Ansible Fundamentals

Ansible is an agentless automation tool that configures systems, deploys software, and orchestrates multi-step tasks over SSH or WinRM. You describe desired state in YAML playbooks, and Ansible pushes the necessary changes to target machines without requiring a resident agent.

itInfrastructure and operations

Ansible Fundamentals

Ansible automates remote systems from a control node. You describe targets in an inventory and desired work in playbooks. Ansible connects to each managed node, runs modules, and reports whether the node changed.

That model separates Ansible from a shell script copied across a fleet. A shell script usually describes commands to execute. An Ansible task usually describes a state to reach. A package should be present. A service should be running. A configuration file should have specific content.

Most Ansible modules inspect the current state before acting. If the desired state already exists, an idempotent module reports no change. Repeated execution should converge on the same result. Idempotency depends on the module and the way you use it; Ansible does not make every command or playbook idempotent.

The operating model

An Ansible environment has three core parts:

Control node — the system where you install Ansible and run its command-line tools.
Inventory — one or more sources that identify managed nodes, groups, and associated variables.
Managed node — a remote host or device that Ansible controls.

Ansible is normally agentless. You do not install an Ansible daemon on every managed node. The control node uses connection plugins and transports such as SSH or PowerShell remoting. Many POSIX modules require Python on the managed node, while some device-specific modules have different requirements.

You can install either ansible-core or the larger ansible package. ansible-core provides the language, runtime, and a built-in set of modules and plugins. The ansible package adds a community-curated collection set. Choose deliberately, then pin the versions of Ansible and any collections that your automation requires.

Ansible Fundamentals

The operating model

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