doc/nuc/jellyfin-client.md

# jellyfin-client

HTPC kiosk **client** in a privileged Incus container on `nuc`:
Jellyfin Media Player fullscreen inside `cage` (Wayland kiosk compositor)
rendering directly to HDMI via DRM/KMS — no X server or desktop on the host.
Also hosts the Spotify Connect endpoint (go-librespot, see below).

- Image: `images:ubuntu/24.04`, IP: `192.168.0.6` (LAN bridge)
- Video: Intel Alder Lake-N iGPU → HDMI (`gpu` device, full card access)
- Audio: Pioneer USB audio (`08e4:0176`), ALSA card `Device`, set as ALSA
  default via `/etc/asound.conf`
- Input: Logitech Unifying receiver (K400) via `/dev/input` bind + host udev
  database bind; FR (AZERTY) keymap
- Why privileged: hotplug-following directory bind-mounts of `/dev/snd` and
  `/dev/input`. Unprivileged alternative: one `unix-char` device per node
  (doesn't follow card renumbering on replug).

## How the tricky parts work

Container-specific pitfalls that cost debugging time — all handled by the
install script:

1. **seatd must not bind a VT** (`SEATD_VTBOUND=0` drop-in): with VT binding
   it tries to open the host's active tty, which isn't in the container, and
   cage hangs forever ("running", `Tasks: 0`, black screen).
2. **libinput needs a udev database**: it only accepts input devices carrying
   `ID_INPUT*` properties. The container can't run its own udevd (sysfs
   uevent writes are silently denied by the Incus AppArmor profile — an
   explicit deny rule that `raw.apparmor` cannot override), so the **host's**
   `/run/udev` is bind-mounted read-only to `/opt/host-udev` and a
   `run-udev.mount` unit re-binds it onto `/run/udev` at boot (a direct bind
   would be shadowed by systemd's `/run` tmpfs). `WLR_LIBINPUT_NO_DEVICES=1`
   additionally keeps cage alive when no input device is present.
3. **ALSA default must be pinned**: mpv opens device `default`, which maps to
   card 0 (Intel HDA, HDMI-only pcm devices 3/7/8/9) → open fails and mpv
   silently falls back to the **null** output (video OK, no sound).
   `/etc/asound.conf` pins the default to the Pioneer by card *name*.
4. The kiosk service must NOT use `TTYPath`/`StandardInput=tty` — it hides
   all cage/JMP errors on an invisible tty. Log to the journal.

