WebKitGTK launches bubblewrap for its web-content process; bwrap refuses
to run when the parent process still carries unexpected CAP_* bits ("but
not setuid, old file caps config?"). Setting CapabilityBoundingSet= +
AmbientCapabilities= empty and NoNewPrivileges=yes gives bwrap a clean
caps slate to drop from, so the sandbox initialises and web/dashboard
cells render instead of crashing the kiosk.
systemd refuses to spawn the unit with code=216/GROUP when any group in
SupplementaryGroups= doesn't exist. Debian's seatd uses -g video — there
is no 'seat' group on the system. Removing it lets cage start; the video
group already covers seatd access.
Replace the user-mode kiosk service with a system unit that runs cage
(single-app Wayland compositor) on tty1 as a dedicated unprivileged
user. No desktop, no display manager, auto-restart on crash via
Restart=always.
setup-pi-kiosk.sh provisions the user, installs cage + seatd, disables
any display manager, points default.target at multi-user, drops the
PAM stack, and enables the service. Idempotent.
Screen wake "auto-login": with no DM and no lockscreen, DPMS-driven
sleep just turns the panel back on — the kiosk process is already
running.
Bind native backend services and Node-RED to loopback so Angie remains the public auth boundary. Keep Docker on an internal compose network and stop kiosk fallback to a layout when display default is none.
