Glossary

Ad-hoc command — a one-off Ansible run from the command line (ansible web -m ping), no playbook file. For questions and emergencies.

Become — privilege escalation: running a task as another user, usually root via sudo (become: true).

Check mode — --check: simulate a playbook run and report what would change, changing nothing.

Collection — a packaged bundle of modules, roles, and plugins distributed via Galaxy; the modern unit of Ansible content beyond core.

Control machine — the one machine Ansible itself runs on. Everything else is a target it reaches over SSH.

Fact — information gathered from a target by the setup module (OS, addresses, hardware), available to tasks as ansible_facts[...].

Galaxy — the public library of roles and collections (ansible-galaxy install ...), and the command-line tool that fetches them and scaffolds roles.

Group — a named set of hosts in the inventory (webservers), the usual unit of addressing and of group_vars.

Handler — a task that runs only when notified by a task that changed; the standard "restart the service if the config changed" mechanism.

Idempotent — safe to repeat: running a task or playbook again, against an already-correct target, changes nothing and reports changed=0.

Inventory — the list of target hosts, their groups, and how to reach them. INI or YAML.

Jinja2 — the templating language inside templates and {{ ... }} substitutions everywhere in Ansible.

Module — a small program managing one kind of thing (file, copy, apt, service). A task is one module call.

Play / playbook — a playbook is a YAML file of plays; a play aims a set of tasks at a set of hosts.

Role — a reusable bundle of tasks, templates, files, handlers, and variables under a standard directory layout, invoked by name.

Task — one named module invocation: the unit of ok / changed / failed reporting.

Vault — Ansible's built-in encryption for variables and files (ansible-vault), unlocked by a vault password at run time.