# REPORT — v0.97.0: R-82 Slice A — per-target backup tiers (2026-07-26) Slice A of R-82 (the backup target split). **Mechanism only — no box's behaviour changes until a `backup_targets` entry is added to its config, which is Slice D.** An untouched config resolves to exactly one tier and behaves byte-identically to v0.96.0. Phase-0 gates: `felhom.eu/documentation/audits/SPIKE-r82-phase0-2026-07-26.md`. Operator ruling 2026-07-26: datastore growth deferred, proceed. Capacity state recorded in `felhom.eu/documentation/architecture/07-backup-architecture.md` §9.1. **STOPPED at the Slice A boundary as specified.** Slices B/C/D/E not started. --- ## 1. What was wrong `BackupTarget()` returned ONE string and `BackupCadence()` ONE 24 h window. "Local daily **and** PBS weekly" was not expressible at all — which is why the DR promise is unbacked today: demo-felhom holds a single PBS snapshot from 2026-07-18 (a healing artifact, not a job) and demo-hp has **zero, ever**, despite `pbs_dr` reporting `applied` since 07-21. ## 2. Files modified | File | Change | |---|---| | `internal/config/config.go` | `BackupTargetConfig`, `BackupConfig.ExtraTargets` (`backup_targets`), `BackupTier`, `BackupTiers()` | | `internal/localapi/server.go` | per-target due/status/POST, `?target=` resolution, `/backup/tiers`, jobs keyed by (vmid,target), per-tier job ids | | `internal/localapi/backup_tiers.go` | **NEW** — `normalizeBackupTiers` (the compatibility core) | | `cmd/felhom-agent/main.go` | one runner per tier; tier-rejection warnings logged at **ERROR** | | `internal/config/backup_tiers_test.go` | **NEW** — 7 tests | | `internal/localapi/backup_tiers_test.go` | **NEW** — 13 tests | | `CHANGELOG.md`, `REUSE.md` | v0.97.0 entry; new canonical-helper row | Commit: **`739b3c3`** on `main`, pushed. ## 3. The compatibility rule — how it is enforced The agent and controller deploy independently, so the untargeted contract is **frozen**: - `BackupDueResponse.Target` / `BackupResponse.Target` / `BackupStatusResponse.Target` are all `omitempty` and left **EMPTY** for an untargeted request → the response marshals to the pre-R-82 **bytes**, not merely a compatible shape. Verified live: `{"ok":true,"data":{"vmid":8200,"due":false,"reason":"within cadence window","age_seconds":7200}}` - The untargeted verdict comes from the **primary tier only** — a fresh backup on another tier must not satisfy it (own test). - The **primary tier's job-id format is unchanged**; only additive tiers carry a target segment. - An unknown `?target=` is a **400, never a silent fallback**. A controller asking about a tier this agent does not serve must find out, not act on a different tier's freshness. - `GET /backup/tiers` 404s on a pre-R-82 agent — that 404 is Slice B's designed capability probe. ## 4. Design decisions, and why **One runner per tier** (not a target-parameterised runner). The runner holds target, mode, notes and retention as immutable construction state, and `localPruneSpec` reads that retention — parameterising a single runner by target would make it possible to pair tier A's target with tier B's retention. One runner per tier makes each tier's policy structurally inseparable from its target. **A missing cadence is REJECTED, not defaulted.** Defaulting an extra tier to the 24 h local default would quietly turn a weekly DR tier into a daily one and fill the 37.2 GB datastore. A tier whose cadence you did not state is not a tier. `main.go` logs every rejection at **ERROR** — a silently dropped backup tier is the "applied and empty" fault R-82 exists to fix. **`keep_last` unset = never prune.** The fail-safe: a DR tier must not start pruning itself because someone forgot a field. Negative values clamp to the same. **Jobs keyed by (vmid, target).