Initial commit

vendor/sigs.k8s.io/controller-runtime/pkg/webhook/admission/webhook.go

@@ -0,0 +1,259 @@
+/*
+Copyright 2018 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 (
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"net/http"
+	"regexp"
+	"strings"
+	"sync"
+
+	"github.com/mattbaird/jsonpatch"
+
+	admissionv1beta1 "k8s.io/api/admission/v1beta1"
+	admissionregistrationv1beta1 "k8s.io/api/admissionregistration/v1beta1"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"sigs.k8s.io/controller-runtime/pkg/client"
+	"sigs.k8s.io/controller-runtime/pkg/runtime/inject"
+	atypes "sigs.k8s.io/controller-runtime/pkg/webhook/admission/types"
+	"sigs.k8s.io/controller-runtime/pkg/webhook/types"
+)
+
+// Handler can handle an AdmissionRequest.
+type Handler interface {
+	Handle(context.Context, atypes.Request) atypes.Response
+}
+
+// HandlerFunc implements Handler interface using a single function.
+type HandlerFunc func(context.Context, atypes.Request) atypes.Response
+
+var _ Handler = HandlerFunc(nil)
+
+// Handle process the AdmissionRequest by invoking the underlying function.
+func (f HandlerFunc) Handle(ctx context.Context, req atypes.Request) atypes.Response {
+	return f(ctx, req)
+}
+
+// Webhook represents each individual webhook.
+type Webhook struct {
+	// Name is the name of the webhook
+	Name string
+	// Type is the webhook type, i.e. mutating, validating
+	Type types.WebhookType
+	// Path is the path this webhook will serve.
+	Path string
+	// Rules maps to the Rules field in admissionregistrationv1beta1.Webhook
+	Rules []admissionregistrationv1beta1.RuleWithOperations
+	// FailurePolicy maps to the FailurePolicy field in admissionregistrationv1beta1.Webhook
+	// This optional. If not set, will be defaulted to Ignore (fail-open) by the server.
+	// More details: https://github.com/kubernetes/api/blob/f5c295feaba2cbc946f0bbb8b535fc5f6a0345ee/admissionregistration/v1beta1/types.go#L144-L147
+	FailurePolicy *admissionregistrationv1beta1.FailurePolicyType
+	// NamespaceSelector maps to the NamespaceSelector field in admissionregistrationv1beta1.Webhook
+	// This optional.
+	NamespaceSelector *metav1.LabelSelector
+	// Handlers contains a list of handlers. Each handler may only contains the business logic for its own feature.
+	// For example, feature foo and bar can be in the same webhook if all the other configurations are the same.
+	// The handler will be invoked sequentially as the order in the list.
+	// Note: if you are using mutating webhook with multiple handlers, it's your responsibility to
+	// ensure the handlers are not generating conflicting JSON patches.
+	Handlers []Handler
+
+	once sync.Once
+}
+
+func (w *Webhook) setDefaults() {
+	if len(w.Path) == 0 {
+		if len(w.Rules) == 0 || len(w.Rules[0].Resources) == 0 {
+			// can't do defaulting, skip it.
+			return
+		}
+		if w.Type == types.WebhookTypeMutating {
+			w.Path = "/mutate-" + w.Rules[0].Resources[0]
+		} else if w.Type == types.WebhookTypeValidating {
+			w.Path = "/validate-" + w.Rules[0].Resources[0]
+		}
+	}
+	if len(w.Name) == 0 {
+		reg := regexp.MustCompile("[^a-zA-Z0-9]+")
+		processedPath := strings.ToLower(reg.ReplaceAllString(w.Path, ""))
+		w.Name = processedPath + ".example.com"
+	}
+}
+
+// Add adds additional handler(s) in the webhook
+func (w *Webhook) Add(handlers ...Handler) {
+	w.Handlers = append(w.Handlers, handlers...)
+}
+
+// Webhook implements Handler interface.
+var _ Handler = &Webhook{}
+
+// Handle processes AdmissionRequest.
+// If the webhook is mutating type, it delegates the AdmissionRequest to each handler and merge the patches.
+// If the webhook is validating type, it delegates the AdmissionRequest to each handler and
+// deny the request if anyone denies.
