Add simple Bearer authenticator filter for Kube

* Default file based implementation
* Define some simple interfaces
* Add -token_auth_file to apiserver that will start the apiserver
  with a request filter for tokens

pkg/auth/authenticator/interfaces.go

@@ -0,0 +1,53 @@
+/*
+Copyright 2014 Google Inc. All rights reserved.
+
+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 authenticator
+
+import (
+	"net/http"
+
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/auth/user"
+)
+
+// Token checks a string value against a backing authentication store and returns
+// information about the current user and true if successful, false if not successful,
+// or an error if the token could not be checked.
+type Token interface {
+	AuthenticateToken(token string) (user.Info, bool, error)
+}
+
+// Request attempts to extract authentication information from a request and returns
+// information about the current user and true if successful, false if not successful,
+// or an error if the token could not be checked.
+type Request interface {
+	AuthenticateRequest(req *http.Request) (user.Info, bool, error)
+}
+
+// TokenFunc is a function that implements the Token interface.
+type TokenFunc func(token string) (user.Info, bool, error)
+
+// AuthenticateToken implements authenticator.Token.
+func (f TokenFunc) AuthenticateToken(token string) (user.Info, bool, error) {
+	return f(token)
+}
+
+// RequestFunc is a function that implements the Request interface.
+type RequestFunc func(req *http.Request) (user.Info, bool, error)
+
+// AuthenticateRequest implements authenticator.Request.
+func (f RequestFunc) AuthenticateRequest(req *http.Request) (user.Info, bool, error) {
+	return f(req)
+}