shyam334 / hadoop-dns-checker Goto Github PK

######Forked from  sujee/hadoop-dns-checker . Credits to original author for the base code.

We noticed that some parts of `hadoop/hbase` uses JNDI for DNS lookups, which doesn't really respect the OS DNS 
configuration.

The most noticeable symptom : 
`Cannot resolve the host name for <host>/<ip> because of javax.naming
.CommunicationException: 
DNS error [Root exception is java.net.SocketTimeoutException: Receive timed out]; remaining name '<ip>.in-addr.arpa'`

I have hacked together the `hadoop` DNS code to this utility. (I needed to quickly verify our issues with DNS , So
didnt care much about the code hygiene)
It will give a reasonable idea if the infrastructure is
 `hadoop` friendly.

## Original readme content follows ##

Hadoop is picky about DNS (and reverse DNS!)
Every node in the cluster has to have DNS working properly.

This script checks DNS and reverse DNS for hosts given.  Hosts are specified in a file, on a line by line basis.

What is needed:
    - Java (JDK 1.6) : which you will have installed in a Hadoop cluster anyway
    - rsync (to distribute files to remote machines)
    - SSH (and password less SSH setup between hosts)

Compile the source files first:
    ./compile.sh
this will create a file 'a.jar'.  This jar will be used by run scripts

the script 'run.sh'  runs the checks on the current host:
    ./run.sh   hosts_file

'run-on-cluster.sh' runs the tests on all machines specified in hosts file
    - it uses SSH to login to remote hosts and run the tests.  So it is handy to have password-less SSH configured.  
      In a typical Hadoop cluster, 'master' host is setup to have password-less SSH to all slaves.  So this script can be run from master server

    - it logs into each host and runs the DNS test

    ./run-on-cluster.sh  hosts_file

Happy Hadooping!

Sujee Maniyam
[email protected]