# Virtualization tab — plan (2026-10-09, revised the same day; not started)

A tab for creating, watching, consoling into and deleting **LXC containers and KVM virtual
machines**, the way Proxmox does with `pct` and `qm` — **per machine, like every other
page.** This is the scoping PLAN.md asked for. Nothing here is built. Live state of the
hosts stays in `hamlet/docs/hosts.md`.

## The governing rule: capability, not policy

Stated by Mitchell 2026-10-09, after the first draft of this plan excluded hosts on the
strength of the homelab's deployment rules:

> Anything that's done when a different machine is selected SHOULD GO ON THAT machine. I
> want the option to do it anywhere I want, unless the hardware / software literally
> doesn't support it. Ham Lab needs to be built in a general-purpose way that can run on
> any Linux system. If certain parts / libraries aren't available on that machine, those
> tabs should just report that.

So:

- **Every action lands on the machine in the switcher.** There is no "VM host", no default
  machine, no cross-machine placement. `grid` is where he will most likely click first;
  the tab does not know or care.
- **The tab is gated by what the machine can do, detected live** — never by a rule about
  what *should* run there. The `hamlet/CLAUDE.md` do-not-break rules (Mac mini for
  single-core workloads, `hamtv` not spare hardware) bind the *agent's* unasked
  deployments. They are not feature gates for the product, and the first draft was wrong
  to treat them as such.
- **Ham Lab owns the install and the data layout.** It detects what is missing, offers to
  install it where it knows how, chooses and records where instance storage lives and which
  subnet the bridge takes, and runs the backups. Where it cannot install or the hardware
  cannot do the job, it says so in one sentence and offers what *does* work (containers
  without KVM, for instance).

## Decision: Incus 6.0 LTS as the engine

| Option | Verdict |
|---|---|
| **Incus** (LXD fork, linuxcontainers.org) | **Chosen.** One daemon, one CLI and one JSON API for both containers and VMs. Packaged by Debian 13 (`incus` 6.0.4 LTS — `apt install incus` pulls `qemu-system-x86`, `swtpm`, `virtiofsd`, `incus-agent`, so VMs work out of the box), Fedora (6.23), Arch, Alpine, Ubuntu (Zabbly repo); not by OpenWrt. Storage drivers for ZFS, btrfs, LVM and plain directories, so it fits a machine with or without ZFS. Built-in image server (`images:debian/13`, `images:ubuntu/24.04`, Alpine, Fedora, Arch… as container *or* VM, per architecture), snapshot schedules with expiry, `incus export` backups, per-instance CPU/memory limits, cloud-init, text and VGA console over websocket. Everything is reachable as `incus … --format json` or `incus query`, which is exactly how Ham Lab already drives Docker: `exec.Command`, no new Go dependency, no cgo. |
| libvirt/KVM + `virsh`, plus LXC separately | Two daemons, two models, XML. libvirt's official Go binding needs cgo, which the static binary rules out (the pure-Go `go-libvirt` exists but then containers are a second project). Rejected. |
| Proxmox | An OS, not a library. Rejected. |

## What each machine can do today

Probed 2026-10-09 (`/dev/kvm`, cpu flags, kvm modules, RAM, disk, package availability).
These are **facts the tab will detect at runtime**, not a list of where instances are
allowed. The last column is what the tab would show the day it ships.

| Machine | Arch | KVM | RAM (free) | Incus from the package manager | Pool driver available | Tab state on first open |
|---|---|---|---|---|---|---|
| `grid` | x86-64 | yes — VT-x, `kvm_intel` loaded, nested on | 62 GiB (~25; ARC holds 23 of the rest, max 40) | apt: `incus` 6.0.4 | **zfs** (2.3.9, `tank`) | **Install** — containers and VMs |
| `core` | x86-64 | yes — N100, `kvm_intel` loaded | 7.5 GiB (~4) | apt: `incus` 6.0.4 | btrfs or dir (ZFS was purged 2026-09-23) | **Install** — containers and VMs; the create form shows free memory so a VM's size is an informed choice |
| Mac mini | aarch64 | yes — Asahi KVM, 16K pages | 15 GiB (~8) | dnf: `incus` 6.23, `qemu-system-aarch64-core`, `edk2-aarch64` | btrfs or dir | **Install** — containers and VMs, **arm64 images only** (the picker filters by host arch). Whether a stock 4K-page guest kernel boots under the 16K host is untested; `muvm` does exactly that, so it is expected to. |
| `hamtv` | x86-64 | yes | 3.7 GiB (~2.9) | apt: `incus` 6.0.4 | btrfs or dir | **Install** — containers and small VMs |
| `gate` | x86-64 | **no** `/dev/kvm` | 8 GiB (~6) | **none** — OpenWrt's opkg has no Incus | — | **Unavailable**: "Incus isn't packaged for OpenWrt, and this kernel has no KVM." Nothing to install. |

Nothing is installed anywhere today: no qemu, libvirt, lxc or incus on any host.

