felhom.eu/documentation/controller/network-storage-nas.md

# Network storage (NAS) — bulk-media shares with verify-before-commit

**Status:** authoritative feature doc, code-verified against felhom-agent v0.81.0 +
felhom-controller v0.113.0 (2026-07-11).
**Evidence base:** `documentation/audits/SPIKE-nas-storage-2026-06-29.md` (the locked mount recipe)
and `documentation/audits/SPIKE-nas-verify-2026-07-11.md` (the verify mechanisms, squash matrix,
error taxonomy — commit b57f6c1). Code: agent `internal/storage/netmount.go` /
`internal/storage/netverify.go` / `internal/localapi/netverifyjob.go`; controller
`internal/web/netstorage_job.go` / `internal/web/netprobe*.go`.

## What it is

A customer's NAS serves **bulk media** (film, photo, music) to media apps. The share is mounted
**host-side** by the agent under `/mnt/felhom-drives/<name>` via a systemd `.automount` + `.mount`
pair (on-demand + idle-unmount), propagates into the guest through the existing shared `mp8` bind,
and is selectable as a media app's data path. A NAS is a **distinct storage class from a drive**:
no durable-id, no SMART, no enroll/eject/decommission/wipe/migrate — remove is the only lifecycle
action (`refuseNetworkLifecycle` blocks the drive verbs).

## The locked mount recipe

- **NFS (nfs4):** `vers=4.1,soft,timeo=50,retrans=2,noatime,_netdev,retry=0`. `soft` = failure
  isolation (clean EIO, never a wedge). **`retry=0`** (SPIKE-nas-verify Q4-vi): without it a
  dead-NAS on-demand access wedges the accessing app until systemd's 90 s start cap (measured
  91 s); with it the access fails clean in ~3.8 s (ENODEV) and each autofs re-access is a fresh
  attempt. `retry` only governs retrying a FAILED first attempt — the happy path is untouched.
  The uid mapping is the EXPORT's job (squash), never the client mount.
- **SMB (cifs):** `vers=3.0,credentials=<0600 file>,uid=<uid+100000>,gid=<gid+100000>,forceuid,
  forcegid,file_mode=0664,dir_mode=0775,_netdev`. No `retry=` (a mount.nfs option; mount.cifs
  rejects it). Credentials live in an agent-written 0600 file, never in the registry, never
  controller-persisted.
- **The +100000 rule:** container uid/gid N = host N+100000 (unprivileged-LXC idmap).

## Verify-before-commit (the add pipeline)

`POST /api/storage/netstorage/add` never registers blind. The controller orchestrates
(detached job, single-flight, ~150 s budget, status on `GET /api/storage/netstorage/add/status`):

1. **agent add** (`POST /netstorage/add`): role-gate → **sync fast-fail** (spec validation + 2 s
   TCP pre-probe; an unreachable server is refused with NOTHING installed) → stage SMB creds →
   install unit pair + enable the automount → start the agent's detached verify job.
2. **agent verify** (polled on `GET /netstorage/verify-status` every 2 s): a directory read
   through the automount triggers a REAL mount (spike Q1: an in-guest or host-side access wakes
   it, ~1 s LAN); success is judged from **/proc/mounts only** (truth table below); a failure is
   classified from the mount unit's journal and **auto-rolled-back** agent-side (units + creds).
3. **in-guest uid-1000 write probe:** the controller re-execs itself
   (`felhom-controller --netprobe <dir>`) with `SysProcAttr.Credential{Uid:1000,Gid:1000}` —
   create a `.felhom-proba-<random>` dot-file, write a nonce, read back, compare, delete. This
   catches the **squash trap**: an export that mounts fine but denies every uid-1000 write
   (spike Q3 row c). A failed delete after a good write is a WARN, not a failure.
4. **register** (`AddStoragePath`, Kind=network, Schedulable) — **the LAST step**. The worst
   crash outcome is an agent-side orphan (surfaced in the list as a remove-only "Árva megosztás"
   row), never a registered-but-broken path.

Any failure = **full rollback**: nothing registered, no units left installed, no creds file.
If the agent restarts mid-verify, its in-memory verify slot reports phase `none`; the controller
treats that as verify-lost and rolls back (the orphan row is the belt-and-braces surface).

### Mount-success truth table (SPIKE-nas-verify §8)

| Trigger `ReadDir(where)` | /proc/mounts shows nfs4/cifs at where | Verdict |
|---|---|---|
| ok | yes | mount OK → the uid-1000 probe decides writability |
| EACCES / EPERM | yes | mount OK (the agent user just can't read it — a 0700 export is fine) |
| any result | no | mount FAILED → classify from the journal |
| still blocked at 95 s | — | `timeout` (black-holed-but-routed; systemd's 90 s cap resolves it) |

Readability is NEVER the truth source — /proc/mounts is.

