# Prometheus
All Prometheus notes →1 — Recording Rules
Why recording rules exist in an alerting pipeline: pre-computing expensive or frequently-evaluated expressions so alert rules stay cheap, and how that ties to rule-group evaluation cadence.
2 — Alerting Rules
The alert state lifecycle — inactive, pending, firing — built from Prometheus's scrape and evaluation clocks, plus a line-by-line walk through a real alert rule's for:, labels:, and annotation templating.
3 — Alertmanager
How Alertmanager groups and deduplicates alerts in practice — group_wait, group_interval, and repeat_interval — with routing/receiver depth and open gaps called out honestly.
# Observability
All Observability notes →1 — Dashboard Design
The three-question test for a vanity panel, why the same underlying data needs a different dashboard for different audiences, and the top-down layout that mirrors how an investigation actually drills down.
1 — Alerting & Alert Routing
Symptom-based vs. cause-based alerting, the noise-reduction problem (dedup, grouping, correlation), and routing/escalation — the design discipline standing between a real page and a bad one.
2 — SLOs & Error Budgets
SLI/SLO/SLA, the error budget as a spendable resource rather than a compliance number, burn rate as the mechanism connecting the two, and why multi-window multi-burn-rate alerting exists at all.
2 — Symptoms vs Causes
Covers distinguishing 'users are affected' alerts from 'a specific subsystem misbehaved' alerts, and why only the former should page.
3 — Slo Based Alerts
Covers deriving alert thresholds from an SLO's error budget rather than from arbitrary static thresholds.
4 — Multi Window Burn Rate Alerts
Covers the multi-window, multi-burn-rate alerting technique that balances fast detection against alert noise.
5 — Alert Deduplication
Covers grouping and suppressing duplicate alerts from the same root cause so on-call sees one page, not fifty.
6 — Routing
Covers alert routing rules — team ownership, severity, and escalation paths — as configuration distinct from the alert condition itself.
7 — Alert Fatigue
Covers diagnosing and reversing an alert-fatigue trend before it causes a real page to get ignored.
8 — On Call Engineering
Covers structuring on-call rotations, handoffs, and runbook discipline as an engineering practice, not just a schedule.