Ansible: Interview Set

Module

The actual unit of work a task calls (apt, copy, service, template, file)

Role

Packages tasks, vars, templates, files, and handlers around one piece of functionality — reusable, like a Terraform child module

Plugin

Code that extends Ansible's core behavior — modules, connection, inventory, callback, filter are all plugin types

Collection

The versioned, installable package that ships plugins, modules, and roles together — like a package on Galaxy

Namespace

The top-level publisher/org identifier in a collection name — the "amazon" in amazon.aws

FQCN

namespace.collection.module — the full reference to a module outside Ansible core, e.g. amazon.aws.ec2_instance

Playbook

The top-level YAML file that defines what plays/tasks to run — roles are called from here

Play

One execution unit — targets a set of hosts and runs a list of tasks against them

Task

One action within a play — a module call plus optional modifiers

Handler

A task that only runs when notified by another task via notify: — e.g. restart a service after its config changes

Template

A Jinja2 (.j2) file rendered with variables substituted before being written to the target host

template: vs copy:

copy moves a file as-is, no substitution

Inventory

The list of managed hosts Ansible knows about — INI or YAML format, defaults to SSH

hostvars

Magic variable — dictionary of every host's variables, the mechanism for reading another host's data from wherever you currently are

groups

Magic variable — dictionary of every inventory group and the hosts in each

Idempotency

An operation is idempotent if running it once produces the same result as running it repeatedly

ansible.cfg precedence

$ANSIBLE_CONFIG env var > ./ansible.cfg > ~/.ansible.cfg > /etc/ansible/ansible.cfg

host_key_checking

ansible.cfg [defaults] setting — disables SSH host-key verification prompts, common in disposable lab environments

Variable precedence (low to high)

role defaults < inventory vars < playbook group/host vars < play vars < task vars < extra_vars (-e)

when:

Task modifier — conditional, only runs the task if the expression is true

register:

Task modifier — captures a task's output into a variable for later use

delegate_to:

Task modifier — runs this one task on a different host than the play targets, without a separate play

loop:

Task modifier — runs the task once per item in a list (modern replacement for with_items)

block / rescue / always

Ansible's try / catch / finally — group tasks, handle failures, always run cleanup

state:

A common module parameter (not a task modifier) — declares desired end-state, e.g. present/absent/started/stopped

lineinfile + regexp:

Finds a line matching a pattern in a file and replaces or appends it — YAML-wrapped sed

connection: local

Runs a task on the control node itself instead of SSHing out — common for local report/file generation

Ad-hoc command

ansible -m -a "" — runs one module against hosts without a playbook

ansible-vault

Encrypts secrets (passwords, keys) inside playbooks or vars files

Grouping

A host can belong to multiple groups at once (e.g. functional + geographic)

ansible_user

Correct connection variable for SSH user — not ansible_username

apt / yum / dnf

Install/manage packages on Debian or RHEL-family systems

shell vs command

command runs without shell processing (no pipes/redirects)

become:

Task or play modifier — privilege escalation (sudo), defaults to root

ignore_errors:

Task modifier — continues the play even if this task fails

tags:

Task modifier — labels a task for selective run/skip via --tags/--skip-tags

gather_facts:

Play-level setting — collects system info (OS, IP, hostname, memory, CPU) at the start of a play

serial:

Play-level setting — how many hosts to run against at once, for rolling updates

changed_when: / failed_when:

Task modifiers — override how Ansible decides a task "changed" or "failed", useful for command/shell tasks

Check mode (--check)

Reports what would change without actually making changes

Syntax check (--syntax-check)

Confirms playbook syntax is correct without running it

ansible-inventory --list / --graph

Inspect what Ansible actually resolves as your inventory structure