Ansible

• Refer Here for Ansible official page
• Ansible is majorly used in DevOps to deploy applications into servers across various environments.
• Ansible in CI/CD pipeline is called by some engine (Jenkins => Ansible, AzureDevOps => Ansible …)
• Configuration Management types
  • pull based CM
    • Nodes communicate with CM Server to deploy configuration
    • For this to happen, We need to
      • install agent software on node and configure it to connect to the server.
    • Examples:
      • Chef
      • Puppet
  • push based CM:
    • CM Server communicates with Nodes to deploy configuration
    • For this to happen we need details such as
      • ip address of node
      • credentials
    • Examples:
      • Ansible
      • Salt
        

Declarative vs Procedural

• Understanding Declarative vs Procedural
  
  
• In Declarative programming, we define what we want (desired state).
• The job of the tool is to ensure desired state is met every time during execution.
• Idempotance: The result of execution of CM Script is same when we execute it once or multiple times
• Configuration Drift: Difference between desired state and actual state.

Ansible Architecture

• Overview
  
• Components
  • Ansible control node: This is where ansible is installed
  • Nodes: This is where we want o perform deployments
  • Inventory: list of nodes and their information
  • Playbook: What has to be done on the node
• Workflow
  • We develop playook and specify inventory and execute the playbook on ansible control node
  • Now ansible tries to establish connection to node
  • Now the ansible playbook is executed with the help of python on node.