Ansible Variable

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

Instead of hard-coding values, you define variables and reuse them wherever needed.

Simple Definition

Ansible Variable = Placeholder for data

Example

app_port: 8080

app_port: 8080

app_port → variable name
8080 → value

You can use this variable anywhere in your playbook as:

{{ app_port }}

{{ app_port }}

Why Use Variables in Ansible?

Avoid hard-coding values
Easily manage different environments (dev, test, prod)
Reuse the same playbook for multiple servers
Reduce human errors
Improve readability and maintainability

Types of Ansible Variables (With Examples)

Variable Type	Example	Purpose
Play vars	`vars:`	Used only 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 values at runtime
vars_files	`vars_files:`	Load variables from file
Environment vars	`environment:`	Set environment variables
Loop vars	`item`	Loop iteration
Magic vars	`hostvars`	Built-in variables

Example Playbook With Explanation

Playbook Code

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

  vars_files:
    - ak.yaml   # External variable file

  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 }}"

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

  vars_files:
    - ak.yaml   # External variable file

  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

- hosts: web

The playbook runs on the web host group.

2️⃣ Playbook Variables (`vars`)

vars:
  myname: "shan"
  myage: 26

vars:
  myname: "shan"
  myage: 26

These variables are defined inside the playbook
Available only within this play

Usage:

{{ myname }}
{{ myage }}

{{ myname }}
{{ myage }}

3️⃣ External Variable File (`vars_files`)

vars_files:
  - ak.yaml

vars_files:
  - ak.yaml

Example ak.yaml:

fname: Kumar
mname: Lakshmi

fname: Kumar
mname: Lakshmi

These variables can be used directly in tasks:

{{ fname }}
{{ mname }}

{{ fname }}
{{ mname }}

4️⃣ Using Variables in Tasks

msg: "My name is {{ myname }} and my age is {{ myage }}"

msg: "My name is {{ myname }} and my age is {{ myage }}"

{{ }} is Jinja2 syntax
Used to print or reference variables

5️⃣ Using Facts (Built-in Variables)

{{ ansible_distribution }}

{{ ansible_distribution }}

Facts are automatically collected system information
Example outputs: Ubuntu, CentOS, Amazon Linux

6️⃣ Host-Specific Variables (Host Vars)

File:

host_vars/node1.yaml

host_vars/node1.yaml

Content:

location: Chennai

location: Chennai

Usage in playbook:

{{ location }}

{{ location }}

This value applies only to that specific host