How would you perform a rolling update of an application across multiple servers to ensure zero downtime?

Use the serial keyword to update servers in batches.

- hosts: app_servers
  serial: 2  # Update 2 servers at a time
  tasks:
    - name: Deploy the new application
      copy:
        src: /path/to/app
        dest: /var/www/app
      notify: restart app service
        

• Ensure that a load balancer routes traffic away from the servers being updated. You can automate this by interacting with APIs (e.g., AWS ALB or NGINX).
• Use health checks to confirm that each server is healthy before proceeding to the next batch.