agent v0.37.0: host-reboot remount re-resolves enrolled drives by fs-UUID

TASK A — close out the reboot story (agent half). Root cause (pinned live on
felhom-pve): an enrolled .mount unit left `disabled` by a prior detach never
auto-mounts at boot, and kernel re-enumeration can move a drive's node
(/dev/sdb->sdc). Fix re-asserts every enrolled mount by filesystem UUID at
startup + on the periodic tick.

- ResolveStorageDevice: resolve uuid:<fs-uuid> -> current /dev node via
  /dev/disk/by-uuid (never a cached node); errors if absent.
- parseFelhomMountUnit: pure inverse of renderMountUnit (marker-gated).
- (*SudoHostOps).ReassertEnrolledMounts: re-run EnsureMount (enable --now) for
  any enrolled unit not in /proc/mounts; idempotent, skips mounted/absent.
- main.go: runs before ReassertGuestBinds at startup + on the 20s tick.
- tests (Linux, seam=device resolution): letter-move tolerated (sdb->sdc) +
  red-proof companion, absent/scheme rejection, render->parse round-trip.

TASK A2 verdict: enrolling a NEW drive does NOT need an LXC restart — the path
lands on the live AttachDrive (shared parent, named live slots), not RebootGuest.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
This commit is contained in:
2026-06-16 17:49:00 +02:00
parent 437f096d9d
commit a621f4c5a0
8 changed files with 305 additions and 40 deletions
+31
View File
@@ -3,6 +3,37 @@
All notable changes to **felhom-agent** are recorded here. Update on every code
change that gets pushed.
## v0.37.0 — host-reboot remount re-resolves enrolled drives by filesystem UUID (2026-06-16)
**TASK A — close out the reboot story (agent half).** On a host reboot the kernel can re-enumerate block
devices and move a drive's node (felhom-usb `/dev/sdb``/dev/sdc`), and a `.mount` unit left `disabled`
by a prior detach never auto-mounts at boot — so an enrolled drive could stay unmounted (or, with any
node-trusting remount, mount the WRONG device). Root cause pinned LIVE: felhom-usb's systemd mount unit
was `disabled` (no `multi-user.target.wants` symlink) while felhom-flash's was `enabled`; `What=` was
already correct (by-UUID), but nothing re-asserted the unit at startup.
- `storage.ResolveStorageDevice(durableID)` — resolves the enrolled `uuid:<fs-uuid>` storage scheme to its
CURRENT backing `/dev` node by re-scanning `/dev/disk/by-uuid` (never a cached node); errors if the UUID
is genuinely absent so a caller skips a gone drive instead of fail-mounting a stale node.
- `storage.parseFelhomMountUnit` — pure inverse of `renderMountUnit` (Name/UUID/Where/Type/Options) keyed
on a `Managed by felhom-agent` marker; ignores any foreign `.mount` unit.
- `(*SudoHostOps).ReassertEnrolledMounts(ctx)` — at startup (BEFORE binding into the guest) and on the
periodic 20s tick: for each enrolled `.mount` unit not currently mounted (per `/proc/mounts`), re-resolve
by UUID and re-run `EnsureMount` (idempotent `systemctl enable --now`) — re-enables a disabled unit AND
mounts the CURRENT device by UUID, so a `/dev/sdX` reshuffle is a no-op. Already-mounted drives are
skipped (no daemon-reload churn); an absent UUID is skipped (re-asserts on a later tick).
- Wired in `main.go` ahead of `ReassertGuestBinds` so mounts are live before the guest binds re-assert.
- Tests (Linux, seam the device-resolution): `TestResolveStorageDevice_ToleratesDeviceLetterMove`
(UUID symlink moved sdb→sdc → resolves sdc; companion asserts the cached enroll-time node differs from
the freshly-resolved one — a node-based remount would target the wrong device), `..._AbsentAndScheme`
(absent UUID errors; only the `uuid:` scheme resolvable), `TestParseFelhomMountUnit` (render→parse
round-trip + rejects a foreign unit).