## Install script

```bash
#!/usr/bin/env bash
set -euxo pipefail

CNAME="${CNAME:-jellyfin-client}"
IMAGE="${IMAGE:-images:ubuntu/24.04}"
JMP_VER="${JMP_VER:-1.12.0}"   # https://github.com/jellyfin/jellyfin-desktop/releases

incus launch "$IMAGE" "$CNAME" -c security.privileged=true

for i in $(seq 1 30); do
    incus exec "$CNAME" -- getent hosts github.com >/dev/null 2>&1 && break
    sleep 2
done

incus config set "$CNAME" environment.DEBIAN_FRONTEND=noninteractive
incus exec "$CNAME" -- timedatectl set-timezone Europe/Paris

# --- Host devices -------------------------------------------------------------
# iGPU (card + render nodes). gid=44 = "video" group inside the container.
incus config device add "$CNAME" gpu gpu gid=44

# Sound (Pioneer USB audio -> ALSA card) and input devices (keyboard/remote).
# Directory bind-mounts follow hotplug events, so the USB card can be
# re-plugged without restarting the container. No VT/tty devices needed:
# seatd runs with SEATD_VTBOUND=0 (see below).
#
# The host udev database is bound to /opt/host-udev; a mount unit inside the
# container re-binds it to /run/udev at boot (binding /run/udev directly gets
# shadowed when systemd mounts its own tmpfs on /run). libinput only accepts
# input devices that carry ID_INPUT* properties from a udev database, and the
# container cannot run its own udevd (sysfs uevent writes are blocked by the
# Incus AppArmor profile), so it reads the host's database instead.
RAW_LXC="$(cat <<'EOF'
lxc.cgroup2.devices.allow = c 116:* rwm
lxc.cgroup2.devices.allow = c 13:* rwm
lxc.mount.entry = /dev/snd dev/snd none bind,optional,create=dir
lxc.mount.entry = /dev/input dev/input none bind,optional,create=dir
lxc.mount.entry = /run/udev opt/host-udev none bind,ro,optional,create=dir
EOF
)"
incus config set "$CNAME" raw.lxc="$RAW_LXC"
incus restart "$CNAME"   # raw.lxc mount entries apply at container start
sleep 5

# --- Packages ------------------------------------------------------------------
incus exec "$CNAME" -- apt-get update
incus exec "$CNAME" -- apt-get upgrade -y
incus exec "$CNAME" -- apt-get install -y --no-install-recommends software-properties-common curl ca-certificates
incus exec "$CNAME" -- add-apt-repository -y universe
incus exec "$CNAME" -- add-apt-repository -y multiverse
incus exec "$CNAME" -- apt-get install -y --no-install-recommends \
    cage seatd dbus dbus-user-session qtwayland5 \
    intel-media-va-driver-non-free vainfo mesa-utils-bin \
    alsa-utils

# Jellyfin Media Player (repo renamed to jellyfin-desktop upstream)
incus exec "$CNAME" -- bash -c "curl -fLo /tmp/jmp.deb \
  https://github.com/jellyfin/jellyfin-desktop/releases/download/v${JMP_VER}/jellyfin-media-player_${JMP_VER}-noble.deb"
incus exec "$CNAME" -- apt-get install -y /tmp/jmp.deb

# --- Default audio output = Pioneer -------------------------------------------
# mpv opens ALSA device "default", which otherwise maps to card 0 (Intel HDA,
# HDMI-only pcm devices 3/7/8/9 -> open fails with ENOENT and mpv silently
# falls back to the null output). Pin the default to the Pioneer by card NAME
# so it survives card renumbering. "!" is required to override the compound
# definition in alsa.conf.
incus exec "$CNAME" -- bash -c 'cat > /etc/asound.conf <<EOF
# Pioneer USB audio (card name "Device") is the default output
defaults.pcm.!card "Device"
defaults.ctl.!card "Device"
EOF'

# --- Kiosk user + seat management ----------------------------------------------
incus exec "$CNAME" -- bash -c 'id kiosk >/dev/null 2>&1 || useradd -m -G video,render,input,audio kiosk'

# ⚠️ Group names are NOT enough. The host (Debian) and the container
# (Ubuntu) allocate dynamic system gids independently, so the container's
# `input` group does not necessarily have the same gid as the group that
# owns /dev/input/* on the host. Bind the kiosk user to the *numeric*
# host gid, whatever it is called inside:
HOST_INPUT_GID="$(stat -c %g /dev/input/event0)"
incus exec "$CNAME" -- usermod -aG "$HOST_INPUT_GID" kiosk
incus exec "$CNAME" -- id kiosk        # must list $HOST_INPUT_GID

# In a container seatd must NOT bind the seat to a VT (there is no usable VT;
# it would try to open the host's active tty and hang the compositor forever).
incus exec "$CNAME" -- mkdir -p /etc/systemd/system/seatd.service.d
incus exec "$CNAME" -- bash -c 'cat > /etc/systemd/system/seatd.service.d/novt.conf <<EOF
[Service]
Environment=SEATD_VTBOUND=0
EOF'
incus exec "$CNAME" -- systemctl daemon-reload
incus exec "$CNAME" -- systemctl enable --now seatd

# Re-bind the host udev database onto /run/udev after systemd sets up /run
incus exec "$CNAME" -- bash -c 'cat > /etc/systemd/system/run-udev.mount <<EOF
[Unit]
Description=Host udev database (read-only bind)
Before=jellyfin-kiosk.service

[Mount]
What=/opt/host-udev
Where=/run/udev
Type=none
Options=bind,ro

[Install]
WantedBy=multi-user.target
EOF'
incus exec "$CNAME" -- systemctl enable run-udev.mount

# --- Autostart service -----------------------------------------------------------
incus exec "$CNAME" -- bash -c 'cat > /etc/systemd/system/jellyfin-kiosk.service <<EOF
[Unit]
Description=Jellyfin Media Player (cage Wayland kiosk)
After=seatd.service systemd-user-sessions.service network-online.target
Wants=seatd.service network-online.target

[Service]
User=kiosk
PAMName=login
Environment=QT_QPA_PLATFORM=wayland
Environment=LIBSEAT_BACKEND=seatd
Environment=WLR_LIBINPUT_NO_DEVICES=1
Environment=XKB_DEFAULT_LAYOUT=fr
ExecStart=/usr/bin/cage -d -- /usr/bin/jellyfinmediaplayer --tv --fullscreen
Restart=on-failure
RestartSec=5

[Install]
WantedBy=multi-user.target
EOF'
incus exec "$CNAME" -- systemctl daemon-reload
incus exec "$CNAME" -- systemctl enable jellyfin-kiosk

incus config set "$CNAME" boot.autostart=true
incus restart "$CNAME"

echo "Done. The Jellyfin Media Player UI should appear on the HDMI output."
echo "Check status with: incus exec $CNAME -- systemctl status jellyfin-kiosk"
```

