/gardener/plugin/pkg/controllerregistration/resources"
"github.com/gardener/gardener/plugin/pkg/global/customverbauthorizer"
"github.com/gardener/gardener/plugin/pkg/global/deletionconfirmation"
"github.com/gardener/gardener/plugin/pkg/global/extensionlabels"
"github.com/gardener/gardener/plugin/pkg/global/extensionvalidation"
"github.com/gardener/gardener/plugin/pkg/global/resourcereferencemanager"
managedseedshoot "github.com/gardener/gardener/plugin/pkg/managedseed/shoot"
Expand Down Expand Up @@ -50,6 +51,7 @@ var (
lifecycle.PluginName, // NamespaceLifecycle
resourcereferencemanager.PluginName, // ResourceReferenceManager
extensionvalidation.PluginName, // ExtensionValidator
extensionlabels.PluginName, // ExtensionLabels
shoottolerationrestriction.PluginName, // ShootTolerationRestriction
shootexposureclass.PluginName, // ShootExposureClass
shootdns.PluginName, // ShootDNS
Expand Down Expand Up @@ -85,6 +87,7 @@ var (
lifecycle.PluginName, // NamespaceLifecycle
resourcereferencemanager.PluginName, // ResourceReferenceManager
extensionvalidation.PluginName, // ExtensionValidator
extensionlabels.PluginName, // ExtensionLabels
shoottolerationrestriction.PluginName, // ShootTolerationRestriction
shootexposureclass.PluginName, // ShootExposureClass
shootdns.PluginName, // ShootDNS
Expand Down Expand Up @@ -116,6 +119,7 @@ func RegisterAllAdmissionPlugins(plugins *admission.Plugins) {
resourcereferencemanager.Register(plugins)
deletionconfirmation.Register(plugins)
extensionvalidation.Register(plugins)
extensionlabels.Register(plugins)
shoottolerationrestriction.Register(plugins)
shootexposureclass.Register(plugins)
shootquotavalidator.Register(plugins)
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256 changes: 256 additions & 0 deletions plugin/pkg/global/extensionlabels/admission.go
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@@ -0,0 +1,256 @@
// Copyright (c) 2022 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 extensionlabels

import (
"context"
"errors"
"fmt"
"io"
"strings"

"github.com/gardener/gardener/pkg/apis/core"
v1beta1constants "github.com/gardener/gardener/pkg/apis/core/v1beta1/constants"
admissioninitializer "github.com/gardener/gardener/pkg/apiserver/admission/initializer"
internalcoreinformers "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/features"

apierrors "k8s.io/apimachinery/pkg/api/errors"
metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
"k8s.io/apiserver/pkg/admission"
utilfeature "k8s.io/apiserver/pkg/util/feature"
)

const (
// PluginName is the name of this admission plugin.
PluginName = "ExtensionLabels"
)

// Register registers a plugin.
func Register(plugins *admission.Plugins) {
plugins.Register(PluginName, NewFactory)
}

// NewFactory creates a new PluginFactory.
func NewFactory(config io.Reader) (admission.Interface, error) {
return New()
}

// ExtensionLabels contains the admission handler
type ExtensionLabels struct {
*admission.Handler
backupBucketLister corelisters.BackupBucketLister
readyFunc admission.ReadyFunc
}

var (
_ = admissioninitializer.WantsInternalCoreInformerFactory(&ExtensionLabels{})
readyFuncs []admission.ReadyFunc
)

// New creates a new ExtensionLabels admission plugin.
func New() (*ExtensionLabels, error) {
return &ExtensionLabels{
Handler: admission.NewHandler(admission.Create, admission.Update),
}, nil
}

// AssignReadyFunc assigns the ready function to the admission handler.
func (e *ExtensionLabels) AssignReadyFunc(f admission.ReadyFunc) {
e.readyFunc = f
e.SetReadyFunc(f)
}

