Ansible
Agentless configuration management and application deployment - from your first playbook to production-grade automation
Ansible
Ansible is an open-source automation tool from Red Hat. You describe the desired state of your machines in YAML playbooks, and Ansible SSHes into them and runs the tasks needed to get there.
Why Ansible
| Without Ansible | With Ansible |
|---|---|
Manual ssh + shell scripts | One playbook describes the whole fleet |
| Snowflake servers | Idempotent runs converge every host to the same state |
| Custom agents on every box | Agentless — just needs SSH + Python |
| Drift hard to spot | Re-run a playbook to see (or fix) drift |
The Core Loop
write YAML → ansible-playbook --check --diff → review → ansible-playbook
↓
SSH into hosts,
run tasksIdempotency is the key property: every task is written so it does nothing if the target is already in the right state. A second run on a converged fleet is a no-op.
Learning Path
Read in this order if you're new — each page builds on the previous one.
1. Getting Started
Install, set up an inventory, run your first ad-hoc command and playbook
2. Core Concepts
Inventory, plays, tasks, modules, variables, facts
3. Roles & Templates
Package reusable logic into roles; Jinja2 templates; handlers
4. Advanced Patterns
Vault, dynamic inventory, conditionals, loops, rolling deploys, error handling
5. Best Practices
Project layout, CI/CD, testing with Molecule, Terraform integration
Ansible vs. Alternatives
| Tool | Architecture | Approach | When to choose |
|---|---|---|---|
| Ansible | Agentless (SSH) | Procedural YAML | Most teams, mixed fleets, no agent install |
| Chef | Agent (chef-client) | Ruby DSL | Existing Chef shops, complex config |
| Puppet | Agent (puppet-agent) | Declarative DSL | Large enterprise, strong type model |
| Salt | Agent or agentless | YAML + Python | Need real-time event-driven automation |
Ansible and Terraform solve different problems. Use Terraform to provision infrastructure (VMs, networks, DBs), and Ansible to configure what runs on it (packages, users, app deploys). They compose well — Terraform creates the box, Ansible configures it.