DevOps Classroomnotes 20/Mar/2022

Activity 1: Lets install Java 11 (openjdk 11)

• Our desired state is to install java 11
• The target os is ubuntu 20.04
• Manual Steps:
  • Refer Here for the steps
  • Commands
    sudo apt update
sudo apt install openjdk-11-jdk
• Lets verify if the manual steps are working correctly or not
  • Lets create a virtual machine
  • Ensure the manual steps are working
  • Please follow the classroom recordings for creating vm and verifying the manual steps
• In Ansible to automate the manual steps, we have two approaches
  • Adhoc command: We execute the automation by building a command ansible -i inventory -m ping all
  • Playbook:
    • We describe our desired state as a Playbook in a YAML File
    • As of now our playbook can be defined as collection of tasks, In Ansible to execute a task we use Ansible Modules.
    • Ansible module is the smallest unit of ansible where we can express our desired state.
    • Structure:
      “`yaml

    </ul>
    <hr />
    <ul>
    <li>name: <description>
    hosts: <hosts from inventory>
    become: <yes/no>
    tasks:<ul>
    <li>name: <description of individual step>
    <module>:
    <parameter-1-name>: <parameter-1-value>
    ..
    <parameter-n-name>: <parameter-n-value></li>
    </ul>
    </li>
    <li>“`

    • For running the playbook we use the command ansible-playbook
• In our case we need to automate the apt command so search for apt in ansible to find the right module Refer Here
• Refer Here for the changes done.
  
• Validate the syntax and execute the playbook
  
• Now lets execute the playbook again
  
• So when we execute the playbook the desired state is maintained, whether we run playbook once or multiple times.
• If the result of the execution of desired state is always the same no matter the number of executions, then this property is called as idempotency.
• As a good practice try to use state as much as possible. Refer Here for the changes.
• Exercise: Try installing nodejs on the ubuntu vm using ansible