Numerical Group name throws error in yaml formatted hosts file.

[arcreigh]

Summary

When attempting to run a simple playbook to get the hostname of a cisco 3750x ansible fails to parse the yaml formatted hosts file. Playbook works with an INI formatted hosts file, however in an effort to use ansible-vault I need to migrate my file to yaml format.

Issue Type

Bug Report

Component Name

apt

Ansible Version

$ ansible --version
ansible [core 2.12.4]
  config file = /etc/ansible/ansible.cfg
  configured module search path = ['/home/arcreigh/.ansible/plugins/modules', '/usr/share/ansible/plugins/modules']
  ansible python module location = /usr/lib/python3/dist-packages/ansible
  ansible collection location = /home/arcreigh/.ansible/collections:/usr/share/ansible/collections
  executable location = /usr/bin/ansible
  python version = 3.8.10 (default, Mar 15 2022, 12:22:08) [GCC 9.4.0]
  jinja version = 2.10.1
  libyaml = True

Configuration

$ ansible-config dump --only-changed
N/A

OS / Environment

Ubuntu 20.04

Steps to Reproduce

#/etc/ansible/hosts
---

all:
  children:
    Network:
      children:
        IOS:
          hosts:
            3750:
              ansible_host: 3750.arc.net
      vars:
        ansible_connection: ansible.netcommon.network_cli
        ansible_network_os: cisco.ios.ios
        ansible_user: redacted
        ansible_password: redacted

#/home/ansible/playbooks/cisco/get_hostname.yml

---

- name: Get Cisco Device Hostname and Version
  connection: ansible.netcommon.network_cli
  gather_facts: false
  hosts: all
  tasks:

    - name: Get config for IOS device
      cisco.ios.ios_facts:
        gather_subset: all
    - name: Display config
      debug:
        msg: "The hostname is {{ ansible_net_hostname }} and the OS version is {{ ansible_net_version }}"

Expected Results

Expected output would be
The hostname is 3750.arc.net and the OS version is (insert ios version here)

Actual Results

ansible-playbook -i /etc/ansible/hosts get_hostname.yml
[WARNING]:  * Failed to parse /etc/ansible/hosts with yaml plugin: argument of type 'int' is not iterable
[WARNING]:  * Failed to parse /etc/ansible/hosts with ini plugin: Invalid host pattern '---' supplied, '---' is normally a sign this is a YAML file.
[WARNING]: Unable to parse /etc/ansible/hosts as an inventory source
[WARNING]: No inventory was parsed, only implicit localhost is available
[WARNING]: provided hosts list is empty, only localhost is available. Note that the implicit localhost does not match 'all'

PLAY [Get Cisco Device Hostname and Version] *************************************************************************************************************************************************
skipping: no hosts matched

PLAY RECAP ***********************************************************************************************************************************************************************************

Code of Conduct

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Files identified in the description:

• lib/ansible/modules/apt.py

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[arcreigh]

After a bit of testing changing the group name from "3750" to "switches" allowed me to get the expected output. It appears that numerical group names are not possible at the present time.
This is problematic for network devices that are commonly referred to by their model numbers in larger environments.

[s-hertel]

We don't plan on auto-casting unexpected types to strings in the yaml inventory plugin, but the error should be more helpful about what failed and what type is expected. I've opened a PR to do that: #77544.