## First-run configuration

1. On the TV, connect JMP to the server: `http://192.168.0.5:8096`.
2. Settings → Audio: "Auto" lands on the Pioneer (ALSA default). Enable
   AC3/DTS passthrough only if the DAC/amp decodes them (the A-70 doesn't).
3. Control: K400 keyboard/touchpad, or any Jellyfin app via "Play On"
   (JMP announces itself as a remote-control target).

## Spotify Connect (go-librespot)

Same container, same Pioneer output. Announces itself as **"Pioneer A-70"**;
zeroconf auth (no credentials stored), Premium account required.

```bash
#!/usr/bin/env bash
set -euxo pipefail

CNAME="${CNAME:-jellyfin-client}"
GLS_VER="${GLS_VER:-0.7.4}"   # https://github.com/devgianlu/go-librespot/releases
DEVICE_NAME="${DEVICE_NAME:-Pioneer A-70}"

incus exec "$CNAME" -- bash -c "
set -e
curl -fsSL -o /tmp/golibrespot.tar.gz https://github.com/devgianlu/go-librespot/releases/download/v${GLS_VER}/go-librespot_linux_x86_64.tar.gz
tar -xzf /tmp/golibrespot.tar.gz -C /tmp
mv /tmp/go-librespot /usr/local/bin/go-librespot
chmod 755 /usr/local/bin/go-librespot
id spotify >/dev/null 2>&1 || useradd -r -m -d /var/lib/go-librespot -G audio spotify
mkdir -p /var/lib/go-librespot/config
cat > /var/lib/go-librespot/config/config.yml <<EOF
device_name: ${DEVICE_NAME}
device_type: speaker
bitrate: 320
EOF
chown -R spotify:spotify /var/lib/go-librespot
"

incus exec "$CNAME" -- bash -c 'cat > /etc/systemd/system/go-librespot.service <<EOF
[Unit]
Description=Spotify Connect client (go-librespot)
After=network-online.target avahi-daemon.service
Wants=network-online.target avahi-daemon.service

[Service]
User=spotify
Group=spotify
ExecStart=/usr/local/bin/go-librespot --config_dir /var/lib/go-librespot/config
Restart=on-failure
RestartSec=5

[Install]
WantedBy=multi-user.target
EOF'
incus exec "$CNAME" -- systemctl daemon-reload
incus exec "$CNAME" -- systemctl enable --now go-librespot
```

## Input hotplug auto-recovery (host side)

cage only enumerates input devices at startup, and udev hotplug events don't
cross into the container (see tricky-parts #2). So re-plugging the Unifying
receiver leaves the kiosk bound to the old, now-dead device node — no
keyboard/mouse until `jellyfin-kiosk` is restarted. These three files **on the
host** (`nuc`, not the container) automate that: the host *does* receive the
uevent, so a host udev rule fires on the receiver's USB `add` and restarts the
container's kiosk. Match is by vendor/product (`046d:c52b`), not sysfs path, so
it works regardless of which USB port the dongle lands on.

