[jira] [Created] (HBASE-18226) Disable reverse DNS lookup at HMaster and use default hostname provided by RegionServer

["Duo Xu (JIRA)" <ji...@apache.org>]

Duo Xu created HBASE-18226:
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             Summary: Disable reverse DNS lookup at HMaster and use default hostname provided by RegionServer
                 Key: HBASE-18226
                 URL: https://issues.apache.org/jira/browse/HBASE-18226
             Project: HBase
          Issue Type: Bug
            Reporter: Duo Xu
            Priority: Minor


This JIRA is to address the similar problem as HBASE-12954, but there are some little differences,

1. HBASE-12954 provides the configuration "hbase.regionserver.hostname" so users can configure it on every regionserver with preferred hostnames. However, this configuration cannot be set through Ambari because each regionserver has a different value of this setting.

2. In Azure HDInsight clusters, we want to give each RegionServer/workernode a FQDN by modifying /etc/hosts on that node, then when regionserver starts, 
{code}
String hostName = shouldUseThisHostnameInstead() ? useThisHostnameInstead :
      rpcServices.isa.getHostName();
{code}
it uses FQDN names here but on HMaster side, it will do reverse DNS lookup which cannot be resolved.
{code}
 // if regionserver passed hostname to use,
 // then use it instead of doing a reverse DNS lookup
 ServerName rs = master.getServerManager().regionServerStartup(request, ia);
{code}

My proposed fix is to add a new configuration "hbase.hmaster.skip.reverse.dns.lookup". This is a hard switch. If it is set to true, then Regionserver will use the value returned by *_rpcServices.isa.getHostName()_* as the hostname overwriting whatever users specifies in "hbase.regionserver.hostname" and send to HMaster. HMaster will not do reverse DNS lookup, which has been implemented in HBASE-12954. If users want to provide their own hostnames in "hbase.regionserver.hostname", "hbase.hmaster.skip.reverse.dns.lookup" must be false.

I will submit a patch later today.



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