Add support for Azure authentication.

Author: brendandburns

util/src/main/java/io/kubernetes/client/util/KubeConfig.java

@@ -13,6 +13,8 @@
 package io.kubernetes.client.util;
 
 import io.kubernetes.client.util.authenticators.Authenticator;
+import io.kubernetes.client.util.authenticators.AzureActiveDirectoryAuthenticator;
+import io.kubernetes.client.util.authenticators.GCPAuthenticator;
 import java.io.File;
 import java.io.FileNotFoundException;
 import java.io.FileReader;
@@ -58,6 +60,11 @@ public static void registerAuthenticator(Authenticator auth) {
     }
   }
 
+  static {
+    registerAuthenticator(new GCPAuthenticator());
+    registerAuthenticator(new AzureActiveDirectoryAuthenticator());
+  }
+
   /** Load a Kubernetes config from the default location */
   public static KubeConfig loadDefaultKubeConfig() throws FileNotFoundException {
     File config = new File(new File(System.getenv(ENV_HOME), KUBEDIR), KUBECONFIG);
@@ -182,6 +189,8 @@ public String getAccessToken() {
             // TODO persist things here.
           }
           return auth.getToken(authConfig);
+        } else {
+          log.error("Unknown auth provider: " + name);
         }
       }
     }

util/src/main/java/io/kubernetes/client/util/authenticators/AzureActiveDirectoryAuthenticator.java

@@ -0,0 +1,55 @@
+/*
+Copyright 2018 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 io.kubernetes.client.util.authenticators;
+
+import io.kubernetes.client.util.KubeConfig;
+import java.util.Date;
+import java.util.Map;
+
+/**
+ * The Authenticator interface represents a plugin that can handle a specific type of authentication
+ * information (e.g. 'azure')
+ */
+public class AzureActiveDirectoryAuthenticator implements Authenticator {
+  static {
+    KubeConfig.registerAuthenticator(new AzureActiveDirectoryAuthenticator());
+  }
+
+  private static final String ACCESS_TOKEN = "access-token";
+  private static final String EXPIRES_ON = "expires-on";
+
+  @Override
+  public String getName() {
+    return "azure";
+  }
+
+  @Override
+  public String getToken(Map<String, Object> config) {
+    return (String) config.get(ACCESS_TOKEN);
+  }
+
+  @Override
+  public boolean isExpired(Map<String, Object> config) {
+    String expiresOn = (String) config.get(EXPIRES_ON);
+    Date expiry = new Date(Long.parseLong(expiresOn) * 1000);
+    if (expiry != null && expiry.compareTo(new Date()) <= 0) {
+      return true;
+    }
+    return false;
+  }
+
+  @Override
+  public Map<String, Object> refresh(Map<String, Object> config) {
+    throw new RuntimeException("Unimplemented");
+  }
+}