hadoop rack awareness script

rack_info.py

#!/usr/bin/env python

import sys
import socket
data = """
100.200.208.12-100.200.208.46 : /xxx/rack_1
"""

def ip_integer_from_string(s):
    return reduce(lambda a,b: a<<8 | b, map(int, s.split(".")))

def ip_integer_to_string(ip):
     return ".".join(map(lambda n: str(ip>>n & 0xFF), [24,16,8,0]))

def hostname_to_ip(ip):
    socket.setdefaulttimeout(1)
    try:
        return socket.gethostbyname(ip)
    except Exception,e:
        return "255.255.255.255"


if __name__ == "__main__":
    rack_info = {}
    for line in filter(lambda x : ':' in x ,data.split('\n')):
        k,v = map(lambda x: x.strip(), line.split(":"))
        if '-' in k:
            start,end = map(lambda x: ip_integer_from_string(x.strip()), k.split('-'))
            if start < end :
                for ip in range(start, end+1):
                    rack_info[ip_integer_to_string(ip)] = v
        else:
            rack_info[k.strip()] = v
    sys.stdout.write(' '.join(map(lambda x: rack_info.get(hostname_to_ip(x), "/default/default_rack"), sys.argv[1:])))