328 lines
12 KiB
Go
328 lines
12 KiB
Go
/*
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Copyright 2016 The Kubernetes Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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// Package webhook implements the authenticator.Token interface using HTTP webhooks.
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package webhook
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import (
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"context"
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"errors"
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"fmt"
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"strconv"
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"time"
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authenticationv1 "k8s.io/api/authentication/v1"
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authenticationv1beta1 "k8s.io/api/authentication/v1beta1"
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metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
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"k8s.io/apimachinery/pkg/runtime"
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"k8s.io/apimachinery/pkg/runtime/schema"
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"k8s.io/apimachinery/pkg/util/wait"
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"k8s.io/apiserver/pkg/authentication/authenticator"
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"k8s.io/apiserver/pkg/authentication/user"
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"k8s.io/apiserver/pkg/util/webhook"
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"k8s.io/client-go/kubernetes/scheme"
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authenticationv1client "k8s.io/client-go/kubernetes/typed/authentication/v1"
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"k8s.io/client-go/rest"
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"k8s.io/klog/v2"
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)
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// DefaultRetryBackoff returns the default backoff parameters for webhook retry.
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func DefaultRetryBackoff() *wait.Backoff {
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backoff := webhook.DefaultRetryBackoffWithInitialDelay(500 * time.Millisecond)
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return &backoff
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}
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// Ensure WebhookTokenAuthenticator implements the authenticator.Token interface.
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var _ authenticator.Token = (*WebhookTokenAuthenticator)(nil)
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type tokenReviewer interface {
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Create(ctx context.Context, review *authenticationv1.TokenReview, _ metav1.CreateOptions) (*authenticationv1.TokenReview, int, error)
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}
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type WebhookTokenAuthenticator struct {
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tokenReview tokenReviewer
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retryBackoff wait.Backoff
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implicitAuds authenticator.Audiences
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requestTimeout time.Duration
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metrics AuthenticatorMetrics
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}
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// NewFromInterface creates a webhook authenticator using the given tokenReview
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// client. It is recommend to wrap this authenticator with the token cache
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// authenticator implemented in
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// k8s.io/apiserver/pkg/authentication/token/cache.
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func NewFromInterface(tokenReview authenticationv1client.AuthenticationV1Interface, implicitAuds authenticator.Audiences, retryBackoff wait.Backoff, requestTimeout time.Duration, metrics AuthenticatorMetrics) (*WebhookTokenAuthenticator, error) {
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tokenReviewClient := &tokenReviewV1Client{tokenReview.RESTClient()}
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return newWithBackoff(tokenReviewClient, retryBackoff, implicitAuds, requestTimeout, metrics)
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}
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// New creates a new WebhookTokenAuthenticator from the provided rest
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// config. It is recommend to wrap this authenticator with the token cache
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// authenticator implemented in
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// k8s.io/apiserver/pkg/authentication/token/cache.
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func New(config *rest.Config, version string, implicitAuds authenticator.Audiences, retryBackoff wait.Backoff) (*WebhookTokenAuthenticator, error) {
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tokenReview, err := tokenReviewInterfaceFromConfig(config, version, retryBackoff)
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if err != nil {
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return nil, err
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}
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return newWithBackoff(tokenReview, retryBackoff, implicitAuds, time.Duration(0), AuthenticatorMetrics{
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RecordRequestTotal: noopMetrics{}.RequestTotal,
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RecordRequestLatency: noopMetrics{}.RequestLatency,
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})
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}
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// newWithBackoff allows tests to skip the sleep.
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func newWithBackoff(tokenReview tokenReviewer, retryBackoff wait.Backoff, implicitAuds authenticator.Audiences, requestTimeout time.Duration, metrics AuthenticatorMetrics) (*WebhookTokenAuthenticator, error) {
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return &WebhookTokenAuthenticator{
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tokenReview,
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retryBackoff,
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implicitAuds,
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requestTimeout,
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metrics,
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}, nil
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}
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// AuthenticateToken implements the authenticator.Token interface.
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func (w *WebhookTokenAuthenticator) AuthenticateToken(ctx context.Context, token string) (*authenticator.Response, bool, error) {
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// We take implicit audiences of the API server at WebhookTokenAuthenticator
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// construction time. The outline of how we validate audience here is:
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//
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// * if the ctx is not audience limited, don't do any audience validation.
