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 */
018package org.apache.hadoop.hbase.util;
019
020import edu.umd.cs.findbugs.annotations.NonNull;
021import java.lang.reflect.Method;
022import java.net.UnknownHostException;
023import org.apache.hadoop.conf.Configuration;
024import org.apache.hadoop.hbase.HBaseInterfaceAudience;
025import org.apache.yetus.audience.InterfaceAudience;
026
027/**
028 * Wrapper around Hadoop's DNS class to hide reflection.
029 */
030@InterfaceAudience.Private
031@edu.umd.cs.findbugs.annotations.SuppressWarnings(value = "REC_CATCH_EXCEPTION",
032    justification = "If exception, presume HAS_NEW_DNS_GET_DEFAULT_HOST_API false")
033public final class DNS {
034  // key to the config parameter of server hostname
035  // the specification of server hostname is optional. The hostname should be resolvable from
036  // both master and region server
037  @InterfaceAudience.LimitedPrivate(HBaseInterfaceAudience.CONFIG)
038  public static final String UNSAFE_RS_HOSTNAME_KEY = "hbase.unsafe.regionserver.hostname";
039  @InterfaceAudience.LimitedPrivate(HBaseInterfaceAudience.CONFIG)
040  public static final String MASTER_HOSTNAME_KEY = "hbase.master.hostname";
041  @InterfaceAudience.LimitedPrivate(HBaseInterfaceAudience.CONFIG)
042  public static final String UNSAFE_THRIFT_HOSTNAME_KEY = "hbase.unsafe.thrift.hostname";
043
044  private static boolean HAS_NEW_DNS_GET_DEFAULT_HOST_API;
045  private static Method GET_DEFAULT_HOST_METHOD;
046
047  /**
048   * Hostname configuration key
049   * @deprecated since 2.4.0 and will be removed in 4.0.0. Use {@link DNS#UNSAFE_RS_HOSTNAME_KEY}
050   *             instead.
051   * @see <a href="https://issues.apache.org/jira/browse/HBASE-24667">HBASE-24667</a>
052   */
053  @Deprecated
054  @InterfaceAudience.LimitedPrivate(HBaseInterfaceAudience.CONFIG)
055  public static final String RS_HOSTNAME_KEY = "hbase.regionserver.hostname";
056
057  static {
058    try {
059      GET_DEFAULT_HOST_METHOD = org.apache.hadoop.net.DNS.class.getMethod("getDefaultHost",
060        String.class, String.class, boolean.class);
061      HAS_NEW_DNS_GET_DEFAULT_HOST_API = true;
062    } catch (Exception e) {
063      HAS_NEW_DNS_GET_DEFAULT_HOST_API = false; // FindBugs: Causes REC_CATCH_EXCEPTION. Suppressed
064    }
065  }
066
067  public enum ServerType {
068    MASTER("master"),
069    REGIONSERVER("regionserver"),
070    THRIFT("thrift");
071
072    private final String name;
073
074    private ServerType(String name) {
075      this.name = name;
076    }
077
078    public String getName() {
079      return name;
080    }
081  }
082
083  private DNS() {
084  }
085
086  /**
087   * Wrapper around DNS.getDefaultHost(String, String), calling DNS.getDefaultHost(String, String,
088   * boolean) when available.
089   * @param strInterface The network interface to query.
090   * @param nameserver   The DNS host name.
091   * @return The default host names associated with IPs bound to the network interface.
092   */
093  public static String getDefaultHost(String strInterface, String nameserver)
094    throws UnknownHostException {
095    if (HAS_NEW_DNS_GET_DEFAULT_HOST_API) {
096      try {
097        // Hadoop-2.8 includes a String, String, boolean variant of getDefaultHost
098        // which properly handles multi-homed systems with Kerberos.
099        return (String) GET_DEFAULT_HOST_METHOD.invoke(null, strInterface, nameserver, true);
100      } catch (Exception e) {
101        // If we can't invoke the method as it should exist, throw an exception
102        throw new RuntimeException("Failed to invoke DNS.getDefaultHost via reflection", e);
103      }
104    } else {
105      return org.apache.hadoop.net.DNS.getDefaultHost(strInterface, nameserver);
106    }
107  }
108
109  /**
110   * Get the configured hostname for a given ServerType. Gets the default hostname if not specified
111   * in the configuration.
112   * @param conf       Configuration to look up.
113   * @param serverType ServerType to look up in the configuration for overrides.
114   */
115  public static String getHostname(@NonNull Configuration conf, @NonNull ServerType serverType)
116    throws UnknownHostException {
117    String hostname;
118    switch (serverType) {
119      case MASTER:
120        hostname = conf.get(MASTER_HOSTNAME_KEY);
121        break;
122      case REGIONSERVER:
123        hostname = conf.get(UNSAFE_RS_HOSTNAME_KEY);
124        break;
125      case THRIFT:
126        hostname = conf.get(UNSAFE_THRIFT_HOSTNAME_KEY);
127        break;
128      default:
129        hostname = null;
130    }
131    if (hostname == null || hostname.isEmpty()) {
132      return Strings.domainNamePointerToHostName(
133        getDefaultHost(conf.get("hbase." + serverType.getName() + ".dns.interface", "default"),
134          conf.get("hbase." + serverType.getName() + ".dns.nameserver", "default")));
135    } else {
136      return hostname;
137    }
138  }
139}