# Install
pipx install ansible-core               # core engine
pipx inject ansible-core ansible        # add the community collection bundle
ansible --version

# Quick connectivity check
ansible -i inventory.ini all -m ping

# Run an ad-hoc command
ansible -i inventory.ini web -m shell -b -a "uptime"

# Run a playbook
ansible-playbook -i inventory.ini site.yml --check       # dry-run
ansible-playbook -i inventory.ini site.yml --diff        # show file diffs
ansible-playbook -i inventory.ini site.yml --limit web   # subset of hosts
ansible-playbook -i inventory.ini site.yml --tags db     # subset of tasks

# Vault
ansible-vault create  secrets.yml
ansible-vault edit    secrets.yml
ansible-vault encrypt vars/prod.yml
ansible-playbook ... --ask-vault-pass

# inventory.ini — simple, static
[web]
web1.example.com ansible_user=deploy
web2.example.com ansible_user=deploy ansible_port=2222

[db]
db1.example.com

[prod:children]
web
db

[prod:vars]
env=prod
ansible_python_interpreter=/usr/bin/python3

# group_vars/all.yml — variables applied to every host
---
app_user: app
timezone: Europe/London

# host_vars/web1.example.com.yml — host-specific overrides
---
extra_workers: 4

---
# site.yml
- name: Configure web servers
  hosts: web
  become: true
  vars:
    nginx_version: "1.27.*"
  vars_files:
    - vars/prod.yml
  pre_tasks:
    - name: Ensure cache is fresh
      ansible.builtin.apt: { update_cache: yes, cache_valid_time: 3600 }
  roles:
    - { role: base,     tags: [base] }
    - { role: nginx,    tags: [web, nginx] }
    - { role: app,      tags: [app] }
  post_tasks:
    - name: Confirm health
      ansible.builtin.uri:
        url: http://127.0.0.1/healthz
        status_code: 200
      register: health
      retries: 6
      delay: 5
      until: health.status == 200

# roles/nginx/tasks/main.yml
---
- name: Install nginx
  ansible.builtin.apt:
    name: "nginx={{ nginx_version }}"
    state: present
  notify: Restart nginx

- name: Render site config
  ansible.builtin.template:
    src: site.conf.j2
    dest: /etc/nginx/sites-available/{{ site_name }}.conf
    mode: "0644"
  notify: Reload nginx

- name: Enable the site
  ansible.builtin.file:
    src: /etc/nginx/sites-available/{{ site_name }}.conf
    dest: /etc/nginx/sites-enabled/{{ site_name }}.conf
    state: link
  notify: Reload nginx

# roles/nginx/handlers/main.yml
---
- name: Reload nginx
  ansible.builtin.service: { name: nginx, state: reloaded }

- name: Restart nginx
  ansible.builtin.service: { name: nginx, state: restarted }

---
# site.yml — provision + deploy a tiny static-site host.
- name: Bootstrap webserver
  hosts: web
  become: true
  tasks:

    - name: Install packages
      ansible.builtin.apt:
        name: [nginx, curl]
        state: present
        update_cache: yes

    - name: Drop nginx config
      ansible.builtin.copy:
        dest: /etc/nginx/sites-available/site.conf
        content: |
          server {
              listen 80 default_server;
              root /var/www/site;
              index index.html;
          }
        mode: "0644"
      notify: Reload nginx

    - name: Enable site
      ansible.builtin.file:
        src: /etc/nginx/sites-available/site.conf
        dest: /etc/nginx/sites-enabled/site.conf
        state: link
      notify: Reload nginx

    - name: Deploy index.html
      ansible.builtin.copy:
        dest: /var/www/site/index.html
        content: "
{{ ansible_hostname }} is up
"
        mode: "0644"

  handlers:
    - name: Reload nginx
      ansible.builtin.service: { name: nginx, state: reloaded }