get key basis on value by reading property file in python?

I have a property file "holder.txt" like this which is in key=value format. Here key is clientId and value is hostname.

p10=machineA.abc.host.com
p11=machineB.pqr.host.com
p12=machineC.abc.host.com
p13=machineD.abc.host.com

Now I want to read this file in python and get corresponding clientId where this python script is running. For example: if python script is running on machineA.abc.host.com then it should give me p10 as clientId. Similarly for others.

import socket, ConfigParser

hostname=socket.getfqdn()
print(hostname)

# now basis on "hostname" figure out whats the clientId 
# by reading "holder.txt" file

Now I have worked with ConfigParser but my confusion is how can I get value of key which is clientId basis on what hostname it is? Can we do this in python?

Solution

You Need to read and store the holder file in memory as a dictionary:

mappings = {}
with open('holder.txt', 'r') as f:
    for line in f:
        mapping = line.split('=')
        mappings[mapping[1].rstrip()] = mapping[0]

Then perform a mapping every time you want to get clientId from hostname:

import socket, ConfigParser

hostname=socket.getfqdn()
clientId = mappings[hostname]

Hope that helps.