// SetInternalCoreInformerFactory sets the external garden core informer factory.
func (e *ExtensionLabels) SetInternalCoreInformerFactory(f internalcoreinformers.SharedInformerFactory) {
backupBucketInformer := f.Core().InternalVersion().BackupBuckets()
e.backupBucketLister = backupBucketInformer.Lister()

readyFuncs = append(readyFuncs, backupBucketInformer.Informer().HasSynced)
}

func (e *ExtensionLabels) waitUntilReady(attrs admission.Attributes) error {
// Wait until the caches have been synced
if e.readyFunc == nil {
e.AssignReadyFunc(func() bool {
for _, readyFunc := range readyFuncs {
if !readyFunc() {
return false
}
}
return true
})
}

if !e.WaitForReady() {
return admission.NewForbidden(attrs, errors.New("not yet ready to handle request"))
}

return nil
}

// ValidateInitialization checks whether the plugin was correctly initialized.
func (e *ExtensionLabels) ValidateInitialization() error {
if e.backupBucketLister == nil {
return errors.New("missing BackupBucket lister")
}
return nil
}

var _ admission.MutationInterface = &ExtensionLabels{}

// Admit add extension labels to resources.
func (e *ExtensionLabels) Admit(ctx context.Context, a admission.Attributes, o admission.ObjectInterfaces) error {
if err := e.waitUntilReady(a); err != nil {
return fmt.Errorf("err while waiting for ready %w", err)
}

switch a.GetKind().GroupKind() {
case core.Kind("Seed"):
seed, ok := a.GetObject().(*core.Seed)
if !ok {
return apierrors.NewBadRequest("could not convert resource into Seed object")
}

removeLabels(&seed.ObjectMeta)
addMetaDataLabelsSeed(seed)

case core.Kind("Shoot"):
shoot, ok := a.GetObject().(*core.Shoot)
if !ok {
return apierrors.NewBadRequest("could not convert resource into Shoot object")
}

removeLabels(&shoot.ObjectMeta)
addMetaDataLabelsShoot(shoot)

case core.Kind("CloudProfile"):
cloudProfile, ok := a.GetObject().(*core.CloudProfile)
if !ok {
return apierrors.NewBadRequest("could not convert resource into CloudProfile object")
}

removeLabels(&cloudProfile.ObjectMeta)
addMetaDataLabelsCloudProfile(cloudProfile)

case core.Kind("BackupBucket"):
backupBucket, ok := a.GetObject().(*core.BackupBucket)
if !ok {
return apierrors.NewBadRequest("could not convert object into BackupBucket object")
}

removeLabels(&backupBucket.ObjectMeta)
addMetaDataLabelsBackupBucket(backupBucket)

case core.Kind("BackupEntry"):
backupEntry, ok := a.GetObject().(*core.BackupEntry)
if !ok {
return apierrors.NewBadRequest("could not convert object into BackupEntry object")
}

backupBucket, err := e.backupBucketLister.Get(backupEntry.Spec.BucketName)
if err != nil {
return err
}

removeLabels(&backupEntry.ObjectMeta)
addMetaDataLabelsBackupEntry(backupEntry, backupBucket)
}
return nil
}

func addMetaDataLabelsSeed(seed *core.Seed) {
metav1.SetMetaDataLabel(&seed.ObjectMeta, v1beta1constants.LabelExtensionProviderPrefix+seed.Spec.Provider.Type, "true")
if seed.Spec.Backup != nil {
metav1.SetMetaDataLabel(&seed.ObjectMeta, v1beta1constants.LabelExtensionProviderPrefix+seed.Spec.Backup.Provider, "true")
}

if seed.Spec.DNS.Provider != nil && utilfeature.DefaultFeatureGate.Enabled(features.UseDNSRecords) {
metav1.SetMetaDataLabel(&seed.ObjectMeta, v1beta1constants.LabelExtensionDNSRecordPrefix+seed.Spec.DNS.Provider.Type, "true")
}
}

