How to add tracing and observability with Cursor

1// Cursor Chat prompt (Cmd+L):
2// Generate an OpenTelemetry tracing setup module for a
3// Node.js Express service. Use OTLP/gRPC exporter, batch
4// span processor, and the W3C trace context propagator.
5// Service name should come from environment variable
6// OTEL_SERVICE_NAME. Export a getTracer() function.
7
8// Expected output:
9import { NodeSDK } from '@opentelemetry/sdk-node';
10import { getNodeAutoInstrumentations } from '@opentelemetry/auto-instrumentations-node';
11import { OTLPTraceExporter } from '@opentelemetry/exporter-trace-otlp-grpc';
12import { trace } from '@opentelemetry/api';
13
14const sdk = new NodeSDK({
15  traceExporter: new OTLPTraceExporter({
16    url: process.env.OTEL_EXPORTER_OTLP_ENDPOINT || 'http://localhost:4317',
17  }),
18  instrumentations: [getNodeAutoInstrumentations()],
19  serviceName: process.env.OTEL_SERVICE_NAME || 'unknown-service',
20});
21
22sdk.start();
23
24export function getTracer(name: string) {
25  return trace.getTracer(name);
26}

1---
2description: OpenTelemetry tracing conventions
3globs: "src/**/*.ts"
4alwaysApply: false
5---
6
7## Tracing Rules
8- Import tracer: import { getTracer } from '@/tracing/setup'
9- Span naming: '{service}.{operation}' e.g. 'order-service.createOrder'
10- ALWAYS add these attributes to spans:
11  - 'http.method' for HTTP handlers
12  - 'http.route' for the URL pattern
13  - 'user.id' when available from auth context
14  - 'error' boolean attribute on failures
15- Record exceptions with span.recordException(error)
16- Set span status to ERROR on catch blocks
17- Use startActiveSpan for automatic context propagation
18- NEVER create spans inside tight loops (batch them)
19- End spans in finally blocks to prevent leaks

1// Select the handler function, press Cmd+K:
2// @src/tracing/setup.ts Add OpenTelemetry tracing to this
3// handler. Use startActiveSpan with the naming convention
4// 'order-service.getOrder'. Add http.method, http.route,
5// and user.id attributes. Record errors.
6
7// Cursor output:
8import { getTracer } from '@/tracing/setup';
9import { SpanStatusCode } from '@opentelemetry/api';
10
11const tracer = getTracer('order-service');
12
13app.get('/orders/:id', async (req, res) => {
14  return tracer.startActiveSpan('order-service.getOrder', async (span) => {
15    try {
16      span.setAttribute('http.method', 'GET');
17      span.setAttribute('http.route', '/orders/:id');
18      span.setAttribute('user.id', req.user?.id || 'anonymous');
19
20      const order = await orderRepository.findById(req.params.id);
21      if (!order) {
22        span.setAttribute('error', true);
23        return res.status(404).json({ error: 'Order not found' });
24      }
25      res.json(order);
26    } catch (error) {
27      span.recordException(error as Error);
28      span.setStatus({ code: SpanStatusCode.ERROR });
29      res.status(500).json({ error: 'Internal server error' });
30    } finally {
31      span.end();
32    }
33  });
34});

1// Composer prompt (Cmd+I):
2// @src/tracing/setup.ts @.cursor/rules/tracing.mdc
3// @src/routes/ Add OpenTelemetry tracing to all route
4// handlers in the routes directory. Follow the tracing
5// rules for span naming, attributes, and error recording.
6// Process one file at a time and show me the diff before
7// proceeding to the next file.

1// Terminal: Start the service with tracing enabled
2OTEL_SERVICE_NAME=order-service \
3OTEL_EXPORTER_OTLP_ENDPOINT=http://localhost:4317 \
4npm run dev
5
6// Send a test request
7curl http://localhost:3000/orders/123
8
9// If traces are missing, ask Cursor:
10// Cmd+L: @src/tracing/setup.ts My traces are not appearing
11// in Jaeger at localhost:16686. The service starts without
12// errors. What could be wrong?