[HDFS-95] UnknownHostException if the system can't determine its own name and you go DNS.getIPs("name-of-an-unknown-interface");

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 0.21.0
• Assignee: Steve Loughran
• Reporter: Steve Loughran
• Created: 20/Jun/08 19:20
• Updated: 11/Feb/14 00:56
• Resolved: 11/Feb/14 00:56

Description

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

Issue Links

• Is contained by: HADOOP-3426 Datanode does not start up if the local machines DNS isnt working right and dfs.datanode.dns.interface==default
• relates to: HADOOP-3426 Datanode does not start up if the local machines DNS isnt working right and dfs.datanode.dns.interface==default