Ansible suddenly uses svr4pkg as a backend of yum - ansible

Question

Declared YUM task as below:
---
- hosts: all
vars:
tasks:
- name: install package
yum:
name: ntp
state: present
Ran following command:
ansible-playbook test.yml -i localhost, --connection=local -vvvv
Receiving error message:
TASK [install package] ***************************************************************************************************************************************************
task path: /home/osuser/dod/test.yml:6
Using module file /usr/lib/python2.7/site-packages/ansible/modules/system/setup.py
<localhost> ESTABLISH LOCAL CONNECTION FOR USER: osuser
<localhost> EXEC /bin/sh -c '/usr/bin/python && sleep 0'
Running svr4pkg as the backend for the yum action plugin
Using module file /usr/lib/python2.7/site-packages/ansible/modules/packaging/os/svr4pkg.py
<localhost> EXEC /bin/sh -c '/usr/bin/python && sleep 0'
fatal: [localhost]: FAILED! => {
"ansible_facts": {
"pkg_mgr": "svr4pkg"
},
"changed": false,
"invocation": {
"module_args": {
"category": false,
"name": "ntp",
"proxy": null,
"response_file": null,
"src": null,
"state": "present",
"zone": "all"
}
},
"msg": "src is required when state=present",
"name": "ntp"
Note the following message in debug:
Running svr4pkg as the backend for the yum action plugin
Ansible decided to use "srv4pkg" module (which requires src parameter) as backend of yum.
Workaround:
Set use_backend: yum parameter on yum module... if possible ! (I cannot modify the yaml file in my real usage).
Running Ansible 2.7.15 on CentOS 7.6.. with yum installed so there is absolutely no reason svr4pkg as a back-end (which is not supported/documented by yum module).
However, as it seems to be defined as an ansible_fact, I have done following test (result is filtered):
ansible -i localhost, all -m setup -k
SUCCESS => {
"ansible_facts": {
"ansible_distribution": "CentOS",
"ansible_distribution_file_parsed": true,
"ansible_distribution_file_path": "/etc/redhat-release",
"ansible_distribution_file_variety": "RedHat",
"ansible_distribution_major_version": "7",
"ansible_distribution_release": "Core",
"ansible_distribution_version": "7.6.1810",
"ansible_os_family": "RedHat",
"ansible_pkg_mgr": "svr4pkg",
"ansible_python_version": "2.7.5",
"module_setup": true
},
"changed": false
}
Any clue of the reason and how to enforce ansible_pkg_mgr ?

Answer 1

It seems that this distribution is shipped with yum and svr4pkg as we can see below:
$ ll /usr/bin/yum
-rwxr-xr-x. 1 root root 801 Nov 5 2018 /usr/bin/yum
$ ll /usr/sbin/pkgadd
-rwxr-xr-x. 1 root root 207342 Jul 2 16:12 /usr/sbin/pkgadd
So the last available package manager resolved is kept and take precedence /usr/lib/python2.7/site-packages/ansible/module_utils/facts/system/pkg_mgr.py
# A list of dicts. If there is a platform with more than one
# package manager, put the preferred one last. If there is an
# ansible module, use that as the value for the 'name' key.
PKG_MGRS = [{'path': '/usr/bin/yum', 'name': 'yum'},
{'path': '/usr/bin/dnf', 'name': 'dnf'},
{'path': '/usr/bin/apt-get', 'name': 'apt'},
{'path': '/usr/sbin/pkgadd', 'name': 'svr4pkg'},
[...]
def collect(self, module=None, collected_facts=None):
facts_dict = {}
collected_facts = collected_facts or {}
pkg_mgr_name = 'unknown'
for pkg in PKG_MGRS:
if os.path.exists(pkg['path']):
pkg_mgr_name = pkg['name']
# Handle distro family defaults when more than one package manager is
# installed, the ansible_fact entry should be the default package
# manager provided by the distro.
if collected_facts['ansible_os_family'] == "RedHat":
if pkg_mgr_name not in ('yum', 'dnf'):
pkg_mgr_name = self._check_rh_versions(pkg_mgr_name, collected_facts)
[...]
facts_dict['pkg_mgr'] = pkg_mgr_name
return facts_dict
So it seems to be an unmanaged case on ansible.
However, I still have no idea on how to enforce the right value !

Answer 2

Fixed by upgrading to Ansible 2.8+.
See https://github.com/ansible/ansible/issues/49184 when multiple package managers are available on system.