** This is what lets the weekly night run both backups inside ONE quiesce window (Slice B). It also fixed a real defect — see §6. ## 5. The Slice A.4 finding (Slice C depends on this) **A PBS-targeted vzdump will appear in BOTH arrays**, and this is expected, not a bug: - in `backups[]` as `Backup{TargetID:"felhom-pbs", Archive:"felhom-pbs:backup/ct/9201/…"}` — written by the runner, recorded in the agent's in-memory store; - in `pbs_snapshots[]` — enumerated **independently** from the PBS API by the agent's verify loop. **Double-counting is harmless for freshness** (the hub takes a max, which is idempotent). **Mis-attribution is not.** If Slice C treats `backups[]` as "the local tier" and `pbs_snapshots[]` as "the PBS tier", a PBS-target `Backup` record would be attributed to the local tier and make a **stale local tier look fresh**. **The rule Slice C must implement:** classify a `backups[]` entry by joining its `target_id` to `storage_targets[].name` and reading `.type == "pbs"` — **by target type, never by array membership.** Verified live that the discriminator is present in production reports: ``` demo-felhom name=felhom-pbs type=pbs content=backup reachable=true demo-felhom name=local type=local content=…,backup reachable=true demo-hp name=felhom-pbs type=pbs content=backup reachable=true drill-r50 name=local type=local content=backup,… reachable=true (no PBS storage yet) ``` This is preferable to keying off `pbs_dr.storage_id`, which is `null` on drill-r50. ## 6. Tests — 748 → 768 (+20) Full gate green, **`go vet` run unpiped** (rc printed separately; R-81 recorded that piping it into `head` reports rc=0 while failing): ``` go build ./... rc=0 go vet ./... rc=0 go test ./... rc=0 (every package ok) ``` ### Red-proof #1 — old controller ↔ new agent (mandatory) — OBSERVED Removed the untargeted compat branch in `tierFromRequest` so it echoes the primary's id like any other tier: ``` --- FAIL: TestBackupDue_Untargeted_ResponseBytesUnchanged (0.00s) backup_tiers_test.go:105: UNTARGETED response MUST NOT carry a target key — an old controller sees a changed contract; body: {"ok":true,"data":{"vmid":8200,"due":false, "reason":"within cadence window","age_seconds":7200,"target":"local"}} ``` Restored; suite green. ### A defect the tests caught (worth recording) `TestBackupPost_SingleFlightIsPerTierNotPerGuest` **failed on first run**: ``` backup_tiers_test.go:320: PER-TIER single-flight violated: the PBS request was handed the LOCAL job id "backup-8200-1781092800000000000" — the controller would believe the PBS backup ran ``` Job ids were `backup--` — unique only by clock luck, and identical under an injected clock or two tiers starting in the same nanosecond. Fixed so ids are unique **per tier by construction**, with the primary's format left unchanged. This is precisely the failure mode Slice B would have hit on the weekly both-due night. ## 7. Live validation performed **No live deploy — see §8.** The strongest zero-risk check available was run instead: an end-to-end wire test composing the REAL path `agent.json bytes → config.BackupConfig → BackupTiers() → localapi.BackupTier → a real TLS listener`, driven by a real HTTP client (`httptest`'s own trusting client — TLS verification was **not** disabled). Unit tests cover each half; this proves the join, which is where a per-tier mis-wire would actually live. ``` tier armed: target=local cadence=24h0m0s keep_last=3 primary=true tier armed: target=felhom-pbs cadence=168h0m0s keep_last=2 primary=false GET /backup/tiers -> 200 {"tiers":[{"target":"local","cadence_seconds":86400,"primary":true}, {"target":"felhom-pbs","cadence_seconds":604800,"primary":false}]} GET /backup/due (UNTARGETED) -> 200 {"vmid":8200,"due":false,"reason":"within cadence window","age_seconds":7200} GET /backup/due?target=local -> 200 {…,"due":false,"target":"local"} GET /backup/due?target=felhom-pbs -> 200 {…,"due":true,"reason":"older than cadence","age_seconds":691200,"target":"felhom-pbs"} GET /backup/due?target=bogus -> 400 {"ok":false,"error":"unknown backup target: bogus"} ``` The fixture is the exact `agent.json` shape Slice D will write: fresh daily local (2 h) + a PBS snapshot at 8 days. The DR tier correctly reports **due** while the local tier does not — the behaviour whose absence is the entire bug. Harness deleted; tree clean. Binary built and verified: `felhom-agent 0.97.0` (13.9 MB, `/tmp/felhom-agent-0.97.0`). **Not installed anywhere.