[jira] [Commented] (HBASE-4109) Hostname returned via reverse dns lookup contains trailing period if configured interface is not "default"

["Harsh J (Commented) (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HBASE-4109?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13221283#comment-13221283 ] 

Harsh J commented on HBASE-4109:
--------------------------------

Hi,

This affects multihomed DataNodes as well. I've filed HADOOP-8134 upstream.
                
> Hostname returned via reverse dns lookup contains trailing period if configured interface is not "default"
> ----------------------------------------------------------------------------------------------------------
>
>                 Key: HBASE-4109
>                 URL: https://issues.apache.org/jira/browse/HBASE-4109
>             Project: HBase
>          Issue Type: Bug
>          Components: master, regionserver
>    Affects Versions: 0.90.3
>            Reporter: Shrijeet Paliwal
>            Assignee: Shrijeet Paliwal
>             Fix For: 0.90.4
>
>         Attachments: 0001-HBASE-4109-Sanitize-hostname-returned-from-DNS-class.patch
>
>
> If you are using an interface anything other than 'default' (literally that keyword) DNS.java 's getDefaultHost will return a string which will 
> have a trailing period at the end. It seems javadoc of reverseDns in DNS.java (see below) is conflicting with what that function is actually doing. 
> It is returning a PTR record while claims it returns a hostname. The PTR record always has period at the end , RFC:  http://irbs.net/bog-4.9.5/bog47.html 
> We make call to DNS.getDefaultHost at more than one places and treat that as actual hostname.
> Quoting HRegionServer for example
> {code}
> String machineName = DNS.getDefaultHost(conf.get(
>         "hbase.regionserver.dns.interface", "default"), conf.get(
>         "hbase.regionserver.dns.nameserver", "default"));
> {code}
> This causes inconsistencies. An example of such inconsistency was observed while debugging the issue "Regions not getting reassigned if RS is brought down". More here 
> http://search-hadoop.com/m/CANUA1qRCkQ1 
> We may want to sanitize the string returned from DNS class. Or better we can take a path of overhauling the way we do DNS name matching all over.

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