Roles

Roles provide a framework for fully independent, or interdependent collections of variables, tasks, files, templates, and modules.

In Ansible, the role is the primary mechanism for breaking a playbook into multiple files.

This simplifies writing complex playbooks, and it makes them easier to reuse. The breaking of playbook allows you to logically break the playbook into reusable components.

Each role is basically limited to a particular functionality or desired output, with all the necessary steps to provide that result either within that role itself or in other roles listed as dependencies.

Roles are not playbooks. Roles are small functionality which can be independently used but have to be used within playbooks. There is no way to directly execute a role. Roles have no explicit setting for which host the role will apply to.

Top-level playbooks are the bridge holding the hosts from your inventory file to roles that should be applied to those hosts.

Utilizing Roles in Playbook

This is the code of the playbook we have written for demo purpose. This code is of the playbook Guvi.yml. We have defined the hosts: tomcat-node and called the two roles – install-tomcat and start-tomcat.

--- 
- hosts: tomcat-node 
roles: 
   - {role: install-tomcat} 
   - {role: start-tomcat} 

$ ls 
ansible.cfg  hosts  roles  Guvi.yml 

There is a tasks directory under each directory and it contains a main.yml.