**TASK A2 — verdict: enrolling a NEW drive does NOT need an LXC restart.** The enroll path lands on the
live intermediary-mount `AttachDrive` (`/disks/guest-attach``handleDiskGuestAttach``AttachDrive`,
"no pct, no reboot") under the single shared parent — unbounded named live slots — NOT the legacy
`RebootGuest` branch. The operator's pre-created-slot-pool idea is therefore unnecessary.
## v0.36.7 — isolate the shared parent only on CREATE (no peer-group churn) (2026-06-15)
Follow-up to v0.36.6: make-private+make-shared must run ONLY when the self-bind is first created, not on
+7
View File
@@ -58,6 +58,13 @@ and no shell**; tests use a fake (no real root in the suite).
(`What=/dev/disk/by-uuid/<UUID>`, enabled so they survive reboot) — not raw fstab or a
transient `mount`. Benign re-mount is idempotent; **detach** (stop+disable) is destructive
and routes through the gate.
- **Host-reboot remount re-resolution (v0.37.0):** at startup (before binding drives into the
guest) and on the periodic tick, `ReassertEnrolledMounts` re-asserts every enrolled `.mount`
unit that isn't currently mounted: it re-resolves the drive's `uuid:<fs-uuid>` durable id to
its **current** `/dev` node by re-scanning `/dev/disk/by-uuid` (`ResolveStorageDevice`, never a
cached node) and re-runs the idempotent `enable --now`. This re-enables a unit a prior detach
left `disabled` AND tolerates kernel re-enumeration moving a drive's letter (`/dev/sdb``sdc`)
— the reshuffle is a no-op. Already-mounted drives and genuinely-absent UUIDs are skipped.
- **Every argument is validated before any command is constructed** (`validate.go`): UUIDs
against a strict hex regex, mount paths confined + traversal-checked, SMART devices
whitelisted to raw disks, LVM names charset-checked. The adversarial matrix in
+63 -39
View File
@@ -1,45 +1,69 @@
# REPORT — storage lifecycle completion + acceptance sweep (agent half) → v0.36.7 (2026-06-15)
# REPORT — felhom-agent v0.37.0 (host-reboot remount by durable-id/UUID)
## Type
Lifecycle fixes + a full live acceptance sweep (incl. a real HOST REBOOT) on the intermediary-mount
foundation. Built + Linux-gated + deployed to felhom-pve per commit. Pairs with controller v0.68.1. Full
audit: `felhom.eu/documentation/audits/storage-lifecycle-acceptance-2026-06-15.md`.
**TASK — Close out the reboot story (agent half: Task A + Task A2).**
## Shipped (agent), each green-gated + deployed
- **v0.36.0 — guest boot-id on /disks.** `guest_boot_id` = `<host-btime>-<guest-init-starttime>`: changes
on every guest/host boot, stable across a controller-only restart. Lets the controller deterministically
recreate drive-backed apps after a guest reboot (replaces a fragile container-uptime sample). Pure parser
test + companion.
- **v0.36.1 — decommission keeps the raw mounted.** Decommission is now a LOGICAL retire (DetachDrive the
bind under the parent; LEAVE the raw `/mnt/<name>` mounted), so one-click re-enroll re-binds the real
drive. The old raw-unmount orphaned a non-removable drive (re-enroll bound an empty dir). **Caught live
in E10.**
- **v0.36.2 — eject also keeps the raw mounted** (same fix, for the H1 disconnect→reconnect roundtrip).
- **v0.36.3 — DetachDrive loop-umounts** ALL stacked binds (full detach → fail-close intact).
- **v0.36.4 — mutex** serializes AttachDrive/DetachDrive (no TOCTOU double-bind race).
- **v0.36.5 — AttachDrive normalizes to exactly one bind** (`countHostMounts`).