### Detection the tab runs, in order

1. `incus` on `PATH` and its socket answering → **ready**; read pools, networks, instances.
2. Else: a package manager Ham Lab knows (apt, dnf, pacman, apk) that has an `incus`
   candidate → **installable**, with the Install dialog pre-filled (below).
3. Else → **unavailable**, with the reason in one sentence (no package; no root; OpenWrt).
4. Independently: `/dev/kvm` present and openable → VMs offered. Absent → **containers
   only**, said once on the page, and the create form has no VM option.
5. Architecture from `uname -m`, so the image picker only shows images that can run here.
6. Pool driver: `zfs` if the module and tools are present, else `btrfs` (installing
   `btrfs-progs` as part of Install), else `dir`. The dialog says which it picked and why.

## What the tab does (v1)

Mirrors the Docker tab's shape: a list, a detail page, actions that are followed tasks,
destructive ones confirmed by typing the name.

- **Install** — one task that runs *on the selected machine*: install the package(s),
  `incus admin init --preseed` with the layout from the dialog, create the pool and bridge,
  add Ham Lab's user to `incus-admin` (socket access, the `docker`-group shape) and add it
  to the unit's `SupplementaryGroups`, apply the Docker fix where Docker is present (below),
  then restart Ham Lab. Idempotent, so it doubles as "repair". The dialog shows and lets him
  edit: pool driver (detected), pool size (proposed from free space), pool path, bridge
  subnet (computed), whether to apply the Docker rules.
- **Instances** — containers and VMs in one list: type, state, IPv4, CPU and memory live,
  disk, snapshot count, uptime. Click for detail.
- **Create** — container or VM (VM only where KVM is); image from the `images:` remote,
  filtered to this architecture, searchable, with the common ones pinned (Debian 13, Ubuntu
  24.04, Alpine, Fedora); name, CPUs, memory (with this machine's free memory beside it),
  root disk size; network (the NAT bridge, or a LAN bridge if this machine has one);
  optional cloud-init user-data (SSH key, packages, a first command); profile. Create, or
  create and start. Collisions (name taken) named before Create.
- **Lifecycle** — start, stop, restart, force stop, rename, delete (type the name; the
  instance's snapshots go with it, and the dialog says so).
- **Console** — two buttons, both open as tabs in the Terminal page through the existing PTY
  manager (`term.CreateCmd`, the `docker exec` path): **Console** (`incus console`, the
  serial console — works before the network is up, shows boot output) and **Shell**
  (`incus exec <n> -- login shell`). Containers and, via `incus-agent`, VMs.
- **Snapshots** — take, restore (confirmed), delete; a **schedule** per instance with an
  expiry, which is Incus's own `snapshots.schedule`/`snapshots.expiry`, so no cron file of
  ours this time.
- **Resources** — edit CPU and memory limits (live for containers; VMs take CPU hotplug and
  memory balloon live with the agent, else on restart), grow the root disk, add a bind mount
  (a host path into a container; virtiofs into a VM).
- **Images** — what is cached locally, delete, aliases; **publish** a stopped instance as an
  image (Proxmox's "convert to template").
- **Storage and networks** — the pools with their fill, the bridges with their subnets.
  Read-only in v1 beyond what Create and Install need.
- **Sensors** — `instance.<name>.cpu`, `.memory`, `.running` from Incus's state, like the
  `container.*` sensors, so Alerts gets an "instance down" default and widgets can show one.

