How do I `hostnamectl set-icon-name` via Ansible?

Question

Red Hat has a command called hostnamectl set-icon-name. Is it correct to configure this using Ansible?

The usual command

ansible.builtin.shell: "hostnamectl set-icon-name {{ inventory_hostname }}"

is possible, of course, but with each pass the Ansible thinks that it is changing this parameter, which is not good.

Answer 1

"Red Hat has a command called hostnamectl ..."

That's right. It is usually used in order to Changing a hostname. See also hostnamectl — Control the system hostname.

Plase take note about What is different between Static hostname and Icon name and Pretty hostname in RHEL? and the fact that hostname != icon-name.

icon-name [NAME]

If no argument is given, print the icon name of the system. If an optional argument NAME is provided then the command changes the icon name to NAME. The icon name is used by some graphical applications to visualize this host. The icon name should follow the Icon Naming Specification.

So, for a server the Icon name should probably set to computer, computer-vm or computer-server if not already

~/test$ hostnamectl
   Static hostname: test.example.com
         Icon name: computer-vm
           Chassis: vm
        Machine ID: 1234567890abcdefghijkl1234567890
           Boot ID: 1234567890abcdefghijkl1234567890
    Virtualization: microsoft
  Operating System: RHEL
       CPE OS Name: cpe:/o:redhat:enterprise_linux:7.9:GA:server
            Kernel: Linux 3.10.0-1160.105.1.el7.x86_64
      Architecture: x86-64

~/test$ hostnamectl
   Static hostname: test.example.com
         Icon name: computer-server
           Chassis: server
        Machine ID: 1234567890abcdefghijkl1234567890
           Boot ID: 1234567890abcdefghijkl1234567890
  Operating System: Red Hat Enterprise Linux 8.9 (Ootpa)
       CPE OS Name: cpe:/o:redhat:enterprise_linux:8::baseos
            Kernel: Linux 4.18.0-513.9.1.el8_9.x86_64
      Architecture: x86-64

or according the mentioned naming convention to

Icons for hardware that is contained within or connected to the computing device. Naming for extended devices in this group, is of the form <primary function>-<manufacturer>-<model>. This allows ease of fallback to the primary function device name, or ones more targeted for a specific series of models from a manufacturer.

Since the Ansible hostname module – Manage hostname is for setting the hostname only

Set system’s hostname. Supports most OSs/Distributions including those using systemd.

one is left with a command module – Execute commands on targets and Defining "changed" since the hostname Exit status will be just be

On success, 0 is returned, a non-zero failure code otherwise.

and in order to gain Idempotency. This is also due to the fact that Ansible facts do not gather the Icon name and if no additional Custom facts are implemented.

Is it correct to configure this using Ansible? The usual command ansible.builtin.shell: "hostnamectl set-icon-name {{ inventory_hostname }} is possible, of course, but with each pass the Ansible thinks that it is changing this parameter, which is not good.

Finally, a minimal example playbook

---
- hosts: localhost
  become: true
  gather_facts: false

  vars:

    ICON_NAME: computer-vm

  tasks:

  - name: Gather Facts via 'hostnamectl' without leading white-space
    shell: hostnamectl | sed "s/^[ \t]*//"
    register: HOSTNAMECTL
    # Since it is reporting task which should run in any case, set
    check_mode: false
    changed_when: false

  - name: Show Facts to get familiar with the data structure
    debug:
      msg: "{{ (HOSTNAMECTL.stdout | from_yaml) }}"

  - name: Set 'Icon name' via 'hostnamectl' idempotent
    command: hostnamectl set-icon-name {{ ICON_NAME }}
    when: (HOSTNAMECTL.stdout | from_yaml)['Icon name'] != ICON_NAME

will result into an output of

TASK [Gather Facts via 'hostnamectl' without leading white-spaces] *********************
ok: [localhost]

TASK [Show Facts to get familiar with the data structure] ******************************
ok: [localhost] =>
  msg:
    Architecture: x86-64
    Boot ID: 1234567890abcdefghijkl1234567890
    CPE OS Name: cpe:/o:redhat:enterprise_linux:7.9:GA:server
    Chassis: vm
    Icon name: computer-vm
    Kernel: Linux 3.10.0-1160.105.1.el7.x86_64
    Machine ID: 1234567890abcdefghijkl1234567890
    Operating System: RHEL
    Static hostname: test.example.com
    Virtualization: microsoft

PLAY RECAP *****************************************************************************
localhost                  : ok=2    changed=0    unreachable=0    failed=0    skipped=1

If a skipped tasks is not the desired behavior one could change the condition to

  - name: Set 'Icon name' via 'hostnamectl' idempotent
    command: hostnamectl set-icon-name {{ ICON_NAME }}
    changed_when: (HOSTNAMECTL.stdout | from_yaml)['Icon name'] != ICON_NAME