org.apache.hadoop.net.DomainNameResolver 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 java.net.InetAddress;
import java.net.UnknownHostException;
/**
* This interface provides methods for the failover proxy to get IP addresses
* of the associated servers (NameNodes, RBF routers etc). Implementations will
* use their own service discovery mechanism, DNS, Zookeeper etc
*/
public interface DomainNameResolver {
/**
* Takes one domain name and returns its IP addresses based on the actual
* service discovery methods.
*
* @param domainName
* @return all IP addresses
* @throws UnknownHostException
*/
InetAddress[] getAllByDomainName(String domainName)
throws UnknownHostException;
/**
* Reverse lookup an IP address and get the fully qualified domain name(fqdn).
*
* @param address
* @return fully qualified domain name
*/
String getHostnameByIP(InetAddress address);
/**
* This function combines getAllByDomainName and getHostnameByIP, for a single
* domain name, it will first do a forward lookup to get all of IP addresses,
* then for each IP address, it will do a reverse lookup to get the fqdn.
* This function is necessary in secure environment since Kerberos uses fqdn
* in the service principal instead of IP.
*
* @param domainName
* @return all fully qualified domain names belonging to the IPs resolved from
* the input domainName
* @throws UnknownHostException
*/
String[] getAllResolvedHostnameByDomainName(
String domainName, boolean useFQDN) throws UnknownHostException;
}