provides DynamicRequestHeaderController that combines DynamicCAFromConfigMapController and RequestHeaderAuthRequestController into one controller

the unified controller will dynamically fill RequestHeaderConfig struct

staging/src/k8s.io/apiserver/pkg/authentication/request/headerrequest/requestheader_controller.go

@@ -26,6 +26,7 @@ import (
 	"k8s.io/apimachinery/pkg/api/equality"
 	"k8s.io/apimachinery/pkg/api/errors"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/fields"
 	utilruntime "k8s.io/apimachinery/pkg/util/runtime"
 	"k8s.io/apimachinery/pkg/util/wait"
 	coreinformers "k8s.io/client-go/informers/core/v1"
@@ -41,6 +42,16 @@ const (
 	authenticationRoleName = "extension-apiserver-authentication-reader"
 )
 
+// RequestHeaderAuthRequestProvider a provider that knows how to dynamically fill parts of RequestHeaderConfig struct
+type RequestHeaderAuthRequestProvider interface {
+	UsernameHeaders() []string
+	GroupHeaders() []string
+	ExtraHeaderPrefixes() []string
+	AllowedClientNames() []string
+}
+
+var _ RequestHeaderAuthRequestProvider = &RequestHeaderAuthRequestController{}
+
 type requestHeaderBundle struct {
 	UsernameHeaders     []string
 	GroupHeaders        []string
@@ -48,7 +59,7 @@ type requestHeaderBundle struct {
 	AllowedClientNames  []string
 }
 
-// RequestHeaderAuthRequestController a controller that exposes a set of methods for dynamically filling RequestHeaderConfig struct.
+// RequestHeaderAuthRequestController a controller that exposes a set of methods for dynamically filling parts of RequestHeaderConfig struct.
 // The methods are sourced from the config map which is being monitored by this controller.
 // The controller is primed from the server at the construction time for components that don't want to dynamically react to changes
 // in the config map.
@@ -59,6 +70,7 @@ type RequestHeaderAuthRequestController struct {
 	configmapNamespace string
 
 	configmapLister         corev1listers.ConfigMapNamespaceLister
+	configmapInformer       cache.SharedIndexInformer
 	configmapInformerSynced cache.InformerSynced
 
 	queue workqueue.RateLimitingInterface
@@ -77,7 +89,6 @@ func NewRequestHeaderAuthRequestController(
 	cmName string,
 	cmNamespace string,
 	client kubernetes.Interface,
-	cmInformer coreinformers.ConfigMapInformer,
 	usernameHeadersKey, groupHeadersKey, extraHeaderPrefixesKey, allowedClientNamesKey string) (*RequestHeaderAuthRequestController, error) {
 	c := &RequestHeaderAuthRequestController{
 		name: "RequestHeaderAuthRequestController",
@@ -98,7 +109,12 @@ func NewRequestHeaderAuthRequestController(
 		return nil, err
 	}
 
-	cmInformer.Informer().AddEventHandler(cache.FilteringResourceEventHandler{
+	// we construct our own informer because we need such a small subset of the information available.  Just one namespace.
+	c.configmapInformer = coreinformers.NewFilteredConfigMapInformer(client, c.configmapNamespace, 12*time.Hour, cache.Indexers{cache.NamespaceIndex: cache.MetaNamespaceIndexFunc}, func(listOptions *metav1.ListOptions) {
+		listOptions.FieldSelector = fields.OneTermEqualSelector("metadata.name", c.configmapName).String()
+	})
+
+	c.configmapInformer.AddEventHandler(cache.FilteringResourceEventHandler{
 		FilterFunc: func(obj interface{}) bool {
 			if cast, ok := obj.(*corev1.ConfigMap); ok {
 				return cast.Name == c.configmapName && cast.Namespace == c.configmapNamespace
@@ -125,8 +141,8 @@ func NewRequestHeaderAuthRequestController(
 		},
 	})
 
-	c.configmapLister = cmInformer.Lister().ConfigMaps(c.configmapNamespace)
-	c.configmapInformerSynced = cmInformer.Informer().HasSynced
+	c.configmapLister = corev1listers.NewConfigMapLister(c.configmapInformer.GetIndexer()).ConfigMaps(c.configmapNamespace)
+	c.configmapInformerSynced = c.configmapInformer.HasSynced
 
 	return c, nil
 }
@@ -155,6 +171,8 @@ func (c *RequestHeaderAuthRequestController) Run(workers int, stopCh <-chan stru
 	klog.Infof("Starting %s", c.name)
 	defer klog.Infof("Shutting down %s", c.name)
 
