aws · fabisev · Jul 15, 2025 · Jul 16, 2025 · Jul 16, 2025
diff --git a/.github/workflows/test-on-push-and-pr.yml b/.github/workflows/test-on-push-and-pr.yml
@@ -21,14 +21,4 @@ jobs:
         docker build -f test/unit/Dockerfile.nodejs${{ matrix.node-version }}.x -t unit/nodejs.${{ matrix.node-version }}x .
         docker run unit/nodejs.${{ matrix.node-version }}x
 
-  integration-test:
-    runs-on: ubuntu-latest
-    strategy:
-      fail-fast: false
-      matrix:
-        distro: [alpine, amazonlinux, centos, debian, ubuntu]
 
-    steps:
-    - uses: actions/checkout@v4
-    - name: Run ${{ matrix.distro }} integration tests
-      run: DISTRO=${{ matrix.distro }} make test-integ
diff --git a/Makefile b/Makefile
@@ -8,15 +8,6 @@ init:
 test:
 	npm run test
 
-setup-codebuild-agent:
-	docker build -t codebuild-agent - < test/integration/codebuild-local/Dockerfile.agent
-
-test-smoke: setup-codebuild-agent
-	CODEBUILD_IMAGE_TAG=codebuild-agent test/integration/codebuild-local/test_one.sh test/integration/codebuild/buildspec.os.alpine.1.yml alpine 3.16 18
-
-test-integ: setup-codebuild-agent
-	CODEBUILD_IMAGE_TAG=codebuild-agent DISTRO="$(DISTRO)" test/integration/codebuild-local/test_all.sh test/integration/codebuild
-
 copy-files:
 	npm run copy-files
 
@@ -30,7 +21,7 @@ format:
 dev: init test
 
 # Verifications to run before sending a pull request
-pr: build dev test-smoke
+pr: build dev
 
 clean:
 	npm run clean
@@ -42,7 +33,7 @@ build: copy-files
 pack: build
 	npm pack
 
-.PHONY: target init test setup-codebuild-agent test-smoke test-integ install format dev pr clean build pack copy-files
+.PHONY: target init test install format dev pr clean build pack copy-files
 
