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

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 0.90.3
• Fix Version/s: 0.90.4
• Component/s: master, regionserver
• Hadoop Flags: Reviewed
• Assignee: Shrijeet Paliwal
• Reporter: Shrijeet Paliwal
• Created: 15/Jul/11 21:38
• Updated: 20/Nov/15 11:55
• Resolved: 21/Jul/11 06:14

Description

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

String machineName = DNS.getDefaultHost(conf.get(
        "hbase.regionserver.dns.interface", "default"), conf.get(
        "hbase.regionserver.dns.nameserver", "default"));

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.

Issue Links

• is related to: HBASE-7693 Hostname returned by TableInputFormatBase.reverseDNS contains trailing period
• relates to: HADOOP-8134 DNS claims to return a hostname but returns a PTR record in some cases
• relates to: HADOOP-8156 Remove ability to specify a custom nameserver for an interface in DNS.java