Mastering Ansible: From Basics to Advanced Automation

Fundamentals

Operations automation is evolving from simple All‑In‑One deployments to complex clusters, high‑availability, caching, message queues, and more, demanding tools that can complete tasks in minutes rather than days.

1.1 Definition

The automation goal is to run repeatable tasks automatically without human intervention. Ansible, named after a sci‑fi communication device, is a popular open‑source automation engine that simplifies software deployment, configuration, management, continuous integration, and zero‑downtime upgrades.

System layer: Linux, Windows

Virtualization: VMWare, Docker, OpenStack

Commercial hardware: F5, ASA

Applications: Apache, Zabbix, RabbitMQ, SVN, Git

1.2 Why Choose Ansible

Python‑based, low learning curve for operations staff

Rich built‑in modules and commercial extensions

Decentralized – simple migration of configuration centers

Agentless – only the control node needs configuration

1.3 How It Works

Ansible is agentless; it uses OpenSSH on Linux and PowerShell on Windows. The control node (must be Linux) runs modules that push commands to managed hosts and cleans up temporary files after execution.

The workflow involves three roles: the user, the Ansible toolset, and the target objects (hosts, clouds, etc.). Key components include Playbook, Inventory, Modules, Plugins, and API.

1.4 Communication

Since Ansible 1.3 the default transport is OpenSSH (or PowerShell for Windows) with password or key authentication.

1.5 Installation

# Install Python
yum install python-pip python-devel -y

# Upgrade pip
pip install --upgrade pip

# Install Ansible
pip install ansible --upgrade

# Install via yum
yum install ansible -y

Verify the installation with ansible --version.

1.6 Directory Layout

Configuration files: /etc/ansible/

Executables: /usr/bin/ansible‑*

Python libraries: /usr/lib/pythonX.X/site‑packages/ansible/

Documentation: /usr/share/doc/ansible‑*/

1.7 Configuration File Details

The main configuration file is /etc/ansible/ansible.cfg. Important sections include [defaults], [privilege_escalation] (sudo), [ssh_connection], [accelerate], and [colors]. Example snippets illustrate how to enable sudo, set SSH arguments, and customize output colors.

1.8 Common Commands

Key executables reside in /usr/bin/. Examples: ansible – ad‑hoc command execution ansible-doc – view module documentation ansible-galaxy – role management ansible-playbook – run playbooks ansible-pull – pull mode execution ansible-vault – encrypt/decrypt sensitive data

Sample usage: ansible all -m win_ping shows success or failure with colored output.

1.9 Inventory File

Inventory is an INI‑style file (default /etc/ansible/hosts) that defines hosts and groups, supports ranges, host variables, group variables, and nested groups. Examples demonstrate host definitions, host‑specific variables, group variables, and group children.

Two Major Command Sets

2.1 Ad‑hoc Commands

Ad‑hoc commands are one‑off tasks such as checking host reachability or running a command on a group.

Example: ansible linux -m ping returns “pong”.

Example: ansible linux -m command -a 'hostname' returns each host’s hostname.

Example: ansible linux --list-hosts lists all hosts in the “linux” group.