Use Ansible to Configure Multiple Linux Servers

Who This Is For

Intermediate.

Think of it like a recipe card instead of cooking from memory every time. Write the steps once, and every kitchen that follows the card turns out the same dish.

What You’ll Build

One playbook applies the same baseline configuration to two Linux servers.

Prerequisites

• A control node (your workstation or a dedicated host)
• At least two managed Linux hosts with SSH access

Why Configuration Drift Happens

Manual setup works fine for one server. By the third or fourth, small inconsistencies creep in silently, Ansible exists to stop that.

Core Concepts

• Control node, where you run Ansible from
• Inventory, the list of managed hosts, grouped
• Playbooks, the automation itself
• Roles, reusable, organized playbook building blocks

Example Inventory

$ all:
$   children:
$     docker_hosts:
$       hosts:
$         docker01:
$         docker02:
$     monitoring:
$       hosts:
$         monitor01:

Set Up SSH Keys

$ ssh-copy-id user@docker01

Write Your First Playbook

$ - hosts: docker_hosts
$   become: true
$   tasks:
$     - name: Update apt cache
$       apt: update_cache=yes
$     - name: Install Docker
$       apt: name=docker.io state=present

Idempotence

A well-written playbook can run repeatedly with no unintended effect, re-running it should only change what actually needs changing.

Secrets: Use Ansible Vault

$ ansible-vault encrypt secrets.yml

Never commit plaintext passwords or keys to a repository, even a private one.

Roles for Reuse

• Base Linux baseline
• Docker host role
• Monitoring agent role
• Backup client role

Test on One Host First

Always run a new or changed playbook against a single test host with --limit before applying it fleet-wide.

Security & Backup Notes

• Store playbooks and roles in Gitea for version history, and always Vault-encrypt anything containing credentials

Troubleshooting

• SSH access issue, confirm the control node’s key is actually authorized on every managed host
• Python missing on target, Ansible needs Python on the managed host; some minimal images don’t include it by default
• Host key mismatch, a reinstalled host will have a new SSH host key; update known_hosts
• Wrong inventory group, double-check which group a playbook targets before running it
• Playbook changes more than intended, always test with --check (dry run) before applying for real

Lab Finish Line

One playbook applies the same baseline configuration to two Linux servers.

What to Build Next

• Gitea
• Home Lab Inventory Report