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🌱 Support for kube-api-access volume mount #348
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233 changes: 233 additions & 0 deletions
233
virtualcluster/pkg/syncer/resources/pod/mutatorplugin/podkubeapiaccessmutator.go
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/* | ||
Copyright 2023 The Kubernetes Authors. | ||
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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 | ||
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http://www.apache.org/licenses/LICENSE-2.0 | ||
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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. | ||
*/ | ||
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package mutatorplugin | ||
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import ( | ||
"context" | ||
"fmt" | ||
"strings" | ||
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corev1 "k8s.io/api/core/v1" | ||
metav1 "k8s.io/apimachinery/pkg/apis/meta/v1" | ||
"k8s.io/apimachinery/pkg/util/sets" | ||
"k8s.io/apiserver/pkg/storage/names" | ||
"k8s.io/client-go/kubernetes" | ||
"k8s.io/klog/v2" | ||
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"sigs.k8s.io/cluster-api-provider-nested/virtualcluster/pkg/syncer/constants" | ||
"sigs.k8s.io/cluster-api-provider-nested/virtualcluster/pkg/syncer/conversion" | ||
"sigs.k8s.io/cluster-api-provider-nested/virtualcluster/pkg/syncer/util/featuregate" | ||
uplugin "sigs.k8s.io/cluster-api-provider-nested/virtualcluster/pkg/util/plugin" | ||
) | ||
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const ( | ||
// DefaultServiceAccountName is the name of the default service account to set on pods which do not specify a service account | ||
DefaultServiceAccountName = "default" // #nosec G101 | ||
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// ServiceAccountVolumeName is the prefix name that will be added to volumes that mount ServiceAccount secrets | ||
ServiceAccountVolumeName = "kube-api-access" // #nosec G101 | ||
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// DefaultAPITokenMountPath is the path that ServiceAccountToken secrets are automounted to. | ||
// The token file would then be accessible at /var/run/secrets/kubernetes.io/serviceaccount | ||
DefaultAPITokenMountPath = "/var/run/secrets/kubernetes.io/serviceaccount" // #nosec G101 | ||
) | ||
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func init() { | ||
MutatorRegister.Register(&uplugin.Registration{ | ||
ID: "00_PodKubeAPIAccessMutator", | ||
InitFn: func(ctx *uplugin.InitContext) (interface{}, error) { | ||
return NewPodKubeAPIAccessMutatorPlugin(ctx) | ||
}, | ||
}) | ||
} | ||
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type PodKubeAPIAccessMutatorPlugin struct { | ||
client kubernetes.Interface | ||
generateName func(string) string | ||
} | ||
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func NewPodKubeAPIAccessMutatorPlugin(ctx *uplugin.InitContext) (*PodKubeAPIAccessMutatorPlugin, error) { | ||
plugin := &PodKubeAPIAccessMutatorPlugin{ | ||
client: ctx.Client, | ||
generateName: names.SimpleNameGenerator.GenerateName, | ||
} | ||
return plugin, nil | ||
} | ||
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func (pl *PodKubeAPIAccessMutatorPlugin) Mutator() conversion.PodMutator { | ||
return func(p *conversion.PodMutateCtx) error { | ||
if !featuregate.DefaultFeatureGate.Enabled(featuregate.KubeAPIAccessSupport) { | ||
return nil | ||
} | ||
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// Don't modify the spec of mirror pods. | ||
// That makes the kubelet very angry and confused, and it immediately deletes the pod (because the spec doesn't match) | ||
// That said, don't allow mirror pods to reference ServiceAccounts or SecretVolumeSources either | ||
if _, isMirrorPod := p.PPod.Annotations[corev1.MirrorPodAnnotationKey]; isMirrorPod { | ||
return nil | ||
} | ||
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// Set the default service account if needed | ||
if len(p.PPod.Spec.ServiceAccountName) == 0 { | ||
p.PPod.Spec.ServiceAccountName = DefaultServiceAccountName | ||
} | ||
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targetNamespace := conversion.ToSuperClusterNamespace(p.ClusterName, p.PPod.Namespace) | ||
serviceAccount, err := pl.client.CoreV1().ServiceAccounts(targetNamespace).Get(context.TODO(), p.PPod.Spec.ServiceAccountName, metav1.GetOptions{}) | ||
if err != nil { | ||
return fmt.Errorf("error looking up serviceAccount %s/%s: %v", targetNamespace, p.PPod.Spec.ServiceAccountName, err) | ||
} | ||
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secret, err := pl.getSecret(p.ClusterName, targetNamespace, serviceAccount) | ||
if err != nil || secret == nil { | ||
klog.Errorf("not found serviceAccount %s/%s token secret, err: %v", targetNamespace, p.PPod.Spec.ServiceAccountName, err) | ||
return fmt.Errorf("error looking up secret of serviceAccount %s/%s: %v", targetNamespace, p.PPod.Spec.ServiceAccountName, err) | ||
} | ||
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if shouldAutomount(serviceAccount, p.PPod) { | ||
pl.mountServiceAccountToken(secret, p.PPod) | ||
} | ||
return nil | ||
} | ||
} | ||
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func (pl *PodKubeAPIAccessMutatorPlugin) getSecret(cluster, namespace string, sa *corev1.ServiceAccount) (*corev1.Secret, error) { | ||
