Use python function for inventory

[Fizzadar]

We can already do this with deploys/operations:

pyinfra inventory.py my_python_module.my_op

So why not inventory?

[mechanarchy]

This was added in ed8196d; there are no docs (fair enough, it's experimental) but I feel like this simplifying use-case of inventory_module.host_group would be beneficial. Consider the following inventory.py contents:

proxmox_hosts = ["pve01", "pve02", "pve03"]
access_points = ["unifi01", "unifi02", "unifi03"]

It would be nice to use pyinfra inventory.proxmox_hosts deploy.py instead of the more verbose and potentially more error prone pyinfra inventory.py deploy.py --limit proxmox_hosts.

Currently the code assumes that this argv syntax always refers to a callable, I think checking if the user parameter is an iterable would be a reasonably simple addition and would enhance UX.

pyinfra/pyinfra_cli/inventory.py

Lines 134 to 143 in 511e7c3

	def make_inventory_from_func(
	inventory_func: Callable[[], Dict[str, List[HostType]]],
	override_data: Optional[Dict[Any, Any]] = None,
	):
	logger.warning("Loading inventory via import function is in alpha!")
	try:
	groups = inventory_func()
	except Exception as e:
	raise CliError(f"Failed to load inventory function: {inventory_func.__name__}: {e}")

[mechanarchy]

Ah, I was wondering where I originally saw this documented. It's here:
https://github.com/pyinfra-dev/pyinfra-examples/tree/main/inventory-functions