Mark ovh-prod leg of 2026-07-04 backup incident resolved (pipefail grep root cause)
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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jared
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@ -4,6 +4,92 @@ Dated entries for diagnosed-and-fixed system incidents on this machine.
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Newest first. Keep entries factual: symptom, root cause, what was ruled out,
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fix applied, and any follow-up.
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## 2026-07-04 — Backup monitor alert diagnosed: three independent, compounding failures (desktop x2, ovh-prod x1) — not fixed yet
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**Symptom:** Weekly n8n digest (2026-06-26) reported all 3 monitored sources
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RED — "no runs reported all week — silent failure": `desktop/synology`,
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`desktop/backblaze-b2`, `vps-ovh-prod-01/local`. Prior sessions had tried
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several times to fix the automatic trigger without success.
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**Investigation (via direct systemd/journal inspection on desktop, SSH to
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ovh-prod, and the n8n REST API against `n8n.swansoncloud.com`):**
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- Confirmed the alerting/reporting pipeline itself (n8n Workflow 1 receiver →
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`backup_runs` data table, Workflow 2 weekly reporter) works correctly —
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manually POSTing to `https://n8n.swansoncloud.com/webhook/backup-notify`
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with production credentials returns `200 {"ok":true}` and creates a real
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execution + row. Credentials/URL/token are byte-identical (sha256-verified)
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between desktop and ovh-prod. **The monitor is not the bug.**
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- Pulled the full historical content of the `backup_runs` data table via the
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n8n API: only **5 rows ever existed**, all from the 2026-05-07/05-15 setup
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day (a mix of stale-lock failures and one manual "test" row). **Zero rows
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from any real automated run on either machine, ever** — the RED status has
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been silently true since the system was built, not just "this week."
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**Root cause 1 — desktop, `restic-backup.service` (systemd --user):** `backup.sh`
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calls `notify_backup.rb` as a bare command name. The systemd user manager's
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PATH (`systemctl --user show-environment`) is
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`~/.cargo/bin:~/.nodenv/shims:~/.nodenv/bin:/usr/local/bin:/usr/bin` — it does
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**not** include `~/.local/bin`, where `notify_backup.rb` actually lives.
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Confirmed by reproducing with `env -i PATH="<that exact PATH>" which
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notify_backup.rb` → not found. The call silently no-ops (swallowed by
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`|| true`), so the notifier has never once run from the real timer-triggered
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service, even on nights the backup itself succeeded (e.g. 2026-07-02, which
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has a real B2 snapshot but produced zero n8n rows).
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**Root cause 2 — desktop, `restic-backup.timer` (separate, affects the backup
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itself, not just reporting):** The timer is `Persistent=true` + `WakeSystem=true`,
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firing catch-up runs at odd hours (08:36, 09:08, 11:57 seen on 07-01/07-03/07-04)
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when the machine missed the 01:58 AM slot. `ExecStart` wraps `backup.sh` in
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`systemd-inhibit --why=... `, which requires interactive polkit authentication.
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When the timer fires outside an active/unlocked session, `systemd-inhibit`
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itself fails with `Access denied ... requires interactive authentication` and
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exits 1 **before `backup.sh` ever runs** — no log file, no restic invocation,
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nothing. Confirmed in `journalctl --user -u restic-backup.service`. This is why
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3 of the last 4 calendar days had zero backup activity at all, not just zero
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notifications. (2026-07-02, the one day the timer fired on schedule during an
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active session, did back up successfully to B2; Synology failed separately
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that day with `Network is unreachable` reaching `192.168.86.31:22`.)
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**Root cause 3 — ovh-prod, `backup.sh` (cron, `0 7 * * *`):** The archive
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creation itself has kept succeeding every night (`cron.log` shows a fresh
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`backup_YYYYMMDD.tar.gz` created nightly through 2026-07-04). But
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`grep -c 'Backup completed successfully' cron.log` shows the **last occurrence
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was 2026-05-07** — the setup day. Every run since (2 months, ~55 nights) stops
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silently right after the `cleanup_old_backups()` log line ("Cleaning up backups
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older than 2 days...") and never reaches the notifier call a few lines later,
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despite `set -euo pipefail` normally surfacing a visible error on early exit.
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Manually re-running the exact same `find ... -delete` commands and the exact
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`notify_backup.rb` invocation right now both succeed cleanly (the manual test
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call created a real row: `2026-07-04T16:21:37Z vps-ovh-prod-01 local success`).
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No OOM kill in `dmesg`, disk not full (23% used).
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**RESOLVED 2026-07-04 (same day, follow-up session):** root cause was NOT a cron
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environment difference — it was the `SNAP=$(grep -oE 'snapshot ...' "$LOG_FILE" ...)`
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line in `main()`. The ovh box produces tar archives (no restic), so the grep never
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matches → exits 1 → `pipefail` + `set -e` kill the script silently right between
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cleanup and the notifier. Fails identically over interactive SSH; earlier manual
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reproductions only re-ran the `find`/notify commands individually, never that
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pipeline under the script's own shell options. Fixed by deleting the dead SNAP
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extraction and `--snapshot` flag; verified end-to-end (full run exits 0, real
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`backup_runs` row `2026-07-04 17:26:04 vps-ovh-prod-01 local success`). Details in
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`ovh-prod/docs/incidents.md`, 2026-07-04 entry.
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**Ruled out:** n8n workflow config/auth/data table wiring (verified working
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live); credential/token mismatch between machines (hashes match); OVH archive
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creation itself (still succeeds nightly); OVH disk space; OOM kill.
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**Not yet fixed** — this entry is the diagnosis only, at the user's request,
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to avoid fixing the wrong problem before a fix is designed. Follow-ups:
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1. Desktop: call `notify_backup.rb` by full path (`~/.local/bin/notify_backup.rb`)
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in `backup.sh`, matching what ovh-prod's copy already does correctly.
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2. Desktop: replace/guard the `systemd-inhibit` interactive-auth dependency
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(e.g. drop `--why` interactive prompt requirement, or add
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`ConditionACPower`/session-active guards) so catch-up runs outside an
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active session don't abort before starting.
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3. ~~ovh-prod: instrument `cleanup_old_backups()`/the cron invocation~~ — **done
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2026-07-04**: root cause found without instrumentation (pipefail-killed snapshot
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grep) and fixed; see Root cause 3 above.
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## 2026-06-26 — memtest86+ confirms bad RAM (root cause of the 2026-06-24 Btrfs corruption)
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**Result: FAILED.** Ran memtest86+ v8.10 from the GRUB boot entry on the
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