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admission.go
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admission.go
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/*
Copyright 2017 The Kubernetes Authors.
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 admission
import (
"fmt"
"io"
"reflect"
"github.com/golang/glog"
"k8s.io/apimachinery/pkg/api/errors"
metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
"k8s.io/apimachinery/pkg/labels"
"k8s.io/apiserver/pkg/admission"
"k8s.io/kubernetes/pkg/api"
"k8s.io/kubernetes/pkg/apis/settings"
"k8s.io/kubernetes/pkg/client/clientset_generated/internalclientset"
informers "k8s.io/kubernetes/pkg/client/informers/informers_generated/internalversion"
settingslisters "k8s.io/kubernetes/pkg/client/listers/settings/internalversion"
kubeapiserveradmission "k8s.io/kubernetes/pkg/kubeapiserver/admission"
)
const (
annotationPrefix = "podpreset.admission.kubernetes.io"
pluginName = "PodPreset"
)
func init() {
admission.RegisterPlugin(pluginName, func(config io.Reader) (admission.Interface, error) {
return NewPlugin(), nil
})
}
// podPresetPlugin is an implementation of admission.Interface.
type podPresetPlugin struct {
*admission.Handler
client internalclientset.Interface
lister settingslisters.PodPresetLister
}
var _ = kubeapiserveradmission.WantsInternalKubeInformerFactory(&podPresetPlugin{})
var _ = kubeapiserveradmission.WantsInternalKubeClientSet(&podPresetPlugin{})
// NewPlugin creates a new pod preset admission plugin.
func NewPlugin() *podPresetPlugin {
return &podPresetPlugin{
Handler: admission.NewHandler(admission.Create, admission.Update),
}
}
func (plugin *podPresetPlugin) Validate() error {
if plugin.client == nil {
return fmt.Errorf("%s requires a client", pluginName)
}
if plugin.lister == nil {
return fmt.Errorf("%s requires a lister", pluginName)
}
return nil
}
func (a *podPresetPlugin) SetInternalKubeClientSet(client internalclientset.Interface) {
a.client = client
}
func (a *podPresetPlugin) SetInternalKubeInformerFactory(f informers.SharedInformerFactory) {
podPresetInformer := f.Settings().InternalVersion().PodPresets()
a.lister = podPresetInformer.Lister()
a.SetReadyFunc(podPresetInformer.Informer().HasSynced)
}
// Admit injects a pod with the specific fields for each pod preset it matches.
func (c *podPresetPlugin) Admit(a admission.Attributes) error {
// Ignore all calls to subresources or resources other than pods.
// Ignore all operations other than CREATE.
if len(a.GetSubresource()) != 0 || a.GetResource().GroupResource() != api.Resource("pods") || a.GetOperation() != admission.Create {
return nil
}
pod, ok := a.GetObject().(*api.Pod)
if !ok {
return errors.NewBadRequest("Resource was marked with kind Pod but was unable to be converted")
}
list, err := c.lister.PodPresets(pod.GetNamespace()).List(labels.Everything())
if err != nil {
return fmt.Errorf("listing pod presets failed: %v", err)
}
// get the pod presets and iterate over them
for _, pip := range list {
selector, err := metav1.LabelSelectorAsSelector(&pip.Spec.Selector)
if err != nil {
return fmt.Errorf("listing pod presets for namespace:%s failed: %v", pod.GetNamespace(), err)
}
// check if the pod labels match the selector
if !selector.Matches(labels.Set(pod.Labels)) {
continue
}
glog.V(4).Infof("PodPreset %s matches pod %s labels", pip.GetName(), pod.GetName())
// merge in policy for Env
if pip.Spec.Env != nil {
for i, ctr := range pod.Spec.Containers {
r, err := mergeEnv(pip, ctr.Env)
if err != nil {
// add event to pod
c.addEvent(pod, pip, err.Error())
return nil
}
pod.Spec.Containers[i].Env = r
}
}
// merge in policy for EnvFrom
if pip.Spec.EnvFrom != nil {
for i, ctr := range pod.Spec.Containers {
r, err := mergeEnvFrom(pip, ctr.EnvFrom)
if err != nil {
// add event to pod
c.addEvent(pod, pip, err.Error())
return nil
}
pod.Spec.Containers[i].EnvFrom = r
}
}
// merge in policy for VolumeMounts
if pip.Spec.VolumeMounts != nil {
for i, ctr := range pod.Spec.Containers {
r, err := mergeVolumeMounts(pip, ctr.VolumeMounts)
if err != nil {
// add event to pod
c.addEvent(pod, pip, err.Error())
return nil
}
pod.Spec.Containers[i].VolumeMounts = r
}
}
// merge in policy for Volumes
if pip.Spec.Volumes != nil {
r, err := mergeVolumes(pip, pod.Spec.Volumes)
if err != nil {
// add event to pod
c.addEvent(pod, pip, err.Error())
return nil
}
pod.Spec.Volumes = r
}
glog.V(4).Infof("PodPreset %s merged with pod %s successfully", pip.GetName(), pod.GetName())
// add annotation
if pod.ObjectMeta.Annotations == nil {
pod.ObjectMeta.Annotations = map[string]string{}
}
pod.ObjectMeta.Annotations[fmt.Sprintf("%s/%s", annotationPrefix, pip.GetName())] = pip.GetResourceVersion()
}
return nil
}
func mergeEnv(pip *settings.PodPreset, original []api.EnvVar) ([]api.EnvVar, error) {
// if there were no original envvar just return the pip envvar
if original == nil {
return pip.Spec.Env, nil
}
orig := map[string]interface{}{}
for _, v := range original {
orig[v.Name] = v
}
// check for conflicts.
