# Runs the Alloy installer on VT1 when booted from the installer ISO.
#
# Gated on a kernel command line flag rather than shipped disabled and
# enabled by the ISO build: the same image is both the live installer and
# the system it installs, and an installer that could start on an installed
# machine is a way to lose a disk. `alloy.installer` is set only by the
# GRUB entries in build/build-iso.sh, so this unit is inert everywhere else.
#
# Three things want VT1: this, greetd, and getty@tty1. The kernel flag above
# settles it, and each of the three answers for itself.
#
# greetd stays away by its own condition, the negation of this one, in
# etc/systemd/system/greetd.service.d/10-installer-medium.conf. That file
# carries the history of the two arrangements that did not work, both of
# which were versions of this unit reaching across to stop the greeter.
#
# getty@tty1 is stopped here, from ExecStartPre rather than `Conflicts=`.
# `Conflicts=` is applied when the start job is ENQUEUED, before the
# condition above is checked, so on an installed machine it would displace
# getty even though the installer never runs. ExecStartPre runs only after
# the condition has passed. Unlike greetd, getty@tty1 is not pulled by a
# target that would restart it, so stopping it once is enough. The leading
# `-` keeps stopping a unit that is not running from failing the install
# before it starts.
[Unit]
Description=Alloy installer
Documentation=https://git.sr.ht/~maxmj/alloy
ConditionKernelCommandLine=alloy.installer
After=systemd-user-sessions.service systemd-logind.service
Before=getty.target

[Service]
ExecStartPre=-/usr/bin/systemctl stop getty@tty1.service
# Type=idle so the boot's own console output has finished before a
# full-screen TUI takes the terminal; without it the first frame draws
# over service status lines and the user sees a torn screen.
Type=idle
ExecStart=/usr/bin/alloy install
TTYPath=/dev/tty1
StandardInput=tty
StandardOutput=tty
StandardError=journal
TTYReset=yes
TTYVHangup=yes
TTYVTDisallocate=yes

# A crashed installer must not leave a blank VT with no way forward. It is
# also not something to retry forever: the disk may be half written, so
# coming back to a fresh wizard would invite a second pass over it.
Restart=no

[Install]
WantedBy=multi-user.target