# nuc — bare-metal reinstall procedure

How to rebuild the Incus host from scratch if `/dev/sda` (512 GB SSD,
`XINCUU-512GB`) has to be replaced.

## Hardware

- NUC-class mini PC, Intel Alder Lake-N (iGPU `i915`, HDMI to projector/TV)
- `sda`: 512 GB SSD — OS **and** ZFS pool `data` (all Incus instance disks)
- `sdb`: 4 TB WD Red (USB enclosure) — ZFS pool `usb4t`:
  `usb4t/backup` → `/backup` (incus exports for nuc + ks4, 1 TB quota),
  `usb4t/media` → `/srv/media` (media library)
- USB: Pioneer USB audio (`08e4:0176`), Logitech Unifying receiver (K400),
  CSCTEK USB Audio and HID
- NIC: `enp1s0` (static `192.168.0.3/24`, gw `192.168.0.2`)

## ⚠️ What dies with sda

The ZFS pool `data` lives on `sda5` → **all instance root disks are lost**
with the OS. The USB pool `usb4t` (backups + media) survives — all
instances are replicated onto it with
[`scripts/incus-copy.sh`](https://git.lutran.fr/julien/scripts/src/branch/main/incus-copy.sh) (deployed at
`/root/scripts/` on nuc; set up 2026-08-09):

```sh
# one-time setup (already done; re-run only on a fresh install)
incus storage create nucbackup zfs source=usb4t/backup/nuc
incus project create backup -c features.images=false -c features.profiles=false

# refresh the replicas (all instances, stopped ones included)
/root/scripts/incus-copy.sh -p backup -s nucbackup
```

Runs nightly via `/etc/cron.d/incus-copy` at **03:30** (30 min after
the profile-scheduled 03:00 instance snapshots, so VM refreshes stay
incremental), logging to `/var/log/incus-copy.log` (logrotate:
`/etc/logrotate.d/incus-copy`). Note the script's `flock` is global:
if a future 02:30 ks4 pull overruns past 03:30, the local run aborts
loudly for that night instead of overlapping.

Replicas sit **stopped** in project `backup` with `boot.autostart=false`
(the script enforces it). Containers refresh in seconds; the
homeassistant **VM re-sends its full volume** unless the source has
snapshots (`snapshots.schedule`) to diff against.

`jellyfin-server` / `jellyfin-client` are also rebuildable from
[jellyfin-server.md](jellyfin-server.md) /
[jellyfin-client.md](jellyfin-client.md); the media library lives on
`usb4t/media` (originals on the NAS `//192.168.0.10/Shared`).

## 1. Install Debian 13 (trixie)

Netinst ISO, manual partitioning of the new sda (GPT/UEFI):

| Part | Size    | Type / FS | Mount       |
|------|---------|-----------|-------------|
| sda1 | ~1 GB   | EFI vfat  | `/boot/efi` |
| sda2 | ~2 GB   | ext4      | `/boot`     |
| sda3 | ~47 GB  | ext4      | `/`         |
| sda4 | ~1 GB   | swap      | —           |
| sda5 | rest (~427 GB) | **leave unformatted** (ZFS later) | — |

- Tasks: only "SSH server" + standard utilities (no desktop).
- Sources: `main contrib non-free-firmware` (contrib is required for
  `zfs-dkms`).

## 2. Base system

```sh
apt update && apt full-upgrade -y
apt install -y \
  firmware-intel-graphics firmware-iwlwifi firmware-realtek \
  firmware-sof-signed intel-microcode \
  linux-headers-amd64 zfs-dkms zfsutils-linux zfs-zed \
  cifs-utils curl vim htop ripgrep sysstat dmidecode pciutils usbutils
```

Static network — `/etc/network/interfaces` (ifupdown):

```
source /etc/network/interfaces.d/*

auto lo
iface lo inet loopback

allow-hotplug enp1s0
iface enp1s0 inet static
    address 192.168.0.3
    netmask 255.255.255.0
    gateway 192.168.0.2
    dns-nameservers 1.1.1.1 9.9.9.9
```

Restore `/root/.ssh/authorized_keys` (3 keys; one is `id_rsa_claude.pub`
from this repo).

