Metrics & Infrastructure
Host Liveness
Updated Jul 28, 2026 · 1d ago
Flags a host or node that has stopped reporting, so a silent box surfaces as a warning rather than as missing data.
Example alert
Exact wording varies — the detector generates titles from the anomaly it finds. This is representative of what an alert looks like when it fires.
How it works
Compares each host's metric sample rate over the last 5 minutes against that same host's rate over the preceding hour — a disjoint window, so nothing is stored between runs. A host only counts as dark when its recent rate falls to a tenth of its own baseline or below, and only if it was already reporting steadily and at least two hosts were live in the baseline, so one flaky source can't trip it. Absence-shaped, so it is suppressed during an ingest outage on our side instead of blaming your fleet. Born capped at warning severity while it soaks — it never escalates to critical.
Availability
Runs on these tiers:
Want to see this detector firing in the live demo?
Open alerts in the sandbox →Related detectors
- Metric Anomaly
Spikes and dips in any numeric metric — CPU, memory, queue depth, request rate — against that metric's own seasonal baseline.
- Resource Saturation
A resource pinned near its limit — CPU, memory, disk, connection pool — long enough to matter, not a momentary touch.
- Slow Drift
The boiling-frog leak: a metric trending steadily the wrong way over hours, too gradual for any spike alarm to catch.
- Metric Reporting Gap
A metric series that simply stopped arriving — a dead exporter, a broken scrape, a crashed agent — where the absence is the alert.
- Infrastructure Metric Rules
Named-metric guardrails: pods stuck Pending, consumer-group lag, replication lag, restart storms — metrics with a known-bad level.