Ansible roles directory structure explained

# Introduction

I will explain the ansible roles directory structure. The confusing using roles are understanding the file hierarch. Ansible provides a feature called Ansible galaxy that helps you play roles.

For example, Ansible roles directory will look like as below:

[vagrant@ansible_controller demo]$ tree nodejs
nodejs
├── defaults
│   └── main.yml
├── files
├── handlers
│   └── main.yml
├── meta
│   └── main.yml
├── README.md
├── tasks
│   └── main.yml
├── templates
├── tests
│   ├── inventory
│   └── test.yml
└── vars
    └── main.yml

8 directories, 8 files

You can be using ansible galaxy it creates a role.

$ sudo ansible-galaxy init <role-name>
# Example init nodejs role
$ sudo ansible-galaxy init nodejs

Explain Ansible directories

• Tasks: The main list of tasks to be exectued by role. it contains the main.yml file.
• Files: Contains files that can be deployed by this role
• Handlers: Contains handlers which may be used by this role or even anywhere outside this role.
• Defaults: Contains the default variables used by this role.
• Vars: This directory consists of other variables that used by the roles. These variables can be defined in ansible playbook.
• Meta: Defines metadata for this role. it contains file role dependencies.

Demo Using Ansible install nodejs

I use ansible-galaxy to download template nodejs role as command below:

[vagrant@ansible_controller demo]$ ansible-galaxy init nodejs

My Ansible structure folder and file as below:

[vagrant@ansible_controller ~]$ tree demo
demo
├── ansible.cfg
├── install-nodejs.yml
├── inventory
│   └── hosts
└── roles
    └── nodejs
        ├── defaults
        │   └── main.yml
        ├── files
        ├── handlers
        │   └── main.yml
        ├── meta
        │   └── main.yml
        ├── README.md
        ├── tasks
        │   └── main.yml
        ├── templates
        └── vars
            └── main.yml

10 directories, 9 files

Write roles/nodejs/tasks/main.yml for nodejs role as below:

---
# Example, tasks file for nodejs
- name: Node.js - Get script
  get_url:
    url: "https://rpm.nodesource.com/setup_10.x"
    dest: "{{ var_node }}/nodejs.sh"

- name: Node.js - Set execution permission to script
  file:
    path: "{{ var_node }}/nodejs.sh"
    mode: "u+x"

- name: Node.js - Execute installation script
  shell: "{{ var_node }}/nodejs.sh"

- name: Node.js - Remove installation script
  file:
    path: "{{ var_node}}/nodejs.sh"
    state: absent

- name: Node.js - Install Node.js
  yum: name={{ item }} state=present update_cache=yes
  with_items:
    - epel-release
    - nodejs

- name: Node.js - Install bower and gulp globally
  npm: name={{ item }} state=present global=yes
  with_items:
    - bower
    - gulp

# check version
- name: "Check if nodejs is installed"
  package_facts:
    manager: "auto"
- name: "nodejs result"
  debug:
     msg: "nodejs found"
  when: "'nodejs' in ansible_facts.packages"
- name: "nodejs result"
  debug:
     msg: "nodejs NOT found"
  when: "'nodejs' not in ansible_facts.packages"

Write your main playbook. Example, install-nodejs.yml file.

---
- hosts: web-server
  become: yes
  vars:
    # variable needed during node installation
    var_node: /tmp
  roles:
       - nodejs

Ansible run command

[vagrant@ansible_controller demo]$ ansible-playbook -i inventory/hosts install-nodejs.yml

The result, install nodejs on the target server as below:

Conclusion

I hope will this your helpful. Thank you for reading the DevopsRoles page!