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 than 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.

To download and install an ansible-galaxy role


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

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

Step 3: Copy the installation step.

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: Goto /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.


To create user-defined roles.

Step 1:- Create an apache user-defined role

          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:- Open main.yml file and add below code where I am including 2 yaml files, one for installing apache and second for configuring apache service


--- 

- include: install.yml

- include: configure.yml

Step 5:- Create Install.yml file

   

 ---
 - 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 6:- Create Configure.yml file

---
  - name: apache status
    copy: src=status.txt dest=/tmp/status.txt
    notify:
       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

Step 7:- Define handler in main.yml file.

 ---
  # handlers file for apache
  - name: restart apache service
    service: name=apache2 state=restarted
  - name: restart httpd service
    service: name=httpd state=restarted

Step 8:- 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 9:- Create playbook (apache.yaml) and call apache role.     

---

 - hosts: webservers

       roles:

           - apache

Step 10: Execute playbook and verify on webservers that apache is installed and running.        

   ansible-playbook apache.yml


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