Ansible Roles

 Overtime working with ansible a user may create hundreds of playbooks, variables, templates, defaults etc. Roles allow users to group this logic into an organized manner making reusability and sharing of ansible structure easier.

• Overtime working with ansible a user may create hundreds of playbooks, variables, templates, defaults etc.

• Roles allow users to group this logic into an organized manner making reusability and sharing of ansible structure easier.

• Roles uses directories to structure and group all the playbooks, variables, templates, tasks, handlers, files, and defaults.

• This collected logic can be grouped in any way the user wants, for example you can group server specific roles together

• These roles can then be used inside playbooks and even as in-line commands


Ansible Galaxy

• Galaxy provides pre-packaged units of work known to Ansible as roles

• Roles can be dropped into Ansible PlayBooks and immediately put to work

• To create a Ansible roles, use ansible-galaxy command which has the templates to create it

• This will create it under the default directory /etc/ansible/roles and do the modifications else we need to create each directories and files manually # ansible-galaxy init /etc/ansible/roles/apache –offline

• where, ansible-glaxy is the command to create the roles using the templates

• init is to initiliaze the role

• apache is the name of role

• offline - create offline mode rather than getting from online repository

• You can also download Ansible roles from https://galaxy.ansible.com/ 


Exercise  - Ansible Roles

To create a Ansible roles, use ansible-galaxy command which has the templates to create it. This will create it under the default directory /etc/ansible/roles and do the modifications else we need to create each directories and files manually

# ansible-galaxy init /etc/ansible/roles/apache –offline

where, ansible-glaxy is the command to create the roles using the templates

- init is to initiliaze the role

- apache is the name of role

- offline - create offline mode rather than getting from online repository

List out the directory created under /etc/ansible/roles

# tree /etc/ansible/roles/apache/

We have got the clean directory structure with the ansible-galaxy command. Each directory must contain a main.yml file, which contains the relevant content

Directory Structure:

- tasks - contains the main list of tasks to be executed by the role

- handlers - contains handlers, which may be used by this role or even anywhere outside this role

- defaults - default variables for the role

- vars - other variables for the role. Vars has the higher priority than defaults

- files - contains files required to transfer or deployed to the target machines via this role

- templates - contains templates which can be deployed via this role

- meta - defines some data / information about this role (author, dependency, versions, examples, etc,.)


Below is a sample playbook codes to deploy Apache web server. Lets convert this playbook codes into Ansible roles

---

- hosts: all

tasks:

- name: Install httpd Package

yum: name=httpd state=latest

- name: Copy httpd configuration file

copy: src=/data/httpd.original dest=/etc/httpd/conf/httpd.conf

- name: Copy index.html file

copy: src=/data/index.html dest=/var/www/html

notify:

- restart apache

- name: Start and Enable httpd service

service: name=httpd state=restarted enabled=yes

handlers:

- name: restart apache

service: name=httpd state=restarted


First, move on to the Ansible roles directory and start editing the yml files

# cd /etc/ansible/roles/apache


1. Tasks

Edit main.yml available in the tasks folder to define the tasks to be executed

---

# tasks file for apache

- name: Install httpd package

yum: name=httpd state=latest

- name: Copy httpd configuration file

copy: src="/etc/ansible/roles/apache/files/httpd.original"

dest="/etc/httpd/conf/httpd.conf" owner=root remote_src=True

- name: Copy index.html file

copy: src="/etc/ansible/roles/apache/files/index.html" dest="/var/www/html" owner=root remote_src=True

notify:

- restart apache

- name: Start and Enable htpd service

service: name=httpd state=restarted enabled=yes


2. Files

Copy the required files (httpd.conf and index.html) to the files directory

# cat files/index.html

This is a homepage created for ansible roles.


3. Handlers

Edit handlers main.yml to restart the server when there is a change. Because we have already defined it in the tasks with notify option. Use the same name "restart apache" within the main.yml file as below

# cat handlers/main.yml

---

# handlers file for /etc/ansible/roles/apache

- name: restart apache

service: name=httpd state=restarted


4. Meta

Edit meta main.yml to add the information about the roles like author, descriptions, license, platforms supported

# cat meta/main.yml

galaxy_info:

author: manika

description: Apache Webserver Role

company: Leading Partners

# If the issue tracker for your role is not on github, uncomment the

# next line and provide a value

# issue_tracker_url: http://example.com/issue/tracker

# Some suggested licenses:

# - BSD (default)

# - MIT

# - GPLv2

# - GPLv3

# - Apache

# - CC-BY

license: license (GPLv2, CC-BY, etc)

min_ansible_version: 1.2

# If this a Container Enabled role, provide the minimum Ansible Container version.

------skipped


List out the created files

# tree

.

|-- README.md

|-- defaults

| `-- main.yml

|-- files

| |-- httpd.conf

| `-- index.html

|-- handlers

| `-- main.yml

|-- meta

| `-- main.yml

|-- tasks

| |-- configure.yml

| |-- install.yml

| |-- main.yml

| `-- service.yml

|-- templates

|-- tests

| |-- inventory

| `-- test.yml

`-- vars

`-- main.yml

8 directories, 13 files


We have got all the required files for Apache roles. Lets apply this role into the ansible playbook "runsetup.yml" as below to deploy it on the client nodes

# cat /etc/ansible/runsetup.yml

---

- hosts: all

remote_user: test

become: yes

become_method: sudo

roles:

- apache


Lets verify for syntax errors:

# ansible-playbook /etc/ansible/runsetup.yml --syntax-check

Lets deploy the role

# ansible-playbook /etc/ansible/runsetup.yml

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