Here's a method I use to provision new Debian hosts without known ssh keys. Host needs to have python and python-apt packages installed for this playbook to work out of the box. If you want to test it on a VM, you can run Debian installer with boot parameter url=drybjed.github.io - installer will download a preseed file with python and python-apt packages selected (among others). After installation, default password for root account will be debian and you will be forced to change it upon first login.
After installation and first login:
Make sure that you can ssh into the root@host using password (accept host fingerprint, etc.).
- ssh_user: $ENV(USER)
- name: INIT | Create admin system group
group: name=admins system=yes state=present
- name: INIT | Create admin account from current user
user: name=$ssh_user state=present shell=/bin/bash groups=admins
- name: INIT | Make sure essential software is installed
apt: pkg=$item state=latest install_recommends=no
- name: INIT | Install ssh public key from current account
authorized_key: user=$ssh_user key="$FILE(~/.ssh/id_rsa.pub)"
- name: INIT | Install sudoers file for admin accounts
lineinfile: "dest=/etc/sudoers.d/admins state=present create=yes regexp='^%admins' line='%admins ALL=(ALL:ALL) NOPASSWD: SETENV: ALL' owner=root group=root mode=0440"
Run Ansible with: ansible-playbook -k -l host init.yml. Ansible will ask for root password, create a system admins group with access to sudo, create an user account based on your current user, copy your ~/.ssh/id_rsa.pub to your new account, and add it to the admins group.
From now you can use Ansible through your user account using sudo.
You could try a dirty hack with expect, but that's all it is: a dirty hack.
The correct way of having a public key in a just provisioned host is to add that step to the provision itself, i.e., include it it your pressed, kickstart or custom method you use to provision you hosts.