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, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018
019 package org.apache.hadoop.security.alias;
020
021 import java.io.IOException;
022 import java.net.URI;
023 import java.net.URISyntaxException;
024 import java.util.ArrayList;
025 import java.util.List;
026 import java.util.ServiceLoader;
027
028 import org.apache.hadoop.classification.InterfaceAudience;
029 import org.apache.hadoop.classification.InterfaceStability;
030 import org.apache.hadoop.conf.Configuration;
031
032 /**
033 * A factory to create a list of CredentialProvider based on the path given in a
034 * Configuration. It uses a service loader interface to find the available
035 * CredentialProviders and create them based on the list of URIs.
036 */
037 @InterfaceAudience.Public
038 @InterfaceStability.Unstable
039 public abstract class CredentialProviderFactory {
040 public static final String CREDENTIAL_PROVIDER_PATH =
041 "hadoop.security.credential.provider.path";
042
043 public abstract CredentialProvider createProvider(URI providerName,
044 Configuration conf
045 ) throws IOException;
046
047 private static final ServiceLoader<CredentialProviderFactory> serviceLoader =
048 ServiceLoader.load(CredentialProviderFactory.class);
049
050 public static List<CredentialProvider> getProviders(Configuration conf
051 ) throws IOException {
052 List<CredentialProvider> result = new ArrayList<CredentialProvider>();
053 for(String path: conf.getStringCollection(CREDENTIAL_PROVIDER_PATH)) {
054 try {
055 URI uri = new URI(path);
056 boolean found = false;
057 for(CredentialProviderFactory factory: serviceLoader) {
058 CredentialProvider kp = factory.createProvider(uri, conf);
059 if (kp != null) {
060 result.add(kp);
061 found = true;
062 break;
063 }
064 }
065 if (!found) {
066 throw new IOException("No CredentialProviderFactory for " + uri + " in " +
067 CREDENTIAL_PROVIDER_PATH);
068 }
069 } catch (URISyntaxException error) {
070 throw new IOException("Bad configuration of " + CREDENTIAL_PROVIDER_PATH +
071 " at " + path, error);
072 }
073 }
074 return result;
075 }
076 }