hosts

nova01
keystone01
mysql01
neutron01
nova-compute-ironic01
nova-compute-kvm01
glance01
haproxy01
horizon01
rabbitmq01
memcached01
aptcache01

lxd-inventory.py

#!/usr/bin/env python

import json
import os
import sys
import time
from pylxd import api

lxd = api.API()

inventory = {}
inventory['_meta'] = { 'hostvars': {} }
inventory['all'] = []

for container in lxd.container_list():
    state = lxd.container_state(container)[1]['metadata']
    ip = state['network']['eth0']['addresses'][0]['address']

    inventory['all'].append(container)
    # strip digits, eg. neutron01 becomes neutron
    group = ''.join(i for i in container if not i.isdigit())
    try:
       inventory[group].append(container)
    except:
       inventory[group] = []
       inventory[group].append(container)

    inventory['_meta']['hostvars'][container] = {}
    inventory['_meta']['hostvars'][container]['ansible_ssh_host'] = ip

print(json.dumps(inventory, indent=4))

test run

$ ./inventory.py 
{
    "haproxy": [
        "haproxy01"
    ], 
    "aptcache": [
        "aptcache01"
    ], 
    "all": [
        "aptcache01", 
        "glance01", 
        "glance02", 
        "haproxy01", 
        "horizon01", 
        "keystone01", 
        "memcached01", 
        "mysql01", 
        "neutron01", 
        "neutron02", 
        "nova-compute-ironic01", 
        "nova-compute-kvm01", 
        "nova01", 
        "rabbitmq01", 
        "t1"
    ], 
    "_meta": {
        "hostvars": {
            "mysql01": {
                "ansible_ssh_host": "10.245.29.130"
            }, 
            "nova-compute-kvm01": {
                "ansible_ssh_host": "10.245.29.128"
            }, 
            "memcached01": {
                "ansible_ssh_host": "10.245.29.114"
            }, 
            "neutron02": {
                "ansible_ssh_host": "10.245.29.75"
            }, 
            "haproxy01": {
                "ansible_ssh_host": "10.245.29.46"
            }, 
            "rabbitmq01": {
                "ansible_ssh_host": "10.245.29.70"
            }, 
            "nova01": {
                "ansible_ssh_host": "10.245.29.126"
            }, 
            "horizon01": {
                "ansible_ssh_host": "10.245.29.152"
            }, 
            "glance01": {
                "ansible_ssh_host": "10.245.29.52"
            }, 
            "glance02": {
                "ansible_ssh_host": "10.245.29.23"
            }, 
            "keystone01": {
                "ansible_ssh_host": "10.245.29.166"
            }, 
            "aptcache01": {
                "ansible_ssh_host": "10.245.29.207"
            }, 
            "neutron01": {
                "ansible_ssh_host": "10.245.29.190"
            }, 
            "t1": {
                "ansible_ssh_host": "10.245.29.206"
            }, 
            "nova-compute-ironic01": {
                "ansible_ssh_host": "10.245.29.200"
            }
        }
    }, 
    "nova": [
        "nova01"
    ], 
    "nova-compute-ironic": [
        "nova-compute-ironic01"
    ], 
    "keystone": [
        "keystone01"
    ], 
    "rabbitmq": [
        "rabbitmq01"
    ], 
    "horizon": [
        "horizon01"
    ], 
    "mysql": [
        "mysql01"
    ], 
    "glance": [
        "glance01", 
        "glance02"
    ], 
    "memcached": [
        "memcached01"
    ], 
    "nova-compute-kvm": [
        "nova-compute-kvm01"
    ], 
    "neutron": [
        "neutron01", 
        "neutron02"
    ], 
    "t": [
        "t1"
    ]
}