Added /_whoami and integration test for auth(z|n)

Added new endpoint /_whoami for debugging authentication.
Added integration test which checks that a user is authenticated
using token authentication.
Rearranged initialization of authenticator to support preceeding.

pkg/master/handlers.go

@@ -0,0 +1,48 @@
+/*
+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 master
+
+import (
+	"net/http"
+
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/auth/authenticator"
+)
+
+// handleWhoAmI returns the user-string which this request is authenticated as (if any).
+// Useful for debugging authentication.  Always returns HTTP status okay and a human
+// readable (not intended as API) description of authentication state of request.
+func handleWhoAmI(auth authenticator.Request) func(w http.ResponseWriter, req *http.Request) {
+	return func(w http.ResponseWriter, req *http.Request) {
+		w.Header().Set("Content-Type", "text/plain")
+		w.WriteHeader(http.StatusOK)
+		if auth == nil {
+			w.Write([]byte("NO AUTHENTICATION SUPPORT"))
+			return
+		}
+		userInfo, ok, err := auth.AuthenticateRequest(req)
+		if err != nil {
+			w.Write([]byte("ERROR WHILE AUTHENTICATING"))
+			return
+		}
+		if !ok {
+			w.Write([]byte("NOT AUTHENTICATED"))
+			return
+		}
+		w.Write([]byte("AUTHENTICATED AS " + userInfo.GetName()))
+		return
+	}
+}