- **v0.36.6 — ROOT CAUSE of the double-bind:** the shared-parent self-bind inherited `/`'s shared peer
group, so every drive bind propagated back and DOUBLED. `make-private` (own group) BEFORE `make-shared`.
- **v0.36.7 — isolate the parent only on CREATE** (re-doing make-private/shared each reconcile churns the
peer-group id and orphans the guest's slave → propagation silently dies).
## Task A — host-reboot remount resolves by filesystem UUID, never a cached node
Non-hollow tests + companions updated: decommission/eject keep the raw mounted (`d.unmountCalls==0` +
DetachDrive called); the boot-id parser; etc.
### Diagnose-first (root cause, pinned LIVE on felhom-pve)
## Acceptance sweep highlights (live)
- **HOST REBOOT live-validated (×2):** `journalctl -b` proves felhom-shared-parent FINISHED before
pve-guests STARTED; the guest auto-started (onboot=1); both drives re-propagated; all 8 apps converged
via the gate with no manual intervention; data intact.
- Fail-close capability-proof (guest-root + root-app writes DENIED, no leak), confinement (both drives),
two-drive isolation, eject/decommission/re-enroll roundtrips, rapid eject/reconnect (single bind after
the double-bind root-cause fix).
On a host reboot the kernel re-enumerates block devices; a drive can move node (felhom-usb
`/dev/sdb``/dev/sdc`). Two things could leave an enrolled drive unmounted after a reboot:
## End state
Both external drives on the intermediary model, **single bind each**, propagation live, **25 containers
healthy**, felhom-flash default. agent v0.36.7 deployed (backups at /usr/local/bin/felhom-agent.bak-*).
1. A systemd `.mount` unit left **`disabled`** by a prior detach (`Unmount` = stop + disable)
never gets a `multi-user.target.wants` symlink, so it does **not** auto-mount at boot — and
nothing in the agent re-asserted it at startup.
2. Any remount that trusted a remembered `/dev/sdX` node would target the WRONG device after a
letter move.
## Known residuals
- Pre-start hook vs an agent restart can race the parent-bind churn (exit 255) — resolved by the
on-create-only isolation (parent no longer churned); operationally, don't restart the agent and reboot
the guest in the same instant.
- "Safely removable" fs-flush before a physical pull is the separate "remove from system" action's job.
Confirmed live: felhom-usb's mount unit was `disabled` (`systemctl is-enabled``disabled`,
no wants-symlink) while felhom-flash's was `enabled`. The `What=` line was already correct
(`/dev/disk/by-uuid/<UUID>`), so the fix is to **re-assert the unit by UUID at startup**, not to
rewrite the unit.
### Fix
- `storage.ResolveStorageDevice(durableID)` (`durable_device.go`) — resolves the enrolled
`uuid:<fs-uuid>` storage scheme to its **current** backing `/dev` node by re-scanning
`/dev/disk/by-uuid` (`EvalSymlinks`); rejects any non-`uuid:` scheme (anti-node-binding) and
errors when the UUID is absent so a caller skips a gone drive instead of fail-mounting.
- `storage.parseFelhomMountUnit` (`mountunit.go`) — pure inverse of `renderMountUnit`, gated on a
`Managed by felhom-agent` marker; extracts Name/UUID/Where/Type/Options, ignores foreign units.
- `(*SudoHostOps).ReassertEnrolledMounts(ctx)` (`hostops.go`) — for each enrolled `.mount` unit
not in `/proc/mounts`, re-resolve by UUID and re-run `EnsureMount` (idempotent
`systemctl enable --now`). Re-enables a disabled unit AND mounts the current device by UUID;
already-mounted drives skipped (no daemon-reload churn), absent UUIDs skipped (retry next tick).
- `main.go` — runs `ReassertEnrolledMounts` at startup **before** `ReassertGuestBinds`, and again
ahead of the bind re-assert on the periodic 20s tick, so host mounts are live before the guest
binds re-establish.
