counterweight
3a9e1d5851
Three changes: detection windows tightened, a Signal transport deployed, and
alerts attached to all 84 non-transport endpoints.
── Failing faster ──────────────────────────────────────────────────────────
The heartbeat is a TICKER, not a deadline: Gatus wakes every interval and asks
"did anything arrive in the last interval", so real detection is 1-2x the
window. And a window can only ever be as tight as the push frequency - which is
why two checks moved rather than just having their numbers changed.
liveness, cpu, ups, service-health, probes 16m -> 11m
disk, zfs daily/30h -> 6-hourly/7h
backup store + pull job daily/30h -> 6-hourly/7h
DNS records 24h -> 6h
backup dump 30h -> 26h
backup-dump stays slow because the dump genuinely is daily. The store-side check
catches the same fault within 6h by reading the source's dump timestamp out of
the artefact filename, so 26h is a backstop rather than the primary signal.
── Thresholds differ by check type, deliberately ───────────────────────────
`failure-threshold` counts consecutive failures, but "consecutive" is a
different amount of wall-clock time per check: a push endpoint produces one
failure per heartbeat window, a pulled one per interval. The default of 3 would
mean 33 minutes on an 11m heartbeat and over a day on a 7h one.
More importantly the heartbeat window ALREADY encodes the tolerance - an 11m
window on a 5-minute push is exactly "one missed push forgiven" - so stacking a
threshold of 3 triples a tolerance that was already chosen. Hence:
push/heartbeat endpoints failure-threshold 1
pulled, 5m (public) failure-threshold 3 (= 15 minutes)
pulled, 6h/24h (dns, domain) failure-threshold 1
── The Signal transport ────────────────────────────────────────────────────
roles/signal_api runs signal-cli-rest-api on the observability host, pinned by
digest, MODE=native.
It publishes NO PORTS. The API has no authentication of any kind - anything that
reaches it can send messages as you and read your Signal. Gatus talks to it over
a shared docker network by service name, which is also WHY the network exists:
Gatus runs in a container, so the host's loopback is unreachable from it and a
port published on 127.0.0.1 would not have worked.
MODE=native and not json-rpc because this VPS has 464MB of RAM and already runs
Gatus and Caddy. The json-rpc modes hold a resident JVM; native runs a binary
per request, and alerts are rare enough that startup cost per alert is the right
trade.
Monitored - Gatus polls /v1/health over the same network path the alerts take,
so it proves the delivery route rather than mere container liveness. Deliberately
NOT backed up: the data directory holds Signal private keys and the recovery
path is to link the device again from the phone.
Neither the signal-api endpoint nor Gatus's self-check carries a Signal alert.
If either is down, Signal is precisely what cannot deliver the alert.
── Four traps hit while linking, all now in the role README ────────────────
* /v1/qrcodelink is BROKEN in native mode - returns "no data to encode" while
the binary itself emits a perfectly good URI. Not worked around by switching
MODE, which would put a JVM in the path of every alert permanently.
* The data dir must be owned by uid 1000, not root. A root-owned 0700 dir
cannot be traversed by the container user, so linking silently never
completes and /v1/accounts returns "Failed to read local accounts list".
* `docker exec` runs as ROOT while the service runs as uid 1000, so without
--config the account is written to /root/... on the container's ephemeral
layer. It reports success and is destroyed on the next recreate.
* The phone reporting "network error" was IPv6: chat.signal.org resolves to
dualstack AAAA records first, the container has no IPv6 address, and this
host's IPv6 path is broken - the same edge that 404'd the Go tarball. Fixed
with a mounted gai.conf that prefers IPv4.
Verified: provider loads (configuredProviders=[signal]), a test message was
delivered and confirmed received, 84 endpoints carry alerts, 86 UP / 0 DOWN.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
71 lines
3.3 KiB
YAML
71 lines
3.3 KiB
YAML
---
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# The per-service health probes.
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#
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# These are NOT the same thing as the systemd checks in infra/401. Those answer
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# "is the unit running"; these answer "does the service actually respond" - an
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# RPC call to bitcoind, a TCP connect to Fulcrum's Electrum port, an HTTP fetch
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# from the Mempool backend. A process can be perfectly `active` and useless,
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# which is precisely the gap these close.
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#
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# The checks themselves live in each service's own role, deployed by that
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# service's playbook. This play only registers where they report, because the
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# endpoints must exist in Gatus before the first push arrives.
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#
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# They used to push to Uptime Kuma. The scripts now POST with a bearer token
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# instead of GETting ?status=up, and each host uses its own token.
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# ─────────────────────────────────────────────────────────────────────────────
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# Alerting thresholds, and why they differ by check type.
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#
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# `failure-threshold` counts CONSECUTIVE failures, but "consecutive" means a
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# different amount of wall-clock time per check:
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#
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# push/heartbeat endpoints a failure is produced once per heartbeat window
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# pulled endpoints a failure is produced once per interval
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#
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# So the default of 3 would mean 33 minutes on an 11m heartbeat and over a day
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# on a 7h one - and the heartbeat window ALREADY encodes the tolerance. An 11m
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# window on a 5-minute push is precisely "one missed push forgiven"; stacking a
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# threshold of 3 on top triples a tolerance that was already chosen.
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#
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# Hence: push endpoints alert on the FIRST heartbeat failure. Pulled endpoints
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# have no built-in tolerance, so the threshold is where it belongs for them.
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# ─────────────────────────────────────────────────────────────────────────────
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- name: Register the per-service probes with Gatus
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hosts: observability
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become: yes
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vars:
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probes:
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- {name: bitcoin-knots, host: knots_box_local}
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- {name: datum-gateway, host: knots_box_local}
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- {name: fulcrum, host: fulcrum_box_local}
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- {name: phoenixd, host: vipy}
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- {name: forgejo-runner, host: forgejo_runner_local}
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- {name: mempool-mariadb, host: mempool_box_local}
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- {name: mempool-backend, host: mempool_box_local}
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- {name: mempool-frontend, host: mempool_box_local}
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tasks:
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- name: Build the probe endpoint list
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ansible.builtin.set_fact:
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probe_endpoints: "{{ probe_endpoints | default([]) + [{
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'name': item.name,
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'group': 'probe',
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'token': gatus_push_tokens[item.host],
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'heartbeat': '11m'}] }}"
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loop: "{{ probes }}"
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- name: Register the probe endpoints
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ansible.builtin.include_role:
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name: gatus_endpoint
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vars:
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gatus_endpoint_default_alerts:
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- type: signal
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# 1, not 3: the heartbeat window is the tolerance. See the note above.
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failure-threshold: 1
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success-threshold: 2
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send-on-resolved: true
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minimum-reminder-interval: 6h
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gatus_endpoint_name: probes
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gatus_endpoint_external: "{{ probe_endpoints }}"
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