Ansible — Quick Reference

Ansible is an open-source, agentless automation tool by Red Hat. It uses simple, human-readable YAML files called playbooks to automate configuration management, application deployment, task automation, and orchestration across many systems.

What You Can Do

• Automate configuration and deployments across many servers.
• Run ad-hoc commands for troubleshooting or on-the-fly fixes.
• Orchestrate complex workflows (deployments, rolling updates).
• Integrate with cloud providers, networking devices, and CI/CD pipelines.

Key Characteristics

• Agentless: No agents required on managed nodes — uses SSH (OpenSSH) for Linux/UNIX and WinRM for Windows.
• Declarative Playbooks: Describe the desired state; Ansible figures out the steps to reach it.
• Idempotent Modules: Most modules are idempotent — safe to run multiple times.
• Extensible: Custom modules, plugins, and roles allow flexible extension.

Architecture

• Control node: Machine where you run ansible or ansible-playbook (typically Linux/macOS with Python). Multiple control nodes are allowed.
• Managed nodes (hosts): Servers, network devices, or virtual machines that Ansible manages.
• Inventory: A file or directory that lists your managed hosts and groups (INI or YAML format).
• Modules: Reusable units that perform tasks (package management, file operations, service control).
• Playbooks & Tasks: Playbooks are ordered lists of plays (target hosts + tasks). Tasks call modules.
• Connection plugins: Control how Ansible connects (SSH, WinRM, local).

Common Module Categories

• System modules (user, group, package, service)
• File modules (copy, template, file)
• Command modules (command, shell)
• Networking modules (nxos, ios, eos, junos)
• Cloud modules (aws, azure, gcp)
• Application modules (docker, kubernetes)

Quick Commands

• Run an ad-hoc command:

ansible all -m ping -i inventory

ansible all -m ping -i inventory

• Run a playbook:

ansible-playbook -i inventory site.yml

ansible-playbook -i inventory site.yml

• Check host connectivity:

ansible all -m ping -i inventory

ansible all -m ping -i inventory