### Tests (non-hollow, seam = device resolution; Linux)
- `TestResolveStorageDevice_ToleratesDeviceLetterMove` — fake `/dev/disk/by-uuid/<uuid>` symlink
pointed at `sdc` (moved from the enroll-time `sdb`); asserts `ResolveStorageDevice` returns the
CURRENT node `sdc`. **Companion (red-proof):** asserts the cached enroll-time node (`sdb`) differs
from the freshly-resolved node — a node-trusting remount would mount the wrong device.
- `TestResolveStorageDevice_AbsentAndScheme` — absent UUID errors; only `uuid:` is resolvable
(`/dev/sdb1`, `store:`, `byid:`, `""` all rejected).
- `TestParseFelhomMountUnit``renderMountUnit``parseFelhomMountUnit` round-trip + rejects a
non-felhom unit.
## Task A2 — verdict: enrolling a NEW drive does NOT need an LXC restart
**NO.** Source-verified the enroll path: `/disks/guest-attach``handleDiskGuestAttach`
`GuestBinder.AttachDrive` (intermediary-mount model, "no pct, no reboot") — a live bind under the
single shared parent `/mnt/felhom-drives`, which provides unbounded **named** live slots. It does
NOT take the legacy `RebootGuest` branch. The operator's pre-created-slot-pool idea is unnecessary.
## Gate
`go build ./...`, `go vet ./...`, `go test ./...` all green locally (Windows: the symlink tests
skip — they assert on Linux, the agent's OS). Linux green gate + companion red-proof run on the
build server (192.168.0.180, go1.26.0) — see live-acceptance section.
## Live acceptance
Real host reboot ×2 on felhom-pve: before/after `lsblk`, shared-parent-before-pve-guests ordering,
both drives (felhom-usb + felhom-flash) remount by UUID across a `/dev/sdX` reshuffle, guest 9201
drive-backed apps recover, FileBrowser non-stale. (Captured during the supervised run.)
Secrets (local_api token / leaf fingerprint) handled out-of-band — none committed.
+15 -1
View File
@@ -44,7 +44,7 @@ import (
// version is the agent version. Overridable at build time with
// -ldflags "-X main.version=<v>"; defaults to the in-repo CHANGELOG version.
var version = "0.36.7"
var version = "0.37.0"
// runGuestHook is the PVE pre-start hook body (`felhom-agent guest-hook <vmid> <phase>`). On the
// pre-start phase it creates placeholder dirs for any absent bind-mount source so the guest always boots
@@ -506,6 +506,15 @@ func runDaemon(cfg config.Config, logger *slog.Logger) int {
go func() { errc <- pbsLoop.Run(ctx) }()
if localSrv != nil {
localServers = 1
// Host-reboot remount fix: BEFORE binding into the guest, re-assert enrolled drive MOUNTS on the
// host. A `disabled` mount unit (left so by a prior detach) doesn't auto-mount at boot, and kernel
// re-enumeration can move the device (/dev/sdb→sdc); ReassertEnrolledMounts re-resolves each by
// filesystem UUID and re-mounts (idempotent `enable --now`) so a letter reshuffle is a no-op.
// Type-asserted (the concrete op exposes it; the interface stays lean).
mountReasserter, _ := hostOps.(*storage.SudoHostOps)
if mountReasserter != nil {
mountReasserter.ReassertEnrolledMounts(ctx)
}
// F9: on startup (the host's bring-up/reconcile trigger), re-assert any enrolled guest data-drive
// bind that a re-provision dropped — before serving, so the drive is back in the guest config
// (activates on the guest's next reboot). On-durable-id-match; absent/swapped drives are skipped.
