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a63409c843
Six red-proofs with observed failure text, the bounds chosen for contention (15m retry / 3h alarm) justified against the agent's own 120m PBS restore-test ceiling and the 12m01s longest observed restore-test, and the live replay of both findings on demo-hp with the hub DB as arbiter: - failed restart alarmed 9s after grace expiry; banner shows (stopped) - a deliberate user stop stayed silent through 9 dead-app scans - 409 contention produced 0 operator emails (8 -> 8) - a real transport failure produced 1 (8 -> 9) Same box, same event type; the only difference is 409 vs a genuine error.
194 lines
11 KiB
Markdown
194 lines
11 KiB
Markdown
# REPORT — F-CRIT-1 + F-A1: one alarm that never fired, one that fired wrongly (v0.179.0) (2026-07-28)
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**Overwritten** per the standing rule. Controller **v0.178.0 → v0.179.0**. Both Campaign 8 findings,
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fixed together because both are "the alarm is wrong" and both live in `internal/quiesce` plus its
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`classifyRunStates` consumer. No wire/contract change; no agent behaviour change (its 409 is correct
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and was left alone — only a wrong comment there was corrected).
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## Baselines (reconfirmed, not copied)
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Controller `0.178.0` live on both boxes; agent `0.106.0`; `felhom-controller 8f46495`,
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`felhom.eu d0cec9d`, `felhom-agent af1c21a`, all clean.
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---
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## F-CRIT-1 — a failed app restart never alarmed. Two independent causes.
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### Cause 1 — the outcome was thrown away
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`restartAll` returned nothing; a failed `StartStack` was logged and dropped on the spot, so no
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caller could learn a customer's app had not come back. It now **returns the stacks that failed**, and
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both call sites (the cycle's unquiesce and crash recovery) record the result via
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`noteRestartOutcome`.
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### Cause 2 — a documented invariant the quiesce path had made false
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`classifyRunStates` whitelists `StateStopped` because v0.164.0 correctly refused to alarm on
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deliberate user stops, resting on I1: *"StateStopped means deployed, deliberately stopped by the
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user."* **The quiesce loop stops stacks by the same `docker compose down` path**, so a stack it
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stopped and then failed to restart is also `StateStopped` — byte-identical on the Docker side — and
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was whitelisted into total silence.
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No state test can separate them; they *are* the same state. The distinguishing fact is that the loop
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**tried to restart it and could not**, now surfaced by `Loop.FailedRestarts()`. That set is the only
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thing that lifts the whitelist:
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```go
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userStopped := st.State == stacks.StateStopped && !failedRestart[st.Name]
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down := stacks.IsDownState(st.State) && !userStopped && !quiesced[st.Name]
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```
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The flag is only ever consulted for an already-down stack, so a stale entry cannot manufacture an
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alarm on a healthy app; it clears the moment a later restart of that stack succeeds.
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### Why the existing tests missed it
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R-97b's Scenario F asserted that **suppression expires**. It never asserted that **an alarm
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follows**. Suppression lifted correctly and the whitelist ate the alarm one layer down — a green,
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red-proofed suite over a production path broken two independent ways. That is why §5 exists.
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---
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## F-A1 — a correct refusal reported as a failure
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HTTP 409 from `POST /backup` is the agent's R-85 single-flight gate refusing while a restore-test
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holds it. The start path had no 409 branch, so it called `noteTierFailure`: breaker armed,
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`whole_guest_backup_failed` emailed. At real cadences a ~12-minute restore-test against a daily
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backup collides roughly once per 420 guest-days — about **every 4 days on a 100-guest fleet** —
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training the operator to ignore the alarm and quietly undoing R-97a.
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409 is now contention: `agentapi` returns a typed `*StatusError` on POST (it was `fmt.Errorf`, i.e.
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string-only), the adapter maps 409 → `quiesce.ErrTierBusy` at the same seam that maps 404 →
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`ErrTiersUnsupported`, and the loop defers. No breaker, no event, no email; the tier stays **DUE**.
