Verifique o exemplo / default ansible.cfg
file e você encontrará isto:
# default user to use for playbooks if user is not specified
# (/usr/bin/ansible will use current user as default)
#remote_user = root
Remova o comentário de remote_user
e defina o usuário para o que você deseja efetuar login.
Onde o Ansible obtém ansible.cfg
? O mesmo arquivo explica:
# nearly all parameters can be overridden in ansible-playbook
# or with command line flags. ansible will read ANSIBLE_CONFIG,
# ansible.cfg in the current working directory, .ansible.cfg in
# the home directory or /etc/ansible/ansible.cfg, whichever it
# finds first