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// * if ctx is audience-limited, add the audiences to the tokenreview spec
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// * if the tokenreview returns with audiences in the status that intersect
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// with the audiences in the ctx, copy into the response and return success
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// * if the tokenreview returns without an audience in the status, ensure
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// the ctx audiences intersect with the implicit audiences, and set the
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// intersection in the response.
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// * otherwise return unauthenticated.
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wantAuds, checkAuds := authenticator.AudiencesFrom(ctx)
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r := &authenticationv1.TokenReview{
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Spec: authenticationv1.TokenReviewSpec{
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Token: token,
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Audiences: wantAuds,
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},
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}
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var (
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result *authenticationv1.TokenReview
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auds authenticator.Audiences
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cancel context.CancelFunc
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)
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// set a hard timeout if it was defined
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// if the child has a shorter deadline then it will expire first,
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// otherwise if the parent has a shorter deadline then the parent will expire and it will be propagate to the child
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if w.requestTimeout > 0 {
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ctx, cancel = context.WithTimeout(ctx, w.requestTimeout)
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defer cancel()
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}
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// WithExponentialBackoff will return tokenreview create error (tokenReviewErr) if any.
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if err := webhook.WithExponentialBackoff(ctx, w.retryBackoff, func() error {
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var tokenReviewErr error
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var statusCode int
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start := time.Now()
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result, statusCode, tokenReviewErr = w.tokenReview.Create(ctx, r, metav1.CreateOptions{})
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latency := time.Since(start)
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if statusCode != 0 {
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w.metrics.RecordRequestTotal(ctx, strconv.Itoa(statusCode))
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w.metrics.RecordRequestLatency(ctx, strconv.Itoa(statusCode), latency.Seconds())
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return tokenReviewErr
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}
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if tokenReviewErr != nil {
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w.metrics.RecordRequestTotal(ctx, "<error>")
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w.metrics.RecordRequestLatency(ctx, "<error>", latency.Seconds())
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}
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return tokenReviewErr
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}, webhook.DefaultShouldRetry); err != nil {
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// An error here indicates bad configuration or an outage. Log for debugging.
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klog.Errorf("Failed to make webhook authenticator request: %v", err)
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return nil, false, err
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}
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if checkAuds {
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gotAuds := w.implicitAuds
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if len(result.Status.Audiences) > 0 {
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gotAuds = result.Status.Audiences
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}
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auds = wantAuds.Intersect(gotAuds)
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if len(auds) == 0 {
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return nil, false, nil
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}
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}
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r.Status = result.Status
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if !r.Status.Authenticated {
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var err error
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if len(r.Status.Error) != 0 {
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err = errors.New(r.Status.Error)
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}
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return nil, false, err
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}
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var extra map[string][]string
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if r.Status.User.Extra != nil {
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extra = map[string][]string{}
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for k, v := range r.Status.User.Extra {
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extra[k] = v
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}
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}
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return &authenticator.Response{
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User: &user.DefaultInfo{
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Name: r.Status.User.Username,
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UID: r.Status.User.UID,
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Groups: r.Status.User.Groups,
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Extra: extra,
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},
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Audiences: auds,
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}, true, nil
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}
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// tokenReviewInterfaceFromConfig builds a client from the specified kubeconfig file,
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// and returns a TokenReviewInterface that uses that client. Note that the client submits TokenReview
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// requests to the exact path specified in the kubeconfig file, so arbitrary non-API servers can be targeted.
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func tokenReviewInterfaceFromConfig(config *rest.Config, version string, retryBackoff wait.Backoff) (tokenReviewer, error) {
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localScheme := runtime.NewScheme()
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if err := scheme.AddToScheme(localScheme); err != nil {
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return nil, err
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}
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switch version {
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case authenticationv1.SchemeGroupVersion.Version:
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groupVersions := []schema.GroupVersion{authenticationv1.SchemeGroupVersion}
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if err := localScheme.SetVersionPriority(groupVersions...); err != nil {
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return nil, err
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}
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gw, err := webhook.NewGenericWebhook(localScheme, scheme.Codecs, config, groupVersions, retryBackoff)
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if err != nil {
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return nil, err
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}
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return &tokenReviewV1ClientGW{gw.RestClient}, nil
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case authenticationv1beta1.SchemeGroupVersion.Version:
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groupVersions := []schema.GroupVersion{authenticationv1beta1.SchemeGroupVersion}
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if err := localScheme.SetVersionPriority(groupVersions...); err != nil {
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return nil, err
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}
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gw, err := webhook.NewGenericWebhook(localScheme, scheme.Codecs, config, groupVersions, retryBackoff)
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if err != nil {
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return nil, err
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}
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return &tokenReviewV1beta1ClientGW{gw.RestClient}, nil
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default:
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return nil, fmt.Errorf(
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"unsupported authentication webhook version %q, supported versions are %q, %q",
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version,
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authenticationv1.SchemeGroupVersion.Version,
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authenticationv1beta1.SchemeGroupVersion.Version,
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)
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}
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}
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type tokenReviewV1Client struct {
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client rest.Interface
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}
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// Create takes the representation of a tokenReview and creates it. Returns the server's representation of the tokenReview, HTTP status code and an error, if there is any.