+	go c.configmapInformer.Run(stopCh)
+
 	// wait for caches to fill before starting your work
 	if !cache.WaitForNamedCacheSync(c.name, stopCh, c.configmapInformerSynced) {
 		return
@@ -224,6 +242,7 @@ func (c *RequestHeaderAuthRequestController) syncConfigMap(configMap *corev1.Con
 	}
 	if hasChanged {
 		c.exportedRequestHeaderBundle.Store(newRequestHeaderBundle)
+		klog.V(2).Infof("Loaded a new request header values for %v", c.name)
 	}
 	return nil
 }

staging/src/k8s.io/apiserver/pkg/server/options/authentication.go

@@ -17,8 +17,6 @@ limitations under the License.
 package options
 
 import (
-	"context"
-	"encoding/json"
 	"fmt"
 	"strings"
 	"time"
@@ -27,7 +25,6 @@ import (
 
 	"github.com/spf13/pflag"
 
-	"k8s.io/apimachinery/pkg/api/errors"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apiserver/pkg/authentication/authenticatorfactory"
 	"k8s.io/apiserver/pkg/authentication/request/headerrequest"
@@ -330,66 +327,23 @@ const (
 	// by --requestheader-username-headers. This is created in the cluster by the kube-apiserver.
 	// "WARNING: generally do not depend on authorization being already done for incoming requests.")
 	authenticationConfigMapName = "extension-apiserver-authentication"
-	authenticationRoleName      = "extension-apiserver-authentication-reader"
 )
 
 func (s *DelegatingAuthenticationOptions) createRequestHeaderConfig(client kubernetes.Interface) (*authenticatorfactory.RequestHeaderConfig, error) {
-	requestHeaderCAProvider, err := dynamiccertificates.NewDynamicCAFromConfigMapController("client-ca", authenticationConfigMapNamespace, authenticationConfigMapName, "requestheader-client-ca-file", client)
+	dynamicRequestHeaderProvider, err := newDynamicRequestHeaderController(client)
 	if err != nil {
 		return nil, fmt.Errorf("unable to create request header authentication config: %v", err)
 	}
 
-	authConfigMap, err := client.CoreV1().ConfigMaps(authenticationConfigMapNamespace).Get(context.TODO(), authenticationConfigMapName, metav1.GetOptions{})
-	switch {
-	case errors.IsNotFound(err):
-		// ignore, authConfigMap is nil now
-		return nil, nil
-	case errors.IsForbidden(err):
-		klog.Warningf("Unable to get configmap/%s in %s.  Usually fixed by "+
-			"'kubectl create rolebinding -n %s ROLEBINDING_NAME --role=%s --serviceaccount=YOUR_NS:YOUR_SA'",
-			authenticationConfigMapName, authenticationConfigMapNamespace, authenticationConfigMapNamespace, authenticationRoleName)
-		return nil, err
-	case err != nil:
-		return nil, err
-	}
-
-	usernameHeaders, err := deserializeStrings(authConfigMap.Data["requestheader-username-headers"])
-	if err != nil {
-		return nil, err
-	}
-	groupHeaders, err := deserializeStrings(authConfigMap.Data["requestheader-group-headers"])
-	if err != nil {
-		return nil, err
-	}
-	extraHeaderPrefixes, err := deserializeStrings(authConfigMap.Data["requestheader-extra-headers-prefix"])
-	if err != nil {
-		return nil, err
-	}
-	allowedNames, err := deserializeStrings(authConfigMap.Data["requestheader-allowed-names"])
-	if err != nil {
-		return nil, err
-	}
-
 	return &authenticatorfactory.RequestHeaderConfig{
-		CAContentProvider:   requestHeaderCAProvider,
-		UsernameHeaders:     headerrequest.StaticStringSlice(usernameHeaders),
-		GroupHeaders:        headerrequest.StaticStringSlice(groupHeaders),
-		ExtraHeaderPrefixes: headerrequest.StaticStringSlice(extraHeaderPrefixes),
-		AllowedClientNames:  headerrequest.StaticStringSlice(allowedNames),
+		CAContentProvider:   dynamicRequestHeaderProvider,
+		UsernameHeaders:     headerrequest.StringSliceProvider(headerrequest.StringSliceProviderFunc(dynamicRequestHeaderProvider.UsernameHeaders)),
+		GroupHeaders:        headerrequest.StringSliceProvider(headerrequest.StringSliceProviderFunc(dynamicRequestHeaderProvider.GroupHeaders)),
+		ExtraHeaderPrefixes: headerrequest.StringSliceProvider(headerrequest.StringSliceProviderFunc(dynamicRequestHeaderProvider.ExtraHeaderPrefixes)),
+		AllowedClientNames:  headerrequest.StringSliceProvider(headerrequest.StringSliceProviderFunc(dynamicRequestHeaderProvider.AllowedClientNames)),
 	}, nil
 }
 
