/
handler.go
165 lines (144 loc) · 4.72 KB
/
handler.go
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package function
import (
"encoding/json"
"fmt"
log "github.com/sirupsen/logrus"
"io/ioutil"
"k8s.io/api/admission/v1beta1"
corev1 "k8s.io/api/core/v1"
metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
"net/http"
"strings"
)
const (
nameLabel = "app.kubernetes.io/name"
instanceLabel = "app.kubernetes.io/instance"
versionLabel = "app.kubernetes.io/version"
componentLabel = "app.kubernetes.io/component"
partOfLabel = "app.kubernetes.io/part-of"
managedByLabel = "app.kubernetes.io/managed-by"
admissionWebhookAnnotationValidateKey = "admission-webhook-example.qikqiak.com/validate"
)
var (
ignoredNamespaces = []string{
metav1.NamespaceSystem,
metav1.NamespacePublic,
}
requiredLabels = []string{
nameLabel,
instanceLabel,
versionLabel,
componentLabel,
partOfLabel,
managedByLabel,
}
)
func admissionRequired(ignoredList []string, admissionAnnotationKey string, metadata *metav1.ObjectMeta) bool {
// skip special kubernetes system namespaces
for _, namespace := range ignoredList {
if metadata.Namespace == namespace {
log.Infof("Skip validation for %v for it's in special namespace:%v", metadata.Name, metadata.Namespace)
return false
}
}
annotations := metadata.GetAnnotations()
if annotations == nil {
annotations = map[string]string{}
}
var required bool
switch strings.ToLower(annotations[admissionAnnotationKey]) {
default:
required = true
case "n", "no", "false", "off":
required = false
}
return required
}
func validationRequired(ignoredList []string, metadata *metav1.ObjectMeta) bool {
required := admissionRequired(ignoredList, admissionWebhookAnnotationValidateKey, metadata)
log.Infof("Validation policy for %v/%v: required:%v", metadata.Namespace, metadata.Name, required)
return required
}
func Handle(w http.ResponseWriter, r *http.Request) {
var (
response *v1beta1.AdmissionResponse
availableLabels map[string]string
objectMeta *metav1.ObjectMeta
resourceNamespace, resourceName string
)
var input []byte
if r.Body != nil {
defer r.Body.Close()
body, _ := ioutil.ReadAll(r.Body)
input = body
}
var req v1beta1.AdmissionRequest
if err := json.Unmarshal(input, &req); err != nil {
response = &v1beta1.AdmissionResponse{
Allowed: false,
Result: &metav1.Status{
Message: err.Error(),
},
}
w.WriteHeader(http.StatusInternalServerError)
responseasBytes, _ := json.Marshal(response)
if _, err := w.Write(responseasBytes); err != nil {
log.Errorf("Can't write response: %v", err)
http.Error(w, fmt.Sprintf("could not write response: %v", err), http.StatusInternalServerError)
}
return
}
log.Infof("AdmissionReview for Kind=%v, Namespace=%v Name=%v (%v) UID=%v patchOperation=%v UserInfo=%v",
req.Kind, req.Namespace, req.Name, resourceName, req.UID, req.Operation, req.UserInfo)
switch req.Kind.Kind {
case "Pod":
var pod corev1.Pod
if err := json.Unmarshal(req.Object.Raw, &pod); err != nil {
log.Errorf("Could not unmarshal raw object: %v", err)
w.WriteHeader(http.StatusInternalServerError)
responseasBytes, _ := json.Marshal(response)
if _, err := w.Write(responseasBytes); err != nil {
log.Errorf("Can't write response: %v", err)
http.Error(w, fmt.Sprintf("could not write response: %v", err), http.StatusInternalServerError)
}
return
}
resourceName, resourceNamespace, objectMeta = pod.Name, pod.Namespace, &pod.ObjectMeta
availableLabels = pod.Labels
}
if !validationRequired(ignoredNamespaces, objectMeta) {
log.Infof("Skipping validation for %s/%s due to policy check", resourceNamespace, resourceName)
response = &v1beta1.AdmissionResponse{
Allowed: true,
}
w.WriteHeader(http.StatusOK)
responseasBytes, _ := json.Marshal(response)
if _, err := w.Write(responseasBytes); err != nil {
log.Errorf("Can't write response: %v", err)
http.Error(w, fmt.Sprintf("could not write response: %v", err), http.StatusInternalServerError)
}
return
}
allowed := true
var result *metav1.Status
log.Info("available labels:", availableLabels)
log.Info("required labels", requiredLabels)
for _, rl := range requiredLabels {
if _, ok := availableLabels[rl]; !ok {
allowed = false
result = &metav1.Status{
Reason: "required labels are not set",
}
break
}
}
response = &v1beta1.AdmissionResponse{
Allowed: allowed,
Result: result,
}
responseasBytes, _ := json.Marshal(response)
if _, err := w.Write(responseasBytes); err != nil {
log.Errorf("Can't write response: %v", err)
http.Error(w, fmt.Sprintf("could not write response: %v", err), http.StatusInternalServerError)
}
}