Update to kube v1.17

Signed-off-by: Humble Chirammal <hchiramm@redhat.com>

vendor/k8s.io/apiserver/pkg/util/webhook/webhook.go

@@ -0,0 +1,148 @@
+/*
+Copyright 2016 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 webhook implements a generic HTTP webhook plugin.
+package webhook
+
+import (
+	"context"
+	"fmt"
+	"time"
+
+	apierrors "k8s.io/apimachinery/pkg/api/errors"
+	"k8s.io/apimachinery/pkg/runtime"
+	"k8s.io/apimachinery/pkg/runtime/schema"
+	"k8s.io/apimachinery/pkg/runtime/serializer"
+	"k8s.io/apimachinery/pkg/util/net"
+	"k8s.io/apimachinery/pkg/util/wait"
+	"k8s.io/client-go/rest"
+	"k8s.io/client-go/tools/clientcmd"
+)
+
+// defaultRequestTimeout is set for all webhook request. This is the absolute
+// timeout of the HTTP request, including reading the response body.
+const defaultRequestTimeout = 30 * time.Second
+
+// GenericWebhook defines a generic client for webhooks with commonly used capabilities,
+// such as retry requests.
+type GenericWebhook struct {
+	RestClient     *rest.RESTClient
+	InitialBackoff time.Duration
+	ShouldRetry    func(error) bool
+}
+
+// DefaultShouldRetry is a default implementation for the GenericWebhook ShouldRetry function property.
+// If the error reason is one of: networking (connection reset) or http (InternalServerError (500), GatewayTimeout (504), TooManyRequests (429)),
+// or apierrors.SuggestsClientDelay() returns true, then the function advises a retry.
+// Otherwise it returns false for an immediate fail.
+func DefaultShouldRetry(err error) bool {
+	// these errors indicate a transient error that should be retried.
+	if net.IsConnectionReset(err) || apierrors.IsInternalError(err) || apierrors.IsTimeout(err) || apierrors.IsTooManyRequests(err) {
+		return true
+	}
+	// if the error sends the Retry-After header, we respect it as an explicit confirmation we should retry.
+	if _, shouldRetry := apierrors.SuggestsClientDelay(err); shouldRetry {
+		return true
+	}
+	return false
+}
+
+// NewGenericWebhook creates a new GenericWebhook from the provided kubeconfig file.
+func NewGenericWebhook(scheme *runtime.Scheme, codecFactory serializer.CodecFactory, kubeConfigFile string, groupVersions []schema.GroupVersion, initialBackoff time.Duration) (*GenericWebhook, error) {
+	return newGenericWebhook(scheme, codecFactory, kubeConfigFile, groupVersions, initialBackoff, defaultRequestTimeout)
+}
+
+func newGenericWebhook(scheme *runtime.Scheme, codecFactory serializer.CodecFactory, kubeConfigFile string, groupVersions []schema.GroupVersion, initialBackoff, requestTimeout time.Duration) (*GenericWebhook, error) {
+	for _, groupVersion := range groupVersions {
+		if !scheme.IsVersionRegistered(groupVersion) {
+			return nil, fmt.Errorf("webhook plugin requires enabling extension resource: %s", groupVersion)
+		}
+	}
+
+	loadingRules := clientcmd.NewDefaultClientConfigLoadingRules()
+	loadingRules.ExplicitPath = kubeConfigFile
+	loader := clientcmd.NewNonInteractiveDeferredLoadingClientConfig(loadingRules, &clientcmd.ConfigOverrides{})
+
+	clientConfig, err := loader.ClientConfig()
+	if err != nil {
+		return nil, err
+	}
+
+	// Kubeconfigs can't set a timeout, this can only be set through a command line flag.
+	//
+	// https://github.com/kubernetes/client-go/blob/master/tools/clientcmd/overrides.go
+	//
+	// Set this to something reasonable so request to webhooks don't hang forever.
+	clientConfig.Timeout = requestTimeout
+
+	// Avoid client-side rate limiting talking to the webhook backend.
+	// Rate limiting should happen when deciding how many requests to serve.
+	clientConfig.QPS = -1
+
+	codec := codecFactory.LegacyCodec(groupVersions...)
+	clientConfig.ContentConfig.NegotiatedSerializer = serializer.NegotiatedSerializerWrapper(runtime.SerializerInfo{Serializer: codec})
+
+	restClient, err := rest.UnversionedRESTClientFor(clientConfig)
+	if err != nil {
+		return nil, err
+	}
+
+	return &GenericWebhook{restClient, initialBackoff, DefaultShouldRetry}, nil
+}
+
+// WithExponentialBackoff will retry webhookFn() up to 5 times with exponentially increasing backoff when
+// it returns an error for which this GenericWebhook's ShouldRetry function returns true, confirming it to
+// be retriable. If no ShouldRetry has been defined for the webhook, then the default one is used (DefaultShouldRetry).
+func (g *GenericWebhook) WithExponentialBackoff(ctx context.Context, webhookFn func() rest.Result) rest.Result {
+	var result rest.Result
+	shouldRetry := g.ShouldRetry
+	if shouldRetry == nil {
+		shouldRetry = DefaultShouldRetry
+	}
+	WithExponentialBackoff(ctx, g.InitialBackoff, func() error {
+		result = webhookFn()
+		return result.Error()
+	}, shouldRetry)
+	return result
+}
+
+// WithExponentialBackoff will retry webhookFn up to 5 times with exponentially increasing backoff when
+// it returns an error for which shouldRetry returns true, confirming it to be retriable.
+func WithExponentialBackoff(ctx context.Context, initialBackoff time.Duration, webhookFn func() error, shouldRetry func(error) bool) error {
+	backoff := wait.Backoff{
+		Duration: initialBackoff,
+		Factor:   1.5,
+		Jitter:   0.2,
+		Steps:    5,
+	}
+
+	var err error
+	wait.ExponentialBackoff(backoff, func() (bool, error) {
+		err = webhookFn()
+		if ctx.Err() != nil {
+			// we timed out or were cancelled, we should not retry
+			return true, err
+		}
+		if shouldRetry(err) {
+			return false, nil
+		}
+		if err != nil {
+			return false, err
+		}
+		return true, nil
+	})
+	return err
+}