A playbook is a YAML file that describes the desired state of your servers as an ordered list of tasks. Unlike ad-hoc commands, playbooks are reusable, readable, and version-controlled — this is how Ansible is used in real projects.

🎯 Learning Objectives

By the end of this lesson you will:

• Read and write playbook YAML structure
• Use modules, variables, and handlers
• Run a playbook and read its output
• Understand idempotency in practice

Anatomy of a Playbook

Here’s a complete playbook that installs and starts nginx on all web servers — webserver.yml:

---
- name: Configure web servers
hosts: web
become: true

tasks:
  - name: Install nginx
    apt:
      name: nginx
      state: present
      update_cache: true

  - name: Ensure nginx is running and enabled
    service:
      name: nginx
      state: started
      enabled: true

Reading it top to bottom:

• hosts: web — target the web group from the inventory.
• become: true — run with sudo.
• tasks: — an ordered list; each task calls a module (apt, service) with parameters.
• name: — a human-readable label shown in the output.

Run the Playbook

ansible-playbook -i inventory.ini webserver.yml

PLAY [Configure web servers] **************************

TASK [Install nginx] **********************************
changed: [web-01]
changed: [web-02]

TASK [Ensure nginx is running and enabled] ************
ok: [web-01]
ok: [web-02]

PLAY RECAP ********************************************
web-01  : ok=3  changed=1  unreachable=0  failed=0
web-02  : ok=3  changed=1  unreachable=0  failed=0

Run it again and watch changed drop to 0 — everything is already in the desired state. That’s idempotency in action.

Variables and Handlers

Variables keep playbooks flexible:

- name: Configure web servers
hosts: web
become: true
vars:
  package_name: nginx

tasks:
  - name: Install the web server
    apt:
      name: "{{ package_name }}"
      state: present

Handlers run only when notified by a changed task — ideal for restarting a service only when its config actually changed:

  tasks:
  - name: Copy nginx config
    copy:
      src: nginx.conf
      dest: /etc/nginx/nginx.conf
    notify: Restart nginx

handlers:
  - name: Restart nginx
    service:
      name: nginx
      state: restarted

🧪 Hands-on Lab

---
- name: Base setup
hosts: web
become: true
tasks:
  - name: Install htop
    apt:
      name: htop
      state: present
      update_cache: true

🧠 Knowledge Check

💼 Interview Preparation

🎉 You’ve Completed the Core Curriculum

Congratulations — you’ve worked through Linux, Git & GitHub, Python, AWS, Azure, and Ansible. You can now operate Linux servers, version and collaborate on code, script automation in Python, deploy across the two largest clouds, and configure fleets of servers with Ansible. That’s a genuinely strong DevOps foundation.

From the homepage roadmap, natural next steps are Docker, Kubernetes, Terraform, and CI/CD — all ready to be built in this same format whenever you are.