DevOps Classroom Series – 09/Oct/2021

Ansible Contd

• Manual Steps:

sudo apt update
sudo apt install apache2 -y
sudo apt install php libapache2-mod-php php-mysql -y
# Create a file in /var/www/html/info.php "<?php phpinfo(); ?>"
echo "<?php phpinfo(); ?>" | sudo tee /var/www/html/info.php
sudo service apache2 restart

• We have written the play book for the following steps

sudo apt update
sudo apt install apache2 -y

• Now lets try to use the ansible module for this manual step

sudo apt install php libapache2-mod-php php-mysql -y

• Refer Here for the changes done
• Lets do syntax check
• Now lets apply changes
• Now we need to create a file using ansible. Manual steps

# Create a file in /var/www/html/info.php "<?php phpinfo(); ?>"
echo "<?php phpinfo(); ?>" | sudo tee /var/www/html/info.php

• To create empty files we have file module but to create files with pre-existing content we have either copy the files from ansible control node to nodes or create a file from content using copy module Refer Here
• Refer Here for the changes
• Now we need to restart the apache service. Manual steps

sudo service apache2 restart

• Refer Here for the service module. Lets enable the apache2 service to start automatically during system restarts and ensure the service is restarted after php info page creation.
• Refer Here for the changes done
• Lets try to rerun the playbook
• Ideally we would like to restart apache only when info.php is created.
  • We need to execute Restart Apache2 Task only when create info.php task is executed.
  • In ansible when we want to execute some tasks as a reaction to other tasks we need to use handlers.
  • Refer Here for the changeset containing restarting the service as handler
  • Refer Here for handler documentation
• The playbook which we have written

---
- name: Install apache and php
  hosts: all
  become: yes
  tasks:
    - name: install apache2
      apt:
        name: apache2
        update_cache: yes
        state: present
    - name: install php modules
      apt:
        name:
          - php 
          - libapache2-mod-php 
          - php-mysql 
        state: present
    - name: create info.php
      copy:
        dest: /var/www/html/info.php
        content: |
          <?php 
          phpinfo(); 
          ?>
      notify:
        - Restart Apache2
  handlers:
    - name: Restart Apache2
      service:
        name: apache2
        enabled: yes
        state: restarted

• To be effective in playbook development, we should

  • install softwares/deploy applications manually to know the steps
  • Become good in searching right ansible modules
  • Good with YAML understanding

• Exercise:

  • Try to install the following applications manually on any linux machine
    • Tomcat
    • Nginx
    • mysql
    • Postgres
    • Mongo db