`/etc/udev/rules.d/99-jellyfin-kiosk-recover.rules`:

```
# A Logitech receiver was (re)plugged -> recover the jellyfin-client kiosk.
# c52b = Unifying receiver (K400); c539 = Lightspeed receiver (G603).
ACTION=="add", SUBSYSTEM=="usb", ENV{DEVTYPE}=="usb_device", ATTR{idVendor}=="046d", ATTR{idProduct}=="c52b", RUN+="/usr/bin/systemctl --no-block start jellyfin-kiosk-recover.service"
ACTION=="add", SUBSYSTEM=="usb", ENV{DEVTYPE}=="usb_device", ATTR{idVendor}=="046d", ATTR{idProduct}=="c539", RUN+="/usr/bin/systemctl --no-block start jellyfin-kiosk-recover.service"
```

⚠️ The match is per product ID, so **a receiver not listed here will not
auto-recover** — the kiosk must be restarted by hand after plugging it in
(`incus exec jellyfin-client -- systemctl restart jellyfin-kiosk`). Add
the new id here when introducing different input hardware.

`/etc/systemd/system/jellyfin-kiosk-recover.service` — oneshot, so a burst of
udev events during one plug merges into a single restart (natural debounce):

```
[Unit]
Description=Restart jellyfin-client kiosk after Logitech receiver hotplug

[Service]
Type=oneshot
ExecStart=/usr/local/bin/jellyfin-kiosk-recover.sh
```

`/usr/local/bin/jellyfin-kiosk-recover.sh` — waits for the receiver to enumerate
its paired K400 node, then restarts the kiosk only if the container is up (so
host-boot coldplug events are a no-op):

```bash
#!/bin/bash
# Restart the jellyfin-client Wayland kiosk after the Logitech Unifying
# receiver is (re)plugged, so cage/libinput re-enumerates the keyboard/mouse.
sleep 6
if ! incus info jellyfin-client 2>/dev/null | grep -qi 'Status:.*RUNNING'; then
    exit 0
fi
incus exec jellyfin-client -- systemctl restart jellyfin-kiosk.service
logger -t jellyfin-kiosk-recover "Restarted jellyfin-kiosk after Logitech receiver hotplug"
```

Apply, then watch it work by replugging the dongle:

```sh
chmod +x /usr/local/bin/jellyfin-kiosk-recover.sh
udevadm control --reload-rules && systemctl daemon-reload
journalctl -t jellyfin-kiosk-recover -f
```

## ⚠️ Never boot nuc with the display active (2026-08-30)

**Symptom:** after a reboot, *no* Incus container starts. `incus list`
answers but `incus start <anything>` hangs forever, `systemctl status
incus` sits in `activating (start-post)`, and LAN DNS is down because
blocky never came up. Nothing in the incus logs explains it.

**Cause — nothing to do with incus.** If the TV/projector is connected
**and powered on** when nuc boots, firmware hands i915 an already-lit
pipe. The driver's state readback then trips a series of warnings and
the probe never completes:

```
drm_WARN_ON(!pll_active)                    intel_ddi.c:4019   intel_ddi_get_clock
drm_WARN_ON(p0 == 0 || p1 == 0 || p2 == 0)  intel_dpll_mgr.c:2878
drm_WARN_ON(pixel_rate == 0)                skl_watermark.c:1729
```
(all inside `intel_modeset_setup_hw_state` ← `intel_display_driver_probe_nogem`)

The cascade:

1. i915 probe dies → **`/dev/dri` never appears** (no GPU at all)
2. `snd_hda_intel` waits forever for i915's audio component →
   permanent **deferred probe** holding the PCI device lock on `0000:00:1f.3`
3. incusd reads that device's `sriov_numvfs` while enumerating
   resources → blocks in **D state** → the daemon never signals ready,
   so nothing autostarts and every `incus start` hangs

**Reproduced identically on 6.12.107 and 6.12.105** — it is the display
path, not a kernel regression. Do not waste time pinning kernels.

