use istio client-go library instead of knative (#1661)

use istio client-go library instead of knative
bump kubernetes dependency version
change code coverage to codecov

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

@@ -0,0 +1,108 @@
+/*
+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"
+	"net/http"
+
+	"k8s.io/api/admission/v1beta1"
+	"k8s.io/apimachinery/pkg/runtime"
+)
+
+// Validator defines functions for validating an operation
+type Validator interface {
+	runtime.Object
+	ValidateCreate() error
+	ValidateUpdate(old runtime.Object) error
+	ValidateDelete() error
+}
+
+// ValidatingWebhookFor creates a new Webhook for validating the provided type.
+func ValidatingWebhookFor(validator Validator) *Webhook {
+	return &Webhook{
+		Handler: &validatingHandler{validator: validator},
+	}
+}
+
+type validatingHandler struct {
+	validator Validator
+	decoder   *Decoder
+}
+
+var _ DecoderInjector = &validatingHandler{}
+
+// InjectDecoder injects the decoder into a validatingHandler.
+func (h *validatingHandler) InjectDecoder(d *Decoder) error {
+	h.decoder = d
+	return nil
+}
+
+// Handle handles admission requests.
+func (h *validatingHandler) Handle(ctx context.Context, req Request) Response {
+	if h.validator == nil {
+		panic("validator should never be nil")
+	}
+
+	// Get the object in the request
+	obj := h.validator.DeepCopyObject().(Validator)
+	if req.Operation == v1beta1.Create {
+		err := h.decoder.Decode(req, obj)
+		if err != nil {
+			return Errored(http.StatusBadRequest, err)
+		}
+
+		err = obj.ValidateCreate()
+		if err != nil {
+			return Denied(err.Error())
+		}
+	}
+
+	if req.Operation == v1beta1.Update {
+		oldObj := obj.DeepCopyObject()
+
+		err := h.decoder.DecodeRaw(req.Object, obj)
+		if err != nil {
+			return Errored(http.StatusBadRequest, err)
+		}
+		err = h.decoder.DecodeRaw(req.OldObject, oldObj)
+		if err != nil {
+			return Errored(http.StatusBadRequest, err)
+		}
+
+		err = obj.ValidateUpdate(oldObj)
+		if err != nil {
+			return Denied(err.Error())
+		}
+	}
+
+	if req.Operation == v1beta1.Delete {
+		// In reference to PR: https://github.com/kubernetes/kubernetes/pull/76346
+		// OldObject contains the object being deleted
+		err := h.decoder.DecodeRaw(req.OldObject, obj)
+		if err != nil {
+			return Errored(http.StatusBadRequest, err)
+		}
+
+		err = obj.ValidateDelete()
+		if err != nil {
+			return Denied(err.Error())
+		}
+	}
+
+	return Allowed("")
+}