Table of Contents

Ansible

Ansible is an open-source automation engine for configuration management, application deployment, and orchestration. It is agentless — it connects to managed nodes over SSH (or WinRM) and executes tasks described declaratively in YAML — so there is no software to install or maintain on the systems it manages.

This section is a complete, practical guide to Ansible: from installing the control node through writing playbooks, structuring reusable roles, managing secrets, and running it reliably in production.

Note

The guide targets ansible-core 2.16/2.17 conventions, including fully-qualified collection names (FQCN, e.g. ansible.builtin.copy) throughout. Examples use a repo-local project layout rather than the global /etc/ansible directory.

Why Ansible

  • Agentless — no agents or daemons on managed nodes; only SSH and Python are required.
  • Idempotent — modules converge a system to a desired state, so runs can be repeated safely.
  • Declarative and readable — automation is expressed in YAML that doubles as documentation.
  • Batteries included — thousands of modules and a large collection ecosystem for OSes, clouds, network gear, and services.
  • Push-based — you decide when automation runs; there is no central server the nodes poll.

How it fits together

Concept What it is Page
Control node The machine that runs Ansible and connects out to managed nodes Installation
Inventory The list of managed hosts and how to reach and group them Inventory
Playbook An ordered set of plays mapping hosts to tasks Playbooks
Module / Task A unit of work (invoked by FQCN) and its invocation in a play Playbooks
Variables & Facts Data that parameterizes automation, plus gathered system facts Variables, Facts, and Templating
Role A reusable, shareable bundle of tasks, templates, and defaults Roles and Collections
Collection A distributable package of roles, modules, and plugins Roles and Collections
Vault Encryption for secrets kept alongside your code Vault and Secrets

In this section

  1. Installation and Setup — install Ansible on the control node, configure ansible.cfg, lay out a project, and prepare managed nodes.
  2. Inventory — define hosts with static INI/YAML inventories, groups, group_vars/host_vars, dynamic inventory, and targeting patterns.
  3. Playbooks and Tasks — plays, tasks, handlers, conditionals, loops, blocks, error handling, and controlling execution.
  4. Variables, Facts, and Templating — variable precedence, gathered and custom facts, magic variables, and Jinja2 templating.
  5. Roles and Collections — structure reusable roles and distribute content with collections and Ansible Galaxy.
  6. Vault and Secrets Management — encrypt sensitive data with Ansible Vault and integrate external secret managers.
  7. Best Practices — project structure, idempotency, linting and testing, performance, CI/CD, and scaling with Automation Platform.

Quick start

Install Ansible, define a host, and run an ad-hoc command — no playbook required:

# 1. Install (isolated) on the control node
pipx install --include-deps ansible

# 2. A minimal inventory
cat > inventory.ini <<'EOF'
[web]
web01.example.com
EOF

# 3. Verify connectivity (uses your SSH config / keys)
ansible web -i inventory.ini -m ansible.builtin.ping

Then capture the same intent as a repeatable playbook:

---
- name: Install and start nginx
  hosts: web
  become: true
  tasks:
    - name: Install nginx
      ansible.builtin.package:
        name: nginx
        state: present

    - name: Ensure nginx is running and enabled
      ansible.builtin.service:
        name: nginx
        state: started
        enabled: true

ansible-playbook -i inventory.ini site.yml --check   # dry run first
ansible-playbook -i inventory.ini site.yml           # apply

Continue with Installation and Setup for a production-ready control node and project layout.

  • Infrastructure overview — where Ansible fits among the other infrastructure tooling.
  • Terraform — provisioning infrastructure that Ansible then configures (if present in your environment).
  • Docker — a common target and driver for Ansible automation.

References

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