1// OpenTelemetry: auto-instrument Node.js service
2// Must be initialized BEFORE other imports
OTel must initialize BEFORE other imports to successfully instrument libraries
3 
4import { NodeSDK } from '@opentelemetry/sdk-node';
5import { getNodeAutoInstrumentations } from '@opentelemetry/auto-instrumentations-node';
6import { OTLPTraceExporter } from '@opentelemetry/exporter-trace-otlp-http';
7import { Resource } from '@opentelemetry/resources';
8import { SemanticResourceAttributes } from '@opentelemetry/semantic-conventions';
9 
10const sdk = new NodeSDK({
11  resource: new Resource({
service.name is how you identify this service in trace visualizations
12    [SemanticResourceAttributes.SERVICE_NAME]: 'order-service',
13    [SemanticResourceAttributes.SERVICE_VERSION]: process.env.GIT_SHA ?? 'unknown',
14    environment: process.env.NODE_ENV,
15  }),
16  traceExporter: new OTLPTraceExporter({
17    url: process.env.OTEL_EXPORTER_OTLP_ENDPOINT,
18  }),
19  instrumentations: [
Auto-instrumentation patches HTTP, Express, pg, Redis with zero code changes
20    getNodeAutoInstrumentations({
21      '@opentelemetry/instrumentation-http': { enabled: true },     // auto-traces HTTP
22      '@opentelemetry/instrumentation-express': { enabled: true },  // auto-traces Express
23      '@opentelemetry/instrumentation-pg': { enabled: true },       // auto-traces PostgreSQL
24      '@opentelemetry/instrumentation-redis': { enabled: true },    // auto-traces Redis
25    }),
26  ],
27});
28 
29sdk.start();
30 
31// Manual spans for custom operations
32import { trace, SpanStatusCode } from '@opentelemetry/api';
33 
34const tracer = trace.getTracer('order-service');
35 
36async function processPayment(orderId: string, amountCents: number) {
37  const span = tracer.startSpan('process-payment');
Add business-relevant attributes to spans — makes searching and filtering traces useful
38  span.setAttributes({
39    'order.id': orderId,
40    'payment.amount_cents': amountCents,
41    'payment.currency': 'USD',
42  });
43 
44  try {
45    const result = await paymentProvider.charge({ orderId, amountCents });
46    span.setStatus({ code: SpanStatusCode.OK });
47    return result;
48  } catch (error) {
Always end spans in finally — leaked spans cause memory issues
49    span.setStatus({ code: SpanStatusCode.ERROR, message: (error as Error).message });
50    span.recordException(error as Error);
51    throw error;
52  } finally {
53    span.end();  // Always end spans — leaked spans cause memory issues
54  }
55}