Watch: Difference Between ansible_hostname and inventory_hostname Explained

Discover the differences between ansible_hostname, inventory_hostname, and ansible_fqdn in Ansible. Learn how these variables affect your playbooks and ad-hoc commands.

What is the difference between ansible_hostname vs inventory_hostname?

These two ansible internal variables sometimes confuse one for another but they're fundamentally different.

I'm Luca Berton and welcome to today's episode of Ansible Pilot.

ansible_hostname and ansible_fqdn

Read from the target machine hostname from the facts:

ansible_hostname read the hostname from the facts collected during the gather_facts

Same as the uname -n or hostname command-line

Need gather_facts enabled, otherwise the ansible_facts variable would be unavailable to use in your playbook

Same as hostname of the target host

As this is based on the gather_facts step. ansible_hostname not available in ad-hoc command

inventory_hostname

Read from Ansible inventory or hosts files:

inventory_hostname read the hostname from the inventory configuration or the hosts file. Could be different from the hostname configuration of the remote system. It could be only a name on the controller machine

inventory_hostname is always available to use in your playbook.

Could be different from the hostname of the target host

Available for both playbook and ad-hoc command

Playbook

Let me show you the difference between ansible_hostname vs inventory_hostname vs ansible_fqdn internal variables in a simple Ansible Playbook.

code

hostnames.yml

``yaml


---
name: hostnames Playbook
  hosts: all
  gather_facts: true
  tasks:
    - name: print inventory_hostname
      ansible.builtin.debug:
        var: inventory_hostname
    - name: print ansible_hostname
      ansible.builtin.debug:
        var: ansible_hostname
    - name: print ansible_fqdn
      ansible.builtin.debug:
        var: ansible_fqdn


inventory

`yaml


foo.example.com ansible_host=192.168.0.190
[all:vars]
ansible_connection=ssh
ansible_user=devops
ansible_ssh_private_key_file=~/.ssh/id_rsa



execution

``bash

ansible-pilot $ ansible-playbook -i ansible\ statements/inventory ansible\ statements/hostnames.yml

PLAY [hostnames Playbook] *

TASK [Gathering Facts]

ok: [foo.example.com]

TASK [print inventory_hostname] *

ok: [foo.example.com] => {

"inventory_hostname": "foo.example.com"

}

TASK [print ansible_hostname] *