observability-monitoringlisted

# Observability & Monitoring Skill Comprehensive frameworks for implementing observability including structured logging, metrics, distributed tracing, and alerting. ## When to Use - Setting up application monitoring - Implementing structured logging - Adding metrics and dashboards - Configuring distributed tracing - Creating alerting rules - Debugging production issues ## Three Pillars of Observability ``` ┌─────────────────┬─────────────────┬─────────────────┐ │ LOGS │ METRICS │ TRACES │ ├─────────────────┼─────────────────┼─────────────────┤ │ What happened │ How is system │ How do requests │ │ at specific │ performing │ flow through │ │ point in time │ over time │ services │ └─────────────────┴─────────────────┴─────────────────┘ ``` ## Structured Logging ### Log Levels | Level | Use Case | |-------|----------| | **ERROR** | Unhandled exceptions, failed operations | | **WARN** | Deprecated API, retry attempts | | **INFO** | Business events, successful operations | | **DEBUG** | Development troubleshooting | ### Best Practice ```typescript // Good: Structured with context logger.info('User action completed', { action: 'purchase', userId: user.id, orderId: order.id, duration_ms: 150 }); // Bad: String interpolation logger.info(`User ${user.id} completed purchase`); ``` > See `templates/structured-logging.ts` for Winston setup and request middleware ## Metrics Collection ### RED Method (Rate, Err