OpenTelemetry for Node.js: Distributed Tracing, Metrics, and Logs

Introduction Modern backend systems are rarely a single process. A single user request might touch an API gateway, three microservices, a PostgreSQL database, a Redis cache, and an external payment provider — all in under 200 milliseconds. When something goes wrong (and it will), you need to know exactly where. Traditional logging — console.log("request received") — doesn't cut it here. You need observability: the ability to ask arbitrary questions about your system's behavior from the outside, without modifying the code. OpenTelemetry (OTel) is the open-source standard that gives you that power. It's vendor-neutral, CNCF-graduated, and has become the de facto way to instrument Node.js services. This guide walks you through everything: setting up the SDK, auto-instrumenting Express and database drivers, writing custom spans, collecting metrics, correlating logs with trace IDs, and shipping data to Jaeger or Grafana Tempo. 1. Why Observability Matters: The Three Pillars Observability is