 define HELP_MESSAGE
 

diff --git a/README.md b/README.md
@@ -162,8 +162,6 @@ make init build
 ```
 Then,
 * to run unit tests: `make test`
-* to run integration tests: `make test-integ`
-* to run smoke tests: `make test-smoke`
 
 ### Raising a PR
 When modifying dependencies (`package.json`), make sure to:

diff --git a/package-lock.json b/package-lock.json
diff --git a/src/Errors.js b/src/Errors.js
@@ -38,9 +38,9 @@ function toRapidResponse(error) {
   try {
     if (util.types.isNativeError(error) || _isError(error)) {
       return {
-        errorType: error.name?.replace(/\x7F/g, '%7F'),
-        errorMessage: error.message?.replace(/\x7F/g, '%7F'),
-        trace: error.stack.replace(/\x7F/g, '%7F').split('\n'),
+        errorType: error.name?.replaceAll('\x7F', '%7F'),
+        errorMessage: error.message?.replaceAll('\x7F', '%7F'),
+        trace: error.stack.replaceAll('\x7F', '%7F').split('\n'),
       };
     } else {
       return {
@@ -106,6 +106,13 @@ const errorClasses = [
   class UserCodeSyntaxError extends Error {},
   class MalformedStreamingHandler extends Error {},
   class InvalidStreamingOperation extends Error {},
+  class NodeJsExit extends Error {
+    constructor() {
+      super(
+        'The Lambda runtime client detected an unexpected Node.js exit code. This is most commonly caused by a Promise that was never settled. For more information, see https://nodejs.org/docs/latest/api/process.html#exit-codes',
+      );
+    }
+  },
   class UnhandledPromiseRejection extends Error {
     constructor(reason, promise) {
       super(reason);

diff --git a/src/Runtime.js b/src/Runtime.js
@@ -12,7 +12,9 @@ const CallbackContext = require('./CallbackContext.js');
 const StreamingContext = require('./StreamingContext.js');
 const BeforeExitListener = require('./BeforeExitListener.js');
 const { STREAM_RESPONSE } = require('./UserFunction.js');
+const { NodeJsExit } = require('./Errors.js');
 const { verbose, vverbose } = require('./VerboseLog.js').logger('RAPID');
+const { structuredConsole } = require('./LogPatch');
 
 module.exports = class Runtime {
   constructor(client, handler, handlerMetadata, errorCallbacks) {
@@ -69,7 +71,7 @@ module.exports = class Runtime {
 
     try {
       this._setErrorCallbacks(invokeContext.invokeId);
-      this._setDefaultExitListener(invokeContext.invokeId, markCompleted);
+      this._setDefaultExitListener(invokeContext.invokeId, markCompleted, this.handlerMetadata.isAsync);
 
       let result = this.handler(
         JSON.parse(bodyJson),
@@ -178,12 +180,22 @@ module.exports = class Runtime {
    * called and the handler is not async.
    * CallbackContext replaces the listener if a callback is invoked.
    */
-  _setDefaultExitListener(invokeId, markCompleted) {
+  _setDefaultExitListener(invokeId, markCompleted, isAsync) {
     BeforeExitListener.set(() => {
       markCompleted();
-      this.client.postInvocationResponse(null, invokeId, () =>
-        this.scheduleIteration(),
-      );
+      // if the handle signature is async, we do want to fail the invocation
+      if (isAsync) {
+        const nodeJsExitError = new NodeJsExit();
+        structuredConsole.logError('Invoke Error', nodeJsExitError);
+        this.client.postInvocationError(nodeJsExitError, invokeId, () =>
+          this.scheduleIteration(),
+        );
+        // if the handler signature is sync, or use callback, we do want to send a successful invocation with a null payload if the customer forgot to call the callback
+      } else {
+        this.client.postInvocationResponse(null, invokeId, () =>
+          this.scheduleIteration(),
+        );
+      }
     });
   }
 

diff --git a/src/UserFunction.js b/src/UserFunction.js
@@ -311,10 +311,25 @@ module.exports.isHandlerFunction = function (value) {
   return typeof value === 'function';
 };
 
+function _isAsync(handler) {
+  try {
+    return (
+      handler &&
+      typeof handler === 'function' &&
+      handler.constructor &&
+      handler.constructor.name === 'AsyncFunction'
+    );
+  } catch (error) {
+    return false;
+  }
+}
+
 module.exports.getHandlerMetadata = function (handlerFunc) {
   return {
     streaming: _isHandlerStreaming(handlerFunc),
     highWaterMark: _highWaterMark(handlerFunc),
+    isAsync: _isAsync(handlerFunc),
+    argsNum: handlerFunc.length,
   };
 };
 

diff --git a/src/WarningForCallbackHandlers.js b/src/WarningForCallbackHandlers.js
@@ -0,0 +1,24 @@
+/*
+Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+SPDX-License-Identifier: Apache-2.0
+*/
+
+'use strict';
+
+const shouldWarnOnCallbackFunctionUse = (metadata) => {
+  return (
+    process.env.AWS_LAMBDA_NODEJS_DISABLE_CALLBACK_WARNING === undefined &&
+    metadata !== undefined &&
+    metadata.argsNum == 3 &&
+    metadata.isAsync == false &&
+    metadata.streaming == false
+  );
+};
+
+module.exports.checkForDeprecatedCallback = function (metadata) {
+  if (shouldWarnOnCallbackFunctionUse(metadata)) {
+    console.warn(
+      `AWS Lambda plans to remove support for callback-based function handlers starting with Node.js 24. You will need to update this function to use an async handler to use Node.js 24 or later. For more information and to provide feedback on this change, see https://github.com/aws/aws-lambda-nodejs-runtime-interface-client/issues/137. To disable this warning, set the AWS_LAMBDA_NODEJS_DISABLE_CALLBACK_WARNING environment variable.`,
+    );
+  }
+};
diff --git a/src/index.mjs b/src/index.mjs
@@ -11,6 +11,7 @@ const UserFunction = require('./UserFunction.js');
 const Errors = require('./Errors.js');
 const BeforeExitListener = require('./BeforeExitListener.js');
 const LogPatch = require('./LogPatch');
+const { checkForDeprecatedCallback } = require('./WarningForCallbackHandlers');
 
 export async function run(appRootOrHandler, handler = '') {
   LogPatch.patchConsole();
@@ -44,6 +45,7 @@ export async function run(appRootOrHandler, handler = '') {
     : await UserFunction.load(appRootOrHandler, handler);
 
   const metadata = UserFunction.getHandlerMetadata(handlerFunc);
+  checkForDeprecatedCallback(metadata);
   new Runtime(
     client,
     handlerFunc,

diff --git a/test/handlers/isAsync.mjs b/test/handlers/isAsync.mjs
@@ -0,0 +1,17 @@
+/** Copyright 2025 Amazon.com, Inc. or its affiliates. All Rights Reserved. */
+
+export const handlerAsync = async () => {
+  const response = {
+    statusCode: 200,
+    body: JSON.stringify('Hello from Lambda!'),
+  };
+  return response;
+};
+
+export const handlerNotAsync = () => {
+  const response = {
+    statusCode: 200,
+    body: JSON.stringify('Hello from Lambda!'),
+  };
+  return response;
+};
diff --git a/test/handlers/isAsyncCallback.js b/test/handlers/isAsyncCallback.js
@@ -0,0 +1,12 @@
+/** Copyright 2025 Amazon.com, Inc. or its affiliates. All Rights Reserved. */
+
+'use strict';
+
+exports.handler = (_event, _context, callback) => {
+  callback(null, {
+    statusCode: 200,
+    body: JSON.stringify({
+      message: 'hello world',
+    }),
+  });
+};
diff --git a/test/integration/codebuild-local/Dockerfile.agent b/test/integration/codebuild-local/Dockerfile.agent