🧑‍🏫 Ansible Training - Day 2: Playbooks, Variables, Tasks & Conditions

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📘 1. What is a Playbook?

A Playbook is a YAML file containing one or more "plays". Each play targets a group of hosts and runs a list of tasks using Ansible modules.

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🔹 Basic Playbook Structure

- name: Play Name (describes the purpose)
  hosts: group_name
  become: true  # use sudo
  tasks:
    - name: Task name
      module_name:
        option1: value1
        option2: value2

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📁 2. Create Your First Playbook: web_setup.yml

- name: Install and start Apache on Web Servers
  hosts: web
  become: true
  tasks:
    - name: Install Apache
      yum:
        name: httpd
        state: present

    - name: Start and enable Apache
      service:
        name: httpd
        state: started
        enabled: yes

🔄 Run the playbook:

ansible-playbook -i inventory web_setup.yml

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💡 3. Variables in Playbooks

You can define variables at different levels:

• Inside playbooks
• Inside inventory (host/group)
• External files

🔸 Inline variable

vars:
  my_package: httpd

tasks:
  - name: Install a package
    yum:
      name: "{{ my_package }}"
      state: present

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📁 4. Example: DB Setup Playbook db_setup.yml

- name: Install and start MariaDB
  hosts: db
  become: true
  tasks:
    - name: Install MariaDB
      yum:
        name: mariadb-server
        state: present

    - name: Start and enable MariaDB
      service:
        name: mariadb
        state: started
        enabled: yes

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🔄 5. Using when Condition

Run a task only when a condition is met.

- name: Create special user only on Amazon Linux
  hosts: all
  become: true
  tasks:
    - name: Create user
      user:
        name: specialuser
      when: ansible_distribution == "Amazon"

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🧪 6. Real-World Lab: Web + DB Setup Using Playbooks

📁 Inventory file (same as Day 1):

[web]
172.31.9.115 ansible_user=ec2-user ansible_ssh_private_key_file=~/.ssh/your-key.pem

[db]
172.31.15.215 ansible_user=ec2-user ansible_ssh_private_key_file=~/.ssh/your-key.pem

📘 Playbook file 1: web_setup.yml

- name: Configure Apache web server
  hosts: web
  become: true
  tasks:
    - name: Install Apache
      yum:
        name: httpd
        state: present

    - name: Start Apache
      service:
        name: httpd
        state: started
        enabled: yes

    - name: Copy homepage
      copy:
        content: "Welcome to the Apache Web Server"
        dest: /var/www/html/index.html

📘 Playbook file 2: db_setup.yml

- name: Configure MariaDB server
  hosts: db
  become: true
  tasks:
    - name: Install MariaDB
      yum:
        name: mariadb-server
        state: present

    - name: Start MariaDB
      service:
        name: mariadb
        state: started
        enabled: yes

▶️ Run:

ansible-playbook -i inventory web_setup.yml
ansible-playbook -i inventory db_setup.yml

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🧠 7. Homework & Practice

• Create a playbook to:
  • Install git on all nodes
  • Create a user devops on only web nodes
  • Set the timezone to Asia/Kolkata on all hosts

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📝 Summary (What Students Learned)

Topic	Covered
Playbook Syntax	✅
YAML Structure	✅
Tasks and Modules	✅
Variables	✅
Conditions (when)	✅
Multiple Playbooks	✅
Hands-on Lab	✅

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