## 3. ZFS pools

```sh
# instance pool on the new SSD
ls -l /dev/disk/by-id/ | grep sda5
zpool create data /dev/disk/by-id/<new-ssd-id>-part5

# USB pool (backups + media) survived — just import it
zpool import usb4t
```

(If the old sda still works and only the OS was reinstalled elsewhere:
`zpool import data` instead — the instances survive.)

`usb4t` reference (as created 2026-08: whole disk, `ashift=12`,
`compression=zstd`, `atime=off`, `xattr=sa`, `acltype=posixacl`;
datasets `usb4t/backup` → `/backup` with `quota=1T`, subdatasets
`nuc`/`ks4`, and `usb4t/media` → `/srv/media`).

## 4. Incus (Zabbly stable repo)

```sh
mkdir -p /etc/apt/keyrings
curl -fsSL https://pkgs.zabbly.com/key.asc -o /etc/apt/keyrings/zabbly.asc
cat > /etc/apt/sources.list.d/zabbly-incus-stable.sources <<EOF
Enabled: yes
Types: deb
URIs: https://pkgs.zabbly.com/incus/stable
Suites: trixie
Components: main
Architectures: amd64
Signed-By: /etc/apt/keyrings/zabbly.asc
EOF
apt update && apt install -y incus
```

Initialize with the existing pool and the macvlan network (this is what
gives every instance a real LAN IP):

```sh
cat <<EOF | incus admin init --preseed
storage_pools:
- name: data
  driver: zfs
  config:
    source: data          # use the existing/just-created zpool
networks:
- name: macvlan
  type: macvlan
  config:
    parent: enp1s0
profiles:
- name: default
  devices:
    eth0:
      name: eth0
      network: macvlan
      type: nic
    root:
      path: /
      pool: data
      type: disk
EOF
```

Known macvlan quirk: the **host cannot talk to its own instances** (and
vice versa) over macvlan — management is via `incus exec`, and other LAN
hosts reach them normally. (So test a container's LAN service from inside
the container or from an external LAN host — never by pinging its IP from
the nuc or a sibling container; that always fails by design.)

LAN gateway note: the router/gateway is **`192.168.0.2`** (migrated from
`192.168.0.1`, 2026-08 — `.1` is gone). DHCP-configured instances pick the
new gateway up automatically; **statically-configured ones must be updated
by hand.** Current static holdouts: privoxy
(`/etc/systemd/network/eth0.network`, `Gateway=`) and transmission-bt
(netplan `routes: via:` + the WG kill-switch `/32`). Symptom of a missed
one: the service is up and its port answers, but nothing it fetches works.

Let `julien` run harmless incus commands (list/info/config/show…)
without a password — mutating ones (`exec`, `start/stop`, `delete`)
still prompt:

```sh
cat > /etc/sudoers.d/incus <<'EOF'
## Allow harmless incus commands to be called through sudo
## without a password.
##
## CAUTION: Any syntax error introduced here will break sudo.
## Always edit/validate with: visudo -cf /etc/sudoers.d/incus
##
## Note: "incus config *" also covers config set/edit and device add,
## which can escalate (e.g. security.privileged, host disk mounts).
## Trim to "config show/get" if strict read-only is wanted.

## Cmnd alias specification
Cmnd_Alias C_INCUS = \
  /usr/bin/incus config, /usr/bin/incus config *, \
  /usr/bin/incus list, /usr/bin/incus list *, \
  /usr/bin/incus info, /usr/bin/incus info *, \
  /usr/bin/incus version, \
  /usr/bin/incus top, \
  /usr/bin/incus monitor, /usr/bin/incus monitor *, \
  /usr/bin/incus snapshot list, /usr/bin/incus snapshot list *, \
  /usr/bin/incus image list, /usr/bin/incus image list *, \
  /usr/bin/incus image info *, \
  /usr/bin/incus profile list, /usr/bin/incus profile show *, \
  /usr/bin/incus project list, /usr/bin/incus project info *, \
  /usr/bin/incus network list, /usr/bin/incus network list *, \
  /usr/bin/incus network show *, /usr/bin/incus network info *, \
  /usr/bin/incus storage list, /usr/bin/incus storage show *, \
  /usr/bin/incus storage info *, \
  /usr/bin/incus storage volume list, /usr/bin/incus storage volume list *, \
  /usr/bin/incus operation list, /usr/bin/incus operation show *, \
  /usr/bin/incus remote list, \
  /usr/bin/incus warning list, /usr/bin/incus warning show *

## allow julien to use harmless incus commands without a password
julien ALL = (root) NOPASSWD: C_INCUS
EOF
chmod 0440 /etc/sudoers.d/incus
visudo -cf /etc/sudoers.d/incus   # must print "parsed OK"
```

