agones.dev/agones@v1.54.0/pkg/util/webhooks/webhooks.go (about)

     1  // Copyright 2018 Google LLC All Rights Reserved.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  // Package webhooks manages and receives Kubernetes Webhooks
    16  package webhooks
    17  
    18  import (
    19  	"encoding/json"
    20  	"net/http"
    21  
    22  	"agones.dev/agones/pkg/util/runtime"
    23  	"github.com/pkg/errors"
    24  	"github.com/sirupsen/logrus"
    25  	admissionv1 "k8s.io/api/admission/v1"
    26  	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
    27  	"k8s.io/apimachinery/pkg/runtime/schema"
    28  )
    29  
    30  // WebHook manage Kubernetes webhooks
    31  type WebHook struct {
    32  	logger   *logrus.Entry
    33  	mux      *http.ServeMux
    34  	handlers map[string][]operationHandler
    35  }
    36  
    37  // operationHandler stores the data for a handler to match against
    38  type operationHandler struct {
    39  	handler   Handler
    40  	groupKind schema.GroupKind
    41  	operation admissionv1.Operation
    42  }
    43  
    44  // Handler handles a webhook's AdmissionReview coming in, and will return the
    45  // AdmissionReview that will be the return value of the webhook
    46  type Handler func(review admissionv1.AdmissionReview) (admissionv1.AdmissionReview, error)
    47  
    48  // NewWebHook returns a Kubernetes webhook manager
    49  func NewWebHook(mux *http.ServeMux) *WebHook {
    50  	wh := &WebHook{
    51  		mux:      mux,
    52  		handlers: map[string][]operationHandler{},
    53  	}
    54  
    55  	wh.logger = runtime.NewLoggerWithType(wh)
    56  	return wh
    57  }
    58  
    59  // AddHandler adds a handler for a given path, group and kind, and operation
    60  func (wh *WebHook) AddHandler(path string, gk schema.GroupKind, op admissionv1.Operation, h Handler) {
    61  	if len(wh.handlers[path]) == 0 {
    62  		wh.mux.HandleFunc(path, func(w http.ResponseWriter, r *http.Request) {
    63  			err := wh.handle(path, w, r)
    64  			if err != nil {
    65  				runtime.HandleError(wh.logger.WithField("url", r.URL), err)
    66  				w.WriteHeader(http.StatusInternalServerError)
    67  			}
    68  		})
    69  	}
    70  	wh.logger.WithField("path", path).WithField("groupKind", gk).WithField("op", op).Debug("Added webhook handler")
    71  	wh.handlers[path] = append(wh.handlers[path], operationHandler{groupKind: gk, operation: op, handler: h})
    72  }
    73  
    74  // handle Handles http requests for webhooks
    75  func (wh *WebHook) handle(path string, w http.ResponseWriter, r *http.Request) error { // nolint: interfacer
    76  	wh.logger.WithField("path", path).Debug("running webhook")
    77  
    78  	var review admissionv1.AdmissionReview
    79  	err := json.NewDecoder(r.Body).Decode(&review)
    80  	if err != nil {
    81  		return errors.Wrapf(err, "error decoding decoding json for path %v", path)
    82  	}
    83  
    84  	// set it to true, in case there are no handlers
    85  	if review.Response == nil {
    86  		review.Response = &admissionv1.AdmissionResponse{Allowed: true}
    87  	}
    88  	review.Response.UID = review.Request.UID
    89  	wh.logger.WithField("name", review.Request.Name).WithField("path", path).WithField("kind", review.Request.Kind.Kind).WithField("group", review.Request.Kind.Group).Debug("handling webhook request")
    90  
    91  	for _, oh := range wh.handlers[path] {
    92  		if oh.operation == review.Request.Operation &&
    93  			oh.groupKind.Kind == review.Request.Kind.Kind &&
    94  			review.Request.Kind.Group == oh.groupKind.Group {
    95  
    96  			review, err = oh.handler(review)
    97  			if err != nil {
    98  				review.Response.Allowed = false
    99  				details := metav1.StatusDetails{
   100  					Name:  review.Request.Name,
   101  					Group: review.Request.Kind.Group,
   102  					Kind:  review.Request.Kind.Kind,
   103  					Causes: []metav1.StatusCause{{
   104  						Type:    metav1.CauseType("InternalError"),
   105  						Message: err.Error(),
   106  					}},
   107  				}
   108  				review.Response.Result = &metav1.Status{
   109  					Status:  metav1.StatusFailure,
   110  					Message: err.Error(),
   111  					Reason:  metav1.StatusReasonInternalError,
   112  					Details: &details,
   113  				}
   114  			}
   115  		}
   116  	}
   117  	err = json.NewEncoder(w).Encode(review)
   118  	if err != nil {
   119  		return errors.Wrapf(err, "error decoding encoding json for path %v", path)
   120  	}
   121  
   122  	return nil
   123  }