Installation and configuration

---

Chapter objectives

• Install Ansible on different systems
• Configure the ansible.cfg file
• Establish SSH connectivity
• Validate the installation

---

1 - Prerequisites

Control Node (Ansible machine)

System	Support
Linux	✅ Full
macOS	✅ Full
Windows	⚠️ Via WSL only

Managed Nodes (targets)

Prerequisite	Description
Python 2.7+ or 3.5+	To run the modules
SSH Server	Remote access
User with sudo	For privileged tasks

---

2 - Installation on Linux

Ubuntu/Debian

# Méthode 1: Via apt (version stable)
sudo apt update
sudo apt install ansible

# Méthode 2: Via PPA (dernière version)
sudo apt install software-properties-common
sudo add-apt-repository --yes --update ppa:ansible/ansible
sudo apt install ansible

# Méthode 3: Via pip (recommandé)
sudo apt install python3-pip
pip3 install ansible

RHEL/CentOS/Rocky

# RHEL 8+
sudo dnf install ansible-core

# CentOS 7
sudo yum install epel-release
sudo yum install ansible

# Via pip
pip3 install ansible

Arch Linux

sudo pacman -S ansible

---

3 - Installation on macOS

# Via Homebrew
brew install ansible

# Via pip
pip3 install ansible

---

4 - Installation on Windows (WSL)

# 1. Installer WSL (PowerShell admin)
wsl --install

# 2. Redémarrer Windows

# 3. Dans WSL Ubuntu
sudo apt update
sudo apt install ansible

---

5 - Verifying the installation

# Version d'Ansible
ansible --version

# Sortie attendue
ansible [core 2.15.0]
  config file = /etc/ansible/ansible.cfg
  configured module search path = ['/home/user/.ansible/plugins/modules']
  ansible python module location = /usr/lib/python3/dist-packages/ansible
  ansible collection location = /home/user/.ansible/collections
  executable location = /usr/bin/ansible
  python version = 3.10.12

# Lister les modules disponibles
ansible-doc -l | head -20

# Documentation d'un module
ansible-doc apt

---

6 - SSH configuration

Connection architecture

Generate an SSH key

# Générer une paire de clés
ssh-keygen -t ed25519 -C "ansible@control-node"

# Ou avec RSA (compatibilité)
ssh-keygen -t rsa -b 4096 -C "ansible@control-node"

# Accepter les valeurs par défaut (Enter)
# La clé sera dans ~/.ssh/id_ed25519

Distribute the public key

# Copier la clé vers les serveurs cibles
ssh-copy-id user@server1
ssh-copy-id user@server2
ssh-copy-id user@server3

# Ou manuellement
cat ~/.ssh/id_ed25519.pub | ssh user@server "mkdir -p ~/.ssh && cat >> ~/.ssh/authorized_keys"

Test the connection

# Connexion sans mot de passe
ssh user@server1

# Test Ansible
ansible all -i "server1," -m ping

---

7 - Ansible configuration

Hierarchy of configuration files

Create ansible.cfg

# ansible.cfg - Configuration recommandée
[defaults]
# Inventaire par défaut
inventory = ./inventory/hosts.ini

# Désactiver la vérification des clés host (dev uniquement!)
host_key_checking = False

# Utilisateur distant par défaut
remote_user = ansible

# Nombre de connexions parallèles
forks = 10

# Timeout de connexion
timeout = 30

# Fichier de log
log_path = ./ansible.log

# Ne pas créer de fichiers .retry
retry_files_enabled = False

# Format de sortie
stdout_callback = yaml

# Collecter les facts au début
gathering = smart

[privilege_escalation]
# Devenir root par défaut
become = True
become_method = sudo
become_user = root
become_ask_pass = False

[ssh_connection]
# Optimisation SSH
pipelining = True
control_path = /tmp/ansible-%%h-%%p-%%r

Important options

Option	Description	Recommended value
inventory	Path to the inventory	./inventory/
host_key_checking	Verify SSH keys	False (dev), True (prod)
forks	Parallelism	10-50 depending on network
pipelining	SSH optimization	True
become	Privilege escalation	True

---

8 - Recommended project structure

Create the structure

# Créer le projet
mkdir -p ansible-project/{inventory,playbooks,roles,group_vars,host_vars,files,templates}
cd ansible-project

# Créer les fichiers de base
touch ansible.cfg
touch inventory/hosts.ini
touch playbooks/site.yml

Example of a complete structure

ansible-project/
├── ansible.cfg
├── inventory/
│   ├── hosts.ini          # Inventaire principal
│   ├── production/        # Inventaire prod
│   │   └── hosts.ini
│   └── staging/           # Inventaire staging
│       └── hosts.ini
├── playbooks/
│   ├── site.yml           # Playbook principal
│   ├── webservers.yml
│   └── databases.yml
├── roles/
│   ├── common/            # Rôle commun à tous
│   ├── nginx/             # Rôle serveur web
│   └── postgresql/        # Rôle base de données
├── group_vars/
│   ├── all.yml            # Variables pour tous
│   ├── webservers.yml     # Variables groupe web
│   └── databases.yml      # Variables groupe db
├── host_vars/
│   └── web-01.yml         # Variables spécifiques
├── files/                 # Fichiers statiques
│   └── config.conf
└── templates/             # Templates Jinja2
    └── nginx.conf.j2

---

9 - First test

Create the minimal inventory

# inventory/hosts.ini
[local]
localhost ansible_connection=local

[webservers]
web-01 ansible_host=192.168.1.10
web-02 ansible_host=192.168.1.11

[databases]
db-01 ansible_host=192.168.1.20

[all:vars]
ansible_user=ansible
ansible_python_interpreter=/usr/bin/python3

Test the connectivity

# Ping localhost
ansible localhost -m ping

# Ping tous les hôtes
ansible all -m ping

# Ping un groupe spécifique
ansible webservers -m ping

# Avec plus de détails
ansible all -m ping -v

Expected result

localhost | SUCCESS => {
    "changed": false,
    "ping": "pong"
}
web-01 | SUCCESS => {
    "changed": false,
    "ping": "pong"
}

---

10 - Troubleshooting

Common problems

Diagnostic commands

# Test SSH manuel
ssh -v user@target-host

# Vérifier la configuration Ansible
ansible-config dump

# Mode verbose
ansible all -m ping -vvv

# Vérifier l'inventaire
ansible-inventory --list

# Graphique de l'inventaire
ansible-inventory --graph

Resolve SSH errors

# Erreur: Host key verification failed
# Solution 1: Ajouter la clé
ssh-keyscan -H target-host >> ~/.ssh/known_hosts

# Solution 2: Désactiver la vérification (dev uniquement)
# Dans ansible.cfg: host_key_checking = False

# Erreur: Permission denied (publickey)
# Vérifier que la clé est copiée
ssh-copy-id user@target-host

# Vérifier les permissions
chmod 700 ~/.ssh
chmod 600 ~/.ssh/id_ed25519
chmod 644 ~/.ssh/id_ed25519.pub

---

Summary

Key points

• Install Ansible on the Control Node only
• Configure SSH with keys (no password)
• Use one ansible.cfg per project
• Test with ansible all -m ping before continuing

---

Practical exercises

1. Install Ansible on your machine
2. Create a project structure
3. Configure SSH to a VM or container
4. Validate with an Ansible ping

---

← Introduction | Inventory →