Roles

What it is

In Ansible, roles are a structured way to organize reusable automation logic. A role encapsulates all the components needed to configure a particular piece of infrastructure – including tasks (the actual steps to perform), handlers (actions triggered by changes, like restarting a service), templates (dynamic configuration files), static files, variables, and default values – in a standardized directory layout. Roles allow you to modularize your playbooks, making them easier to read, maintain, and reuse across different projects or hosts. Instead of writing all tasks directly in a playbook, you reference a role in the playbook and optionally override variables or defaults, which makes modifying behavior simple without touching the role itself.

Ansible Galaxy

Ansible Galaxy is the community hub for sharing and downloading roles and collections. Instead of writing everything from scratch, you can leverage existing automation.

Install roles from Galaxy:

# Install a role
ansible-galaxy install geerlingguy.nginx
 
# OR
 
# Install from requirements file
ansible-galaxy install -r requirements.yml

Example requirements.yml:

# Install from Galaxy
- name: geerlingguy.nginx
  version: "2.8.0"
 
# Install from Git
- src: https://github.com/company/custom-role.git
  name: custom-role

Use Galaxy roles in playbooks:

- hosts: webservers
  roles:
    - geerlingguy.nginx
    - custom-role

Collections

Collections are distribution packages that can contain roles, modules, plugins, and other Ansible content. They provide a way to organize and distribute related automation content.

Install collections:

ansible-galaxy collection install community.general
ansible-galaxy collection install -r requirements.yml

Example collection requirements:

collections:
  - name: community.general
    version: ">=3.0.0"
  - name: ansible.posix

Example

---
- name: Deploy customized nginx webserver
  hosts: webservers # A group defined in the inventory
  become: yes # Use elevated permissions
 
  roles:
    - role: nginx
      vars:
        nginx_port: 8080           # Override default HTTP port
        nginx_service_name: nginx   # Ensure correct service name
        index_message: "Welcome to Nginx!"  # Custom content for index page

Nginx Role

1. defaults/main.yml (defaults for all variables)

---
nginx_port: 80
nginx_service_name: nginx
index_message: "Hello from Ansible!"   # Default index page message

---

2. templates/nginx.conf.j2 (uses overridden port)

user www-data;
worker_processes auto;
pid /run/nginx.pid;
 
events {
    worker_connections 1024;
}
 
http {
    server {
        listen {{ nginx_port }};
        server_name _;
 
        root /var/www/html;
        index index.html;
 
        location / {
            try_files $uri $uri/ =404;
        }
    }
}

---

3. tasks/main.yml (dynamic content for index page)

---
- name: Install nginx
  apt:
    name: "{{ nginx_service_name }}"
    state: present
    update_cache: yes
 
- name: Deploy nginx config
  template:
    src: nginx.conf.j2
    dest: /etc/nginx/nginx.conf
  notify: Restart nginx
 
- name: Deploy custom index page
  copy:
    content: "{{ index_message }}"
    dest: /var/www/html/index.html
    owner: www-data
    group: www-data
    mode: '0644'

---

4. handlers/main.yml

---
- name: Restart nginx
  service:
    name: "{{ nginx_service_name }}" #
    state: restarted