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### The two traps, and the bounds chosen
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**Silence.** "Just ignore 409" would let a wedged restore-test block backups forever with nobody
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told. So contention outliving **`contentionAlarmAfter` = 3h** raises its own signal, headlined
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**BLOCKED**, not FAILED. The bound is set by the agent's own ceiling, not taste: its PBS restore-test
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task is capped at **120 minutes** (`config.RestoreTestPBSRestoreTimeout`, default 120m), after which
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the agent times out and releases the gate itself — so contention outliving that is a *stuck* gate,
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not a busy one. 3h adds an hour of margin for teardown and 5-minute poll granularity, and is 15×
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the longest contention actually observed (12m01s).
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**App thrash.** Removing the failure treatment also removes the breaker's deferral, which had been
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(accidentally) preventing a re-quiesce every 5 minutes. Without a replacement the customer's apps
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would be stopped and restarted on **every poll** for the whole restore-test — worse than the bug. A
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contended tier is therefore dropped from the due set **before anything stops**, on
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**`contentionRetryAfter` = 15m** (longest observed restore-test 12m01s; the agent's local
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restore-test wait is 10m), capping churn at 4/hour instead of 12/hour.
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---
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## Red-proofs — all six observed failing
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| # | red-proof | observed failure |
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|---|---|---|
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| 1 | restore the unconditional `StateStopped` whitelist | `a stack that FAILED to restart is silent (Down=false) — this is F-CRIT-1` · `absent from the dashboard dead-list` |
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| 2 | treat every `StateStopped` as a failed restart | `a deliberate user stop alarmed — that is the v0.164.0 regression this must not reintroduce` · `stopped alarmed with no failed restarts` |
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| 3 | make `restartAll` drop its errors again | `restartAll returned [], want exactly [immich]` · `want immich to be recorded as a failed restart, got map[]` |
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| 4 | remove the 409 branch | `runOnce: start backup on (untargeted): quiesce: tier busy — a concurrent heavy operation holds the agent: agentapi: POST /backup: HTTP 409` |
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| 5 | treat all errors as contention | `breaker did not arm on a real 500 (failures=0) — a real 500 was swallowed as contention` · `operator was NOT notified of a real failure` |
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| 6 | remove the contention alarm bound | `no alarm after 3h0m0s of unbroken contention — that is a silence path, the exact thing this fix must not create` |
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`go build`, `go vet ./...`, `go test ./...` — all green, run separately from the commit.
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(Red-proof 6 first produced a *compile* error, which is a weaker proof; it was redone so the code
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compiles and the alarm simply never fires.)
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---
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## §5 — LIVE replay of BOTH findings on demo-hp, with the hub DB as arbiter
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### F-CRIT-1
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One image tag made unresolvable, then a normal quiesce:
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```
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06:54:30 unquiescing (snapshotted (early resume, last tier)): restarting 1 stack(s)
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06:54:36 [ERROR] [quiesce] restart paperless-ngx: starting stack paperless-ngx: exit code 1
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containers: 0
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```
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| moment | result |
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|---|---|
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| during grace (06:54:59) | 0 events, 0 banner markers, 0 pushes — **suppressed** |
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| grace expiry | 06:54:30 + 180s = **06:57:30** |
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| **06:57:39** | `PushEvent: type=app_start_failed severity=warn` → hub `Event from demo-hp: app_start_failed` |
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| dashboard | `alert-icon … Telepített alkalmazás nem fut: Paperless-ngx (stopped)` |
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The banner names the `(stopped)` state explicitly — the whitelist was lifted, not bypassed. Nine
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seconds after the window closed, on the first scan.
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### Scenario B live — the inverse, same box
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The app was restored to healthy, then stopped **deliberately** via the UI path:
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```
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containers after deliberate stop: 0 stack state: stopped
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deadapp scans during the silent window: 9
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app_start_failed events for demo-hp TODAY (events table) = 1 ← still just the failed restart
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```
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Same box, same `stopped` state, opposite outcomes — driven purely by whether the loop failed to
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restart it. The 9 scans are the positive observable that the silence is suppression, not a dead
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detector.