secrets, err := pl.client.CoreV1().Secrets(namespace).List(context.Background(), metav1.ListOptions{}) | ||
if err != nil { | ||
klog.Errorf("error listing secret from super control plane informer cache: %v", err) | ||
return nil, err | ||
} | ||
for _, secret := range secrets.Items { | ||
if secret.Type != corev1.SecretTypeOpaque { | ||
continue | ||
} | ||
annotations := secret.GetAnnotations() | ||
if annotations[constants.LabelCluster] != cluster || annotations[corev1.ServiceAccountNameKey] != sa.Name { | ||
continue | ||
} | ||
return &secret, nil | ||
} | ||
return nil, nil | ||
} | ||
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func (pl *PodKubeAPIAccessMutatorPlugin) mountServiceAccountToken(secret *corev1.Secret, pod *corev1.Pod) { | ||
// Determine a volume name for the ServiceAccountTokenSecret in case we need it | ||
tokenVolumeName := pl.generateName(ServiceAccountVolumeName + "-") | ||
klog.V(4).Infof("generate a new VolumeMount.name: %s", tokenVolumeName) | ||
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// Create the prototypical VolumeMount | ||
tokenVolumeMount := corev1.VolumeMount{ | ||
Name: tokenVolumeName, | ||
ReadOnly: true, | ||
MountPath: DefaultAPITokenMountPath, | ||
} | ||
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// Find the volume and volume name for the ServiceAccountTokenSecret if it already exists | ||
serviceAccountVolumeExist := false | ||
allVolumeNames := sets.NewString() | ||
for i, volume := range pod.Spec.Volumes { | ||
allVolumeNames.Insert(volume.Name) | ||
if strings.HasPrefix(volume.Name, ServiceAccountVolumeName+"-") { | ||
for _, source := range volume.Projected.Sources { | ||
if source.ServiceAccountToken != nil { | ||
klog.V(4).Infof("pod: %s/%s volume: %s mount service account token, mutate it!", pod.Namespace, pod.Name, volume.Name) | ||
pod.Spec.Volumes[i] = corev1.Volume{ | ||
Name: tokenVolumeName, | ||
VolumeSource: corev1.VolumeSource{ | ||
Projected: TokenVolumeSource(secret), | ||
}, | ||
} | ||
pl.MutateAutoKubeAPIAccessVolumeMounts(volume.Name, tokenVolumeName, pod) | ||
serviceAccountVolumeExist = true | ||
break | ||
} | ||
} | ||
break | ||
} | ||
} | ||
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// Ensure every container mounts the APISecret volume | ||
for i, container := range pod.Spec.InitContainers { | ||
existingContainerMount := false | ||
for _, volumeMount := range container.VolumeMounts { | ||
// Existing mounts at the default mount path prevent mounting of the API token | ||
if volumeMount.MountPath == DefaultAPITokenMountPath { | ||
existingContainerMount = true | ||
break | ||
} | ||
} | ||
if serviceAccountVolumeExist && !existingContainerMount { | ||
pod.Spec.InitContainers[i].VolumeMounts = append(pod.Spec.InitContainers[i].VolumeMounts, tokenVolumeMount) | ||
} | ||
} | ||
for i, container := range pod.Spec.Containers { | ||
existingContainerMount := false | ||
for _, volumeMount := range container.VolumeMounts { | ||
// Existing mounts at the default mount path prevent mounting of the API token | ||
if volumeMount.MountPath == DefaultAPITokenMountPath { | ||
existingContainerMount = true | ||
break | ||
} | ||
} | ||
if serviceAccountVolumeExist && !existingContainerMount { | ||
pod.Spec.Containers[i].VolumeMounts = append(pod.Spec.Containers[i].VolumeMounts, tokenVolumeMount) | ||
} | ||
} | ||
} | ||
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func (pl *PodKubeAPIAccessMutatorPlugin) MutateAutoKubeAPIAccessVolumeMounts(old, new string, pod *corev1.Pod) { | ||
for i, container := range pod.Spec.InitContainers { | ||
for j := 0; j < len(container.VolumeMounts); j++ { | ||
if container.VolumeMounts[j].Name == old { | ||
klog.V(4).Infof("mutate initContainer %s volumeMount.name from %s to %s", container.Name, old, new) | ||
pod.Spec.InitContainers[i].VolumeMounts[j].Name = new | ||
continue | ||
} | ||
} | ||
} | ||
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for i, container := range pod.Spec.Containers { | ||
for j := 0; j < len(container.VolumeMounts); j++ { | ||
if container.VolumeMounts[j].Name == old { | ||
klog.V(4).Infof("mutate containers %s volumeMount.name from %s to %s", container.Name, old, new) | ||
pod.Spec.Containers[i].VolumeMounts[j].Name = new | ||
continue | ||
} | ||
} | ||
} | ||
} | ||
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func shouldAutomount(sa *corev1.ServiceAccount, pod *corev1.Pod) bool { | ||
// Fixme: Now we will always return true. | ||
// Perhaps in the future, some distinction between pods needs to be made here. | ||
return true | ||
} | ||
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// TokenVolumeSource returns the projected volume source for service account token. | ||
func TokenVolumeSource(secret *corev1.Secret) *corev1.ProjectedVolumeSource { | ||
return &corev1.ProjectedVolumeSource{ | ||
Sources: []corev1.VolumeProjection{ | ||
{ | ||
Secret: &corev1.SecretProjection{ | ||
LocalObjectReference: corev1.LocalObjectReference{ | ||
Name: secret.Name, | ||
}, | ||
}, | ||
}, | ||
}, | ||
} | ||
} |
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Can we use
automountServiceAccountToken
on the pod spec?There was a problem hiding this comment.
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We explicitly override this from vc-syncer so the value in the pPod should always be false, seems like if we have the vPod object we could get that value.