org.apache.hadoop.net.DomainNameResolverFactory 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.net;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.util.ReflectionUtils;
import java.io.IOException;
import java.net.URI;
/**
* This class creates the DomainNameResolver instance based on the config.
* It can either create the default resolver for the whole resolving for
* hadoop or create individual resolver per nameservice or yarn.
*/
@InterfaceAudience.Private
@InterfaceStability.Evolving
public final class DomainNameResolverFactory {
private DomainNameResolverFactory() {
// Utility classes should not have a public or default constructor
}
/**
* Create a domain name resolver to convert the domain name in the config to
* the actual IP addresses of the Namenode/Router/RM.
*
* @param conf Configuration to get the resolver from.
* @param uri the url that the resolver will be used against
* @param configKey The config key name suffixed with
* the nameservice/yarnservice.
* @return Domain name resolver.
*/
public static DomainNameResolver newInstance(
Configuration conf, URI uri, String configKey) throws IOException {
String host = uri.getHost();
String confKeyWithHost = configKey + "." + host;
return newInstance(conf, confKeyWithHost);
}
/**
* This function gets the instance based on the config.
*
* @param conf Configuration
* @param configKey config key name.
* @return Domain name resolver.
* @throws IOException when the class cannot be found or initiated.
*/
public static DomainNameResolver newInstance(
Configuration conf, String configKey) {
Class resolverClass = conf.getClass(
configKey,
DNSDomainNameResolver.class,
DomainNameResolver.class);
return ReflectionUtils.newInstance(resolverClass, conf);
}
}