gistfile1.txt

from ansible.plugins.inventory import BaseInventoryPlugin
import yaml

class CustomInventoryPlugin(BaseInventoryPlugin):

    NAME = 'custom_inventory'

    def parse(self, inventory, loader, path, cache=True):
        super(CustomInventoryPlugin, self).parse(inventory, loader, path)

        # Load the YAML inventory file
        with open(path, 'r') as file:
            inventory_data = yaml.safe_load(file)

        for hostname, hostvars in inventory_data.items():
            # Calculate additional variables based on the hostname
            if 'hostname_prefix' in hostvars:
                hostvars['calculated_value'] = len(hostvars['hostname_prefix'])

            # Inject the calculated variables into the host
            inventory.add_host(hostname)
            inventory.set_host_variable(hostname, 'calculated_value', hostvars.get('calculated_value', 0))

        # Set the default group
        inventory.add_group('all')
        for hostname in inventory_data.keys():
            inventory.add_child('all', hostname)

# Required for Ansible to recognize and load the plugin properly
CustomInventoryPlugin()


[defaults]
inventory = /path/to/inventory.yaml

[inventory]
enable_plugins = custom_inventory_plugin.py