Ansible Complete Guide

TERMINAL# Install on Ubuntu/Debian (control node only!) sudo apt update sudo apt install ansible -y # Install on CentOS/RHEL sudo yum install epel-release -y sudo yum install ansible -y # Install via pip (any OS) pip install ansible # Verify ansible --version # ansible [core 2.16.x] # Key point: Install Ansible ONLY on YOUR machine (control node) # Target servers need NOTHING installed — just SSH access

INVENTORY# /etc/ansible/hosts (or inventory.ini) [webservers] web1 ansible_host=10.0.1.10 ansible_user=deploy web2 ansible_host=10.0.1.11 ansible_user=deploy web3 ansible_host=10.0.1.12 ansible_user=deploy [dbservers] db1 ansible_host=10.0.2.10 ansible_user=deploy db2 ansible_host=10.0.2.11 ansible_user=deploy [monitoring] prometheus ansible_host=10.0.3.10 [production:children] # Group of groups! webservers dbservers monitoring [all:vars] # Variables for ALL servers ansible_ssh_private_key_file=~/.ssh/deploy_key ansible_python_interpreter=/usr/bin/python3

TERMINAL# Ping all servers (test connectivity) ansible all -m ping -i inventory.ini # Check uptime on web servers ansible webservers -a "uptime" -i inventory.ini # Install nginx on all web servers ansible webservers -m apt -a "name=nginx state=present" -b -i inventory.ini # -b = become root (sudo) # Restart a service ansible webservers -m service -a "name=nginx state=restarted" -b # Copy a file to all servers ansible all -m copy -a "src=config.yml dest=/opt/app/config.yml" -b # Check disk space on all servers ansible all -a "df -h /" -i inventory.ini

YAML# deploy_nginx.yml --- # YAML document start - name: Install and configure Nginx # Play name (description) hosts: webservers # Target group from inventory become: yes # Run as root (sudo) vars: # Variables app_port: 3000 server_name: myapp.com tasks: # List of things to do - name: Update apt cache apt: update_cache: yes cache_valid_time: 3600 # Only update if older than 1 hour - name: Install Nginx apt: name: nginx state: present # present=install, absent=remove - name: Copy Nginx config template: src: nginx.conf.j2 # Jinja2 template dest: /etc/nginx/sites-available/myapp.conf notify: Restart Nginx # Trigger handler if file changed - name: Enable site file: src: /etc/nginx/sites-available/myapp.conf dest: /etc/nginx/sites-enabled/myapp.conf state: link # Create symbolic link - name: Start Nginx service: name: nginx state: started enabled: yes # Start on boot handlers: # Only run when "notified" - name: Restart Nginx service: name: nginx state: restarted # Run: ansible-playbook deploy_nginx.yml -i inventory.ini

JINJA2# templates/nginx.conf.j2 server { listen 80; server_name {{ server_name }}; # Variable from playbook location / { proxy_pass http://localhost:{{ app_port }}; } } # {{ variable }} gets replaced with actual values when Ansible runs

YAML- name: Install multiple packages apt: name: "{{ item }}" state: present loop: - nginx - docker.io - git - curl - htop - name: Create multiple users user: name: "{{ item.name }}" groups: "{{ item.groups }}" state: present loop: - { name: deploy, groups: sudo } - { name: monitor, groups: docker }

YAML- name: Install on Ubuntu only apt: name: nginx state: present when: ansible_os_family == "Debian" - name: Install on CentOS only yum: name: nginx state: present when: ansible_os_family == "RedHat"

DIRECTORY# Role directory structure roles/ nginx/ tasks/ main.yml # What to do handlers/ main.yml # Restart handlers templates/ nginx.conf.j2 # Config templates vars/ main.yml # Variables defaults/ main.yml # Default values (overridable) files/ index.html # Static files to copy # Use role in playbook: # site.yml --- - hosts: webservers become: yes roles: - nginx - docker - monitoring

YAML--- - name: Install Docker hosts: all become: yes tasks: - name: Install prerequisites apt: name: [apt-transport-https, ca-certificates, curl, gnupg] state: present - name: Add Docker GPG key apt_key: url: https://download.docker.com/linux/ubuntu/gpg - name: Add Docker repository apt_repository: repo: "deb https://download.docker.com/linux/ubuntu {{ ansible_distribution_release }} stable" - name: Install Docker apt: name: [docker-ce, docker-ce-cli, containerd.io] state: present update_cache: yes - name: Add deploy user to docker group user: name: deploy groups: docker append: yes - name: Start Docker service: name: docker state: started enabled: yes

TERMINAL# Encrypt a file ansible-vault encrypt secrets.yml # Enter password → file is now encrypted # Edit encrypted file ansible-vault edit secrets.yml # Run playbook with vault ansible-playbook site.yml --ask-vault-pass # Or use a password file: ansible-playbook site.yml --vault-password-file .vault_pass

TERMINAL# Search roles ansible-galaxy search docker # Install a role ansible-galaxy install geerlingguy.docker ansible-galaxy install geerlingguy.nginx # Use in playbook --- - hosts: all become: yes roles: - geerlingguy.docker - geerlingguy.nginx