for _, v := range pip.Spec.Env {
found, ok := orig[v.Name]
if !ok {
// if we don't already have it append it and continue
original = append(original, v)
continue
}
// make sure they are identical or throw an error
if !reflect.DeepEqual(found, v) {
return nil, fmt.Errorf("merging env for %s has a conflict on %s: \n%#v\ndoes not match\n%#v\n in container", pip.GetName(), v.Name, v, found)
}
}
return original, nil
}
func mergeEnvFrom(pip *settings.PodPreset, original []api.EnvFromSource) ([]api.EnvFromSource, error) {
// if there were no original envfrom just return the pip envfrom
if original == nil {
return pip.Spec.EnvFrom, nil
}
return append(original, pip.Spec.EnvFrom...), nil
}
func mergeVolumeMounts(pip *settings.PodPreset, original []api.VolumeMount) ([]api.VolumeMount, error) {
// if there were no original volume mount just return the pip volume mount
if original == nil {
return pip.Spec.VolumeMounts, nil
}
// first key by name
orig := map[string]interface{}{}
for _, v := range original {
orig[v.Name] = v
}
// check for conflicts.
for _, v := range pip.Spec.VolumeMounts {
found, ok := orig[v.Name]
if !ok {
// if we don't already have it continue
continue
}
// make sure they are identical or throw an error
if !reflect.DeepEqual(found, v) {
return nil, fmt.Errorf("merging volume mounts for %s has a conflict on %s: \n%#v\ndoes not match\n%#v\n in container", pip.GetName(), v.Name, v, found)
}
}
// key by mount path
orig = map[string]interface{}{}
for _, v := range original {
orig[v.MountPath] = v
}
// check for conflicts.
for _, v := range pip.Spec.VolumeMounts {
found, ok := orig[v.MountPath]
if !ok {
// if we don't already have it append it and continue
original = append(original, v)
continue
}
// make sure they are identical or throw an error
if !reflect.DeepEqual(found, v) {
return nil, fmt.Errorf("merging volume mounts for %s has a conflict on mount path %s: \n%#v\ndoes not match\n%#v\n in container", pip.GetName(), v.MountPath, v, found)
}
}
return original, nil
}
func mergeVolumes(pip *settings.PodPreset, original []api.Volume) ([]api.Volume, error) {
// if there were no original volumes just return the pip volumes
if original == nil {
return pip.Spec.Volumes, nil
}
orig := map[string]api.Volume{}
for _, v := range original {
orig[v.Name] = v
}
// check for conflicts.
for _, v := range pip.Spec.Volumes {
found, ok := orig[v.Name]
if !ok {
// if we don't already have it append it and continue
original = append(original, v)
continue
}
if !reflect.DeepEqual(found, v) {
return nil, fmt.Errorf("merging volumes for %s has a conflict on %s: \n%#v\ndoes not match\n%#v\nin pod spec", pip.GetName(), v.Name, v, found)
}
}
return original, nil
}
func (c *podPresetPlugin) addEvent(pod *api.Pod, pip *settings.PodPreset, message string) {
ref, err := api.GetReference(api.Scheme, pod)
if err != nil {
glog.Errorf("pip %s: get reference for pod %s failed: %v", pip.GetName(), pod.GetName(), err)
return
}
e := &api.Event{
InvolvedObject: *ref,
Message: message,
Source: api.EventSource{
Component: fmt.Sprintf("pip %s", pip.GetName()),
},
Type: "Warning",
}
if _, err := c.client.Core().Events(pod.GetNamespace()).Create(e); err != nil {
glog.Errorf("pip %s: creating pod event failed: %v", pip.GetName(), err)
return
}
}