@@ -523,6 +532,11 @@ func runDaemon(cfg config.Config, logger *slog.Logger) int {
case <-ctx.Done():
return
case <-t.C:
// Re-assert mounts first (handles a USB that enumerated late after a host reboot, or a
// unit re-disabled at runtime), then re-assert the guest binds against the now-live mounts.
if mountReasserter != nil {
mountReasserter.ReassertEnrolledMounts(ctx)
}
localSrv.ReassertGuestBinds(ctx)
}
}
+18
View File
@@ -73,6 +73,24 @@ func ResolveDurableDevice(durableID string) (string, error) {
}
}
// ResolveStorageDevice resolves an enrolled STORAGE durable-id (the `uuid:<fs-uuid>` scheme that
// deriveDurableID emits for usb/local-dir drives) to its CURRENT backing /dev path by re-scanning
// /dev/disk/by-uuid. This is the load-bearing host-reboot fix: kernel re-enumeration can move a drive
// from /dev/sdb to /dev/sdc, so a remount MUST re-resolve by UUID (never trust a remembered node) — the
// reshuffle is then a no-op. Errors if the UUID no longer resolves (the drive is genuinely absent), so a
// caller can skip re-mounting a gone drive instead of failing on a stale node.
func ResolveStorageDevice(durableID string) (string, error) {
const scheme = "uuid:"
if !strings.HasPrefix(durableID, scheme) {
return "", fmt.Errorf("storage: durable id %q is not the uuid: scheme — cannot resolve by filesystem UUID", durableID)
}
uuid := strings.TrimPrefix(durableID, scheme)
if !safeLinkName(uuid) {
return "", fmt.Errorf("storage: unsafe durable id %q", durableID)
}
return filepath.EvalSymlinks(filepath.Join(devDiskRoot, "by-uuid", uuid))
}
// bestByIDLink returns the highest-priority /dev/disk/by-id link name whose target is `device`
// (already symlink-resolved), or "" if none.
func bestByIDLink(device string) string {
+78
View File
@@ -46,6 +46,84 @@ func withDevDiskRoot(t *testing.T, root string) {
t.Cleanup(func() { devDiskRoot = old })
}
// TestResolveStorageDevice_ToleratesDeviceLetterMove (Task A): on a host reboot the kernel can move a
// drive from /dev/sdb to /dev/sdc; ResolveStorageDevice re-resolves the enrolled durable-id by filesystem
// UUID and returns the CURRENT node, so the reshuffle is a no-op. COMPANION: a node-based resolver (what
// the broken remount effectively did — trust the enroll-time node) returns the STALE node → the WRONG
// device once the letter moves.
func TestResolveStorageDevice_ToleratesDeviceLetterMove(t *testing.T) {
if runtime.GOOS == "windows" {
t.Skip("symlink-based device resolution runs on Linux (the agent's OS)")
}
base := t.TempDir()
sdb := filepath.Join(base, "sdb") // the enroll-time node (now holds some OTHER drive after reboot)
sdc := filepath.Join(base, "sdc") // where felhom-usb's UUID now lives after re-enumeration
if err := os.WriteFile(sdb, []byte("x"), 0o600); err != nil {
t.Fatal(err)
}
if err := os.WriteFile(sdc, []byte("x"), 0o600); err != nil {
t.Fatal(err)
}
root := filepath.Join(base, "disk")
if err := os.MkdirAll(filepath.Join(root, "by-uuid"), 0o755); err != nil {
t.Fatal(err)
}
const uuid = "da9e7089-cf8e-4617-adcb-a377743fae00"
if err := os.Symlink(sdc, filepath.Join(root, "by-uuid", uuid)); err != nil { // moved: UUID → sdc
t.Fatal(err)
}
withDevDiskRoot(t, root)
// FIX: resolve by UUID → the CURRENT node (sdc), tolerating the move.
got, err := ResolveStorageDevice("uuid:" + uuid)
if err != nil {
t.Fatalf("ResolveStorageDevice: %v", err)
}
wantSdc, _ := filepath.EvalSymlinks(sdc)
if got != wantSdc {
t.Fatalf("resolved %q, want the CURRENT node %q (the UUID moved sdb→sdc)", got, wantSdc)
}
// COMPANION: a node-based remount that trusts the recorded enroll-time node (sdb) now targets the
// WRONG device — sdb is no longer where this UUID lives.