-func deserializeStrings(in string) ([]string, error) {
-	if len(in) == 0 {
-		return nil, nil
-	}
-	var ret []string
-	if err := json.Unmarshal([]byte(in), &ret); err != nil {
-		return nil, err
-	}
-	return ret, nil
-}
-
 // getClient returns a Kubernetes clientset. If s.RemoteKubeConfigFileOptional is true, nil will be returned
 // if no kubeconfig is specified by the user and the in-cluster config is not found.
 func (s *DelegatingAuthenticationOptions) getClient() (kubernetes.Interface, error) {

staging/src/k8s.io/apiserver/pkg/server/options/authentication_dynamic_request_header.go

@@ -0,0 +1,62 @@
+package options
+
+import (
+	"fmt"
+
+	"k8s.io/apiserver/pkg/authentication/request/headerrequest"
+	"k8s.io/apiserver/pkg/server/dynamiccertificates"
+	"k8s.io/client-go/kubernetes"
+)
+
+var _ dynamiccertificates.ControllerRunner = &DynamicRequestHeaderController{}
+var _ dynamiccertificates.Notifier = &DynamicRequestHeaderController{}
+var _ dynamiccertificates.CAContentProvider = &DynamicRequestHeaderController{}
+
+var _ headerrequest.RequestHeaderAuthRequestProvider = &DynamicRequestHeaderController{}
+
+// DynamicRequestHeaderController combines DynamicCAFromConfigMapController and RequestHeaderAuthRequestController
+// into one controller for dynamically filling RequestHeaderConfig struct
+type DynamicRequestHeaderController struct {
+	*dynamiccertificates.ConfigMapCAController
+	*headerrequest.RequestHeaderAuthRequestController
+}
+
+// newDynamicRequestHeaderController creates a new controller that implements DynamicRequestHeaderController
+func newDynamicRequestHeaderController(client kubernetes.Interface) (*DynamicRequestHeaderController, error) {
+	requestHeaderCAController, err := dynamiccertificates.NewDynamicCAFromConfigMapController(
+		"client-ca",
+		authenticationConfigMapNamespace,
+		authenticationConfigMapName,
+		"requestheader-client-ca-file",
+		client)
+	if err != nil {
+		return nil, fmt.Errorf("unable to create DynamicCAFromConfigMap controller: %v", err)
+	}
+
+	requestHeaderAuthRequestController, err := headerrequest.NewRequestHeaderAuthRequestController(
+		authenticationConfigMapName,
+		authenticationConfigMapNamespace,
+		client,
+		"requestheader-username-headers",
+		"requestheader-group-headers",
+		"requestheader-extra-headers-prefix",
+		"requestheader-allowed-names",
+	)
+	if err != nil {
+		return nil, fmt.Errorf("unable to create RequestHeaderAuthRequest controller: %v", err)
+	}
+	return &DynamicRequestHeaderController{
+		ConfigMapCAController:              requestHeaderCAController,
+		RequestHeaderAuthRequestController: requestHeaderAuthRequestController,
+	}, nil
+}
+
+func (c *DynamicRequestHeaderController) RunOnce() error {
+	return c.ConfigMapCAController.RunOnce()
+}
+
+func (c *DynamicRequestHeaderController) Run(workers int, stopCh <-chan struct{}) {
+	go c.ConfigMapCAController.Run(workers, stopCh)
+	go c.RequestHeaderAuthRequestController.Run(workers, stopCh)
+	<-stopCh
+}