diskimage-builder/diskimage_builder/elements/ironic-agent/static/etc/systemd/system/ironic-agent-create-rescue-user.service

[Unit]
Description=Ironic agent rescue user creation

[Service]
ExecStart=/bin/bash /usr/local/bin/ironic-python-agent-create-rescue-user.sh
Type=oneshot
RemainAfterExit=yes

[Install]
WantedBy=multi-user.target