Sample executable inventory script to read an INI and output in JSON for Ansible.

hosts

# Sample hosts file in INI format.

[webservers]
web1.example.com ansible_ssh_host=w1.example.net
web2.example.com ansible_ssh_port=1022

[webservers:vars]   # Comment on a section
webvar=blah         # Comment on an option

[dbservers]
db1.example.com
db2.example.com

[dbservers:vars]
dbvar=ugh

[servers:children]
webservers
dbservers

[servers:vars]
varb=B

[all:vars]
vara=A

hosts.py

#!/usr/bin/env python

import json
import shlex

inv = {'_meta': {'hostvars': {}}}

section = group_name = 'all'
for line in open('hosts'):
    line = line.split('#')[0].strip()
    if not line:
        continue
    if line.startswith('[') and line.endswith(']'):
        section = line[1:-1].strip()
        group_name = section.split(':')[0]
    else:
        group_dict = inv.setdefault(group_name, {})
        tokens = shlex.split(line)
        if section.endswith(':vars'):
            group_vars = group_dict.setdefault('vars', {})
            group_vars.update(dict([t.split('=', 1) for t in tokens]))
        elif section.endswith(':children'):
            group_children = group_dict.setdefault('children', [])
            group_children.append(line)
        else:
            group_hosts = group_dict.setdefault('hosts', [])
            group_hosts.append(tokens[0])
            host_vars = inv['_meta']['hostvars'].setdefault(tokens[0], {})
            host_vars.update(dict([t.split('=', 1) for t in tokens[1:]]))

print json.dumps(inv, indent=4)