From dd9429a102a6a3bdab28f2715bfe76872ffbe89a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Rafa=C5=82=20Sumis=C5=82awski?=
 <rafal.sumislawski@coralogix.com>
Date: Wed, 4 Dec 2024 12:50:29 +0100
Subject: [PATCH] Warm up http/proto exporter by sending special spans (#56)

* Use http/proto exporter instead of grpc to reduce the cost of loading libraries

* Disable tracing/metrics of http exporter

* Warm up http/proto exporter by sending special spans
---
 nodejs/packages/cx-wrapper/index.ts         | 24 +++++++++++++++++++--
 nodejs/packages/cx-wrapper/provider-init.ts |  6 ++++--
 nodejs/packages/layer/package-lock.json     |  2 +-
 3 files changed, 27 insertions(+), 5 deletions(-)

diff --git a/nodejs/packages/cx-wrapper/index.ts b/nodejs/packages/cx-wrapper/index.ts
index d26df611fe..0285b264c1 100644
--- a/nodejs/packages/cx-wrapper/index.ts
+++ b/nodejs/packages/cx-wrapper/index.ts
@@ -10,25 +10,45 @@ import { load } from './loader.js';
 import { initializeInstrumentations } from './instrumentation-init.js';
 import { initializeProvider } from './provider-init.js';
 import { makeLambdaInstrumentation } from './lambda-instrumentation-init.js';
+import { parseBooleanEnvvar } from './common.js';
 
 const instrumentations = initializeInstrumentations();
-initializeProvider(instrumentations);
+const tracerProvider = initializeProvider(instrumentations);
 const lambdaInstrumentation = makeLambdaInstrumentation();
 
 if (process.env.CX_ORIGINAL_HANDLER === undefined)
   throw Error('CX_ORIGINAL_HANDLER is missing');
 
 // We want user code to get initialized during lambda init phase
-diag.debug(`Initialization: Loading original handler ${process.env.CX_ORIGINAL_HANDLER}`);
 try {
   (async () => {
+    diag.debug(`Initialization: Loading original handler ${process.env.CX_ORIGINAL_HANDLER}`);
     await load(
       process.env.LAMBDA_TASK_ROOT,
       process.env.CX_ORIGINAL_HANDLER
     );
+    diag.debug(`Initialization: Original handler loaded`);
   })();
 } catch (e) {}
 
+if (parseBooleanEnvvar("OTEL_WARM_UP_EXPORTER") ?? true) {
+  // We want exporter code to get initialized during lambda init phase
+  try {
+    (async () => {
+      try {
+        diag.debug(`Initialization: warming up exporter`);
+        const warmupSpan = tracerProvider.getTracer('cx-wrapper').startSpan('warmup');
+        warmupSpan.setAttribute('cx.internal.span.role', 'warmup');
+        warmupSpan.end();
+        await tracerProvider.forceFlush();
+        diag.debug(`Initialization: exporter warmed up`);
+      } catch (e) {
+        diag.error(`Initialization: exporter warmup failed: ${e}`);
+      }
+    })();
+  } catch (e) {}
+}
+
 export const handler = (event: any, context: Context, callback: Callback) => {
   diag.debug(`Loading original handler ${process.env.CX_ORIGINAL_HANDLER}`);
   load(
diff --git a/nodejs/packages/cx-wrapper/provider-init.ts b/nodejs/packages/cx-wrapper/provider-init.ts
index dd01344b7d..17f35bbeb4 100644
--- a/nodejs/packages/cx-wrapper/provider-init.ts
+++ b/nodejs/packages/cx-wrapper/provider-init.ts
@@ -22,7 +22,7 @@ declare global {
   
 const DEFAULT_OTEL_EXPORT_TIMEOUT = 2000; // this is a localhost call, and we don't want to block the function for too long
 
-export function initializeProvider(instrumentations: any[]): void {
+export function initializeProvider(instrumentations: any[]): NodeTracerProvider {
   diag.debug('Initializing OpenTelemetry providers');
 
   const export_timeout = parseIntEnvvar("OTEL_EXPORT_TIMEOUT") ?? DEFAULT_OTEL_EXPORT_TIMEOUT;
@@ -106,4 +106,6 @@ export function initializeProvider(instrumentations: any[]): void {
     tracerProvider,
     meterProvider
   });
-}
\ No newline at end of file
+
+  return tracerProvider
+}
diff --git a/nodejs/packages/layer/package-lock.json b/nodejs/packages/layer/package-lock.json
index 10dabc1626..9895f67d01 100644
--- a/nodejs/packages/layer/package-lock.json
+++ b/nodejs/packages/layer/package-lock.json
@@ -788,7 +788,7 @@
     "node_modules/cx-wrapper": {
       "version": "0.0.1",
       "resolved": "file:../cx-wrapper/cx-wrapper-0.0.1.tgz",
-      "integrity": "sha512-yq8alkohZzFLDOjgM/1FBlLwBQf4+M0+jM7yrVeabMnHrcFdeyyJNyj1wuAXxaYfLXwFwnaYN3HndvxvzD5FTA==",
+      "integrity": "sha512-dXU/aOLoYO7DM6bkdoIZ81c2cF/UJ+u/CeC1H2aE2WoayMTvkZp7apBHE3HrYrktF14MGkXxxJrskGCzH6oPoA==",
       "dependencies": {
         "@opentelemetry/api": "1.9.0",
         "@opentelemetry/auto-configuration-propagators": "0.3.0",