produce ansible hosts inventory from yaml file python

Different ways

Parse YAML with PyYaml

Install with pip install pyyaml and then

import yaml

with open("sot-inventory.yaml", "r") as stream:
    try:
        print(yaml.safe_load(stream))
    except yaml.YAMLError as exc:
        print(exc)

Regex old school method

You can use a regex with multiple matching and named groups, and the print the output with the format you want

Example:

r"- Hostname: (?P<hostname>.*)\n\s*IP mgmt address: (?P<ip>.*)\n"gm

will create 3 matches with 2 groups (group hostname and group IP).

See how group works : https://docs.python.org/3/howto/regex.html#grouping

You can try your regex here : https://regex101.com/r/7Gz3JQ/2

Don't hesitate to paste your script here if you're stuck. We will help.

For example, the Ansible playbook

- hosts: localhost
  tasks:
    - set_fact:
        sot: "{{ lookup('file', 'sot-inventory.yaml')|from_yaml }}"
    - template:
        src: hosts.yaml.j2
        dest: hosts.yaml

and the template

shell> cat hosts.yaml.j2
---
{% for i in sot|groupby('Site') %}
  {{ i.0|lower }}:
    hosts:
{% for j in i.1 %}
      {{ j['Hostname']|lower }}:
         ansible_host: {{ j['IP mgmt address'] }}
         os: {{ j['OS']|lower }}
         'role of work': {{ j['Role of work']|lower }}
{% endfor %}
{% endfor %}

create the file hosts.yaml

shell> cat hosts.yaml
---
  maiami:
    hosts:
      mi-sw1:
         ansible_host: 11.1.1.1
         os: nx-os
         'role of work': switch
  new_york:
    hosts:
      ny-sw1:
         ansible_host: 10.1.1.1
         os: ios
         'role of work': switch
  paris:
    hosts:
      pa-sw1:
         ansible_host: 12.1.1.1
         os: arista
         'role of work': witch

Test it

shell> ansible-inventory -i hosts.yaml --list --yaml
all:
  children:
    maiami:
      hosts:
        mi-sw1:
          ansible_host: 11.1.1.1
          os: nx-os
          role of work: switch
    new_york:
      hosts:
        ny-sw1:
          ansible_host: 10.1.1.1
          os: ios
          role of work: switch
    paris:
      hosts:
        pa-sw1:
          ansible_host: 12.1.1.1
          os: arista
          role of work: witch
    ungrouped: {}