Description of problem:

The nova-status validation was initially created for deployed environments and as such, it relies on the container_cli parameter. However, during FFWD wokflow, the validation gets triggered as part of the pre-upgrade group. The moment in which it gets triggered, the environment is in a unusual state where the Undercloud has been upgrade to OSP16.1 (container engine is podman) but the Overcloud nodes are still on OSP13 (container engine is still docker).

As the validation relies on container_cli parameter, and the Undercloud has been upgraded, the container_cli parameter indicates to use podman. But the Overcloud nodes do not know anything about Podman yet, so the validation fails in all controller nodes with:

{
    "hosts": {
        "controller-2": {
            "_ansible_no_log": false,
            "action": "command",
            "changed": false,
            "cmd": "exec -u root nova_api nova-status upgrade check",
            "failed": true,
            "invocation": {
                "module_args": {
                    "_raw_params": " exec -u root nova_api nova-status upgrade check",
                    "_uses_shell": false,
                    "argv": null,
                    "chdir": null,
                    "creates": null,
                    "executable": null,
                    "removes": null,
                    "stdin": null,
                    "stdin_add_newline": true,
                    "strip_empty_ends": true,
                    "warn": true
                }
            },
            "msg": "[Errno 2] No such file or directory",
            "rc": 2
        }
    },
    "name": "Check nova upgrade status",
    "status": "FAILED"
}

One solution is doing something similar to what is being performed in the ceph validation (ceph-health):
https://github.com/openstack/tripleo-validations/blob/master/roles/ceph/tasks/ceph-health.yaml#L13-L26

    - name: Check for docker cli
      stat:
        path: "/var/run/docker.sock"
      register: check_docker_cli
      check_mode: false

    - name: Set container_client fact
      set_fact:
        container_client: |-
          {% set container_client = 'podman' %}
          {%   if check_docker_cli.stat.exists|bool %}
          {%     set container_client = 'docker' %}
          {%   endif %}
          {{ container_client }}

Instead of relying on container_cli.

If required, a reproducer can be deployed.

Version-Release number of selected component (if applicable):


How reproducible:


Steps to Reproduce:
1. Run FFWD 13 to 16.1. Upgrade first the Undercloud
2. Once upgraded, run the pre-upgrade group to check the Overcloud's status
3. See the container-status validation fail.

Actual results:


Expected results:


Additional info: