GCP inventory, inventory_hostname returning IP address

[Lorenzo Milesi]

Hi.
I configured inventory according to the example [1]:

hostnames:
  - name
compose:
  ansible_host: networkInterfaces[0].accessConfigs[0].natIP

And the inventory correctly uses hostname. But to my experience, the `inventory_hostname` variable (which should be the primary variable for setting the hostname) still contains the IP address. As a result, using that var for setting hostname ends up with something like `192` as machine name.
I tried several `compose` combination, but I've read in the docs this is a readonly variable and as such it cannot be manually set.

The only method I found so far to have a usable `inventory_hostname` is to comment the `ansible_host` directive in the `compose` and set the hostname in /etc/hosts, in order to allow Ansible to connect. But this way I'm losing the benefit of using GCP inventory.
So I was wondering what am I doing wrong.
Thanks


[1] https://docs.ansible.com/ansible/latest/collections/google/cloud/gcp_compute_inventory.html#examples

[Brian Coca]

Compose happens to late to set inventory_hostname, this is not a
'settable variable' but a variable that reflects the name with which
the host was added to inventory.

Being able to choose what to use as inventory_hostname depends on the
inventory plugin,
many allow you to set inventory_hostname others do not.

In this case, the gcp_compute inventory plugin does allow it, and from
the docs it should work with 'name'

hostnames:
description: A list of options that describe the ordering for which
hostnames should be assigned. Currently supported hostnames are
'public_ip', 'private_ip', 'name' or 'labels.vm_name'.
default: ['public_ip', 'private_ip', 'name']

But docs can be wrong, so I looked at the code:
https://github.com/ansible-collections/google.cloud/blob/0cd64a4a68b7d4393c97b801e3f24e6b63882294/plugins/inventory/gcp_compute.py#L231,
this does seem to use the hostnames options/ordering to assign the
name. That code is then used to create the host
https://github.com/ansible-collections/google.cloud/blob/0cd64a4a68b7d4393c97b801e3f24e6b63882294/plugins/inventory/gcp_compute.py#L302
(which sets inventory_hostname to hostname()).

So the only thing I can think of .. the API is not returning 'name' as
part of the host information.
----------
Brian Coca

[Lorenzo Milesi]

Thanks for the feedback!

Unfortunately, I'm not that familiar with Python to grab the whole process, but I checked what you suggested, and at least in the REST I see when opening the instance detail, I **don't** see the "hostname" key. I only have the "name" one. But that should be correct, according to the config above, it should take the hostname from the "name" attribute.

[Brian Coca]

it will take inventory_hostname from that, but not ansible_hostname,
again, this is a fact gathered at runtime from the host.

The first variable represents the 'unique identifier' with which the
host was added to the inventory, the second is a result of running
gather_facts/setup on the remote system.

--
----------
Brian Coca

[Lorenzo Milesi]

Thanks again for the feedback. I finally sorted it out, and of course it was a fault on my side.

I didn't notice in the playbook someone had overridden hostname with:

hostname: "{{ ansible_hostname }}"

thus causing this behavior.