# 4. Roles

* It is a concept that deals with ideas rather than events. It is basically another level of abstraction used to organize playbooks
* They provide a skeleton for an independent and reusable collection of variables, tasks, templates, files and modules which can be automatically loaded into the playbook

***

### Creation

#### ansible galaxy

it is a website that lets ansible users share their roles and modules

#### usage

```sh
ansible-galaxy init roleName
```

***

### Directory Structure

#### default

contain the default variables that are going to be used for by this role

#### files

contains files that can be deployed by this role. It contains files that need to be sent to the hosts while configuring the role.

#### handlers

contains handlers which may be used by this role or outside this particular role

#### meta

defines metadata for this role. Basically, it contains files that establish role dependencies.

#### tasks

contains main list of tasks that are to be executed by the role. It contains the main.yml file for that particular role.

#### templates

contains files which can be modified and added to the host being provisioned Jinja2(template language) is used to achieve the modifications.

#### tests

it is used to integrate testing with Ansible Playbooks.

#### vars

it consists of other variables that are going to be used by the role. these variables can be defined in your playbook, but it's a good habit to define them in this section.

***

### Sample Role NodeJS

Create a role named `nodejs` inside `/etc/ansible/roles` directory and then create a file named `main.yml` inside `/etc/ansible/roles/nodejs` directory.

```yaml
- name: Node.Js - Get script
  get_url:
    url: "http://deb.nodesource.com/setup_6.x"
    dest: "{{ var_node }}/nodejs.sh"

- name: Node.Js - Set exec perm to script
  file:
    path: "{{ var_node }}/nodejs.sh"
    mode: "u+x"

- name: Node.Js - Exec install script
  shell: "http://deb.nodesource.com/setup_6.x"

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

- name: Node.Js - Install Node.js
  apt: name={{ item }} state=present update_cache=yes
  with_items:
    - build-essential
    - nodejs

- name: Install NPM
  apt:
    name: npm
    state: present

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

***

### Sample Playbook

This playbook will be created in `/etc/ansible` directory and will refer the role `nodejs`

```yaml
- hosts: all
  become: true
  vars:
    # needed for node installation
	  ansible_become_pass: aziz
	  var_node: /tmp
  roles:
    - nodejs
```

***


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