Example

Prepare admin/ansible user

This will setup GROUP machines by ssh'ing as REMOTE_USER with the SSH private key/identity file KEY_FILE. It will prompt for the sudo'ing password.

ansible-playbook -b -K -i inventory.yml -l GROUP -u REMOTE_USER --key-file=KEY_FILE prep.yml

If you have the root identity file, just use

ansible-playbook -i inventory.yml -l GROUP -u root --key-file=KEY_FILE prep.yml

ansible-playbook -i inventory.yml -u itzg site.yml