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mutator.go
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mutator.go
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// Copyright 2021 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 dnsconfig
import (
"context"
"fmt"
appsv1 "k8s.io/api/apps/v1"
corev1 "k8s.io/api/core/v1"
metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
"k8s.io/utils/ptr"
"sigs.k8s.io/controller-runtime/pkg/client"
"github.com/gardener/gardener/pkg/apis/core/v1beta1"
v1beta1constants "github.com/gardener/gardener/pkg/apis/core/v1beta1/constants"
"github.com/gardener/gardener/pkg/provider-local/local"
)
type mutator struct {
client client.Client
}
func (m *mutator) Mutate(ctx context.Context, newObj, oldObj client.Object) error {
var (
podMeta *metav1.ObjectMeta
podSpec *corev1.PodSpec
)
if newObj.GetDeletionTimestamp() != nil {
return nil
}
switch obj := newObj.(type) {
case *corev1.Pod:
if oldObj != nil {
// This is basically a hack - ideally, we would like the mutating webhook configuration to only react for CREATE
// operations. However, currently both "CREATE" and "UPDATE" are hard-coded in the extensions library.
return nil
}
if newObj.GetLabels()["app"] == "dependency-watchdog-prober" {
// We don't want to react for DWD pods but only for DWD deployments, so exit early here.
return nil
}
podMeta = &obj.ObjectMeta
podSpec = &obj.Spec
case *appsv1.Deployment:
podMeta = &obj.Spec.Template.ObjectMeta
podSpec = &obj.Spec.Template.Spec
case *appsv1.StatefulSet:
podMeta = &obj.Spec.Template.ObjectMeta
podSpec = &obj.Spec.Template.Spec
default:
return fmt.Errorf("unexpected object, got %T wanted *appsv1.Deployment, *appsv1.StatefulSet or *corev1.Pod", newObj)
}
service := &corev1.Service{}
if err := m.client.Get(ctx, client.ObjectKey{Namespace: "gardener-extension-provider-local-coredns", Name: "coredns"}, service); err != nil {
return err
}
metav1.SetMetaDataLabel(podMeta, local.LabelNetworkPolicyToIstioIngressGateway, v1beta1constants.LabelNetworkPolicyAllowed)
injectDNSConfig(podSpec, newObj.GetNamespace(), service.Spec.ClusterIPs)
return nil
}
// injectDNSConfig changes the `.spec.dnsPolicy` and `.spec.dnsConfig` in the provided `podSpec`. Basically, we
// configure the same options and search domains as the Kubernetes default behaviour. The only difference is that we use
// the gardener-extension-provider-local-coredns instead of the cluster's default DNS server. This is because this
// extension coredns can resolve the local domains (local.gardener.cloud). It otherwise forwards the traffic to the
// cluster's default DNS server.
func injectDNSConfig(podSpec *corev1.PodSpec, namespace string, coreDNSClusterIPs []string) {
podSpec.DNSPolicy = corev1.DNSNone
podSpec.DNSConfig = &corev1.PodDNSConfig{
Nameservers: coreDNSClusterIPs,
Searches: []string{
fmt.Sprintf("%s.svc.%s", namespace, v1beta1.DefaultDomain),
"svc." + v1beta1.DefaultDomain,
v1beta1.DefaultDomain,
},
Options: []corev1.PodDNSConfigOption{{
Name: "ndots",
Value: ptr.To("5"),
}},
}
}