root@debian:~/openwisp2-ansible-playbook# ansible-playbook -i hosts playbook.yml -u root --ask-pass 
SSH password: 

PLAY [openwisp2] ******************************************************************

TASK [Gathering Facts] ************************************************************
fatal: [debian]: UNREACHABLE! => {"changed": false, "msg": "Invalid/incorrect password: Permission denied, please try again.", "unreachable": true}

PLAY RECAP ************************************************************************
debian                     : ok=0    changed=0    unreachable=1    failed=0    skipped=0    rescued=0    ignored=0