feat: per-endpoint SLO monitor - #759
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greatest0fallt1me merged 1 commit intoJul 29, 2026
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Merged into main via admin resolver (-X theirs). |
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Merged ⭐ nicely done |
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Description
This PR implements per-endpoint SLO monitoring for latency and error rate metrics with alert thresholds, adhering to project styles and guidelines.
Closes #286
Changes
Metrics Registration: Restored missing endpointRequestsTotal (Counter) and endpointRequestDuration (Histogram) metrics to resolve downstream merge conflict errors, and added sloViolationsTotal (Counter).
SLO Monitor Service: Created src/services/sloMonitor.ts to manage in-memory sliding window request logs per endpoint. Evaluates requests against configured limits (using src/config/slo.ts) and increments sloViolationsTotal for breaches.
Middleware Integration: Updated src/middleware/metricsHistogram.ts to sanitize and pass completed request metadata to the SLO Monitor.
Unit Tests: Added focused tests in tests/sloMonitor.test.ts to cover latency thresholds, sliding window sample eviction (simulated using mocked timers), and configuration fallback routing.
Verification & Edge Cases
Test Output
bash
PASS tests/metricsHistogram.test.ts
PASS tests/sloMonitor.test.ts
Test Suites: 2 passed, 2 total
Tests: 16 passed, 16 total
Snapshots: 0 total
Time: 30.926 s
ESLint Output
bash
$ npx eslint src/config/slo.ts src/services/sloMonitor.ts src/metrics/registry.ts src/middleware/metricsHistogram.ts
(0 errors, 0 warnings)