Source code

001/*
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *   http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing,
013 * software distributed under the License is distributed on an
014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015 * KIND, either express or implied.  See the License for the
016 * specific language governing permissions and limitations
017 * under the License.
018 */
019package org.apache.reef.runtime.common;
020
021import org.apache.reef.annotations.audience.ClientSide;
022import org.apache.reef.annotations.audience.DriverSide;
023import org.apache.reef.annotations.audience.Public;
024import org.apache.reef.runtime.common.client.defaults.DefaultUserCredentials;
025import org.apache.reef.tang.annotations.DefaultImplementation;
026
027import java.io.IOException;
028import java.security.PrivilegedExceptionAction;
029
030/**
031 * A holder object for REEF user credentials.
032 * Implementations of this interface are used e.g. for Unmanaged AM applications on YARN.
033 */
034@Public
035@ClientSide
036@DriverSide
037@DefaultImplementation(DefaultUserCredentials.class)
038public interface UserCredentials {
039
040  /**
041   * Copy credentials from another existing user.
042   * This method can be called only once per instance.
043   * @param name name of the new user.
044   * @param other Credentials of another user.
045   * @throws IOException if unable to copy.
046   */
047  void set(final String name, final UserCredentials other) throws IOException;
048
049  /**
050   * Check if the user credentials had been set.
051   * @return true if set() method had been called successfully before, false otherwise.
052   */
053  boolean isSet();
054
055  /**
056   * Execute the privileged action as a given user.
057   * If user credentials are not set, execute the action outside the user context.
058   * @param action an action to run.
059   * @param <T> action return type.
060   * @return result of an action.
061   * @throws Exception whatever the action can throw.
062   */
063  <T> T doAs(final PrivilegedExceptionAction<T> action) throws Exception;
064}