** ## 8. NOT live-validated — and the deploy target problem **Slice A's "deploy to the drill VM only" step was NOT performed: no drill target is reachable.** | Candidate | Status | |---|---| | **drill-r50** (`drill-r50-0a4f9a`) — the correct target: a live, hub-enrolled drill host | **UNREACHABLE.** Its operator path is wg-only (`10.77.0.4:8822`, OOB `felhom_sshd_active:true`). DooPlex has **no wg interface** — TCP connect to `10.77.0.4:8822` fails. No SSH alias exists | | **`/mnt/5_hdd/felhom.eu/drill/drill.qcow2`** on DooPlex | Present but **not a Felhom host** — a bare PVE install whose only snapshot is `virgin` (2026-07-03), powered off. Using it means a full greenfield run (host-install → guest provision → hub enrol), which is a different task with real half-state risk, not "deploy the agent" | | demo-felhom / demo-hp | **Production — explicitly excluded by this slice** | Consequently the following are unproven and must be proven at Slice D step 1: 1. **The tier-arming startup log on a real host** (`backup tier armed` × N, and `backup tier REJECTED` at ERROR for a bad config). Proven by unit test + the composed wire test only. 2. **A real vzdump to `felhom-pbs` via the new per-tier runner** — no PBS-targeted backup has been run by this code. 3. **The A.4 double-appearance in a real host-report.** §5 is derived from source plus the live `storage_targets` shape; it has not been observed with an actual PBS-target `Backup` record present, because none exists yet. 4. **Per-tier retention against a real storage** — `localPruneSpec`'s PBS refusal is unchanged, so no PBS prune can occur, but that is asserted from source, not exercised. 5. **The restore round-trip.** Per the task's own bar, a tier is only real once a `pct` restore from its snapshot yields a working guest. Nothing here approaches that. ## 9. Open decisions carried forward - **PBS pruning is still OFF.** Per-tier retention is plumbed and each tier carries its own `keep_last`, but `localPruneSpec` still refuses to prune a PBS-type target, and an unset `keep_last` means never-prune. Turning on automatic pruning of the DR datastore is irreversible and needs an operator ruling — P0.3 already flagged retention as one of the levers. **Left OFF deliberately; with capacity already tight, the wrong default here is unrecoverable.** - **The P0.3 capacity constraint stands.** Growth deferred by operator ruling; the 80 % warn is still projected at roughly the second additional customer. - **drill-r50 has no Tier-3 offsite** (`offsite: null`), so the P0.1 "weekly is sufficient" verdict does **not** hold for it. It is first in the Slice D rollout order — its PBS cadence cannot simply inherit the fleet ruling. ## 10. Observations 1. `local_backup_target` on both production boxes is `"local"`, so `BackupTarget()`'s `defaultBackupTarget = "felhom-pbs"` fallback is never exercised in production. A box with that key **absent** would send its primary daily backup to PBS — surprising, and worth checking during Slice D before writing any config. 2. The agent's backup `Store` remains in-memory (R-84). Slice A does not change that: after a restart both tiers' records are empty until each next run, so `/backup/due` reports **due** for every tier. That is fail-safe (a spurious backup, not a skipped one), but on the weekly tier it means a restart can pull a PBS backup forward. Worth naming in Slice B's dedup reasoning. 3. `RestoreTest.SourceTier` is still typed as `"local"` with a comment saying PBS is "Phase B". With a real PBS tier arriving, the restore-test's tier attribution should be revisited — not in scope here, recorded.