**Diagnosis, in order:**

```sh
ls /dev/dri/                                  # empty = i915 probe failed
cat /sys/kernel/debug/devices_deferred        # snd_hda_intel entry = the deadlock
ps -eLo pid,tid,stat,wchan:26,comm | awk '$3 ~ /D/'   # incusd in sriov_numvfs_show
dmesg -T | grep -E 'drm_WARN_ON|deferred probe pending'
```

**Fix:** disconnect HDMI (or power the display fully off — not standby),
reboot, then **hotplug the cable back in**. Connecting after boot goes
through normal connector detection instead of firmware state readback
and works fine.

In-place recovery is *not* possible: `modprobe -r i915` fails (module in
use by the wedged probe) and `modprobe i915` times out. A reboot is the
only way out.

**After hotplugging, restart the kiosk** — `cage` started with zero
outputs and will not pick the display up on its own:

```sh
incus exec jellyfin-client -- systemctl restart jellyfin-kiosk
cat /sys/class/drm/card0-HDMI-A-2/status     # expect: connected
```

Note the HDA controller this wedges is only used for **HDMI audio**,
which this setup does not use — audio goes to the Pioneer USB DAC via
`/etc/asound.conf`. It is pure collateral damage, but it takes the whole
host down with it.

## Input gid mismatch — latent, fix it anyway (2026-08-30)

> ⚠️ **This was not the cause of the 2026-08-30 outage.** That turned out
> to be a flat/switched-off K400 — a G603 on the same port and the same
> `event0` worked immediately. The mismatch below is real and worth
> correcting, but with `LIBSEAT_BACKEND=seatd` it is **seatd (running as
> root) that opens input devices** and passes the fd to cage, so the
> kiosk user's group membership is not on the critical path for input.
> Fix it for the direct-open fallback path, not as a debugging lead.
>
> **Before suspecting software, prove the hardware emits anything:**
> ```sh
> timeout 60 cat /dev/input/eventN | wc -c    # press keys; 0 bytes = nothing reached the kernel
> ```
> That one check would have saved an hour.
>
> **Dead K400 batteries are invisible from the host.** This K400 exposes
> no `hidpp_battery_*` node under `/sys/class/power_supply/`, so charge
> cannot be read. Worse, the receiver still lists the keyboard as a paired
> peer (`0003:046D:4024.*` under the `C52B` receiver) whether or not it is
> awake, and `/dev/input/event0` plus a `Logitech K400` entry in
> `/proc/bus/input/devices` are present either way — so every software
> check looks perfectly healthy. **Zero bytes from the raw capture is the
> only signal.** Swapping in a different receiver on the same port is the
> quickest A/B confirmation.

**Symptom (if it ever does bite):** kiosk renders but input does nothing,
with no errors — `WLR_LIBINPUT_NO_DEVICES=1` keeps cage alive rather than
failing loudly.

**Cause:** `/dev/input/*` is `crw-rw---- root:<host input gid>`. The
install script adds `kiosk` to the group *named* `input` inside the
container, but Debian (host) and Ubuntu (container) allocate dynamic
system gids independently:

```
host      /dev/input/event0   gid 996  -> "input"
container "input" group                   gid 995   <- kiosk was here
container gid 996                      -> "systemd-timesync"
```

So the kiosk user was in the wrong group and could not open any input
device. The udev side was fine — check it first to rule it out:
`cat /run/udev/data/c13:64` should show `E:ID_INPUT=1` etc.