### Error taxonomy (live-measured; classification is string-based BY DESIGN — every failure is rc=32)

| Category | Journal substring (verbatim) | Meaning |
|---|---|---|
| `unreachable` | `No route to host` / `Connection refused` / `Connection timed out` (or the 2 s sync pre-probe) | no NAS behind the address |
| `nfs_export` | `reason given by server: No such file or directory` | export missing **OR not permitted — MERGED**: NFSv4 returns the identical string for both (Q4 ii≡iii); the customer message names both possibilities |
| `smb_auth` | `mount error(13)` | wrong SMB username/password |
| `smb_share` | `mount error(2)` | SMB share name not found |
| `timeout` | `Mounting timed out. Terminating` | routed but not answering (systemd 90 s cap) |
| `mount_failed` | (none matched / journal unavailable) | generic; detail carries the raw journal |
| `not_writable` | (probe exit 2) | mounts, but uid-1000 cannot write — the squash trap |
| `probe_io` | (probe exit 3) | write readback failed/differed |

The journal is read **unprivileged** (`journalctl -u <unit> -n 20 -o cat`): the agent user is in
the `systemd-journal` group (host-install ≥ v1.13.0 adds it; existing hosts:
`usermod -aG systemd-journal felhom-agent && systemctl restart felhom-agent`). **No sudoers
grant** — journal access is group-based by rule. Journal unavailable degrades to `mount_failed`
with a hint; the rollback still runs.

## NAS-side recipes (protocol-honest guidance — what the UI tells the customer)

- **SMB (Synology, QNAP — the consumer default, listed FIRST in the UI):** a plain user account
  with rw on the share is sufficient — **zero server-side uid configuration** (spike Q5). Files
  land on the NAS owned by the connecting account; the client mount forces the guest view to
  uid/gid 1000. Hardlinks worked on Debian Samba/ext4 — re-verify per appliance.
- **NFS, simple recipe (Route A — spike Q3 row b, ACCEPTED):** enable "map all users / all
  squash" on the export, rw, to ANY local user. The guest-uid-1000 app gets full
  read/write/rename/**hardlink**/delete. Caveats:
  - guest-visible ownership is `nobody:nogroup` (65534) — cosmetic for apps that just read/write;
  - `chown` fails with an immediate clean EPERM (no hang);
  - **`chmod` SUCCEEDS and persists server-side** (the squashed identity owns every file) — modes
    are app-controlled; operators should know a mode change on the NAS side is real.
- **NFS, full-fidelity recipe (TrueNAS / Linux server):**
  `rw,all_squash,anonuid=<uid+100000>,anongid=<uid+100000>` (e.g. 101000 for a uid-1000 app) —
  ownership information is exact end-to-end.
- **The pinned WRONG case (what `not_writable` usually means):** `anonuid=<x>` **without**
  `all_squash` is a no-op for non-root traffic — the app's wire uid (101000) hits the export
  unmapped and fails on others-perms. The consumer recipe REQUIRES the map-ALL-users mode; an
  anonymous-uid field alone does nothing. The UI's `not_writable` message and the guidance block
  tell this same story.

## Health model

Per-share liveness only (`ok | idle | unreachable`): `idle` (automount idle-unmounted) is the
benign steady state; `unreachable` degrades the affected share's apps ONLY — never box health,
never the drive missing→stop cascade (kind-gated). Timing/budget note for integrators: the verify
worst case is systemd's 90 s (black-holed server) — verify traffic therefore rides the detached
job + status poll, never a single long HTTP call (the agentapi client keeps its global 15 s
timeout).

## Synology (DSM) — validated recipe (SPIKE-nas-dsm-2026-07-11, real DSM 7.2)

The consumer recipes were validated end-to-end against a real DSM 7.2 (virtual-dsm) through the live
add pipeline. Exact steps for the customer/operator:
- **Enable NFS first (off by default, and defaults to NFSv3 which our mount rejects):** Control
  Panel → File Services → NFS → "Enable NFS service" → **Maximum NFS protocol: NFSv4.1** → Apply.
- **NFS rule:** Control Panel → Shared Folder → <share> → Edit → NFS Permissions → Create → the
  Felhom host IP, Read/Write, **Squash: "Map all users to admin"** → Save. The export path shown on
  that tab (`/volume1/<share>`) is what goes in the add form.
- **SMB:** Control Panel → User & Group → create a user with Read/Write on the share — nothing else
  (no force-user). **Hardlinks work on DSM's SMB stack** (the Q5 caveat is closed for Synology).
- Route A on DSM behaves exactly as on Debian: guest sees `nobody`, chown clean-EPERM, chmod
  persists. The SMB error taxonomy (`smb_auth`/`smb_share`) classifies identically to Debian.

**QNAP remains a stated caveat** — no emulator exists; not validated.

## Open items

- **Q1c CLOSED — FAIL (SPIKE-nas-dsm-2026-07-11 §Q1c, supervised):** a configured NAS automount
  trigger does **not** survive a guest reboot. `mp8` is `shared`→`shared,slave`; slave propagation
  only carries mounts established AFTER the guest's post-reboot bind, so the pre-existing host autofs
  trigger is absent from the guest's fresh namespace, and an in-guest access sees an **empty
  directory** (not the share) without triggering the host mount. The controller's per-share health
  still reads `idle`/`ok` (it inspects the HOST automount), masking the gap. **Fix = agent-side
  `ReassertNetworkMounts` on guest reboot** (mirror `ReassertGuestBinds`), spec'd at
  `documentation/backlog/FOLLOWUP-nas-automount-guest-reboot-reassert.md`; interim workaround = re-add
  the share. Until fixed, a customer guest reboot requires re-touching NAS shares.
- QNAP appliance fidelity pass (no emulator) before GA — Synology is now validated.
- The demo's `nas-media` share predates `retry=0`; re-adding re-creates the unit with the current
  option string.