feat: optional axios tracing setup based on axios-debug-log presence

lib/tracing/axios-debug.js

@@ -0,0 +1,207 @@
+const cds = require('@sap/cds')
+const axios = require('axios')
+const LOG = cds.log('axios-telemetry')
+
+let _initialized = false
+
+/**
+ * Setup axios-debug-log mit OpenTelemetry Span Integration
+ */
+function setupAxiosTracing() {
+    if (_initialized) return
+    _initialized = true
+
+    // Dynamisch axios-debug-log laden und konfigurieren
+    require('axios-debug-log')({
+        request: (debug, config) => {
+            const span = _startSpan(config)
+            config._otelSpan = span
+            config._startTime = Date.now()
+
+            debug(
+                `Request: ${config.method?.toUpperCase()} ${config.url}`,
+                config.headers ? `Headers: ${JSON.stringify(config.headers)}` : ''
+            )
+        },
+        response: (debug, response) => {
+            const { config } = response
+            const duration = Date.now() - (config._startTime || Date.now())
+
+            _endSpan(config._otelSpan, response.status, duration)
+
+            debug(
+                `Response: ${response.status} ${response.statusText}`,
+                `Duration: ${duration}ms`
+            )
+        },
+        error: (debug, error) => {
+            const config = error.config || {}
+            const duration = Date.now() - (config._startTime || Date.now())
+
+            _endSpanWithError(config._otelSpan, error, duration)
+
+            debug(
+                `Error: ${error.message}`,
+                error.response ? `Status: ${error.response.status}` : ''
+            )
+        }
+    })
+
+    // Interceptors für alle axios Instanzen
+    _addGlobalInterceptors()
+
+    LOG.debug('axios-debug-log configured with OpenTelemetry spans')
+}
+
+/**
+ * Wrap eine einzelne axios Instanz mit Tracing
+ * @param {import('axios').AxiosInstance} instance 
+ * @returns {import('axios').AxiosInstance}
+ */
+function wrapAxiosInstance(instance) {
+    instance.interceptors.request.use(
+        (config) => {
+            const span = _startSpan(config)
+            config._otelSpan = span
+            config._startTime = Date.now()
+
+            // Trace Context Propagation
+            _injectTraceContext(config)
+
+            return config
+        },
+        (error) => {
+            LOG.error('Request interceptor error:', error.message)
+            return Promise.reject(error)
+        }
+    )
+
+    instance.interceptors.response.use(
+        (response) => {
+            const { config } = response
+            const duration = Date.now() - (config._startTime || Date.now())
+            _endSpan(config._otelSpan, response.status, duration)
+            return response
+        },
+        (error) => {
+            const config = error.config || {}
+            const duration = Date.now() - (config._startTime || Date.now())
+            _endSpanWithError(config._otelSpan, error, duration)
+            return Promise.reject(error)
+        }
+    )
+
+    return instance
+}
+
+/**
+ * Startet einen neuen OpenTelemetry Span für den Request
+ */
+function _startSpan(config) {
+    try {
+        // @cap-js/telemetry nutzt @opentelemetry/api
+        const { trace, SpanKind } = require('@opentelemetry/api')
+        const tracer = trace.getTracer('cds-plugin-axios-telemetry')
+
+        const url = new URL(config.url, config.baseURL || 'http://localhost')
+        const spanName = `HTTP ${config.method?.toUpperCase()} ${url.pathname}`
+
+        const span = tracer.startSpan(spanName, {
+            kind: SpanKind.CLIENT,
+            attributes: {
+                'http.method': config.method?.toUpperCase(),
+                'http.url': url.href,
+                'http.target': url.pathname + url.search,
+                'http.host': url.host,
+                'http.scheme': url.protocol.replace(':', ''),
+                'net.peer.name': url.hostname,
+                'net.peer.port': url.port || (url.protocol === 'https:' ? 443 : 80)
+            }
+        })
+
+        return span
+    } catch (e) {
+        // OpenTelemetry nicht verfügbar - graceful degradation
+        return null
+    }
+}
+
+/**
+ * Beendet den Span mit Success Status
+ */
+function _endSpan(span, statusCode, duration) {
+    if (!span || span._ended) return
+
+    try {
+        const { SpanStatusCode } = require('@opentelemetry/api')
+
+        span.setAttribute('http.status_code', statusCode)
+        span.setAttribute('http.response_time_ms', duration)
+
+        if (statusCode >= 400) {
+            span.setStatus({ code: SpanStatusCode.ERROR })
+        } else {
+            span.setStatus({ code: SpanStatusCode.OK })
+        }
+
+        span.end()
+    } catch (e) {
+        // Ignore errors
+    }
+}
+
+/**
+ * Beendet den Span mit Error Status
+ */
+function _endSpanWithError(span, error, duration) {
+    if (!span || span._ended) return
+
+    try {
+        const { SpanStatusCode } = require('@opentelemetry/api')
+
+        span.setAttribute('http.response_time_ms', duration)
+        span.setAttribute('error', true)
+        span.setAttribute('error.message', error.message)
+        span.setAttribute('error.type', error.name || 'Error')
+
+        if (error.response) {
+            span.setAttribute('http.status_code', error.response.status)
+        }
+
+        span.setStatus({
+            code: SpanStatusCode.ERROR,
+            message: error.message
+        })
+
+        span.recordException(error)
+        span.end()
+    } catch (e) {
+        // Ignore errors
+    }
+}
+
+/**
+ * Injiziert W3C Trace Context Header für Distributed Tracing
+ */
+function _injectTraceContext(config) {
+    try {
+        const { trace, context, propagation } = require('@opentelemetry/api')
+
+        config.headers = config.headers || {}
+        propagation.inject(context.active(), config.headers)
+    } catch (e) {
+        // Ignore if OpenTelemetry not available
+    }
+}
+
+/**
+ * Fügt globale Interceptors zur default axios Instanz hinzu
+ */
+function _addGlobalInterceptors() {
+    wrapAxiosInstance(axios)
+}
+
+module.exports = {
+    setupAxiosTracing,
+    wrapAxiosInstance
+}

lib/tracing/index.js

@@ -179,5 +179,14 @@ module.exports = resource => {
   require('./cds')()
   require('./cloud_sdk')()
 
+  try {
+    // only setup axios tracing if axios-debug-log is present, as it is an optional dependency and we don't want to force users to install it if they don't want axios tracing
+    require.resolve("axios-debug-log")
+    LOG._info && LOG.info('axios-debug-log found, setting up axios tracing')
+    require('./axios-debug').setupAxiosTracing()
+  } catch (e) {
+    LOG._info && LOG.info('axios-debug-log not found, skipping axios tracing setup')
+  }
+
   return tracerProvider
 }