org.apache.hadoop.crypto.key.KeyProviderFactory Maven / Gradle / Ivy
/**
* 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.crypto.key;
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 KeyProvider based on the path given in a
* Configuration. It uses a service loader interface to find the available
* KeyProviders and create them based on the list of URIs.
*/
@InterfaceAudience.Public
@InterfaceStability.Unstable
public abstract class KeyProviderFactory {
public static final String KEY_PROVIDER_PATH =
CommonConfigurationKeysPublic.HADOOP_SECURITY_KEY_PROVIDER_PATH;
public abstract KeyProvider createProvider(URI providerName,
Configuration conf
) throws IOException;
private static final ServiceLoader serviceLoader =
ServiceLoader.load(KeyProviderFactory.class,
KeyProviderFactory.class.getClassLoader());
// Iterate through the serviceLoader to avoid lazy loading.
// Lazy loading would require synchronization in concurrent use cases.
static {
Iterator iterServices = serviceLoader.iterator();
while (iterServices.hasNext()) {
iterServices.next();
}
}
public static List getProviders(Configuration conf
) throws IOException {
List result = new ArrayList();
for(String path: conf.getStringCollection(KEY_PROVIDER_PATH)) {
try {
URI uri = new URI(path);
KeyProvider kp = get(uri, conf);
if (kp != null) {
result.add(kp);
} else {
throw new IOException("No KeyProviderFactory for " + uri + " in " +
KEY_PROVIDER_PATH);
}
} catch (URISyntaxException error) {
throw new IOException("Bad configuration of " + KEY_PROVIDER_PATH +
" at " + path, error);
}
}
return result;
}
/**
* Create a KeyProvider based on a provided URI.
*
* @param uri key provider URI
* @param conf configuration to initialize the key provider
* @return the key provider for the specified URI, or NULL if
* a provider for the specified URI scheme could not be found.
* @throws IOException thrown if the provider failed to initialize.
*/
public static KeyProvider get(URI uri, Configuration conf)
throws IOException {
KeyProvider kp = null;
for (KeyProviderFactory factory : serviceLoader) {
kp = factory.createProvider(uri, conf);
if (kp != null) {
break;
}
}
return kp;
}
}