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>
44 lines
2 KiB
YAML
44 lines
2 KiB
YAML
---
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# One invocation writes ONE file into Gatus's endpoints directory. Gatus merges
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# every *.yaml under GATUS_CONFIG_PATH and appends lists, so each caller owns
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# its own file and they compose without coordinating - the same shape as
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# caddy_site, where each service contributes its own vhost.
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# Filename stem: <name>.yaml
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gatus_endpoint_name: ""
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# PULLED endpoints - Gatus makes the request and evaluates conditions.
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# - {name, group, url, interval, conditions: [...], alerts: [...]}
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#
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# A DNS check adds `dns: {query-type, query-name}` - and note that for those,
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# `url` is the RESOLVER to ask, not the name being looked up.
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# A domain-expiry check is just `url: <domain>` with a [DOMAIN_EXPIRATION]
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# condition; it uses WHOIS/RDAP and needs no scheme.
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gatus_endpoint_pulled: []
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# EXTERNAL endpoints - the host pushes its own result. Gatus never reaches out,
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# which is what makes this work for machines behind NAT and for state that has
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# no pollable surface at all (disk usage, ZFS health, UPS mains).
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#
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# - {name, group, token, heartbeat, alerts: [...]}
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#
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# `heartbeat` is the important one: if nothing reports within that window Gatus
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# alerts. That is what makes a push check detect its own failure - a dead timer
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# looks exactly like a dead host, which is the correct reading.
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gatus_endpoint_external: []
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# Where the files live. Matches roles/gatus.
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gatus_config_dir: /opt/gatus/config
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gatus_endpoints_dir: "{{ gatus_config_dir }}/endpoints"
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gatus_gid: 10001
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# Alerts attached to every endpoint in this file that does not specify its own.
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#
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# Gatus's provider-level `default-alert` only supplies DEFAULTS - an endpoint
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# still has to opt in with `alerts: - type: signal` or it alerts on nothing at
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# all. With ~90 endpoints that cannot be written by hand, so it is applied here.
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#
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# failure-threshold is set by the CALLER, because the right value depends on the
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# check's cadence and there is no single correct default. See the note in
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# infra/400_host_monitoring.yml.
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gatus_endpoint_default_alerts: []
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