Ansible inventory_hostname vs ansible_hostname vs ansible_fqdn (Explained) — Video Tutorial

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] ********************************************************************* ok: [foo.example.com] => { "ansible_hostname": "Playbook" } TASK [print ansible_fqdn] ************************************************************************* ok: [foo.example.com] => { "ansible_fqdn": "demo.example.com" } PLAY RECAP **************************************************************************************** foo.example.com : ok=4 changed=0 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0 ansible-pilot $ ``` idempotency ```