hetzner-robot-init-nixos.sh

# Commands coming from https://nixos.wiki/wiki/Install_NixOS_on_Hetzner_Online and adjusted to automate SSH key
apt-get install -y sudo
mkdir -p /etc/nix
echo "build-users-group =" > /etc/nix/nix.conf
curl -L https://nixos.org/nix/install | sh
. $HOME/.nix-profile/etc/profile.d/nix.sh

EXISTING_AUTHORIZED_KEYS=$(cat $HOME/.ssh/authorized_keys)
VERSION=${1:-1.8.0}

# Install nixos-generators
# This might take a while, so the verbose flag `-v` is included to monitor progress
nix-env -f https://github.com/nix-community/nixos-generators/archive/$VERSION.tar.gz -i -v

# Create a initial config, just to kexec into
cat <<EOF > /root/config.nix
{
  services.openssh.enable = true;
  users.users.root.openssh.authorizedKeys.keys = [
    # Replace with your public key
    "$EXISTING_AUTHORIZED_KEYS"
  ];
}
EOF

# Generate the kexec script
nixos-generate -o /root/result  -f kexec-bundle -c /root/config.nix

# Switch to the new system
/root/result