Structuring an Ansible Playbook You Can Maintain

.
├── ansible.cfg
├── inventory/
│   ├── production/
│   │   ├── hosts.ini
│   │   ├── group_vars/
│   │   │   ├── all.yml
│   │   │   ├── web.yml
│   │   │   └── db.yml
│   │   └── host_vars/
│   │       └── web01.yml
│   └── staging/
│       └── ...
├── roles/
│   ├── common/
│   ├── nginx/
│   └── postgres/
├── playbooks/
│   ├── site.yml
│   ├── web.yml
│   └── db.yml
└── requirements.yml          # external roles/collections

# inventory/production/hosts.ini
[web]
web01 ansible_host=10.0.1.11
web02 ansible_host=10.0.1.12

[db]
db01 ansible_host=10.0.2.11

[production:children]
web
db

roles/nginx/
├── defaults/main.yml      # default variables (overridable)
├── vars/main.yml          # internal constants (high precedence, don't override)
├── tasks/main.yml         # the work
├── handlers/main.yml      # restart/reload triggered by notify
├── templates/nginx.conf.j2
├── files/                 # static files to copy
├── meta/main.yml          # dependencies, supported platforms
└── molecule/              # tests

# roles/nginx/tasks/main.yml
- name: Install nginx
  ansible.builtin.package:
    name: nginx
    state: present

- name: Deploy nginx.conf
  ansible.builtin.template:
    src: nginx.conf.j2
    dest: /etc/nginx/nginx.conf
    validate: nginx -t -c %s
  notify: Reload nginx

- name: Ensure nginx is running
  ansible.builtin.service:
    name: nginx
    state: started
    enabled: true

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

# playbooks/web.yml
- hosts: web
  become: true
  roles:
    - common
    - nginx
    - { role: app, tags: [app] }

- import_playbook: web.yml
- import_playbook: db.yml

ansible-playbook playbooks/site.yml --tags app        # only app-tagged tasks
ansible-playbook playbooks/site.yml --skip-tags slow

# requirements.yml
collections:
  - name: community.postgresql
roles:
  - name: geerlingguy.docker

ansible-galaxy install -r requirements.yml

ansible-inventory -i inventory/production --graph
ansible-inventory -i inventory/production --host web01     # resolved vars for a host
ansible-playbook playbooks/site.yml --check --diff         # dry run
ansible-playbook playbooks/site.yml --list-tasks
ansible-lint