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func (c *tokenReviewV1Client) Create(ctx context.Context, tokenReview *authenticationv1.TokenReview, opts metav1.CreateOptions) (result *authenticationv1.TokenReview, statusCode int, err error) {
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result = &authenticationv1.TokenReview{}
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restResult := c.client.Post().
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Resource("tokenreviews").
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VersionedParams(&opts, scheme.ParameterCodec).
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Body(tokenReview).
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Do(ctx)
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restResult.StatusCode(&statusCode)
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err = restResult.Into(result)
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return
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}
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// tokenReviewV1ClientGW used by the generic webhook, doesn't specify GVR.
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type tokenReviewV1ClientGW struct {
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client rest.Interface
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}
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// Create takes the representation of a tokenReview and creates it. Returns the server's representation of the tokenReview, HTTP status code and an error, if there is any.
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func (c *tokenReviewV1ClientGW) Create(ctx context.Context, tokenReview *authenticationv1.TokenReview, opts metav1.CreateOptions) (result *authenticationv1.TokenReview, statusCode int, err error) {
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result = &authenticationv1.TokenReview{}
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restResult := c.client.Post().
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Body(tokenReview).
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Do(ctx)
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restResult.StatusCode(&statusCode)
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err = restResult.Into(result)
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return
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}
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// tokenReviewV1beta1ClientGW used by the generic webhook, doesn't specify GVR.
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type tokenReviewV1beta1ClientGW struct {
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client rest.Interface
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}
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func (t *tokenReviewV1beta1ClientGW) Create(ctx context.Context, review *authenticationv1.TokenReview, _ metav1.CreateOptions) (*authenticationv1.TokenReview, int, error) {
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var statusCode int
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v1beta1Review := &authenticationv1beta1.TokenReview{Spec: v1SpecToV1beta1Spec(&review.Spec)}
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v1beta1Result := &authenticationv1beta1.TokenReview{}
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restResult := t.client.Post().Body(v1beta1Review).Do(ctx)
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restResult.StatusCode(&statusCode)
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err := restResult.Into(v1beta1Result)
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if err != nil {
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return nil, statusCode, err
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}
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review.Status = v1beta1StatusToV1Status(&v1beta1Result.Status)
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return review, statusCode, nil
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}
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func v1SpecToV1beta1Spec(in *authenticationv1.TokenReviewSpec) authenticationv1beta1.TokenReviewSpec {
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return authenticationv1beta1.TokenReviewSpec{
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Token: in.Token,
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Audiences: in.Audiences,
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}
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}
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func v1beta1StatusToV1Status(in *authenticationv1beta1.TokenReviewStatus) authenticationv1.TokenReviewStatus {
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return authenticationv1.TokenReviewStatus{
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Authenticated: in.Authenticated,
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User: v1beta1UserToV1User(in.User),
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Audiences: in.Audiences,
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Error: in.Error,
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}
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}
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func v1beta1UserToV1User(u authenticationv1beta1.UserInfo) authenticationv1.UserInfo {
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var extra map[string]authenticationv1.ExtraValue
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if u.Extra != nil {
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extra = make(map[string]authenticationv1.ExtraValue, len(u.Extra))
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for k, v := range u.Extra {
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extra[k] = authenticationv1.ExtraValue(v)
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}
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}
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return authenticationv1.UserInfo{
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Username: u.Username,
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UID: u.UID,
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Groups: u.Groups,
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Extra: extra,
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}
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}
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