| /** |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you 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 org.apache.hadoop.security.alias; |
| |
| import java.io.IOException; |
| import java.net.URI; |
| import java.net.URISyntaxException; |
| import java.util.ArrayList; |
| import java.util.Iterator; |
| import java.util.List; |
| import java.util.ServiceLoader; |
| |
| import org.apache.hadoop.classification.InterfaceAudience; |
| import org.apache.hadoop.classification.InterfaceStability; |
| import org.apache.hadoop.conf.Configuration; |
| import org.apache.hadoop.fs.CommonConfigurationKeysPublic; |
| |
| /** |
| * A factory to create a list of CredentialProvider based on the path given in a |
| * Configuration. It uses a service loader interface to find the available |
| * CredentialProviders and create them based on the list of URIs. |
| */ |
| @InterfaceAudience.Public |
| @InterfaceStability.Unstable |
| public abstract class CredentialProviderFactory { |
| public static final String CREDENTIAL_PROVIDER_PATH = |
| CommonConfigurationKeysPublic.HADOOP_SECURITY_CREDENTIAL_PROVIDER_PATH; |
| |
| public abstract CredentialProvider createProvider(URI providerName, |
| Configuration conf |
| ) throws IOException; |
| |
| private static final ServiceLoader<CredentialProviderFactory> serviceLoader = |
| ServiceLoader.load(CredentialProviderFactory.class, |
| CredentialProviderFactory.class.getClassLoader()); |
| |
| // Iterate through the serviceLoader to avoid lazy loading. |
| // Lazy loading would require synchronization in concurrent use cases. |
| static { |
| Iterator<CredentialProviderFactory> iterServices = serviceLoader.iterator(); |
| while (iterServices.hasNext()) { |
| iterServices.next(); |
| } |
| } |
| |
| public static List<CredentialProvider> getProviders(Configuration conf |
| ) throws IOException { |
| List<CredentialProvider> result = new ArrayList<CredentialProvider>(); |
| for(String path: conf.getStringCollection(CREDENTIAL_PROVIDER_PATH)) { |
| try { |
| URI uri = new URI(path); |
| boolean found = false; |
| // Iterate serviceLoader in a synchronized block since |
| // serviceLoader iterator is not thread-safe. |
| synchronized (serviceLoader) { |
| for (CredentialProviderFactory factory : serviceLoader) { |
| CredentialProvider kp = factory.createProvider(uri, conf); |
| if (kp != null) { |
| result.add(kp); |
| found = true; |
| break; |
| } |
| } |
| } |
| if (!found) { |
| throw new IOException("No CredentialProviderFactory for " + uri + " in " + |
| CREDENTIAL_PROVIDER_PATH); |
| } |
| } catch (URISyntaxException error) { |
| throw new IOException("Bad configuration of " + CREDENTIAL_PROVIDER_PATH + |
| " at " + path, error); |
| } |
| } |
| return result; |
| } |
| } |