Run the following commands as root: clone the repo:
git clone https://github.com/christianknauer/rootstrap.git
create admin user (if necessary):
./rootstrap.sh host.domain.de knauer "Christian Knauer" super_secret_password
bootstrap with default ssh key:
./bootstrap.sh knauer@host.domain.de
bootstrap with alternate ssh key:
./bootstrap.sh knauer@host.domain.de "$(cat ~/.ssh/authorized_keys)"