cachedNode, _ := filepath.EvalSymlinks(sdb)
if cachedNode == got {
t.Fatalf("companion: the cached enroll-time node must differ from the freshly-resolved device after a move (cached=%q resolved=%q)", cachedNode, got)
}
}
// TestResolveStorageDevice_AbsentAndScheme: a vanished UUID errors (so the re-assert skips a gone drive),
// and only the uuid: scheme is resolvable (never a bare /dev node — the anti-node-binding invariant).
func TestResolveStorageDevice_AbsentAndScheme(t *testing.T) {
if runtime.GOOS == "windows" {
t.Skip("linux")
}
withDevDiskRoot(t, filepath.Join(t.TempDir(), "empty"))
if _, err := ResolveStorageDevice("uuid:gone-uuid"); err == nil {
t.Fatal("an absent UUID must error so the re-assert skips a gone drive instead of fail-mounting")
}
for _, id := range []string{"/dev/sdb1", "store:felhom-usb", "byid:wwn-x", ""} {
if _, err := ResolveStorageDevice(id); err == nil {
t.Errorf("ResolveStorageDevice(%q) must reject a non-uuid: scheme", id)
}
}
}
// TestParseFelhomMountUnit round-trips renderMountUnit → parseFelhomMountUnit and rejects foreign units.
func TestParseFelhomMountUnit(t *testing.T) {
spec := MountSpec{Name: "felhom-usb", UUID: "da9e7089-cf8e-4617-adcb-a377743fae00", Where: "/mnt/felhom-usb", FSType: "ext4"}
got, ok := parseFelhomMountUnit(renderMountUnit(spec))
if !ok {
t.Fatal("our own rendered unit must parse")
}
if got.Name != spec.Name || got.UUID != spec.UUID || got.Where != spec.Where || got.FSType != spec.FSType {
t.Fatalf("round-trip mismatch: got %+v want %+v", got, spec)
}
if _, ok := parseFelhomMountUnit("[Mount]\nWhat=/dev/sdb1\nWhere=/mnt/x\n"); ok {
t.Fatal("a non-felhom unit (no marker, not by-uuid) must not parse")
}
}
// DeviceDurableID prefers a wwn- by-id link over ata-/serial links and over a uuid.
func TestDeviceDurableID_PrefersWWN(t *testing.T) {
root, device := fakeDevDisk(t,
+58
View File
@@ -226,6 +226,64 @@ func (h *SudoHostOps) EnsureMount(ctx context.Context, spec MountSpec) error {
return nil
}
// ReassertEnrolledMounts re-mounts every enrolled drive whose backing device is present (resolved FRESH
// by filesystem UUID, never a cached /dev node) but whose systemd mount unit is not currently mounted —
// the host-reboot remount fix. On a host reboot a unit left `disabled` by a prior detach never
// auto-mounts, and kernel re-enumeration can move the device (/dev/sdb→sdc); re-running EnsureMount
// (idempotent `enable --now`, What=/dev/disk/by-uuid/<UUID>) re-enables the unit AND mounts the CURRENT
// device by UUID, so a letter reshuffle is a no-op. Idempotent + cheap on the steady state: an
// already-mounted drive is skipped (no daemon-reload churn). A drive whose UUID no longer resolves
// (genuinely absent) is skipped, not failed — its unit re-asserts on a later tick once it enumerates.
