# Common Observability

> Standards for structured logging, distributed tracing, and metrics. (triggers: **/*.service.ts, **/*.handler.ts, **/*.middleware.ts, **/*.interceptor.ts, **/*.go, **/*.java, **/*.kt, **/*.py, logging, tracing, metrics, opentelemetry, observability, slo)

- Skill: `comeonoliver/common-observability` (Agent Skill)
- Install (CLI): `npx skillmds@latest add comeonoliver/common-observability`
- Raw SKILL.md: https://api.skillmd.com/api/skills/comeonoliver/common-observability/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: AI & ML
- Author: ComeOnOliver (https://skillmd.com/u/comeonoliver)
- Updated: 2026-09-08
- Page: https://skillmd.com/skills/comeonoliver/common-observability

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# Common Observability Standards

## **Priority: P1 (OPERATIONAL)**

## 📋 Logging & Tracing

- **JSON Logs**: Always emit JSON structured logs. Never plain-text in prod.
- **Correlation**: Extract `X-Request-Id` or `traceparent`. Attach to async context.
- **Tracing**: Use OpenTelemetry. Propagate W3C `traceparent`. 
- **Spans**: Name spans like `<HTTP_METHOD> <route>` (`GET /users/:id`).

## 📊 Metrics

- **Required**: Request rate, Error rate, Latency histogram (p50/p95/p99), Saturation.
- **SLOs**: Alert on SLO burn rates, not raw threshold spikes.

## 🚫 Anti-Patterns

- **Console.log**: Do not use in prod; use a structured logger (`pino`, `zap`).
- **PII in Logs**: Never log tokens, passwords, or full request bodies.
- **Dynamic Span Names**: `GET /users/123` causes cardinality explosion. Use `GET /users/:id`.
- **Missing Cleanup**: Always end tracing spans.

## References
- [Observability Data Formats](references/observability-formats.md)