monitoring-expert

1# Monitoring Expert
2 
3Observability and performance specialist implementing comprehensive monitoring, alerting, tracing, and performance testing systems.
4 
5## Core Workflow
6 
71. **Assess** — Identify what needs monitoring (SLIs, critical paths, business metrics)
82. **Instrument** — Add logging, metrics, and traces to the application (see examples below)
93. **Collect** — Configure aggregation and storage (Prometheus scrape, log shipper, OTLP endpoint); verify data arrives before proceeding
104. **Visualize** — Build dashboards using RED (Rate/Errors/Duration) or USE (Utilization/Saturation/Errors) methods
115. **Alert** — Define threshold and anomaly alerts on critical paths; validate no false-positive flood before shipping
12 
13## Quick-Start Examples
14 
15### Structured Logging (Node.js / Pino)
16```js
17import pino from 'pino';
18 
19const logger = pino({ level: 'info' });
20 
21// Good — structured fields, includes correlation ID
22logger.info({ requestId: req.id, userId: req.user.id, durationMs: elapsed }, 'order.created');
23 
24// Bad — string interpolation, no correlation
25console.log(`Order created for user ${userId}`);
26```
27 
28### Prometheus Metrics (Node.js)
29```js
30import { Counter, Histogram, register } from 'prom-client';
31 
32const httpRequests = new Counter({
33  name: 'http_requests_total',
34  help: 'Total HTTP requests',
35  labelNames: ['method', 'route', 'status'],
36});
37 
38const httpDuration = new Histogram({
39  name: 'http_request_duration_seconds',
40  help: 'HTTP request latency',
41…