+func (w *Webhook) Handle(ctx context.Context, req atypes.Request) atypes.Response {
+	if req.AdmissionRequest == nil {
+		return ErrorResponse(http.StatusBadRequest, errors.New("got an empty AdmissionRequest"))
+	}
+	var resp atypes.Response
+	switch w.Type {
+	case types.WebhookTypeMutating:
+		resp = w.handleMutating(ctx, req)
+	case types.WebhookTypeValidating:
+		resp = w.handleValidating(ctx, req)
+	default:
+		return ErrorResponse(http.StatusInternalServerError, errors.New("you must specify your webhook type"))
+	}
+	resp.Response.UID = req.AdmissionRequest.UID
+	return resp
+}
+
+func (w *Webhook) handleMutating(ctx context.Context, req atypes.Request) atypes.Response {
+	patches := []jsonpatch.JsonPatchOperation{}
+	for _, handler := range w.Handlers {
+		resp := handler.Handle(ctx, req)
+		if !resp.Response.Allowed {
+			setStatusOKInAdmissionResponse(resp.Response)
+			return resp
+		}
+		if resp.Response.PatchType != nil && *resp.Response.PatchType != admissionv1beta1.PatchTypeJSONPatch {
+			return ErrorResponse(http.StatusInternalServerError,
+				fmt.Errorf("unexpected patch type returned by the handler: %v, only allow: %v",
+					resp.Response.PatchType, admissionv1beta1.PatchTypeJSONPatch))
+		}
+		patches = append(patches, resp.Patches...)
+	}
+	var err error
+	marshaledPatch, err := json.Marshal(patches)
+	if err != nil {
+		return ErrorResponse(http.StatusBadRequest, fmt.Errorf("error when marshaling the patch: %v", err))
+	}
+	return atypes.Response{
+		Response: &admissionv1beta1.AdmissionResponse{
+			Allowed: true,
+			Result: &metav1.Status{
+				Code: http.StatusOK,
+			},
+			Patch:     marshaledPatch,
+			PatchType: func() *admissionv1beta1.PatchType { pt := admissionv1beta1.PatchTypeJSONPatch; return &pt }(),
+		},
+	}
+}
+
+func (w *Webhook) handleValidating(ctx context.Context, req atypes.Request) atypes.Response {
+	for _, handler := range w.Handlers {
+		resp := handler.Handle(ctx, req)
+		if !resp.Response.Allowed {
+			setStatusOKInAdmissionResponse(resp.Response)
+			return resp
+		}
+	}
+	return atypes.Response{
+		Response: &admissionv1beta1.AdmissionResponse{
+			Allowed: true,
+			Result: &metav1.Status{
+				Code: http.StatusOK,
+			},
+		},
+	}
+}
+
+func setStatusOKInAdmissionResponse(resp *admissionv1beta1.AdmissionResponse) {
+	if resp == nil {
+		return
+	}
+	if resp.Result == nil {
+		resp.Result = &metav1.Status{}
+	}
+	if resp.Result.Code == 0 {
+		resp.Result.Code = http.StatusOK
+	}
+}
+
+// GetName returns the name of the webhook.
+func (w *Webhook) GetName() string {
+	w.once.Do(w.setDefaults)
+	return w.Name
+}
+
+// GetPath returns the path that the webhook registered.
+func (w *Webhook) GetPath() string {
+	w.once.Do(w.setDefaults)
+	return w.Path
+}
+
+// GetType returns the type of the webhook.
+func (w *Webhook) GetType() types.WebhookType {
+	w.once.Do(w.setDefaults)
+	return w.Type
+}
+
+// Handler returns a http.Handler for the webhook
+func (w *Webhook) Handler() http.Handler {
+	w.once.Do(w.setDefaults)
+	return w
+}
+
+// Validate validates if the webhook is valid.
+func (w *Webhook) Validate() error {
+	w.once.Do(w.setDefaults)
+	if len(w.Rules) == 0 {
+		return errors.New("field Rules should not be empty")
+	}
+	if len(w.Name) == 0 {
+		return errors.New("field Name should not be empty")
+	}
+	if w.Type != types.WebhookTypeMutating && w.Type != types.WebhookTypeValidating {
+		return fmt.Errorf("unsupported Type: %v, only WebhookTypeMutating and WebhookTypeValidating are supported", w.Type)
+	}
+	if len(w.Path) == 0 {
+		return errors.New("field Path should not be empty")
+	}
+	if len(w.Handlers) == 0 {
+		return errors.New("field Handler should not be empty")
+	}
+	return nil
+}
+
+var _ inject.Client = &Webhook{}
+
+// InjectClient injects the client into the handlers
+func (w *Webhook) InjectClient(c client.Client) error {
+	for _, handler := range w.Handlers {
+		if _, err := inject.ClientInto(c, handler); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+var _ inject.Decoder = &Webhook{}
+
+// InjectDecoder injects the decoder into the handlers
+func (w *Webhook) InjectDecoder(d atypes.Decoder) error {
+	for _, handler := range w.Handlers {
+		if _, err := inject.DecoderInto(d, handler); err != nil {
+			return err
+		}
+	}
+	return nil
+}