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### F-A1
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A restore-test was forced to hold the gate, then a backup triggered:
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```
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agent: backup refused — a heavy operation is already in flight busy=restore-test (both tiers)
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controller: tier local is BUSY — the agent refused ... This is contention, NOT a failure:
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the tier stays due and retries in 15m0s (contended for 0s)
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controller: tier felhom-pbs is BUSY — ... same
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controller: unquiescing (last tier is busy — deferring to a later cycle): restarting 1 stack(s)
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```
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### Scenario G live — the inverse, same box, same event type
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A **real** transport failure (PBS path dropped at nft, not a 409):
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```
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07:41:47 [WARN] tier felhom-pbs: backup job ... failed
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07:41:47 [WARN] tier felhom-pbs has now failed 1 time(s) in a row — deferring by 15m0s
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07:41:47 [INFO] Event pushed: whole_guest_backup_failed (error) — Whole-guest backup FAILED on the felhom-pbs tier
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```
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### The hub DB, not the logs — the decisive numbers
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| injection | `whole_guest_backup_failed` sent(operator), demo-hp |
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| baseline before either replay | **8** |
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| after the **409** contention replay | **8** — zero spurious emails |
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| after the **real failure** (Scenario G) | **9** — fired 09:41:48 CEST |
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Breaker arming lines since deploy: **0** for the 409, **1** for the real failure. Same box, same
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day, same event type; the only difference is 409 versus a genuine error.
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### Scenario F live
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After contention cleared, the backup **ran and both tiers succeeded** (`tier local: done`,
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`tier felhom-pbs: snapshotted`) — contention did not poison the tier. The armed breaker from
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Scenario G was then cleared by a successful backup, with
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`whole_guest_backup_recovered` emitted.
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---
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## Deployed & fleet state
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`felhom-controller 0.179.0` on **demo-hp** and **demo-felhom**, both healthy. demo-felhom 15/15
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containers, demo-hp 8/8, zero unhealthy, no nft leftovers, cadences untouched
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(`local 0`, `rt 302400`, `felhom-pbs 604800`), agent `0.106.0` on both.
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**demo-felhom had no injection and produced 0 event/alarm lines since its deploy** — the fix is not
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chattering on an untouched box.
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One leftover of my own making was cleaned up: Scenario G's block failed a restore-test mid-flight,
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which leaked scratch guest `990000` — the already-filed F-LEAK/R-99 behaviour (a failed restore-test
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cannot destroy its own scratch guest, 403 `VM.Allocate`). Destroyed; `pct list` shows only 9201.
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## Comments corrected (three of the six catalogued)
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- `classifyRunStates` I1 — now states what `StateStopped` actually means and names the quiesce path.
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- `quiesce.go`'s "would record a spurious failure" — records that this was not hypothetical until now.
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- agent `inflight.go`'s "a caller that cannot acquire DEFERS" — records that this was true of the
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restore-test caller and not the backup caller; fixed controller-side.
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Standing rule added to **both** copies of `CLAUDE.md` (live + versioned): *a comment asserting an
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invariant needs a test pinning it, or it is a wish*, with all six instances catalogued.
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## NOT yet live-validated (carried forward, minus what this closes)
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- Fault 4 — restic transport interruption; four injection approaches defeated by guest-bridged
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networking. **Still the most valuable follow-up**: F-CRIT-2 answered the phantom question for PBS
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and it remains open for restic.
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- **R-99** — prune never removes phantom snapshots (no retention bug; they accumulate).
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- **F-LEAK** — a failed restore-test cannot destroy its own scratch guest; observed again here.
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- Fault 12 (host reboot mid-backup); the three-way backup+restore-test+GC overlap; the agent's DR
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bring-up path (`ModeDRGuestLoss`), still read-only-verified.
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- `contentionAlarmAfter` (3h) itself — proven by unit test with an injected clock, **not** live; a
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live proof needs a gate wedged for three hours.
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