#users
root_user: 'root'
root_password: 'root'
prosody_user: 'prosody'
prosody_password: 'prosody'

#databases
oauth_db: "oauth"

#hosts
prosody_hosts: ['10.0.1.4', '10.0.1.5']

- name: add or update mysql user prosody
  mysql_user:
   name: "{{ prosody_user }}"
   host: "{{ item.host }}"
   password: "{{ prosody_password }}"
   login_user: "{{ root_user }}"
   login_password: "{{ root_password }}"
   check_implicit_admin: yes
   append_privs: yes
   priv: "{{ item.database }}.*:ALL,GRANT"
  with_items:
  - { host: "{{ prosody_hosts[0] }}", database: "{{ oauth_db }}" }
  - { host: "{{ prosody_hosts[1] }}", database: "{{ oauth_db }}" }
  - { host: "{{ prosody_hosts[0] }}", database: "{{ prosody_db }}" }
  - { host: "{{ prosody_hosts[1] }}", database: "{{ prosody_db }}" }

...
with_items
- { host: "{{ prosody_hosts }}", database: "{{ oauth_db }}" }
- { host: "{{ prosody_hosts }}", database: "{{ prosody_db }}" }