Variables

Stores information that varies with each host

In playbook.yaml:

name:
hosts:
vars:
	dns_server: 10.1.250.10

In separate file

variable1: value1

Variable Precedence

To assign a variable to a group, you can do:

...
 
[web_servers]
web1
web2
web3
 
[web_servers:vars]
dns_server=10.5.5.3

Note

Precedence hierarchy: Extra vars (while running playbook) > Play vars > Host vars > Group vars

Variable Scope

Scope	Where it lives	When to use it
Global	ansible.cfg or Env vars	For system-wide settings like SSH users.
Group	group_vars/webservers.yml	When you want all your servers to share a setting.
Host	host_vars/pi-brain.yml	For settings unique to one specific server
Task	Inside a specific task	For a one-time setting, like a temporary folder path.

Example File

# --- Host Definitions ---
[web_servers]
# Host variable wins over everything else
raspbi ansible_host=192.168.1.50 storage_path=/mnt/ssd_usb

[db_servers]
db_pi ansible_host=192.168.1.51

# --- Group Variables ---
[web_servers:vars]
http_port=80
is_exposed=true

# --- Parent Group Definitions ---
[lab:children]
web_servers
db_servers

# --- Global/Parent Variables ---
[lab:vars]
ansible_user=atakan
ansible_ssh_private_key_file=~/.ssh/id_rsa

Magic Variables

hostvars

You can access other hosts’ variables using ‘hostvars’ magic variable

msg: '{{ hostvars['web2'].ansible_host }}'

groups

It shows you all the hosts that belong to the specific group msg: '{{ groups['america_servers'] }}'

group_names

It shows you all the group the host is part of msg: '{{ group_names }}'