## Not in v1, with reasons

| Thing | Why not yet |
|---|---|
| **VGA console in the browser** | Incus hands the VM's SPICE socket over a websocket; drawing it needs `spice-html5` in the UI. Doable (the Incus UI does it), but text console + shell cover every Linux guest. Phase 3. |
| **Windows VMs** | Incus runs them (ISO repacked with virtio drivers by `distrobuilder`), but without a VGA console in the browser they are unusable from the tab. After the above. |
| **GPU passthrough to a VM** | Removes the card from the host and from whatever uses it there (Jellyfin on `grid`). Offered only with that warning, later. Sharing a GPU into a *container* (`gpu` device) leaves the host its card and is how `r720-jellyfin` used to run. Phase 3. |
| **Clustering / live migration** | Incus clusters, but these machines differ in size and one is arm64, with no shared storage. Not planned. |
| **A fleet-wide instance list** | One machine per view. The switcher is the machine. |
| **A second engine (bare LXC on OpenWrt, libvirt-only hosts)** | Would double the backend for one router that has no KVM. The tab reports Incus unavailable there and stops. |

## Layout decisions Ham Lab makes per machine (overridable in the Install dialog)

1. **Storage.** A pool on the machine's own disk, driver by the detection above, as a
   loop-backed image where the driver needs one (`incus storage create default zfs
   size=…`) — sized from free space, shown and editable. Bulk data is **bind-mounted in**,
   not stored in the pool: on `grid` that means `/tank/…` paths into instances, the same
   split Docker already has. A second pool on an existing dataset (`tank/incus`) is one
   extra command if a guest wants terabytes. The pool's path and driver are recorded in
   Ham Lab's state so the page can say where the data is.
2. **Bridge subnet, computed.** Incus's `auto` picks a random `10.x.y.0/24`, and **this
   LAN is `10.0.0.0/8`** — every host has a /8 on its NIC, so any 10.x bridge collides.
   Ham Lab reads the machine's routes and picks the first free /24 from `192.168.0.0/16`,
   then `172.16.0.0/12`, that is neither on-link nor routed nor inside Docker's configured
   pool (`172.28.0.0/14` on `grid`; `172.19`–`172.29` and `192.168.80`–`143` live on
   `core`). Instances get `name.incus` DNS from Incus's dnsmasq.
3. **LAN addresses are a later, explicit step.** A `br0` on the machine's uplink lets an
   instance take a lease from `gate` and a Pi-hole name, but it rewrites the host's network
   config and drops it off the network for seconds — never part of Install, always its own
   confirmed action (with the NanoKVM standing by on `grid`). macvlan was considered and
   rejected: no host change, but host and guests cannot talk, so nothing on the host could
   reach an instance.
4. **Docker and Incus on one host.** Docker sets the `FORWARD` policy to `DROP`, which
   silently kills the Incus bridge's traffic. Fix is two `DOCKER-USER` accept rules for the
   bridge, persisted — applied by Install wherever Docker is detected (`grid`, `core`, the
   Mac, `hamtv` all run it).
5. **Memory.** A VM's memory is a hard reservation; the create form shows the machine's
   free memory and warns past it, and never refuses. On a ZFS host Install offers to cap
   the ARC (on `grid`, 40 GiB → 16 GiB) so guest RAM is deterministic; his choice.
6. **Privilege.** Ham Lab's user joins `incus-admin`; no sudo in the hot path. Install
   itself goes through `priv` like the other installers.
7. **Backups.** Nightly `incus export --instance-only` of every instance to a per-machine
   export directory with a retention, as a cron line like the ZFS schedules
   (`hamlab incus-export`), from phase 2. Default is under Ham Lab's data directory (so on
   `core` the nightly rsync already carries it); on `grid` he will point it at
   `/tank/backups/incus/`, since `grid`'s own root disk is backed up nowhere.

## The old Proxmox estate (importable, phase 3)

`/tank/backups/proxmox/` holds the retired `r720` node: `/etc/pve` (12 LXC confs, 2 VM
confs), 118 GiB of `vzdump` archives, and three raw VM disks. Latest of each:

| ID | Name | Latest archive | Size |
|---|---|---|---|
| 100 | r720-docker | 2026-01-11 | 20.7 GB |
| 101 | r720-cockpit | 2026-01-11 | 439 MB |
| 102 | r720-wordpress-alexblaskovich | 2026-01-11 | 1.2 GB |
| 103 | r720-spoonterm | 2025-06-14 | 494 MB |
| 104 | r720-ollama | 2026-01-11 | 11.3 GB |
| 105 | r720-transmission | 2026-01-11 | 322 MB |
| 106 | r720-apache | 2026-01-11 | 347 MB |
| 107 | r720-nut | 2025-03-29 | 205 MB |
| 108 | r720-filebrowser | 2026-01-11 | 262 MB |
| 109 | r720-bookstack | 2025-04-27 | 516 MB |
| 110 | r720-jellyfin | 2026-01-11 | 2.2 GB |
| 111 | r720-wireguard | 2025-04-13 | 510 MB |
| 112 | r720-eggwiki | 2026-01-11 | 634 MB |
| VMs | steam (102), powerpanel (105/107/112) | `.vma.zst` 2024–2025; raw disks `vm-105`, `vm-112`, `base-104` | 19 GB, 1.9 GB ×6, 97 GiB |

