Ansible Fundamentals (Configuration Management)

Ansible is automation for configuration management and deployments.

Core concepts:

• Inventory: list of hosts to manage
• Playbook: YAML describing desired tasks/state
• Modules: the units that actually do work (copy, file, service, template, etc.)
• Idempotency: re-running doesn’t “keep changing” things unnecessarily

Theory first: infrastructure consistency at scale

Ansible’s real value is not just remote command execution—it is consistency. You define expected system state once and apply it repeatedly across environments with predictable outcomes.

Idempotency is the foundation of that consistency: safe re-runs make automation reliable during drift correction, incident recovery, and continuous delivery.

Learning outcomes

By the end, you can:

• create an inventory file
• run a simple playbook
• understand variables and handlers

1) Inventory

inventory.ini:

[web]
web1.example.com
web2.example.com

[db]
db1.example.com

2) Ping test (does Ansible reach hosts?)

site.yml:

---
- name: Connectivity test
  hosts: web
  gather_facts: false
  tasks:
    - name: ping
      ansible.builtin.ping:

Run:

ansible-playbook -i inventory.ini site.yml

3) Example: install and start a service

---
- name: Ensure nginx is installed and running
  hosts: web
  become: true
  tasks:
    - name: Install nginx
      ansible.builtin.apt:
        name: nginx
        state: present
        update_cache: true

    - name: Start nginx
      ansible.builtin.service:
        name: nginx
        state: started
        enabled: true

4) Variables and templates (pattern)

Variables let you reuse playbooks across environments. A simple variable file vars.yml:

nginx_port: 8080

Then use in tasks/templates.

5) Handlers (run only when something changes)

Pattern:

• notify handler when config changes

- name: Deploy nginx config
  ansible.builtin.template:
    src: nginx.conf.j2
    dest: /etc/nginx/nginx.conf
  notify: Restart nginx

handlers:
  - name: Restart nginx
    ansible.builtin.service:
      name: nginx
      state: restarted

Next steps

Next tutorials:

• Ansible roles (reusable components)
• idempotent config patterns
• Terraform + Ansible CI/CD orchestration