**Diagnose:**

```sh
stat -c '%n %a %u:%g' /dev/input/event0                       # host gid
incus exec jellyfin-client -- id kiosk                        # does it include that gid?
# open() test — do NOT use `head`/`cat`, reading an event device blocks
# with no pending events and looks like a permission failure:
incus exec jellyfin-client -- su -s /bin/bash kiosk -c 'exec 3< /dev/input/event0 && echo OPEN_OK'
```

**Fix** (persists in the container's `/etc/group`):

```sh
HOST_INPUT_GID="$(stat -c %g /dev/input/event0)"
incus exec jellyfin-client -- usermod -aG "$HOST_INPUT_GID" kiosk
incus exec jellyfin-client -- systemctl restart jellyfin-kiosk
```

Re-check this after any host reinstall — the host's `input` gid is
dynamically allocated and can come back different.

## Troubleshooting

```sh
incus exec jellyfin-client -- systemctl status seatd jellyfin-kiosk go-librespot
incus exec jellyfin-client -- journalctl -u jellyfin-kiosk -b
incus exec jellyfin-client -- su -s /bin/bash kiosk -c vainfo   # GPU/VAAPI
incus exec jellyfin-client -- aplay -l                          # ALSA cards
incus exec jellyfin-client -- su -s /bin/bash kiosk -c "aplay -D default /usr/share/sounds/alsa/Front_Center.wav"
incus exec jellyfin-client -- udevadm info /dev/input/event0    # udev db visible?
```

- **cage "running" but stuck, `Tasks: 0`, black screen** → seatd VT binding
  (see "How the tricky parts work" #1). Note: `Tasks: 0` alone is normal —
  `PAMName=login` moves the process into a logind session scope.
- **"libinput initialization failed, no input devices"** → udev db not
  visible (#2); check `run-udev.mount` is active.
- **Video OK, no sound; JMP log shows `AO: [null]`** → ALSA default broken
  (#3); check `/etc/asound.conf` and the card name in `aplay -l`.
  **Most common cause: the Pioneer DAC is simply switched off.**
  `/etc/asound.conf` pins the default to it *by card name* (`Device`), so
  with the amp off the name does not exist and `default` fails to open —
  mpv then falls back to null silently: picture, no sound, no error.
  One-line check before blaming anything else:
  ```sh
  incus exec jellyfin-client -- su -s /bin/bash kiosk -c 'aplay -D default -d 1 /usr/share/sounds/alsa/Front_Center.wav'
  ```
  `audio open error: No such device` = amp is off. Power it on; no
  restart needed, JMP opens the device per playback.
- **Display hotplugged after boot → cage exits once, then recovers by
  itself.** If the kiosk started with no outputs, plugging the HDMI in
  makes cage fail (`Failed with result 'exit-code'`); the unit's
  `Restart=on-failure` / `RestartSec=5` restarts it ~5 s later, this time
  with the display present. **Do not restart it by hand** — check
  `systemctl show jellyfin-kiosk -p ActiveEnterTimestamp` first and only
  intervene if the timestamp predates the hotplug. Verified 2026-08-31.
- **Keyboard plugged in after boot isn't seen** — the host udev db is live
  through the bind, but udev hotplug *events* don't cross the container's
  network namespace, so cage only enumerates at startup. Re-plugging the
  Unifying receiver is now handled automatically by the host-side recovery
  rule (see "Input hotplug auto-recovery"); manual fallback for other input
  hardware: `incus exec jellyfin-client -- systemctl restart jellyfin-kiosk`.
- **cage can't open card0** — something on the host holds DRM master; the
  host must boot to `multi-user.target` with no display manager.
- **Jellyfin + Spotify at the same time** — the Pioneer PCM is exclusive;
  the second opener gets "device busy". Add an ALSA `dmix` config if
  simultaneous mixing is ever needed.
- JMP log: `/home/kiosk/.local/share/jellyfinmediaplayer/logs/jellyfinmediaplayer.log`.