Augments response from Ansible EC2 dynamic inventory with additional non-tagged host groups

ec2-augment.py

#!/usr/bin/env python
"""
Augments response from Ansible EC2 dynamic inventory with additional
non-tagged host groups 

To run: 

$ (virtualenv) python ec2-augment.py --list 

Tested with Python 2.7.10
"""

__author__ = "Jakob Henriksson"
__email__ = "jakob@metajungle.net"
__version__ = "1.0.0"

import json 
import re
import subprocess
import sys

# replaces underscores with dashes in host group names if True, 
# and not if False
replace_underscore_in_groups = True

# ec2.py script 
ec2_py_script = "/home/user/bin/ec2.py"

# tag key to convert 
# for example: if ec2_tag_key = "group", then
# will for an existing host group "tag_group_[x]" add 
# the following group "[x]" 
ec2_tag_key = "group"

def main(argv): 
    """
    Augments response from Ansible EC2 dynamic inventory with additional
    non-tagged host groups 
    """
    # result 
    json_augmented = {}
    try:
        # execute command 
        stdout = subprocess.check_output([ec2_py_script] + sys.argv[1:])
        value = stdout.decode('ascii', 'ignore')
        # parse output as JSON
        _json = json.loads(value)
        # construct tag prefix
        prefix = "tag_%s_" % ec2_tag_key
        for key, value in _json.items():
            # look for a match 
            if bool(re.match(prefix, key, re.I)):
                # construct group name to add
                group_name = key[len(prefix):]
                # optionally replace underscores 
                if replace_underscore_in_groups:
                    group_name = group_name.replace("_", "-")
                # propagate value
                json_augmented[key] = value
                # augment result 
                json_augmented[group_name] = value
            else:
                # propagate value 
                json_augmented[key] = value
    except:
        # default empty result
        json_augmented = { 
            "_meta": {
                "hostvars": {}
            }
        }
    # print agumented JSON
    print(json.dumps(json_augmented, indent=4))

if __name__ == "__main__":
    main(sys.argv)