Variables (Overview)¶

This page is a map, not the full explanation — it exists so you can write a real playbook today. The complete precedence order, magic variables, and set_fact/combine behavior live in the dedicated Variables & Data section; come back here as a quick refresher.

Where a Value Can Come From¶

# 1. Inventory (host_vars / group_vars, or inline)
[web]
web01 http_port=8080

# 2. Play-level vars
- hosts: web
  vars:
    http_port: 8080

# 3. Role defaults (defaults/main.yml) — freely overridable
http_port: 80

# 4. Registered from a previous task
- ansible.builtin.command: cat /etc/app/port
  register: port_check

# 5. Facts, gathered automatically from the host
{{ ansible_facts['default_ipv4']['address'] }}

# 6. Extra vars, on the command line — always wins
ansible-playbook site.yml -e "http_port=9090"

Use {{ variable_name }} to reference a variable inside a string, and bare variable_name in most key: value task arguments.

The One Rule Worth Memorizing Now¶

More than one of these can set the same variable name at once — when that happens, Ansible has a strict, memorizable order it resolves conflicts by (-e always wins; role defaults always lose). That full order is the single most-asked Ansible question in real support channels and interviews — it has its own page for a reason: Variable Precedence.

Interview Questions¶

• Name three places a variable's value can come from.
• What's the fastest command to check what value Ansible actually resolved for a variable on a given host?

Next¶

Continue to Conditionals, or jump ahead to Variable Precedence if a variable isn't behaving the way you expect right now.