DevOps Classroom Series – 08/Oct/2021

Approach

• We use ansible in DevOps to automate deploying Applications, So we need to know the manual way of deploying before we automate the deployment.
• Make a note of all the steps involved in deploying an application and try to automate each step using Configuration Management.
• Example 1: Installing Apache and PHP on the Ubuntu server
  • Manual Steps: (Ubuntu 20.04)
    • all steps Refer Here

    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
    

    • Navigate to http://<publicip> and http://<publicip>/info.php

YAML

• We would be using YAML to write Ansible Playbooks
• In YAML we define data as collection of name-value pairs
• Refer Here

Playbook

• Playbook represents collection of plays. Each play is collection of tasks. Each task represents a step to be automated (desired state)

- name: <name of your play>
  hosts: <where do you want to execute>
  become: <For installation do we need to become sudo user>
  tasks:
    - name: <name of the task>
      <module>: <desired state>
    - name: <name of the task>
      <module>: <desired state>
    ..
    - name: <name of the task>
      <module>: <desired state>
         

• Module in Ansible does the actual work (Smallest unit of work), using modules we can describe desired state
• Refer Here for the list of modules
• Lets start writing ansible playbook for installing apache and php
• First step involves updating the ubuntu packages using apt. To find the module in apache which helps in automating apt
• Once we find the module to express our desired we need to use parameters
• So in our case the module is apt Refer Here and lets look at parameters
• Refer Here for the changes done in the class
• To run the playbook the command is

ansible-playbook -i <path to invetory> <path to playbook.yaml>

• When we execute again ansible has dont any thing as apache is already installed