Ansible Roles / Galaxy

 

Reference:

galaxy.ansible.com

user name geerlingguy is very famous in galaxy.ansible.com:

Ansible Roles

• It is a standard directory structure to abstract the functionality of Ansible playbooks.
• You can search and download some of the existing roles from Ansible Galaxy website ( https://galaxy.ansible.com/)

Ansible Roles Directory Structure

When you create or install an ansible galaxy role, then the following directories automatically get created and these directories have a special purpose (except for the templates and tests directory). All the pre-defined directories contain main.yml, if any of these directories get called then the execution of that directory is started from main.yml code only.

defaults:	For default variables values.
files:	files which are referred to in the role.
handler:	Whenever there is any notification is triggered when the handler's main.yml file gets called which should have a definition of those notification services.
meta:	It stores role's metadata like Authorname, version etc
tasks:	Contains the definition of modules which are supposed to execute as a task.
templates:	It includes the Jinja templates definition.
tests:	Contains test cases for role
vars:	To define global variables for the roles.

EXAMPLE 1: USING OTHER PEOPLE's ROLES

Step 1: Download and use apache role from Ansible Galaxy.

Step 2: Go to this Ansible Galaxy Page ( which I got by searching apache2 in galaxy.ansible website).

Step 3: Copy the installation step. (ansible-galaxy install geerlingguy.apache)

Step 4: Uncomment roles_path in ansible.cfg file.

Step 5: Run the installation step which will download the apache role

          ansible-galaxy install geerlingguy.apache

Step 6: Go to /etc/ansible/roles directory and you will find a folder  "geerlingguy.apache"

Step 7: To use this role you need to write a playbook

      ---
          - name: using predefined ansible galaxy role to install apache

            hosts: webservers
            roles:
               - geerlingguy.apache

Step 8: Execute the playbook

          ansible-playbook apacherole.yaml

Step 9: Check all the webservers, apache should be installed on these servers and apache service is up and running.

Step 10: remove the role directory from /etc/ansible/roles

cd /etc/ansible/roles

rm -ifr geerlingguy.apache/

 EXAMPLE 2: MAKE YOUR OWN PRE-DEFINED ROLE

Step 1: Initiate an apache user-defined role in the roles directory.

cd /etc/ansible/roles 

ansible-galaxy init apache --offline

Step 2: By Executing the above command will create a folder under /etc/ansible/roles directory which has the required directory structure for the apache role.

Step 3: Create tasks to install apache on agent node.

cd /etc/ansible/roles/apache/tasks

Step 4: In the tasks folder, open main.yml file and add below code. Then create 2 more yaml files, one for installing apache(step4.1) and second for configuring apache service(step4.2).

--- 

- include: install.yml

- include: configure.yml

Step 4.1: Create Install.yml file in /tasks/

---
 - name: Installing apache on ubuntu 

   apt: 

             name: apache2 

             state: present 

   when: ansible_facts['os_family'] == "Debian" 

 - name: Installing httpd on Redhat 

   yum: 

             name: httpd 

             state: present 

   when: ansible_facts['os_family'] == "RedHat"


Step 4.2: Create Configure.yml file in /tasks/

---
  - name: apache status
    copy: src=status.txt dest=/tmp/status.txt        #should be in the files folder
    notify:                                        #notify will call the handler main.yml
       restart apache service
    when: ansible_facts['os_family'] == "Debian"

  - name: httpd status
    copy: src=status.txt dest=/tmp/status.txt
    notify:
       restart httpd service
    when: ansible_facts['os_family'] == "RedHat"

  - name: send the file
    copy: src=test.html dest=/var/www/html/test.html    #destination at files folder

Step 5: Define handler in /handlers/main.yml (usually being called by 'notify')

--- 

 # handlers file for apache 

 - name: restart apache service 

   service: 

                name=apache2 

                state=restarted 

- name: restart httpd service 

  service: 

                name=httpd 

                state=restarted


Step 6: Create test.html and status.txt file in files folder.

cd /etc/ansible/roles/apache/files

echo "<h1> Super Cool Html file </h1>" >> test.html 

 

touch status.txt

Step 7: Create playbook (apache.yaml) and call apache role.

vi apache.yaml
---
 - hosts: webservers
   roles:
            - apache

Step 8: Execute playbook and verify on webservers that apache is installed and running.

ansible-playbook apache.yaml