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12-Day5-3-roles

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Day 5: Lab Series 2 - Introduction to Roles and Their Directory Structure

Objective:

This lab introduces participants to Ansible roles and their structured directory organization, enabling efficient and reusable playbook design. Participants will learn to create, organize, and use roles in playbooks.

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Lab 2.1: Creating a Basic Role

Scenario:

Set up a web server using an Ansible role.

Steps:

  1. Create the Role Structure:

    Use the ansible-galaxy command to create a role named webserver:

    ansible-galaxy init ~/day5/roles/webserver

    Directory structure will look like this:

    ~/day5/roles/webserver/
├── defaults/
├── files/
├── handlers/
├── meta/
├── tasks/
├── templates/
├── tests/
└── vars/

  2. Define the Role Tasks:

    Edit ~/day5/roles/webserver/tasks/main.yaml:

    ---
- name: Install Apache
  yum:
    name: httpd
    state: present

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

  3. Define Default Variables:

    Edit ~/day5/roles/webserver/defaults/main.yaml:

    ---
web_port: 80

  4. Add a Handler:

    Edit ~/day5/roles/webserver/handlers/main.yaml:

    ---
- name: Restart Apache
  service:
    name: httpd
    state: restarted

  5. Create a Template:

    Save as ~/day5/roles/webserver/templates/index.html.j2:

    <html>
<head>
    <title>Welcome to {{ inventory_hostname }}</title>
</head>
<body>
    <h1>Apache is running on {{ ansible_facts['os_family'] }}!</h1>
</body>
</html>

  6. Modify the Role Tasks to Use the Template:

    Update ~/day5/roles/webserver/tasks/main.yaml:

    ---
- name: Install Apache
  yum:
    name: httpd
    state: present

- name: Deploy web page
  template:
    src: index.html.j2
    dest: /var/www/html/index.html
    mode: '0644'

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

  7. Create a Playbook to Use the Role:

    Save as ~/day5/webserver_role_playbook.yaml:

    ---
- name: Deploy Web Server
  hosts: webservers
  roles:
    - role: webserver

  8. Run the Playbook:

    ansible-playbook ~/day5/webserver_role_playbook.yaml -i inventory

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Lab 2.2: Adding Role Variables

Scenario:

Customize the web server setup by modifying role variables.

Steps:

  1. Update the Default Variable: Edit ~/day5/roles/webserver/defaults/main.yaml to include:

  2. Modify the Tasks to Use the Variable:

    Update ~/day5/roles/webserver/tasks/main.yaml:

  3. Run the Playbook:

  4. Exercise:

    • Modify the role to support SSL configuration by adding another task and variable for the SSL module.

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Lab 2.3: Using Multiple Roles in a Single Playbook

Scenario:

Set up both a web server and a database server using separate roles.

Steps:

  1. Create a Role for the Database Server:

    Use ansible-galaxy init:

  2. Define Tasks for the Database Server Role:

    Edit ~/day5/roles/dbserver/tasks/main.yaml:

  3. Modify the Master Playbook:

    Save as ~/day5/multi_role_playbook.yaml:

  4. Run the Master Playbook:

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Optional Lab: Debugging and Troubleshooting Roles

Scenario:

Test failure scenarios in roles (e.g., missing variables, incorrect templates). Debug and fix the issues.

  1. Remove a required file or variable in the role.

  2. Run the playbook and observe the error.

  3. Add error handling or default values to fix the issue.

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Key Learning Points:

  1. Ansible Role Structure: Understand the modular and organized directory structure of roles.

  2. Reusability and Scalability: Roles make it easier to reuse and scale configurations across multiple environments.

  3. Variables in Roles: Customizing roles using defaults, vars, and command-line overrides (-e).

  4. Combining Roles: Use multiple roles in a single playbook for complex setups.

These exercises lay the foundation for using roles effectively in real-world deployments.

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