Ansible Automation Guide

Introduction

Ansible is an open-source IT automation tool that simplifies configuration management, application deployment, and orchestration. Written in Python, it uses SSH for agentless communication with remote systems.

Key Features

• Agentless Architecture: No client installation required
• Push-based Configuration: Master server pushes changes to nodes
• YAML-based Playbooks: Human-readable automation scripts
• Extensible Modules: 1000+ built-in modules for various tasks
• Multi-Platform Support: Manages Linux, Windows, network devices
• Idempotent Operations: Safe to run multiple times

How Ansible Works

Core Components

1. Inventory (/etc/ansible/hosts):

   [webservers]
   web01 ansible_host=192.168.1.1
   web02 ansible_host=192.168.1.2

2. Modules (Execution units):

   ansible all -m apt -a "name=nginx state=present"

3. Playbooks (YAML automation files):

   - name: Install Apache
     hosts: webservers
     tasks:
       - name: Install package
         apt: 
           name: apache2 
           state: present

Setup Guide

Lab Configuration

1. Master Node Setup:

   sudo apt update
   sudo apt install ansible
   ssh-keygen -t rsa
   ssh-copy-id user@remote-host

2. Verify Installation:

   ansible --version
   ansible localhost -m ping

3. Sample Inventory:

   sudo nano /etc/ansible/hosts

Ad-Hoc Commands Cheatsheet

Command	Description
ansible all -m ping	Test node connectivity
ansible web -m apt -a "name=nginx state=absent" -b	Remove package with sudo
ansible db -m copy -a "src=app.conf dest=/etc/"	Copy configuration files
ansible all -m command -a "uptime"	Check system uptime
ansible web -m service -a "name=apache2 state=restarted"	Restart services

Playbook Examples

Basic Web Server Setup

webserver.yaml:

- name: Configure Web Cluster
  hosts: webservers
  become: yes
  tasks:
    - name: Install Apache
      apt:
        name: apache2
        state: latest
        
    - name: Start Service
      service:
        name: apache2
        state: started
        enabled: yes

Execution Commands:

ansible-playbook --syntax-check webserver.yaml  # Validate syntax
ansible-playbook webserver.yaml --ask-become-pass  # Run with sudo

Configuration Management

File	Purpose	Location
Main Config	Global settings	/etc/ansible/ansible.cfg
Inventory	Host definitions	/etc/ansible/hosts (default)
Roles	Reusable components	/etc/ansible/roles/

Best Practices

1. Use version control for playbooks
2. Implement Ansible Vault for secrets
3. Use tags for selective execution
4. Create modular roles for reuse
5. Test with --check mode before execution