DevOps Classroom Series- Ansible 05/November/2019

Configuration Management

• For any application to work we need some softwares.
• Options for installing necessary softwares and deploying application

Manual

• Administrator will install the necessary softwares
• Admin will deploy the application
• Problems:
  • Slow
  • Error Prone

Shell/Powershell Scripts

• Create a shell/powershell script to perform deployment
• Problems:
  • Multiple ways of doing the same activity. Because it impacts Readability and Maintainability.
  • Every script has assumptions
  • Scripts are Procedural (How it has to done)
• Example:
  • Create a file:
    • Create a file using touch command
    • files path should be at /home/ubuntu/test.txt

Configuration Management

• In this user will write the desired state
• Scripts are Declarative (What has to be done)
• The major theme is to maintain desired state.
• CM has an important property call as idempotance
• Example:
  • Create a file
    • I want an empty file at /home/ubuntu/test.txt
• CM can be done using many tools, some of them are
  • Ansible
  • Chef
  • Salt
  • Puppet
  • CFEngine
  • PowerShell DSC

Architecture of Configuration Management

PUSH

PULL

Ansible Falls under Push based Configuration Management

• Ansible is push based CM tool by default.
• Software requirements of Ansible
  • Ansible Control Server:
    • Python
    • Ansible
  • Nodes:
    • Python

What do the user need to provide to ansible

• Playbook:
  • Written in YAML
  • YAML is all about data representation
• Inventory:
  • List of nodes to be used by Ansible Control