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https://issues.apache.org/jira/browse/HBASE-18226?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16053081#comment-16053081
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Duo Xu commented on HBASE-18226:
--------------------------------
[~tedyu]
Thanks for reviewing. Just realize HBASE-12953 was fixed by you :)
{quote}
Can you come up with better name ?
When reverse DNS is enabled, resolution is also automatic.
How about hbase.regionserver.hostname.from.etc.hosts ?
{quote}
I agree that the configuration name is not so accurate.
I read the source code again (including hadoop-common dns.java). By default RS
gets hostname by calling InetAddress.getLocalHost().getCanonicalHostName(). If
users specify "hbase.regionserver.dns.interface" or
"hbase.regionserver.dns.nameserver" or some underlying system configuration
changes (eg. modifying /etc/nsswitch.conf), it may first read from DNS or other
sources instead of first checking /etc/hosts file.
However, whether RS reads hostname from DNS or /etc/hosts is not a concern
here. This JIRA is to address that HMaster uses the hostname passed from RS
instead of doing reverse DNS lookup to tells RS which hostname to use. This has
already been implemented by HBASE-12954 by adding "useThisHostnameInstead"
field in RegionServerStatusProtos.
Currently "useThisHostnameInstead" is optional and RS by default only passes
port, server start code and server current time info to HMaster during
reportForDuty(). I would like to introduce a setting that if the setting is set
to true, "useThisHostnameInstead" will be set to the hostname RS gets from
rpcServices.isa.getHostName();. Then HMaster will skip reverse DNS lookup
because it sees "useThisHostnameInstead" field is set in the request.
How about hbase.regionserver.report.hostname.to.master?
I will update the JIRA description to make the goal more clearly. It seems I
made people feel confused :)
{quote}
Is it possible to add unit test ?
{quote}
The patch reuses "useThisHostnameInstead" field in RegionServerStatusProtos, so
there is not much to test. I will add a test like
org.apache.hadoop.hbase.regionserver.TestRegionServerHostname.testRegionServerHostname,
with my configuration set to true, and verify e2e working by using the
MiniCluster.
> 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
> Attachments: HBASE-18226.001.patch, HBASE-18226.002.patch
>
>
> 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 or other
> configuration management tools because each regionserver has a different
> value of this setting, which means each node needs a different hbase-site.xml.
> 2. In Azure HDInsight clusters, we want to give each RegionServer/workernode
> a FQDN by modifying /etc/hosts on that node. We do not want HMaster to do
> reverse DNS lookup because HMaster VM's /etc/hosts does not have regionserver
> VM's FQDN mappings. In current implementation 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.regionserver.hostname.auto*". 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 as part of
> RegionServerStartupRequest. 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.regionserver.hostname.auto*" must
> be false.
> I will submit a patch later today.
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