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authorization.go
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authorization.go
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/*
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 options
import (
"time"
"github.com/spf13/pflag"
"k8s.io/apiserver/pkg/authorization/authorizerfactory"
"k8s.io/apiserver/pkg/server"
authorizationclient "k8s.io/client-go/kubernetes/typed/authorization/v1beta1"
"k8s.io/client-go/rest"
"k8s.io/client-go/tools/clientcmd"
)
// DelegatingAuthorizationOptions provides an easy way for composing API servers to delegate their authorization to
// the root kube API server
type DelegatingAuthorizationOptions struct {
// RemoteKubeConfigFile is the file to use to connect to a "normal" kube API server which hosts the
// SubjectAccessReview.authorization.k8s.io endpoint for checking tokens.
RemoteKubeConfigFile string
// AllowCacheTTL is the length of time that a successful authorization response will be cached
AllowCacheTTL time.Duration
// DenyCacheTTL is the length of time that an unsuccessful authorization response will be cached.
// You generally want more responsive, "deny, try again" flows.
DenyCacheTTL time.Duration
}
func NewDelegatingAuthorizationOptions() *DelegatingAuthorizationOptions {
return &DelegatingAuthorizationOptions{
// very low for responsiveness, but high enough to handle storms
AllowCacheTTL: 10 * time.Second,
DenyCacheTTL: 10 * time.Second,
}
}
func (s *DelegatingAuthorizationOptions) Validate() []error {
allErrors := []error{}
return allErrors
}
func (s *DelegatingAuthorizationOptions) AddFlags(fs *pflag.FlagSet) {
fs.StringVar(&s.RemoteKubeConfigFile, "authorization-kubeconfig", s.RemoteKubeConfigFile, ""+
"kubeconfig file pointing at the 'core' kubernetes server with enough rights to create "+
" subjectaccessreviews.authorization.k8s.io.")
fs.DurationVar(&s.AllowCacheTTL, "authorization-webhook-cache-authorized-ttl",
s.AllowCacheTTL,
"The duration to cache 'authorized' responses from the webhook authorizer.")
fs.DurationVar(&s.DenyCacheTTL,
"authorization-webhook-cache-unauthorized-ttl", s.DenyCacheTTL,
"The duration to cache 'unauthorized' responses from the webhook authorizer.")
}
func (s *DelegatingAuthorizationOptions) ApplyTo(c *server.Config) error {
cfg, err := s.ToAuthorizationConfig()
if err != nil {
return err
}
authorizer, err := cfg.New()
if err != nil {
return err
}
c.Authorizer = authorizer
return nil
}
func (s *DelegatingAuthorizationOptions) ToAuthorizationConfig() (authorizerfactory.DelegatingAuthorizerConfig, error) {
sarClient, err := s.newSubjectAccessReview()
if err != nil {
return authorizerfactory.DelegatingAuthorizerConfig{}, err
}
ret := authorizerfactory.DelegatingAuthorizerConfig{
SubjectAccessReviewClient: sarClient,
AllowCacheTTL: s.AllowCacheTTL,
DenyCacheTTL: s.DenyCacheTTL,
}
return ret, nil
}
func (s *DelegatingAuthorizationOptions) newSubjectAccessReview() (authorizationclient.SubjectAccessReviewInterface, error) {
var clientConfig *rest.Config
var err error
if len(s.RemoteKubeConfigFile) > 0 {
loadingRules := &clientcmd.ClientConfigLoadingRules{ExplicitPath: s.RemoteKubeConfigFile}
loader := clientcmd.NewNonInteractiveDeferredLoadingClientConfig(loadingRules, &clientcmd.ConfigOverrides{})
clientConfig, err = loader.ClientConfig()
} else {
// without the remote kubeconfig file, try to use the in-cluster config. Most addon API servers will
// use this path
clientConfig, err = rest.InClusterConfig()
}
if err != nil {
return nil, err
}
// set high qps/burst limits since this will effectively limit API server responsiveness
clientConfig.QPS = 200
clientConfig.Burst = 400
client, err := authorizationclient.NewForConfig(clientConfig)
if err != nil {
return nil, err
}
return client.SubjectAccessReviews(), nil
}