test(agent): add timeout and error logging to checkAgentStatus (#7724)

watson · web-flow · commit c555085d5cf3 · 2026-03-11T11:21:16.000-07:00
The checkAgentStatus function in the test agent helper makes an HTTP
request to the test agent with no timeout. If the TCP connection is
established but no HTTP response is received, the promise hangs
indefinitely. This is a likely cause of flaky test timeouts with no
indication of the root cause (e.g. the AI Guard Windows CI job).

Add a 2s timeout with a descriptive warning so hangs are caught early
and the cause is visible in CI logs. Also log unexpected errors (other
than ECONNREFUSED, which is the normal "no test agent" case) to aid
future debugging.
diff --git a/packages/dd-trace/test/plugins/agent.js b/packages/dd-trace/test/plugins/agent.js
@@ -227,14 +227,29 @@ function handleTraceRequest (req, res, sendToTestAgent) {
 }
 
 function checkAgentStatus () {
-  const agentUrl = process.env.DD_TRACE_AGENT_URL || 'http://127.0.0.1:9126'
-
   return new Promise((resolve) => {
-    const request = http.request(`${agentUrl}/info`, { method: 'GET' }, response => {
+    const agentUrl = process.env.DD_TRACE_AGENT_URL || 'http://127.0.0.1:9126'
+    const timeoutMs = 2000
+
+    const request = http.request(`${agentUrl}/info`, { method: 'GET', timeout: timeoutMs }, response => {
       resolve(response.statusCode === 200)
     })
 
-    request.on('error', (_error_) => {
+    request.on('timeout', () => {
+      // eslint-disable-next-line no-console
+      console.warn(
+        `checkAgentStatus: Timed out after ${timeoutMs}ms trying to reach test agent at ${agentUrl}. ` +
+        'Proceeding without test agent. If this happens frequently, investigate what is listening on that port.'
+      )
+      request.destroy()
+      resolve(false)
+    })
+
+    request.on('error', (/** @type {NodeJS.ErrnoException} */ err) => {
+      if (err.code !== 'ECONNREFUSED') {
+        // eslint-disable-next-line no-console
+        console.warn(`checkAgentStatus: Unexpected error reaching test agent at ${agentUrl}`, err)
+      }
       resolve(false)
     })
 
