[jira] Created: (HADOOP-3613) NPE if the system can't determine its own name and you go DNS.getIPs("name-of-an-unknown-interface");

[Steve Loughran (JIRA)]

NPE if the system can't determine its own name and you go 
DNS.getIPs("name-of-an-unknown-interface");
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                 Key: HADOOP-3613
                 URL: https://issues.apache.org/jira/browse/HADOOP-3613
             Project: Hadoop Core
          Issue Type: Bug
            Reporter: Steve Loughran


If you give an interface that doesnt exist, DNS.getIPs falls back to 
InetAddress.getLocalHost().getHostAddress()

But there's an assumption there: that InetAddress.getLocalHost(). is valid. If 
it doesnt resolve properly, you get an UnknownHostException

java.net.UnknownHostException: k2: k2
        at java.net.InetAddress.getLocalHost(InetAddress.java:1353)
        at org.apache.hadoop.net.DNS.getIPs(DNS.java:96)
        at 
org.apache.hadoop.net.TestDNS.testIPsOfUnknownInterface(TestDNS.java:73)

It is possible to catch this and return something else. The big question: what 
to fall back to? 127.0.0.1 would be an obvious choice

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