12-Day5-3-roles

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.

Lab 2.1: Creating a Basic Role

Scenario:

Set up a web server using an Ansible role.

Steps:

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/

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

Define Default Variables:
Edit ~/day5/roles/webserver/defaults/main.yaml:
```
---
web_port: 80
```

Add a Handler:

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

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

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>

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

Create a Playbook to Use the Role:

Save as ~/day5/webserver_role_playbook.yaml:

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

Run the Playbook:

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

Lab 2.2: Adding Role Variables

Scenario:

Customize the web server setup by modifying role variables.

Steps:

Update the Default Variable: Edit ~/day5/roles/webserver/defaults/main.yaml to include:
```
---
web_port: 8080
```

Modify the Tasks to Use the Variable:

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

---
- name: Configure Apache to Listen on Custom Port
  lineinfile:
    path: /etc/httpd/conf/httpd.conf
    regexp: '^Listen '
    line: "Listen {{ web_port }}"
    state: present
    notify: Restart Apache

Run the Playbook:

ansible-playbook ~/day5/webserver_role_playbook.yaml -e web_port=8080 -i inventory

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

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:

Create a Role for the Database Server:
Use ansible-galaxy init:
```
ansible-galaxy init ~/day5/roles/dbserver
```

Define Tasks for the Database Server Role:

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

---
- name: Install MariaDB
  yum:
    name: mariadb-server
    state: present

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

Modify the Master Playbook:

Save as ~/day5/multi_role_playbook.yaml:

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

- name: Deploy Database Server
  hosts: dbservers
  roles:
    - role: dbserver

Run the Master Playbook:

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

Optional Lab: Debugging and Troubleshooting Roles

Scenario:

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

Remove a required file or variable in the role.
Run the playbook and observe the error.
Add error handling or default values to fix the issue.

Key Learning Points:

Ansible Role Structure: Understand the modular and organized directory structure of roles.
Reusability and Scalability: Roles make it easier to reuse and scale configurations across multiple environments.
Variables in Roles: Customizing roles using defaults, vars, and command-line overrides (-e).
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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Last updated 10 days ago