Advanced Execution¶

---
- name: Rolling update
  hosts: webservers # 10 servers
  serial: 2 # Update 2 at a time
  become: true

  tasks:
    - name: Take host out of load balancer
      ansible.builtin.uri:
        url: "http://lb.example.com/remove/{{ inventory_hostname }}"
        method: POST
      delegate_to: localhost

    - name: Update application
      ansible.builtin.apt:
        name: myapp
        state: latest

    - name: Restart application
      ansible.builtin.service:
        name: myapp
        state: restarted

    - name: Wait for application to be ready
      ansible.builtin.uri:
        url: "http://{{ inventory_hostname }}/health"
        status_code: 200
      retries: 10
      delay: 5

    - name: Re-add host to load balancer
      ansible.builtin.uri:
        url: "http://lb.example.com/add/{{ inventory_hostname }}"
        method: POST
      delegate_to: localhost

# Process 2 hosts at a time
serial: 2

# Process 30% of hosts at a time
serial: "30%"

# Escalating batch sizes: 1, then 5, then rest
serial:
  - 1
  - 5
  - "100%"

# Max failures before stopping
max_fail_percentage: 10

tasks:
  # Run this task on localhost (the control node), not the target
  - name: Send deployment notification
    ansible.builtin.uri:
      url: https://hooks.example.com/deploy
      method: POST
      body_format: json
      body:
        host: "{{ inventory_hostname }}"
        status: deploying
    delegate_to: localhost

  # Run this task on a specific server in inventory
  - name: Trigger backup on the NAS
    ansible.builtin.command:
      cmd: /opt/backup/backup.sh {{ inventory_hostname }}
    delegate_to: backup-server

  # Copy a file FROM one server TO another
  - name: Sync config from primary to secondary
    ansible.posix.synchronize:
      src: /etc/nginx/nginx.conf
      dest: /etc/nginx/nginx.conf
      mode: push
    delegate_to: primary-web

tasks:
  # Run this task only ONCE, on the first host in the group
  - name: Create database schema
    ansible.builtin.command:
      cmd: /opt/app/manage.py migrate
    run_once: true

  # Combine with delegate_to
  - name: Send deployment notification to Slack
    community.general.slack:
      token: "{{ slack_token }}"
      msg: "Deploying {{ app_version }} to {{ ansible_play_hosts | length }} servers"
    run_once: true
    delegate_to: localhost

tasks:
  # Run this task on max 3 hosts simultaneously (even with high forks)
  - name: Restart memcached (rate limited)
    ansible.builtin.service:
      name: memcached
      state: restarted
    throttle: 3

  # Useful for services that can't all restart simultaneously
  - name: Rolling service restart
    ansible.builtin.service:
      name: elasticsearch
      state: restarted
    throttle: 1 # One at a time to maintain cluster quorum

tasks:
  # Wait until a port is open
  - name: Wait for service port to be ready
    ansible.builtin.wait_for:
      host: "{{ inventory_hostname }}"
      port: 8080
      delay: 5
      timeout: 120

  # Wait for a file to exist
  - name: Wait for lock file to disappear
    ansible.builtin.wait_for:
      path: /var/run/deploy.lock
      state: absent
      timeout: 60

  # Wait for HTTP endpoint
  - name: Wait for health check
    ansible.builtin.uri:
      url: "http://{{ inventory_hostname }}:8080/health"
      status_code: 200
    register: health_check
    until: health_check.status == 200
    retries: 12
    delay: 10

  # Pause for a specified time
  - name: Pause to let service stabilize
    ansible.builtin.pause:
      seconds: 30

  # Pause with a message (prompts user to continue)
  - name: Manual approval gate
    ansible.builtin.pause:
      prompt: "Check the deployment. Press Enter to continue or Ctrl+C to abort"

tasks:
  # Retry a task until it succeeds
  - name: Download package (with retries)
    ansible.builtin.get_url:
      url: https://example.com/package.tar.gz
      dest: /tmp/package.tar.gz
    register: download
    until: download is succeeded
    retries: 5
    delay: 10

  # Retry with custom success condition
  - name: Wait for cluster to reach quorum
    ansible.builtin.command:
      cmd: /opt/db/check-quorum.sh
    register: quorum_check
    until: quorum_check.rc == 0
    retries: 10
    delay: 30
    changed_when: false