OpenTelemetry - Quick Reference

Full Reference: See advanced.md for context propagation, detailed metrics API, Collector configuration, Docker Compose stack, sampling strategies, and semantic conventions.

Deep Knowledge: Use mcp__documentation__fetch_docs with technology: opentelemetry for comprehensive documentation.

Concepts

┌─────────────────────────────────────────────────────────────┐
│                      OpenTelemetry                          │
├─────────────────┬─────────────────┬─────────────────────────┤
│     Traces      │     Metrics     │         Logs            │
│  (Distributed)  │  (Aggregated)   │     (Structured)        │
├─────────────────┴─────────────────┴─────────────────────────┤
│                    OTLP Protocol                            │
├─────────────────────────────────────────────────────────────┤
│                 Collector (optional)                        │
├─────────────────────────────────────────────────────────────┤
│  Jaeger │ Zipkin │ Prometheus │ Grafana │ DataDog │ etc.    │
└─────────────────────────────────────────────────────────────┘

Node.js Setup

npm install @opentelemetry/sdk-node \
  @opentelemetry/auto-instrumentations-node \
  @opentelemetry/exporter-trace-otlp-http

Basic Configuration

// tracing.ts - Load FIRST before any other imports
import { NodeSDK } from '@opentelemetry/sdk-node';
import { getNodeAutoInstrumentations } from '@opentelemetry/auto-instrumentations-node';
import { OTLPTraceExporter } from '@opentelemetry/exporter-trace-otlp-http';
import { Resource } from '@opentelemetry/resources';
import { SEMRESATTRS_SERVICE_NAME } from '@opentelemetry/semantic-conventions';

const sdk = new NodeSDK({
  resource: new Resource({
    [SEMRESATTRS_SERVICE_NAME]: 'my-service',
  }),
  traceExporter: new OTLPTraceExporter({
    url: process.env.OTEL_EXPORTER_OTLP_ENDPOINT || 'http://localhost:4318/v1/traces',
  }),
  instrumentations: [getNodeAutoInstrumentations()],
});

sdk.start();

process.on('SIGTERM', () => {
  sdk.shutdown().finally(() => process.exit(0));
});

Application Entry Point

// index.ts
import './tracing'; // MUST be first import
import express from 'express';

const app = express();

Manual Traces

import { trace, SpanStatusCode } from '@opentelemetry/api';

const tracer = trace.getTracer('my-service', '1.0.0');

async function processOrder(orderId: string) {
  return tracer.startActiveSpan('process-order', async (span) => {
    try {
      span.setAttribute('order.id', orderId);
      await processOrderLogic(orderId);
      span.setStatus({ code: SpanStatusCode.OK });
    } catch (error) {
      span.setStatus({ code: SpanStatusCode.ERROR, message: error.message });
      span.recordException(error);
      throw error;
    } finally {
      span.end();
    }
  });
}

Spring Boot Setup

<dependency>
    <groupId>io.micrometer</groupId>
    <artifactId>micrometer-tracing-bridge-otel</artifactId>
</dependency>
<dependency>
    <groupId>io.opentelemetry</groupId>
    <artifactId>opentelemetry-exporter-otlp</artifactId>
</dependency>

management:
  tracing:
    sampling:
      probability: 1.0
  otlp:
    tracing:
      endpoint: http://localhost:4318/v1/traces

Environment Variables

OTEL_SERVICE_NAME=my-service
OTEL_EXPORTER_OTLP_ENDPOINT=http://localhost:4318
OTEL_TRACES_SAMPLER=parentbased_traceidratio
OTEL_TRACES_SAMPLER_ARG=0.1  # 10% sampling

When NOT to Use This Skill

Simple application logging: Use logging frameworks instead
Monolithic applications: May be overkill
Vendor-specific APM: DataDog, New Relic have their own SDKs
Development/debugging only: Standard logging may suffice
Legacy systems: Migration effort may be high

Anti-Patterns

Anti-Pattern	Why It's Bad	Solution
Creating spans for every function	Massive overhead	Span only meaningful operations
100% sampling in production	Performance impact, cost	Use 1-10% sampling
Not propagating context	Breaks distributed traces	Inject/extract at service boundaries
Logging PII in span attributes	Security/compliance violation	Filter sensitive data
Forgetting to end spans	Memory leak	Always end spans in finally block
Synchronous exporters	Blocks application	Use batch processors

Quick Troubleshooting

Issue	Cause	Solution
Traces not appearing	Exporter not configured	Check OTEL_EXPORTER_OTLP_ENDPOINT
High memory usage	Too many spans	Enable sampling
Missing context propagation	Not injecting headers	Use propagation API
Performance degradation	High sampling rate	Reduce to 1-10%
SDK initialization error	Import order wrong	Initialize SDK before other imports

Monitoring Metrics

Metric	Target
Trace latency (p99)	< 10ms overhead
Span drop rate	< 1%
Collector memory	< 1GB
Export success rate	> 99%

Checklist

Reference

Deep Knowledge: Use mcp__documentation__fetch_docs with technology: opentelemetry for comprehensive documentation

OpenTelemetry Docs