fix(startup-log): emit config early at init, integrations on first ag… (#7643)

bm1549 · claude · web-flow · commit b7fbc2d3dcc3 · 2026-03-06T11:58:57.000-05:00
* fix(startup-log): emit config early at init, integrations on first agent payload Split startupLog into three independent functions so config is logged immediately at init (via proxy.js) while integrations are logged later on first agent payload (via writer.js). This gives users config info faster without losing the integrations_loaded field that was regressed in #7470. Also fixes broken agent error logging introduced in #7212 where `startupLog({ agentError: err })` didn't match the expected `{ status, message }` shape. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com> * ci: re-run CI --------- Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
diff --git a/packages/dd-trace/src/exporters/agent/writer.js b/packages/dd-trace/src/exporters/agent/writer.js
@@ -1,7 +1,8 @@
 'use strict'
 
+const { inspect } = require('node:util')
 const request = require('../common/request')
-const { startupLog } = require('../../startup-log')
+const { logIntegrations, logAgentError } = require('../../startup-log')
 const runtimeMetrics = require('../../runtime_metrics')
 const log = require('../../log')
 const tracerVersion = require('../../../../../package.json').version
@@ -28,7 +29,7 @@ class AgentWriter extends BaseWriter {
     runtimeMetrics.increment(`${METRIC_PREFIX}.requests`, true)
 
     const { _headers, _lookup, _protocolVersion, _url } = this
-    makeRequest(_protocolVersion, data, count, _url, _headers, _lookup, true, (err, res, status, headers) => {
+    makeRequest(_protocolVersion, data, count, _url, _headers, _lookup, (err, res, status, headers) => {
       if (status) {
         runtimeMetrics.increment(`${METRIC_PREFIX}.responses`, true)
         runtimeMetrics.increment(`${METRIC_PREFIX}.responses.by.status`, `status:${status}`, true)
@@ -78,7 +79,7 @@ function getEncoder (protocolVersion) {
     : require('../../encode/0.4').AgentEncoder
 }
 
-function makeRequest (version, data, count, url, headers, lookup, needsStartupLog, cb) {
+function makeRequest (version, data, count, url, headers, lookup, cb) {
   const options = {
     path: `/v${version}/traces`,
     method: 'PUT',
@@ -98,11 +99,9 @@ function makeRequest (version, data, count, url, headers, lookup, needsStartupLo
   log.debug('Request to the agent: %j', options)
 
   request(data, options, (err, res, status, headers) => {
-    if (needsStartupLog) {
-      // Note that logging will only happen once, regardless of how many times this is called.
-      startupLog({
-        agentError: status !== 404 && status !== 200 ? err : undefined,
-      })
+    logIntegrations()
+    if (status !== 404 && status !== 200 && err) {
+      logAgentError({ status, message: err.message ?? inspect(err) })
     }
     cb(err, res, status, headers)
   })
diff --git a/packages/dd-trace/src/proxy.js b/packages/dd-trace/src/proxy.js
@@ -6,7 +6,7 @@ const DatadogTracer = require('./tracer')
 const getConfig = require('./config')
 const runtimeMetrics = require('./runtime_metrics')
 const log = require('./log')
-const { setStartupLogPluginManager } = require('./startup-log')
+const { setStartupLogPluginManager, startupLog } = require('./startup-log')
 const DynamicInstrumentation = require('./debugger')
 const telemetry = require('./telemetry')
 const nomenclature = require('./service-naming')
@@ -292,6 +292,7 @@ class Tracer extends NoopProxy {
       this._pluginManager.configure(config)
       DynamicInstrumentation.configure(config)
       setStartupLogPluginManager(this._pluginManager)
+      startupLog()
     }
   }
 
diff --git a/packages/dd-trace/src/startup-log.js b/packages/dd-trace/src/startup-log.js
@@ -11,41 +11,66 @@ let config
 let pluginManager
 /** @type {import('./sampling_rule')[]} */
 let samplingRules = []
-let alreadyRan = false
+let configAlreadyRan = false
+let integrationsAlreadyRan = false
+let agentErrorAlreadyRan = false
 
 /**
- * @param {{ status: number, message: string } } [agentError]
+ * Logs DATADOG TRACER CONFIGURATION immediately at init time.
+ * Excludes integrations_loaded since plugins haven't loaded yet.
  */
-function startupLog (agentError) {
-  if (alreadyRan || !config || !config.startupLogs || !pluginManager) {
+function startupLog () {
+  if (configAlreadyRan || !config || !config.startupLogs) {
     return
   }
 
-  alreadyRan = true
+  configAlreadyRan = true
 
-  const out = tracerInfo()
+  const out = configInfo()
 
-  if (agentError) {
-    out.agent_error = agentError.message
+  warn('DATADOG TRACER CONFIGURATION - ' + out)
+}
+
+/**
+ * Logs loaded integrations. Called from writer.js on first agent payload,
+ * by which time the app has loaded its dependencies.
+ */
+function logIntegrations () {
+  if (integrationsAlreadyRan || !config || !config.startupLogs || !pluginManager) {
+    return
   }
 
-  warn('DATADOG TRACER CONFIGURATION - ' + out)
-  if (agentError) {
-    warn('DATADOG TRACER DIAGNOSTIC - Agent Error: ' + agentError.message)
-    errors.agentError = {
-      code: agentError.status,
-      message: `Agent Error: ${agentError.message}`,
-    }
+  integrationsAlreadyRan = true
+
+  warn('DATADOG TRACER INTEGRATIONS LOADED - ' + JSON.stringify(Object.keys(pluginManager._pluginsByName)))
+}
+
+/**
+ * Logs agent error diagnostic.
+ * @param {{ status: number, message: string }} agentError
+ */
+function logAgentError (agentError) {
+  if (agentErrorAlreadyRan || !config || !config.startupLogs) {
+    return
+  }
+
+  agentErrorAlreadyRan = true
+
+  warn('DATADOG TRACER DIAGNOSTIC - Agent Error: ' + agentError.message)
+  errors.agentError = {
+    code: agentError.status,
+    message: `Agent Error: ${agentError.message}`,
   }
 }
 
 /**
+ * Returns config info without integrations (used by startupLog).
  * @returns {Record<string, unknown>}
  */
-function tracerInfo () {
+function configInfo () {
   const url = getAgentUrl(config)
 
-  const out = {
+  return {
     [inspect.custom] () {
       return String(this)
     },
@@ -73,11 +98,18 @@ function tracerInfo () {
     log_injection_enabled: !!config.logInjection,
     runtime_metrics_enabled: !!config.runtimeMetrics,
     profiling_enabled: config.profiling?.enabled === 'true' || config.profiling?.enabled === 'auto',
-    integrations_loaded: Object.keys(pluginManager._pluginsByName),
     appsec_enabled: config.appsec.enabled,
     data_streams_enabled: !!config.dsmEnabled,
   }
+}
 
+/**
+ * Returns full tracer info including integrations (used by flare module).
+ * @returns {Record<string, unknown>}
+ */
+function tracerInfo () {
+  const out = configInfo()
+  out.integrations_loaded = Object.keys(pluginManager._pluginsByName)
   return out
 }
 
@@ -104,6 +136,8 @@ function setSamplingRules (theRules) {
 
 module.exports = {
   startupLog,
+  logIntegrations,
+  logAgentError,
   setStartupLogConfig,
   setStartupLogPluginManager,
   setSamplingRules,
diff --git a/packages/dd-trace/test/startup-log.spec.js b/packages/dd-trace/test/startup-log.spec.js
