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handler_shootclient.go
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/
handler_shootclient.go
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// Copyright 2019 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 webhook
import (
"context"
"fmt"
"net/http"
"strings"
"github.com/go-logr/logr"
corev1 "k8s.io/api/core/v1"
metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
"k8s.io/apimachinery/pkg/runtime"
"k8s.io/apimachinery/pkg/runtime/serializer"
"sigs.k8s.io/controller-runtime/pkg/client"
"sigs.k8s.io/controller-runtime/pkg/manager"
"sigs.k8s.io/controller-runtime/pkg/runtime/inject"
"sigs.k8s.io/controller-runtime/pkg/webhook/admission"
extensionsconfig "github.com/gardener/gardener/extensions/pkg/apis/config"
"github.com/gardener/gardener/extensions/pkg/util"
v1beta1constants "github.com/gardener/gardener/pkg/apis/core/v1beta1/constants"
)
// NewHandlerWithShootClient creates a new handler for the given types, using the given mutator, and logger.
func NewHandlerWithShootClient(mgr manager.Manager, types []Type, mutator MutatorWithShootClient, logger logr.Logger) (http.Handler, error) {
// Build a map of the given types keyed by their GVKs
typesMap, err := buildTypesMap(mgr.GetScheme(), objectsFromTypes(types))
if err != nil {
return nil, err
}
// inject RemoteAddr into admission http.Handler, we need it to identify which API server called the webhook server
// in order to create a client for that shoot cluster.
return remoteAddrInjectingHandler{
Handler: &admission.Webhook{
Handler: &handlerShootClient{
typesMap: typesMap,
mutator: mutator,
logger: logger.WithName("handlerShootClient"),
},
RecoverPanic: true,
},
}, nil
}
type handlerShootClient struct {
typesMap map[metav1.GroupVersionKind]client.Object
mutator MutatorWithShootClient
client client.Client
decoder runtime.Decoder
logger logr.Logger
}
// InjectScheme injects the given scheme into the handler.
func (h *handlerShootClient) InjectScheme(s *runtime.Scheme) error {
h.decoder = serializer.NewCodecFactory(s).UniversalDecoder()
return nil
}
// InjectFunc injects stuff into the mutator.
func (h *handlerShootClient) InjectFunc(f inject.Func) error {
return f(h.mutator)
}
// InjectClient injects a client.
func (h *handlerShootClient) InjectClient(client client.Client) error {
h.client = client
return nil
}
func (h *handlerShootClient) Handle(ctx context.Context, req admission.Request) admission.Response {
var mut MutateFunc = func(ctx context.Context, new, old client.Object) error {
// TODO: replace this logic with a proper authentication mechanism
// see https://kubernetes.io/docs/reference/access-authn-authz/extensible-admission-controllers/#authenticate-apiservers
// API servers should authenticate against webhooks servers using TLS client certs, from which the webhook
// can identify from which shoot cluster the webhook call is coming
remoteAddrValue := ctx.Value(remoteAddrContextKey)
if remoteAddrValue == nil {
return fmt.Errorf("didn't receive remote address")
}
remoteAddr, ok := remoteAddrValue.(string)
if !ok {
return fmt.Errorf("remote address expected to be string, got %T", remoteAddrValue)
}
ipPort := strings.Split(remoteAddr, ":")
if len(ipPort) < 1 {
return fmt.Errorf("remote address not parseable: %s", remoteAddr)
}
ip := ipPort[0]
podList := &corev1.PodList{}
if err := h.client.List(ctx, podList, client.MatchingLabels{
v1beta1constants.LabelApp: v1beta1constants.LabelKubernetes,
v1beta1constants.LabelRole: v1beta1constants.LabelAPIServer,
}); err != nil {
return fmt.Errorf("error while listing all pods: %w", err)
}
var shootNamespace string
for _, pod := range podList.Items {
if pod.Status.PodIP == ip {
shootNamespace = pod.Namespace
break
}
}
if len(shootNamespace) == 0 {
return fmt.Errorf("could not find shoot namespace for webhook request from remote address %s", remoteAddr)
}
_, shootClient, err := util.NewClientForShoot(ctx, h.client, shootNamespace, client.Options{}, extensionsconfig.RESTOptions{})
if err != nil {
return fmt.Errorf("could not create shoot client: %w", err)
}
return h.mutator.Mutate(ctx, new, old, shootClient)
}
// Decode object
t, ok := h.typesMap[req.AdmissionRequest.Kind]
if !ok {
return admission.Errored(http.StatusBadRequest, fmt.Errorf("unexpected request kind %s", req.AdmissionRequest.Kind))
}
return handle(ctx, req, mut, t, h.decoder, h.logger)
}