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https://issues.apache.org/jira/browse/HBASE-18226?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16054584#comment-16054584
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Josh Elser commented on HBASE-18226:
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bq. hbase.regionserver.hostname.reported.to.master does not make sense to me
honestly. Maybe name this hbase.regionserver.hostname.disable.reversedns or
something like it.
I'm glad this is getting discussed :) I don't feel like disable.reversedns is
right either -- rDNS is still happening on the RS. I'm trying to wrap my head
around what the user-facing change is...
Nothing is really changing on the RS side (RS still computes its hostname in
the same manner), we're just "telling" the Master to not validate the reported
hostname, right? It's difficult to follow but is nice that it doesn't require
any RPC changes :). I could have gotten this wrong though.
I'm still kind of confused how this would actually work on Azure. The RS is
still sending a hostname to the Master; isn't this patch just delaying the
Master from failing some RPC to a RS? Again, I might just be missing something.
> 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,
> HBASE-18226.003.patch, HBASE-18226.004.patch
>
>
> Description updated:
> In some unusual network environment, forward DNS lookup is supported while
> reverse DNS lookup may not work properly.
> 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 during
> reportForDuty() . 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 RS
> reportForDuty(). In order to use this field, users currently need to specify
> "hbase.regionserver.hostname" on every regionserver node's hbase-site.xml.
> This causes some trouble in
> 1. some deployments managed by some management tools like Ambari, which
> maintains the same copy of hbase-site.xml across all the nodes.
> 2. HBASE-12954 is targeting multihomed hosts, which users want to manually
> set the hostname value for each node. In the other cases (not multihomed), I
> just want RS to use the hostname return by the node and set it in
> useThisHostnameInstead and pass 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 the node.
> Then HMaster will skip reverse DNS lookup because it sees
> "useThisHostnameInstead" field is set in the request.
> "hbase.regionserver.hostname.reported.to.master", is it a good name?
> --------------------
> Regarding the hostname returned by the RS node, 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.
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