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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 namespacedeletion
import (
"context"
"fmt"
"net/http"
"time"
"github.com/go-logr/logr"
admissionv1 "k8s.io/api/admission/v1"
corev1 "k8s.io/api/core/v1"
apierrors "k8s.io/apimachinery/pkg/api/errors"
metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
"sigs.k8s.io/controller-runtime/pkg/cache"
"sigs.k8s.io/controller-runtime/pkg/client"
"sigs.k8s.io/controller-runtime/pkg/webhook/admission"
acadmission "github.com/gardener/gardener/pkg/admissioncontroller/webhooks/admission"
gardencorev1beta1 "github.com/gardener/gardener/pkg/apis/core/v1beta1"
"github.com/gardener/gardener/pkg/logger"
"github.com/gardener/gardener/pkg/utils"
gutil "github.com/gardener/gardener/pkg/utils/gardener"
kutil "github.com/gardener/gardener/pkg/utils/kubernetes"
)
const (
// HandlerName is the name of this admission webhook handler.
HandlerName = "namespace_validator"
// WebhookPath is the HTTP handler path for this admission webhook handler.
WebhookPath = "/webhooks/validate-namespace-deletion"
)
var namespaceGVK = metav1.GroupVersionKind{Group: "", Kind: "Namespace", Version: "v1"}
// New creates a new handler for validating namespace deletions.
func New(ctx context.Context, logger logr.Logger, cache cache.Cache) (*handler, error) {
// Initialize caches here to ensure the readyz informer check will only succeed once informers required for this
// handler have synced so that http requests can be served quicker with pre-syncronized caches.
if _, err := cache.GetInformer(ctx, &corev1.Namespace{}); err != nil {
return nil, err
}
if _, err := cache.GetInformer(ctx, &gardencorev1beta1.Project{}); err != nil {
return nil, err
}
return &handler{
cacheReader: cache,
logger: logger,
}, nil
}
type handler struct {
cacheReader client.Reader
apiReader client.Reader
logger logr.Logger
}
var _ admission.Handler = &handler{}
// InjectAPIReader injects a reader into the handler.
func (h *handler) InjectAPIReader(reader client.Reader) error {
h.apiReader = reader
return nil
}
// Handle implements the webhook handler for namespace deletion validation.
func (h *handler) Handle(ctx context.Context, request admission.Request) admission.Response {
ctx, cancel := context.WithTimeout(ctx, 10*time.Second)
defer cancel()
// If the request does not indicate the correct operation (DELETE) we allow the review without further doing.
if request.Operation != admissionv1.Delete {
return acadmission.Allowed("operation is not DELETE")
}
if request.Kind != namespaceGVK {
return acadmission.Allowed("resource is not corev1.Namespace")
}
if request.SubResource != "" {
return acadmission.Allowed("subresources on namespaces are not handled")
}
requestID, err := utils.GenerateRandomString(8)
if err != nil {
return admission.Errored(http.StatusInternalServerError, err)
}
requestLogger := h.logger.WithValues(logger.IDFieldName, requestID)
// Now that all checks have been passed we can actually validate the admission request.
reviewResponse := h.admitNamespace(ctx, request)
if !reviewResponse.Allowed && reviewResponse.Result != nil {
requestLogger.Info("rejected namespace deletion", "user", request.UserInfo.Username, "message", reviewResponse.Result.Message)
}
return reviewResponse
}
// admitNamespace does only allow the request if no Shoots exist in this specific namespace anymore.
func (h *handler) admitNamespace(ctx context.Context, request admission.Request) admission.Response {
// Determine project for given namespace.
// TODO: we should use a direct lookup here, as we might falsely allow the request, if our cache is
// out of sync and doesn't know about the project. We should use a field selector for looking up the project
// belonging to a given namespace.
project, namespace, err := gutil.ProjectAndNamespaceFromReader(ctx, h.cacheReader, request.Name)
if err != nil {
if apierrors.IsNotFound(err) {
if namespace == nil {
return acadmission.Allowed("namespace is already gone")
}
return acadmission.Allowed("project for namespace not found")
}
return admission.Errored(http.StatusInternalServerError, err)
}
if project == nil {
return acadmission.Allowed("does not belong to a project")
}
switch {
case namespace.DeletionTimestamp != nil:
return acadmission.Allowed("namespace is already marked for deletion")
case project.DeletionTimestamp != nil:
// if project is marked for deletion we need to wait until all shoots in the namespace are gone
namespaceInUse, err := kutil.IsNamespaceInUse(ctx, h.apiReader, namespace.Name, gardencorev1beta1.SchemeGroupVersion.WithKind("ShootList"))
if err != nil {
return admission.Errored(http.StatusInternalServerError, err)
}
if !namespaceInUse {
return acadmission.Allowed("namespace doesn't contain any shoots")
}
return admission.Errored(http.StatusUnprocessableEntity, fmt.Errorf("deletion of namespace %q is not permitted (it still contains Shoots)", namespace.Name))
}
// Namespace is not yet marked for deletion and project is not marked as well. We do not admit and respond that
// namespace deletion is only allowed via project deletion.
return admission.Errored(http.StatusUnprocessableEntity, fmt.Errorf("direct deletion of namespace %q is not permitted (you must delete the corresponding project %q)", namespace.Name, project.Name))
}