random

The random filter is used to make a random selection from a sequence. Let's use this filter to delegate a task to a random selection from the db_servers group:

name: backup the database 
  shell: mysqldump -u root nova > /data/nova.backup.sql 
  delegate_to: "{{ groups['db_servers'] | random }}" 
  run_once: true 

Here, we can easily delegate this task to a single member of the db_servers group, picked at random using our filter.