Ansible Handlers and Notifications

---
- hosts: webservers
  tasks:
    - name: Update nginx config
      ansible.builtin.template:
        src: nginx.conf.j2
        dest: /etc/nginx/nginx.conf
      notify: Restart nginx

    - name: Update SSL certificate
      ansible.builtin.copy:
        src: ssl/cert.pem
        dest: /etc/ssl/certs/app.pem
      notify: Restart nginx

  handlers:
    - name: Restart nginx
      ansible.builtin.service:
        name: nginx
        state: restarted

tasks:
  - name: Task 1
    # ...
    notify: Handler B

  - name: Task 2
    # ...
    notify: Handler A

handlers:
  - name: Handler A    # Runs first (defined first)
    # ...

  - name: Handler B    # Runs second
    # ...

tasks:
  - name: Update config
    ansible.builtin.template:
      src: app.conf.j2
      dest: /etc/app/config.yml
    notify: Restart app

  # Run handlers NOW (before continuing)
  - name: Flush handlers
    ansible.builtin.meta: flush_handlers

  - name: Run smoke test
    ansible.builtin.uri:
      url: "http://localhost:3000/health"
      status_code: 200
    retries: 5
    delay: 3

tasks:
  - name: Update main config
    ansible.builtin.template:
      src: app.conf.j2
      dest: /etc/app/config.yml
    notify:
      - Validate config
      - Restart app

  - name: Update logging config
    ansible.builtin.template:
      src: logging.conf.j2
      dest: /etc/app/logging.yml
    notify: Reload app

handlers:
  - name: Validate config
    ansible.builtin.command: app --validate-config

  - name: Restart app
    ansible.builtin.service:
      name: app
      state: restarted

  - name: Reload app
    ansible.builtin.service:
      name: app
      state: reloaded

tasks:
  - name: Deploy application
    ansible.builtin.copy:
      src: app.jar
      dest: /opt/app/app.jar
    notify: App deployed

handlers:
  - name: Stop app
    ansible.builtin.service:
      name: app
      state: stopped
    listen: App deployed

  - name: Clear cache
    ansible.builtin.file:
      path: /opt/app/cache
      state: absent
    listen: App deployed

  - name: Start app
    ansible.builtin.service:
      name: app
      state: started
    listen: App deployed

roles/
  nginx/
    handlers/
      main.yml
    tasks/
      main.yml
    templates/
      nginx.conf.j2

# roles/nginx/handlers/main.yml
---
- name: Restart nginx
  ansible.builtin.service:
    name: nginx
    state: restarted

- name: Reload nginx
  ansible.builtin.service:
    name: nginx
    state: reloaded

- name: Validate nginx config
  ansible.builtin.command: nginx -t

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

- name: Configure nginx
  ansible.builtin.template:
    src: nginx.conf.j2
    dest: /etc/nginx/nginx.conf
  notify:
    - Validate nginx config
    - Reload nginx

handlers:
  - name: Restart app
    ansible.builtin.service:
      name: "{{ app_service_name }}"
      state: restarted
    when: app_restart_enabled | default(true)

handlers:
  - name: Restart and verify app
    block:
      - name: Restart service
        ansible.builtin.service:
          name: app
          state: restarted

      - name: Wait for app to be ready
        ansible.builtin.uri:
          url: "http://localhost:{{ app_port }}/health"
          status_code: 200
        register: health
        until: health.status == 200
        retries: 10
        delay: 5
    rescue:
      - name: Rollback on failure
        ansible.builtin.debug:
          msg: "App failed to start after restart!"

handlers:
  # Reload: graceful, no downtime
  - name: Reload nginx
    ansible.builtin.service:
      name: nginx
      state: reloaded

  # Restart: full stop/start, brief downtime
  - name: Restart nginx
    ansible.builtin.service:
      name: nginx
      state: restarted

tasks:
  - name: Update nginx config
    ansible.builtin.template:
      src: nginx.conf.j2
      dest: /etc/nginx/nginx.conf
    notify:
      - Validate nginx
      - Reload nginx

handlers:
  - name: Validate nginx
    ansible.builtin.command: nginx -t

  - name: Reload nginx
    ansible.builtin.service:
      name: nginx
      state: reloaded