# What Ansible Is — Ansible: Automate Servers with Playbooks

Source: https://www.geekswithgeeks.com/en/ansible/ans-what-is

> Explain agentless, push-based, declarative automation and where Ansible fits.

## Automation without agents

**Ansible** is an open-source automation tool for configuring servers, deploying applications and orchestrating tasks. It is **agentless**: nothing is installed on the machines you manage; the **control node** connects over **SSH** (or WinRM for Windows), runs small **modules**, and removes them. You describe the **desired state** in readable **YAML** (a **playbook**), and Ansible makes the hosts match it. Because most modules are **idempotent**, running the same playbook again changes nothing if the system is already correct.

## Control node to managed nodes

Your control node reads inventory and playbooks, connects to hosts over SSH and runs small modules there.

![Four stages: inventory, playbook, connection, modules.](assets/figures/ansible/section-1-map.svg) — Figure 1.1 — Inventory, playbook, connection and modules.

## A recipe, not a to-do list

A shell script says "run these steps". A playbook says "the kitchen should end up with these dishes ready". If a dish is already ready, the cook skips it.

## Know the alternatives

Terraform provisions infrastructure (create servers, networks); Ansible configures what runs on it. Puppet and Chef use agents. Many teams use Terraform and Ansible together.

**Quiz:** What does "agentless" mean for Ansible?

- [ ] It cannot use SSH
- [ ] It has no control node
- [x] Nothing needs to be installed on managed hosts
- [ ] It only runs on one machine

*Answer:* Nothing needs to be installed on managed hosts. Ansible connects over SSH and runs modules temporarily, so no resident agent is required.