## 5. Restore instances

The replicas live on `usb4t/backup/nuc` and survived. Re-register them
with the fresh Incus, then copy back onto the rebuilt `data` pool:

```sh
# recreate the containers' home first (section 4), then:
incus project create backup -c features.images=false -c features.profiles=false
incus admin recover        # point it at pool nucbackup (zfs, source=usb4t/backup/nuc)

# copy each replica back to the default project / SSD pool:
incus copy blocky blocky --project backup --target-project default -s data
incus config set blocky boot.autostart=true
incus start blocky
# … same for privoxy, homeassistant, jellyfin-*
```

(jellyfin-* can alternatively be rebuilt from
[jellyfin-server.md](jellyfin-server.md) /
[jellyfin-client.md](jellyfin-client.md); `/srv/media` is already there
once `usb4t` is imported.)

## 6. Nightly automation

| When  | What | Where |
|-------|------|-------|
| 03:00 | instance snapshots (`snapshots.schedule` on the default profile, expiry 7d) | incus |
| 03:30 | replicate all instances to the USB pool (`incus-copy.sh -p backup -s nucbackup`) | `/etc/cron.d/incus-copy` → `/var/log/incus-copy.log` |
| 05:00 | apt dist-upgrade all running containers (`incus-container-upgrade.sh`; VMs and non-apt containers skipped; jellyfin pinned to the 10.11 series in-container) | `/etc/cron.d/incus-container-upgrade` → `/var/log/incus-container-upgrade.log` |

The ordering is deliberate: snapshot → backup → upgrade, so a broken
upgrade is always one snapshot-restore away and the replicas predate it.
Both logs rotate monthly (`/etc/logrotate.d/incus-*`).

## 7. Post-install checklist

- [ ] `zpool status` healthy (both `data` and `usb4t`), `incus list`
      shows expected instances
- [ ] incus ordered after ZFS mounts (instances bind-mount `/srv/media`):
      `/etc/systemd/system/incus.service.d/after-zfs.conf` with
      `[Unit]` / `After=zfs-mount.service zfs.target`
- [ ] `boot.autostart=true` on blocky, privoxy, jellyfin-*
- [ ] Timezone `Europe/Paris` on host and in every container
      (`incus exec <ct> -- timedatectl set-timezone Europe/Paris`;
      the install scripts in the per-container docs include it)
- [ ] Host boots to `multi-user.target`, nothing grabs the GPU
      (required by the jellyfin-client kiosk)
- [ ] Jellyfin web at `http://192.168.0.5:8096`, kiosk UI on HDMI,
      sound on the Pioneer, "Pioneer A-70" visible in Spotify Connect
- [ ] LAN DNS: clients use blocky at `192.168.0.254` (host itself uses
      public `1.1.1.1` + `9.9.9.9`, never blocky, to avoid a bootstrap loop)
- [ ] Optional (only if QSV low-power encoders are wanted):
      `echo 'options i915 enable_guc=3' > /etc/modprobe.d/i915.conf
      && update-initramfs -u`