11.0 - Dynamic Inventory¶

11.1 - Introduction¶

Commonly inventory files are stored in plaintext form.
This generally is bad practice, but becomes tedious and unmanageable for larger inventories.
One may wish to leverage Dynamic Inventories
Inventories stored in the cloud or external databases
Ansible will retrieve this information programmatically during the play

Example¶

Convert a static inventory file into a python script

#!/usr/bin/env python <- Required as Ansible will try to exec this as a Bash script if not included

import json

def get_inventory_data():
  return {
    "databases": {
       "hosts": ["db_server"],
       "vars": {
          "ansible_ssh_pass": "value",
          "ansible_ssh_host": "IP"
       }
     },
    "web": {
       "hosts": ["wev_server"],
       "vars": {
          "ansible_ssh_pass": "value",
          "ansible_ssh_host": "IP"
       }
     }
  }

if __name__ == "__main__":
  inventory_data = get_inventory_data()
  print(json.dumps(inventory_data))

One would then swap refer to this by -i [inventory.py](http://inventory.py) in the ansible-playbook command
When running the script, one should be able to pass --list or --host <hostname> to list the entire inventory details or get the details of a particular host.
This could be supported by using a function:

def read_cli_args():
  global args
  parser = argpars.ArgumentParser()
  parser.add_argument('--list', action='store_true')
  parser.add_argument('--host', action='store')
  args= parser.parse_args()

The final conditional could then be edited for example:

if __name__ == "__main__":
  global args
  read_cli_args()
  inventory_data = get_inventory_data()
  if args and args.list:
    print(json.dumps(inventory_data))
  elif args.host:
    print(json.dumps({'_meta': {'hostvars': {}}})

Many dynamic scripts are available via the Ansible Github predeveloped for providers such as:
AWS
Azure
VMware
Docker