- **LXC:** feasible and scriptable. Unpack the rootfs (`tar --zstd -xpf … --numeric-owner`),
  read `etc/vzdump/pct.conf` for arch/ostype, drop it, write `metadata.yaml`, pack, `incus
  image import`, launch. Unprivileged uid shifting is Incus's job after that. An import
  action in the tab (pick an archive on this machine) is plausible once the script works by
  hand. x86-64 archives only run on x86-64 machines; the picker says so.
- **VMs:** the raw disks import directly (`incus-migrate`, or an empty VM with the disk
  imported into its root volume). The `.vma.zst` archives need Proxmox's `vma` extractor (or
  the Python port) to become raw disks first. Most of these are the same `powerpanel` box
  backed up six times, and `tank-space-audit.md` already has them down for deletion — decide
  which, if any, are wanted before anything is restored.

## Build plan

| Phase | What | Effort |
|---|---|---|
| **1 — detection, Install, the tab** | `internal/incus` (detection, CLI wrapper, JSON types, `incus monitor` for live state, the preseed builder and subnet picker), `internal/api/virt.go` (routes below), `Virtualization.tsx` (the three page states; list, detail, create dialog, snapshot panel), rail entry `virt`, terminal integration, sensors. **Tested by clicking Install on `grid` first, then `core`** — two different pool drivers, both with Docker present. Then the Mac for the arm64 path. `gate` for the unavailable state. | 2–3 sessions |
| **2 — operations** | Snapshot schedules UI, nightly exports with retention and the per-machine export directory, limits editor, bind mounts, the LAN-bridge step, instance alert default, cloud-init presets. | 1–2 sessions |
| **3 — the rest** | Proxmox import, publish-as-image, GPU device for containers, VGA console (`spice-html5`), GPU passthrough to a VM with its warning. | as wanted |

### API sketch

```
GET    /api/virt                               {state: ready|installable|unavailable, reason, kvm, arch,
                                                pool_drivers[], pools[], networks[], instances[], free_memory}
POST   /api/virt/install                       {driver, size, path, subnet, docker_rules, arc_max?}  task
GET    /api/virt/images?remote=images&q=       local cache + remote search, filtered to this arch
DELETE /api/virt/images/{fingerprint}
POST   /api/virt/instances                     {name, type, image, cpu, memory, disk, network, cloudinit, profile, start}  task
GET    /api/virt/instances/{name}              config, state, devices, snapshots
PATCH  /api/virt/instances/{name}              limits, description, devices
POST   /api/virt/instances/{name}/{start|stop|restart|kill|delete|rename|publish|export}
POST   /api/virt/instances/{name}/console      → terminal {id}   (incus console)
POST   /api/virt/instances/{name}/exec         → terminal {id}   (incus exec -- sh -lc …)
POST   /api/virt/instances/{name}/snapshots    {name}; POST …/{snap}/restore; DELETE …/{snap}
PUT    /api/virt/instances/{name}/schedule     {cron, expiry}
POST   /api/virt/import                        {path}  task (export tarball, or phase-3 Proxmox archive)
```

Everything is per machine and reaches a node through the existing `/api/nodes/{name}/…`
proxy with no hub-side code; consoles attach over the existing `/api/terminals/{id}/attach`.
Tasks stream through `/api/tasks/{id}/stream` as Docker's do.

## Sources

- Incus on Debian: https://wiki.debian.org/Incus
- Incus and Docker on one host (the `FORWARD` drop): https://linuxcontainers.org/incus/docs/main/howto/network_bridge_firewalld/
- Bridge options and `ipv4.address: auto`: https://linuxcontainers.org/incus/docs/main/reference/network_bridge/
- Consoles (text and VGA): https://linuxcontainers.org/incus/docs/main/howto/instances_console/
- ZFS storage driver: https://linuxcontainers.org/incus/docs/main/reference/storage_zfs/
- macvlan's host-isolation: https://linuxcontainers.org/incus/docs/main/reference/network_macvlan/
- Image format for the Proxmox import: https://linuxcontainers.org/incus/docs/main/reference/image_format/