Ansible Roles are reusable and modular units in Ansible. They simplify the organization and management of Ansible playbooks by bundling related tasks, variables, and templates into a single directory structure. Roles make it easier to implement consistent configurations and automation across multiple hosts. They encapsulate roles, reducing code duplication, and promoting a structured approach to automation. Roles typically include directories for tasks, handlers, templates, variables, and more, making it simple to manage complex infrastructure tasks. By using roles, Ansible users can enhance the scalability, maintainability, and reusability of their automation code, streamlining configuration management and orchestration.
In this example, we'll use the Nginx web server and include features like templates and handlers. This role will install Nginx, deploy a basic website, and manage the Nginx service.
Create a new Ansible role named webserver:
ansible-galaxy init ./roles/webserverDefaults are used to define default variables that can be overridden by users or other roles. These variables provide flexibility and customization for the role's behavior. Location: Default variables are defined in the defaults/main.yml file within the role directory. Syntax: Variables are defined as key-value pairs in the defaults/main.yml file. Users can override these variables in their playbook or inventory files.
Edit roles/webserver/defaults/main.yml to define default variables:
---
nginx_user: www-data
nginx_worker_processes: auto
nginx_error_log: /var/log/nginx/error.log
nginx_pid: /var/run/nginx.pid
nginx_worker_connections: 1024
nginx_server_name: localhost
nginx_root_dir: /var/www/html
nginx_index_file: index.html
Edit roles/webserver/tasks/main.yml to define the tasks:
---
- name: Install Nginx
apt:
name: nginx
state: present
notify:
- Restart Nginx
- name: Copy Nginx configuration
template:
src: nginx.conf.j2
dest: /etc/nginx/nginx.conf
notify:
- Restart Nginx
- name: Deploy Website
template:
src: index.html.j2
dest: /var/www/html/index.html
notify:
- Restart Nginx
- name: Ensure Nginx is enabled and running
service:
name: nginx
enabled: yes
state: startedPurpose: Handlers are used to define tasks that should be triggered when specific events occur during the playbook run. Common use cases include restarting a service after a configuration change or reloading a web server after deploying new content. Location: Handlers are defined in the handlers/main.yml file within the role directory. Syntax: Handlers are written as named tasks under the handlers section. They are typically associated with specific notify statements in task files. Example: In the role's handlers/main.yml file, you might define a handler named "Restart Nginx" to restart the Nginx service.
Edit the roles/webserver/handlers/main.yml file:
---
- name: Restart Nginx
service:
name: nginx
state: restarted
Create template files for Nginx configuration and the website content.
In the roles/webserver/templates directory, create nginx.conf.j2:
user {{ nginx_user }};
worker_processes {{ nginx_worker_processes }};
error_log {{ nginx_error_log }};
pid {{ nginx_pid }};
events {
worker_connections {{ nginx_worker_connections }};
}
http {
include /etc/nginx/mime.types;
default_type application/octet-stream;
server {
listen 80;
server_name {{ nginx_server_name }};
location / {
root {{ nginx_root_dir }};
index {{ nginx_index_file }};
}
}
}In the same directory, create index.html.j2:
<!DOCTYPE html>
<html>
<head>
<title>Welcome to My Website</title>
</head>
<body>
<h1>Hello, World!</h1>
</body>
</html>In your playbook, include the webserver role. Create or edit your playbook.yml:
---
- name: Configure Web Server
hosts: web_servers
become: yes
roles:
- webserverRun the playbook using the ansible-playbook command:
ansible-playbook -i inventory/hosts.ini playbook.ymlThis Ansible role will install Nginx, deploy a simple website, and manage the Nginx service. It showcases the use of templates for configuration files and handlers for service restarts. Adjust the content of the templates and other tasks to suit your specific web server configuration needs.
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