feat: wrap fetchClient to add HTTP client attributes to remote servic…

lib/tracing/index.js

@@ -178,6 +178,7 @@ module.exports = resource => {
    */
   require('./cds')()
   require('./cloud_sdk')()
+  require('./remote')()
 
   return tracerProvider
 }

lib/tracing/remote.js

@@ -0,0 +1,84 @@
+const cds = require('@sap/cds')
+const LOG = cds.log('telemetry')
+
+const { trace } = require('@opentelemetry/api')
+const {
+  ATTR_HTTP_REQUEST_METHOD,
+  ATTR_HTTP_RESPONSE_STATUS_CODE,
+  ATTR_SERVER_ADDRESS,
+  ATTR_SERVER_PORT,
+  ATTR_URL_FULL
+} = require('@opentelemetry/semantic-conventions')
+
+const wrap = require('./wrap')
+
+function _setRequestAttributes(span, requestConfig, destination) {
+  if (!requestConfig) return
+
+  const { method, url } = requestConfig
+
+  if (method) span.setAttribute(ATTR_HTTP_REQUEST_METHOD, method)
+
+  // build full URL from destination and request path
+  const baseUrl = typeof destination === 'string' ? undefined : destination?.url?.replace(/\/$/, '')
+  if (baseUrl) {
+    const fullUrl = baseUrl + (url?.startsWith('/') ? url : `/${url || ''}`)
+    span.setAttribute(ATTR_URL_FULL, fullUrl)
+
+    // parse server address and port from destination URL
+    try {
+      const parsed = new URL(baseUrl)
+      span.setAttribute(ATTR_SERVER_ADDRESS, parsed.hostname)
+      const port = parsed.port || (parsed.protocol === 'https:' ? 443 : 80)
+      span.setAttribute(ATTR_SERVER_PORT, Number(port))
+    } catch {
+      // ignore URL parsing errors
+    }
+  }
+}
+
+module.exports = () => {
+  cds.on('served', () => {
+    let fetchClient
+    try {
+      fetchClient = require('@sap/cds/libx/_runtime/remote/utils/fetchClient')
+    } catch {
+      LOG._debug && LOG.debug('Could not load remote fetchClient module')
+      return
+    }
+
+    // guard against double-wrapping
+    if (fetchClient.executeHttpRequest.__wrapped) return
+
+    // wrap native fetch client
+    const _fetchExecute = fetchClient.executeHttpRequest
+    fetchClient.executeHttpRequest = wrap(_fetchExecute, {
+      wrapper: async function executeHttpRequest(destination, requestConfig) {
+        const span = trace.getActiveSpan()
+
+        // set request attributes before the call
+        if (span?.isRecording()) {
+          try {
+            _setRequestAttributes(span, requestConfig, destination)
+          } catch (err) {
+            LOG._debug && LOG.debug('Failed to set HTTP request attributes:', err)
+          }
+        }
+
+        // execute the actual request
+        try {
+          const response = await _fetchExecute.apply(this, arguments)
+          if (span?.isRecording() && response?.status) {
+            span.setAttribute(ATTR_HTTP_RESPONSE_STATUS_CODE, response.status)
+          }
+          return response
+        } catch (err) {
+          if (span?.isRecording() && err.response?.status) {
+            span.setAttribute(ATTR_HTTP_RESPONSE_STATUS_CODE, err.response.status)
+          }
+          throw err
+        }
+      }
+    })
+  })
+}

test/bookshop/package.json

@@ -124,5 +124,8 @@
     "fiori": {
       "draft_deletion_timeout": false
     }
+  },
+  "devDependencies": {
+    "@sap/cds-dk": "^9"
   }
 }

test/tracing-attributes.test.js

@@ -2,13 +2,52 @@ process.env.cds_requires_telemetry_tracing_exporter_module = '@opentelemetry/sdk
 
 const cds = require('@sap/cds')
 const { expect, data } = cds.test().in(__dirname + '/bookshop')
+const http = require('http')
 
 describe('tracing attributes', () => {
   beforeEach(data.reset)
 
   const log = jest.spyOn(console, 'dir')
   beforeEach(log.mockClear)
 
+  describe('remote', () => {
+    let server, port
+
+    beforeAll(done => {
+      server = http.createServer((req, res) => {
+        res.writeHead(200, { 'Content-Type': 'application/json' })
+        res.end(JSON.stringify({ value: [] }))
+      })
+      server.listen(0, () => {
+        port = server.address().port
+        done()
+      })
+    })
+
+    afterAll(done => {
+      server.close(done)
+    })
+
+    test('HTTP client attributes are set on remote service span', async () => {
+      // skip for cds 8 due to Cloud SDK resilience module resolution issues in test environment
+      if (Number(cds.version.split('.')[0]) < 9) return
+
+      // configure destination URL directly on credentials
+      cds.env.requires.TestRemote = { kind: 'odata', credentials: { url: `http://localhost:${port}` } }
+      const remote = await cds.connect.to('TestRemote')
+
+      // no mock handler - let it make the actual HTTP call
+      await remote.send({ method: 'GET', path: '/test' })
+
+      const output = JSON.stringify(log.mock.calls)
+      expect(output).to.match(/"http\.request\.method":"GET"/)
+      expect(output).to.match(/"http\.response\.status_code":200/)
+      expect(output).to.match(new RegExp(`"url\\.full":"http://localhost:${port}/test"`))
+      expect(output).to.match(/"server\.address":"localhost"/)
+      expect(output).to.match(new RegExp(`"server\\.port":${port}`))
+    })
+  })
+
   describe('db', () => {
     const _db_spans = require('./_db_spans')
     // prettier-ignore