observability-telemetry

Observability & Telemetry — CAP Best Practices

Primary reference: https://cap.cloud.sap/docs/plugins/#telemetry
Cloud Logging: https://cap.cloud.sap/docs/guides/deployment/to-cf

Structured logging with cds.log

Always use cds.log — never raw console.log in production code:

const log = cds.log('orders')  // scoped logger with module prefix

// Levels: error > warn > info > debug > trace
log.error('Failed to submit order', { orderID, error: err.message })
log.warn('Stock is low for product', { productID, remaining: stock })
log.info('Order submitted successfully', { orderID, amount })
log.debug('Entering validateOrder', { data: req.data })  // only in debug mode

// Conditional check (avoids building the log string when debug is off) if (log.debug) log.debug('Full request data:', req.data)

Configure log level per module:
```json
{
  "cds": {
    "log": {
      "levels": {
        "orders": "debug",
        "remote-services": "warn",
        "*": "info"
      }
    }
  }
}

@cap-js/telemetry plugin (OpenTelemetry)

Version 2 (June 2026+): @cap-js/telemetry v2 supports OpenTelemetry SDK 2.0 and adds @opentelemetry/instrumentation-undici for tracing outbound HTTP calls via the native Fetch API. All @opentelemetry/* dependencies are bumped to 2.x. Upgrade with npm install @cap-js/telemetry@latest.

npm install @cap-js/telemetry

Auto-activated — instruments CAP service calls, DB queries, and HTTP requests automatically.

Export to SAP Cloud Logging

{
  "cds": {
    "requires": {
      "telemetry": {
        "kind": "to-cloud-logging"
      }
    }
  }
}

mta.yaml:

modules:
  - name: my-cap-app-srv
    requires:
      - name: my-cap-app-logging

resources:
  - name: my-cap-app-logging
    type: org.cloudfoundry.managed-service
    parameters:
      service: cloud-logging
      service-plan: standard

Export to Dynatrace

{
  "cds": {
    "requires": {
      "telemetry": {
        "kind": "to-dynatrace"
      }
    }
  }
}

Local development (console output)

{
  "cds": {
    "requires": {
      "telemetry": {
        "[development]": {
          "kind": "to-console"
        }
      }
    }
  }
}

W3C Trace Context propagation

CAP automatically propagates W3C traceparent/tracestate headers in:

• Incoming HTTP requests
• Outgoing remote service calls
• Outbox message processing (since CAP Nov 2025)

This means your end-to-end trace ID is consistent across:

Client → CAP Service → Remote S/4 Call → Outbox → Async Handler

No manual implementation needed — just ensure @cap-js/telemetry is installed.

Outbox metrics (CAP Nov 2025+)

Monitor outbox health with built-in OpenTelemetry metrics:

Metrics exposed:

• cds.outbox.messages.pending — messages waiting to be delivered
• cds.outbox.messages.failed — failed deliveries
• cds.outbox.processing.duration — processing time histogram

Import the Cloud Logging dashboard:

1. Go to Stack Management → Saved Objects → Import
2. Import cap-java-outbox-metrics.ndjson (from CAP docs)
3. Open CAP Java Outbox Metrics dashboard

Custom spans for business operations

const { trace } = require('@opentelemetry/api')
const tracer = trace.getTracer('orders-service')

async function processOrder(orderID) {
  return tracer.startActiveSpan('processOrder', async (span) => {
    try {
      span.setAttribute('order.id', orderID)
      span.setAttribute('order.tenant', cds.context?.tenant)

      const result = await doProcessing(orderID)

      span.setStatus({ code: 0 })  // OK
      return result
    } catch (err) {
      span.setStatus({ code: 2, message: err.message })  // ERROR
      span.recordException(err)
      throw err
    } finally {
      span.end()
    }
  })
}

Health check endpoint

CAP exposes a /health endpoint out of the box:

GET /health → 200 OK  {"status":"UP"}

Use it for Kubernetes liveness/readiness probes:

# Kyma / K8s deployment
livenessProbe:
  httpGet:
    path: /health
    port: 4004
  initialDelaySeconds: 30
  periodSeconds: 10

Debugging in production (safely)

# Enable debug logging for specific modules without redeployment (CF)
cf set-env my-cap-app CDS_LOG_LEVELS '{"remote-services":"debug","db":"debug"}'
cf restage my-cap-app

# Or via cds env (Node.js picks up process.env)
CDS_LOG_LEVELS='{"orders":"debug"}' npm start

Common mistakes to avoid

• ❌ Using console.log in production — not structured, not correlated with traces
• ❌ Logging sensitive data (PII, credentials) even at debug level
• ❌ Not scoping loggers (cds.log('module-name')) — all logs appear as generic CAP logs
• ❌ Skipping @cap-js/telemetry — you lose automatic DB query tracing and service call timing
• ❌ Not propagating traceparent to remote service calls — trace breaks end-to-end
• ❌ Missing cloud-logging service binding in mta.yaml — telemetry silently drops in production