Variables and Facts

Variables and facts make your Ansible automation dynamic and reusable. Variables let you parameterise playbooks, while facts provide real-time information about your managed nodes.

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Defining Variables

In a Playbook

---
- name: Deploy application
  hosts: webservers
  vars:
    app_name: myapp
    app_port: 8080
    app_env: production

  tasks:
    - name: Print app info
      debug:
        msg: "Deploying {{ app_name }} on port {{ app_port }} ({{ app_env }})"

In External Files

---
- name: Deploy application
  hosts: webservers
  vars_files:
    - vars/common.yml
    - vars/{{ env }}.yml

At the Command Line

# Single variable
ansible-playbook site.yml -e "app_env=staging"

# Multiple variables
ansible-playbook site.yml -e "app_env=staging app_port=9090"

# Variables from a file
ansible-playbook site.yml -e "@vars/overrides.yml"

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Variable Precedence

Ansible has a well-defined hierarchy for variable precedence. When the same variable is defined in multiple places, the highest precedence wins: