The estate had zero alert rules. The only contact point was Grafana's factory
default pointing at the literal string <example@email.com>, and beta's
untracked compose override routed Grafana's SMTP at prod's Postfix — so
alerts, had any existed, would have been delivered by the box most likely to
be on fire. Prod served 86 5xx in 24h including five /healthz failures and
nobody was told.
Alerting (deploys to beta, which is where Grafana runs):
- 12 Loki-based rules. There is no Prometheus in this estate and Loki is the
only datasource, so every rule is log-derived.
- Thresholds come from a 24h backtest that happens to contain a real ~20min
prod outage at 04:20Z. Absolute counts, not ratios: prod runs ~7 req/min, so
one bad request is 1.4% and a ratio alert would scream all night. The 5xx
burst rule fires on the outage's 45 and 22 buckets and on nothing else in
the day; the largest benign bucket all day was 5.
- Routed to a new private #ops-alerts channel, not to any existing channel —
#weather-events, #announcements and #prod are product surfaces that notify
real subscribers.
- AlertingWatchdog is a dead-man's switch; its value is its absence.
- Delivery is proven, not assumed: the rules were provisioned into a throwaway
Grafana against beta's live Loki and a real alert arrived in Discord. This
matters because GET /api/v1/provisioning/contact-points returns [REDACTED]
for the URL — a contact point holding an uninterpolated env var looks
perfectly healthy and pages nobody. The only proof is a message arriving.
CI gains a structural check, because the existing one only proves YAML parses:
an alert rule whose condition names a missing refId is valid YAML, provisions
cleanly, and never fires. It also hard-fails on a literal Discord webhook in
the repo. Verified against all three breakages deliberately introduced.
Postfix supervision:
- The 13h outage was a boot-ordering race, not a Docker renumbering: postfix
started at 08:09:49, wg0 came up at :51, postfix fataled at :52 on a missing
docker_gwbridge address, and dockerd did not finish starting until 08:10:16.
Stock postfix@.service is ordered only After=network-online.target and ships
no Restart=, so one lost race became a permanent outage.
- An ExecStartPre gate now blocks up to 60s until every inet_interfaces
address actually exists, which absorbs the transient case inside a single
start attempt. That makes bounded retry correct: 5 attempts in 600s, then
failed — a genuinely broken config reaches a visible failed state in ~100s
instead of re-fataling every 15s forever.
- A 5-minute watchdog timer retries indefinitely and runs reset-failed, so
"failed" still self-heals. Worst case is ~5 minutes, not 13 hours.
- Wants=, not Requires=: a dockerd failure must not take down the loopback and
mesh listeners that do not depend on Docker at all.
Health checks must read config with `postconf -c`, never postmulti/postqueue/
postfix — those three RESOLVE inet_interfaces and so fatal precisely when an
address is missing, which made the first version of this check report
status=ok bound=0/0. A health check that fails open is worse than none.
DEPLOY.md carries the monitoring contract, including that systemctl is-active
postfix is a known-false signal: postfix.service is a wrapper whose
ExecStart=/bin/true, so it reports active forever while the real postfix@-
instance is failed with zero listeners. Reproduced live.
Known gap, documented not fixed: Alloy ships Docker stdout, Caddy files and
app JSONL, not journald — so no Postfix line reaches Loki and the mail rules
cannot fire until loki.source.journal is added.
Claude-Session: https://claude.ai/code/session_0182KTMrsTHJc3TcewCatJFY