func (h *SudoHostOps) ReassertEnrolledMounts(ctx context.Context) {
entries, err := os.ReadDir(h.unitDir)
if err != nil {
h.logger.Warn("storage: reassert enrolled mounts — cannot read unit dir", "dir", h.unitDir, "err", err)
return
}
mounted := h.mountedSet()
for _, e := range entries {
if !strings.HasSuffix(e.Name(), ".mount") {
continue
}
data, rerr := os.ReadFile(filepath.Join(h.unitDir, e.Name()))
if rerr != nil {
continue
}
spec, ok := parseFelhomMountUnit(string(data))
if !ok || mounted[spec.Where] {
continue // not ours, or already mounted → nothing to do (no churn)
}
dev, derr := ResolveStorageDevice("uuid:" + spec.UUID)
if derr != nil {
h.logger.Info("storage: enrolled drive absent by UUID — not re-asserting (will retry when it enumerates)", "name", spec.Name, "where", spec.Where, "uuid", spec.UUID)
continue
}
if err := h.EnsureMount(ctx, spec); err != nil {
h.logger.Warn("storage: re-assert enrolled mount failed", "name", spec.Name, "where", spec.Where, "err", err)
continue
}
h.logger.Info("storage: re-asserted enrolled mount by UUID (enable --now)", "name", spec.Name, "where", spec.Where, "uuid", spec.UUID, "device", dev)
}
}
// mountedSet returns the set of currently-active mountpoints from /proc/mounts (mountpoint is field 2).
// Best-effort: a read failure yields an empty set (every enrolled drive is then considered for
// re-assert, which EnsureMount makes idempotent).
func (h *SudoHostOps) mountedSet() map[string]bool {
out := map[string]bool{}
data, err := os.ReadFile("/proc/mounts")
if err != nil {
return out
}
for _, line := range strings.Split(string(data), "\n") {
f := strings.Fields(line)
if len(f) >= 2 {
out[f[1]] = true
}
}
return out
}
// Unmount stops + disables the unit (detach). The caller is responsible for authorization.
func (h *SudoHostOps) Unmount(ctx context.Context, where string) error {
unitName, err := UnitNameForMount(where)
+35
View File
@@ -5,6 +5,41 @@ import (
"strings"
)
// felhomUnitMarker is the header renderMountUnit writes; parseFelhomMountUnit uses it to tell our
// units apart from any other .mount unit on the host.
const felhomUnitMarker = "Managed by felhom-agent"
// parseFelhomMountUnit is the inverse of renderMountUnit for the fields the host-reboot re-assert needs.
// It returns the MountSpec (Name from Description, UUID from What=/dev/disk/by-uuid/<UUID>, Where, Type,
// Options), or ok=false when the content is not a felhom-rendered by-UUID mount unit. Pure → unit-tested.
func parseFelhomMountUnit(content string) (MountSpec, bool) {
if !strings.Contains(content, felhomUnitMarker) {
return MountSpec{}, false
}
var spec MountSpec
for _, line := range strings.Split(content, "\n") {
line = strings.TrimSpace(line)
switch {
case strings.HasPrefix(line, "Description=Felhom storage mount "):
spec.Name = strings.TrimPrefix(line, "Description=Felhom storage mount ")
case strings.HasPrefix(line, "What="):
if u, found := strings.CutPrefix(strings.TrimPrefix(line, "What="), byUUIDDir+"/"); found {
spec.UUID = u
}
case strings.HasPrefix(line, "Where="):
spec.Where = strings.TrimPrefix(line, "Where=")
case strings.HasPrefix(line, "Type="):
spec.FSType = strings.TrimPrefix(line, "Type=")
case strings.HasPrefix(line, "Options="):
spec.Options = strings.TrimPrefix(line, "Options=")
}
}
if spec.UUID == "" || spec.Where == "" { // not a by-uuid mount we can re-resolve
return MountSpec{}, false
}
return spec, true
}
// renderMountUnit builds the systemd .mount unit content for a (already-validated) spec.
// Keyed by fs-UUID via What=/dev/disk/by-uuid/<UUID> so it survives /dev/sdX renumbering;
// WantedBy=multi-user.target so `enable` makes it persist across reboot.