fix: update resource name when child span is active in store for Next.js (#7000)

Changed how to store the req to reference in page load to consider child spans in the store. It now uses the identifier instance for the lookup instead of the span.

Author: crysmags

packages/datadog-plugin-next/src/index.js

@@ -10,10 +10,10 @@ const errorPages = new Set(['/404', '/500', '/_error', '/_not-found', '/_not-fou
 
 class NextPlugin extends ServerPlugin {
   static id = 'next'
+  #requestsBySpanId = new WeakMap()
 
   constructor (...args) {
     super(...args)
-    this._requests = new WeakMap()
     this.addSub('apm:next:page:load', message => this.pageLoad(message))
   }
 
@@ -35,7 +35,9 @@ class NextPlugin extends ServerPlugin {
 
     analyticsSampler.sample(span, this.config.measured, true)
 
-    this._requests.set(span, req)
+    // Store request by span ID to handle cases where child spans are activated
+    const spanId = span.context()._spanId
+    this.#requestsBySpanId.set(spanId, req)
 
     return { ...store, span }
   }
@@ -89,7 +91,13 @@ class NextPlugin extends ServerPlugin {
     if (!store) return
 
     const span = store.span
-    const req = this._requests.get(span)
+
+    const spanId = span.context()._spanId
+    const parentSpanId = span.context()._parentId
+
+    // Try current span first, then parent span.
+    // This handles cases where pageLoad runs in a child span context
+    const req = this.#requestsBySpanId.get(spanId) ?? this.#requestsBySpanId.get(parentSpanId)
 
     // safeguard against missing req in complicated timeout scenarios
     if (!req) return

packages/datadog-plugin-next/test/index.spec.js

@@ -277,6 +277,35 @@ describe('Plugin', function () {
               .get(`http://127.0.0.1:${port}/api/hello/world`)
               .catch(done)
           })
+
+          it('should handle child spans and still find the request object', done => {
+            agent
+              .assertSomeTraces(traces => {
+                const spans = traces[0]
+
+                const nextRequestSpan = spans.find(span => span.name === 'next.request')
+                assert.ok(nextRequestSpan, 'next.request span should exist')
+
+                assert.strictEqual(nextRequestSpan.resource, 'GET /api/hello/[name]')
+                assert.strictEqual(nextRequestSpan.meta['next.page'], '/api/hello/[name]')
+                assert.strictEqual(nextRequestSpan.meta['http.method'], 'GET')
+                assert.strictEqual(nextRequestSpan.meta['http.status_code'], '200')
+
+                const webRequestSpan = spans.find(span => span.name === 'web.request')
+                assert.ok(webRequestSpan, 'web.request span should exist')
+                assert.strictEqual(webRequestSpan.resource, 'GET /api/hello/[name]')
+
+                const childSpan = spans.find(span => span.name === 'child.operation')
+                assert.ok(childSpan, 'child span should exist')
+                assert.strictEqual(childSpan.parent_id.toString(), nextRequestSpan.span_id.toString())
+              })
+              .then(done)
+              .catch(done)
+
+            axios
+              .get(`http://127.0.0.1:${port}/api/hello/world?createChildSpan=true`)
+              .catch(done)
+          })
         })
 
         describe('for pages', () => {

packages/datadog-plugin-next/test/pages/api/hello/[name].js

@@ -2,6 +2,17 @@
 
 export default (req, res) => {
   const tracer = require('../../../../../dd-trace')
+
+  if (req.query.createChildSpan === 'true') {
+    const childSpan = tracer.startSpan('child.operation', {
+      childOf: tracer.scope().active()
+    })
+
+    tracer.scope().activate(childSpan, () => {
+      childSpan.finish()
+    })
+  }
+
   const span = tracer.scope().active()
   const name = span && span.context()._name