Ansible Variables Guide

What is a Variable in Ansible?

In Ansible, a variable is a name (placeholder) used to store a value that can be reused across playbooks, roles, inventories, and tasks.

Variables help make automation:

✅ Dynamic
✅ Flexible
✅ Reusable
✅ Less error-prone

Simple Definition

Ansible Variable = Placeholder for data

Example

app_port: 8080

app_port → Variable name
8080 → Value

Usage inside playbook:

{{ app_port }}

Why Use Variables?

Avoid hard-coding values
Manage different environments (dev, test, prod)
Reuse playbooks for multiple servers
Reduce human errors
Improve readability & maintainability

Types of Ansible Variables

Variable Type	Example	Purpose
Play vars	vars:	Used inside a playbook
Inventory vars	host var	Per host values
Group vars	group_vars/web.yml	Per group values
Host vars	host_vars/server.yml	Per host values
Role defaults	defaults/main.yml	Lowest priority
Role vars	vars/main.yml	High priority
Facts	ansible_os_family	System information
Extra vars	-e "a=1"	Highest priority
Register	register: result	Capture task output
Set facts	set_fact:	Runtime variables
vars_prompt	User input	Ask at runtime
vars_files	vars_files:	Load from file
Environment vars	environment:	Set environment variables
Loop vars	item	Loop iteration
Magic vars	hostvars	Built-in variables

Example Playbook

---
- hosts: web
  vars:
    myname: "shan"
    myage: 26

  vars_files:
    - ak.yaml

  tasks:
    - name: Display my name and age
      debug:
        msg: "My name is {{ myname }} and my age is {{ myage }}"

    - name: Display OS distribution
      debug:
        msg: "The OS distribution is {{ ansible_distribution }}"

    - name: Display values from external file
      debug:
        msg: "Son of {{ fname }} & {{ mname }}"

    - name: Display host-specific variable
      debug:
        msg: "The server is located in {{ location }}"

Step-by-Step Explanation

1️⃣ Hosts Section

- hosts: web

The playbook runs on the web host group.

2️⃣ Playbook Variables

vars:
  myname: "shan"
  myage: 26

Available only inside this play.

3️⃣ External Variable File

vars_files:
  - ak.yaml

Example ak.yaml:

fname: Kumar
mname: Lakshmi

4️⃣ Using Facts

{{ ansible_distribution }}

Automatically collected system information.

5️⃣ Host-Specific Variables

File: host_vars/node1.yaml

location: Chennai

This value applies only to that specific host.