func addMetaDataLabelsShoot(shoot *core.Shoot) {
for _, extension := range shoot.Spec.Extensions {
if extension.Disabled != nil && *extension.Disabled {
continue
}
metav1.SetMetaDataLabel(&shoot.ObjectMeta, v1beta1constants.LabelExtensionTypePrefix+extension.Type, "true")
}
for _, pool := range shoot.Spec.Provider.Workers {
if pool.CRI != nil {
for _, cr := range pool.CRI.ContainerRuntimes {
metav1.SetMetaDataLabel(&shoot.ObjectMeta, v1beta1constants.LabelExtensionContainerRuntimePrefix+cr.Type, "true")
}
}
if pool.Machine.Image != nil {
metav1.SetMetaDataLabel(&shoot.ObjectMeta, v1beta1constants.LabelExtensionOperatingSystemConfigPrefix+pool.Machine.Image.Name, "true")
}
}
if shoot.Spec.DNS != nil {
for _, provider := range shoot.Spec.DNS.Providers {
if provider.Type == nil || *provider.Type == core.DNSUnmanaged {
continue
}
if utilfeature.DefaultFeatureGate.Enabled(features.UseDNSRecords) {
metav1.SetMetaDataLabel(&shoot.ObjectMeta, v1beta1constants.LabelExtensionDNSRecordPrefix+*provider.Type, "true")
}
}
}
metav1.SetMetaDataLabel(&shoot.ObjectMeta, v1beta1constants.LabelExtensionProviderPrefix+shoot.Spec.Provider.Type, "true")
metav1.SetMetaDataLabel(&shoot.ObjectMeta, v1beta1constants.LabelExtensionNetworkingPrefix+shoot.Spec.Networking.Type, "true")
}

func addMetaDataLabelsCloudProfile(cloudProfile *core.CloudProfile) {
for _, machineImage := range cloudProfile.Spec.MachineImages {
metav1.SetMetaDataLabel(&cloudProfile.ObjectMeta, v1beta1constants.LabelExtensionOperatingSystemConfigPrefix+machineImage.Name, "true")

for _, machineImageVersion := range machineImage.Versions {
for _, cri := range machineImageVersion.CRI {
for _, cr := range cri.ContainerRuntimes {
metav1.SetMetaDataLabel(&cloudProfile.ObjectMeta, v1beta1constants.LabelExtensionContainerRuntimePrefix+cr.Type, "true")
}
}
}
}
metav1.SetMetaDataLabel(&cloudProfile.ObjectMeta, v1beta1constants.LabelExtensionProviderPrefix+cloudProfile.Spec.Type, "true")
}

func addMetaDataLabelsBackupBucket(backupBucket *core.BackupBucket) {
metav1.SetMetaDataLabel(&backupBucket.ObjectMeta, v1beta1constants.LabelExtensionProviderPrefix+backupBucket.Spec.Provider.Type, "true")
}

func addMetaDataLabelsBackupEntry(backupEntry *core.BackupEntry, backupBucket *core.BackupBucket) {
metav1.SetMetaDataLabel(&backupEntry.ObjectMeta, v1beta1constants.LabelExtensionProviderPrefix+backupBucket.Spec.Provider.Type, "true")
}

func removeLabels(objectMeta *metav1.ObjectMeta) {
extensionLabels := []string{
v1beta1constants.LabelExtensionTypePrefix,
v1beta1constants.LabelExtensionProviderPrefix,
v1beta1constants.LabelExtensionDNSRecordPrefix,
v1beta1constants.LabelExtensionNetworkingPrefix,
v1beta1constants.LabelExtensionOperatingSystemConfigPrefix,
v1beta1constants.LabelExtensionContainerRuntimePrefix,
}
for k := range objectMeta.Labels {
for _, label := range extensionLabels {
if strings.Contains(k, label) {
delete(objectMeta.Labels, k)
}
}
}
}

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