Tracing

// OpenTelemetry를 사용한 Node.js 트레이싱 설정
// tracing.js
const { NodeSDK } = require('@opentelemetry/sdk-node');
const { getNodeAutoInstrumentations } = require('@opentelemetry/auto-instrumentations-node');
const { OTLPTraceExporter } = require('@opentelemetry/exporter-trace-otlp-grpc');
const { Resource } = require('@opentelemetry/resources');
const { SemanticResourceAttributes } = require('@opentelemetry/semantic-conventions');

const sdk = new NodeSDK({
  resource: new Resource({
    [SemanticResourceAttributes.SERVICE_NAME]: 'user-service',
    [SemanticResourceAttributes.SERVICE_VERSION]: '1.0.0',
    [SemanticResourceAttributes.DEPLOYMENT_ENVIRONMENT]: process.env.NODE_ENV,
  }),
  traceExporter: new OTLPTraceExporter({
    url: process.env.OTEL_EXPORTER_OTLP_ENDPOINT || 'http://tempo:4317',
  }),
  instrumentations: [
    getNodeAutoInstrumentations({
      '@opentelemetry/instrumentation-fs': { enabled: false },
      '@opentelemetry/instrumentation-http': { enabled: true },
      '@opentelemetry/instrumentation-express': { enabled: true },
    }),
  ],
});

sdk.start();

// 애플리케이션 코드에서 커스텀 span 생성
// userController.js
const { trace, SpanStatusCode } = require('@opentelemetry/api');

const tracer = trace.getTracer('user-service');

async function createUser(req, res) {
  // 커스텀 span 시작
  const span = tracer.startSpan('createUser', {
    attributes: {
      'user.email': req.body.email,
    },
  });

  try {
    // 중첩 span으로 세부 작업 추적
    const validationSpan = tracer.startSpan('validateInput');
    await validateUserInput(req.body);
    validationSpan.end();

    const dbSpan = tracer.startSpan('saveToDatabase');
    const user = await db.users.create(req.body);
    dbSpan.setAttribute('db.rows_affected', 1);
    dbSpan.end();

    // 외부 서비스 호출 (자동으로 context 전파됨)
    const notificationSpan = tracer.startSpan('sendWelcomeEmail');
    await notificationService.sendWelcomeEmail(user.email);
    notificationSpan.end();

    span.setStatus({ code: SpanStatusCode.OK });
    res.json({ success: true, user });

  } catch (error) {
    span.setStatus({
      code: SpanStatusCode.ERROR,
      message: error.message,
    });
    span.recordException(error);
    res.status(500).json({ error: error.message });

  } finally {
    span.end();
  }
}

// package.json 실행 스크립트
// "start": "node --require ./tracing.js app.js"