(Python API question) Recursively expanding Ansible host vars from a standalone Python script

[arviasf]

Hi folks - In a standalone Python script, I need to enumerate and expand all host variables from a given Ansible inventory file. In this inventory file, there are variables which reference other variables using Jinja2 templates, and the level of recursion in those can be 3-4 levels deep. Some of the vars use Jinja2 tests (such as the version (version_compare) test) within their templates.

After some experimentation I could combine Ansible libraries with Jinja2 to do this. But it looks like a lot of work. Is there an intrinsic way to use ansible Python API and recursively expand all host variables?

FYI, here is what currently works for me:

from ansible.parsing.dataloader import DataLoader
from ansible.inventory.manager import InventoryManager
from ansible.vars.manager import VariableManager
from ansible.plugins.test.core import version_compare
from jinja2 import Template, Environment

sources = ['/project/ansible/conf/hosts']
loader = DataLoader()
inventory = InventoryManager(loader=loader, sources=sources)
variable_manager = VariableManager(loader=loader, inventory=inventory)

myhost = inventory.get_hosts()[0]
vars = variable_manager.get_vars(host = myhost)

environment = Environment()
environment.tests["version"] = version_compare

for k, v in vars.items():
    if type(v) == str:
        expanded_value = environment.from_string(v)

        while True:
            expanded_value = expanded_value.render(vars)
            if "{{" not in expanded_value:
                break
            else:
                expanded_value = environment.from_string(expanded_value)

        print(k, ":", expanded_value)

[Matt Martz]

Since you are already importing things from ansible, I'd recommend you import Templar, and use that instead of directly using jinja2.  Templar already has this functionality.

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Matt Martz
@sivel
sivel.net

[Dick Visser]

I'm interested in this as well, if possible please post any results

To view this discussion on the web visit https://groups.google.com/d/msgid/ansible-project/CAD8N0v9pVwt1UboaAGA%3D9pWHOBOryJFUVTPUCLXsErBNbSJTdQ%40mail.gmail.com.

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Sent from a mobile device - please excuse the brevity, spelling and punctuation.

[arviasf]

Thank you for the suggestion re: Templar. I was able to accomplish the needed functionality with this code:

from ansible.parsing.dataloader import DataLoader

from ansible.inventory.manager import InventoryManager

from ansible.vars.manager import VariableManager

from ansible.template import Templar

sources = ['/project/ansible/conf/hosts']

loader = DataLoader()

inventory = InventoryManager(loader=loader, sources=sources)

variable_manager = VariableManager(loader=loader, inventory=inventory)

myhost = inventory.get_hosts()[0]

vars = variable_manager.get_vars(host = myhost)

templar = Templar(loader= loader, variables=vars)

for k, v in vars.items():

    if type(v) == str:

        expanded_value = templar.template(v)

        print(k, ":", expanded_value)

[Vincent Rubiolo]

Hi there,

I have a very similar problem using ansible-inventory which does not perform this expansion either and this is causing me issues with AWX (see https://groups.google.com/g/awx-project/c/uW2jyvqA9MY for more information).

Your code opens up new possibilities for me as I could use it as a base to write a custom inventory plugin which I think could perform this expansion using the extra variables specified via --extra-vars (my inventory variables reference those extra vars via Jinja templates and do not currently get expanded).

Thanks a lot for sharing !

Vincent