使用Webpack打包TypeScript代码后AWS Lambda出现Runtime.HandlerNotFound错误求助

I see exactly what's going on here—Webpack is wrapping your entire code in an IIFE (Immediately Invoked Function Expression) by default, which means your handler function isn't being exposed to Node.js's module system (i.e., it's not attached to module.exports). That's why Lambda can't find notifier.handler when you use the Webpack bundle, but it works fine with the raw TypeScript-compiled JS.

Let's fix this step by step:

1. Fix Your Webpack Configuration #

First, your current Webpack config has a couple of critical issues:

• You're pointing the entry to ./src/notifier.js instead of the TypeScript source file
• You haven't configured Webpack to output code compatible with Node.js's module system

Update your webpack.config.js to look like this:

const path = require('path');

module.exports = {
  target: 'node', // Critical: tells Webpack to target Node.js runtime
  entry: './src/notifier.ts', // Use the TypeScript file directly
  output: {
    filename: 'notifier.js',
    path: path.resolve(__dirname, 'dist'),
    libraryTarget: 'commonjs2', // Ensures exports are attached to module.exports
  },
  resolve: {
    extensions: ['.ts', '.js'], // Lets Webpack resolve TypeScript files automatically
  },
  module: {
    rules: [
      {
        test: /\.ts$/,
        use: 'ts-loader',
        exclude: /node_modules/,
      },
    ],
  },
};

2. Add ts-loader to Your Dependencies #

Since we're now having Webpack handle TypeScript compilation directly, you need to install ts-loader (no more manual tsc command required!):

npm install --save-dev ts-loader

Your updated package.json devDependencies should include this new entry:

"devDependencies": {
  "@types/aws-lambda": "^8.10.84",
  "@types/node": "^16.11.6",
  "webpack-cli": "^4.9.1",
  "ts-loader": "^9.2.6" // Add this line
}

3. Simplify Your Build Command #

You no longer need to run tsc separately—Webpack will handle TypeScript compilation and bundling in one single step:

npx webpack --config webpack.config.js
cd dist && zip notifier.zip notifier.js

4. Verify the Bundle Output #

After rebuilding, check your dist/notifier.js file—you should see something like this at the end of the bundle:

module.exports = __webpack_exports__;

This confirms that your handler function is now properly exposed via module.exports, which Lambda's runtime can detect.

Bonus: Optimize Bundle Size #

Since Lambda's environment already includes the AWS SDK, you can exclude it from your bundle to reduce its size. Install webpack-node-externals:

npm install --save-dev webpack-node-externals

Then update your Webpack config to add the externals rule:

const nodeExternals = require('webpack-node-externals');

module.exports = {
  // ... existing config
  externals: [nodeExternals()], // Excludes most node_modules from bundle (keeps Firebase)
};

This will keep Firebase and your custom code in the bundle but skip dependencies that Lambda already provides out of the box.

Why This Works #

• target: 'node' ensures Webpack doesn't use browser-specific features and preserves Node.js module behavior
• libraryTarget: 'commonjs2' tells Webpack to export your code using module.exports, which is exactly what Lambda expects for handler functions
• Using ts-loader lets Webpack handle TypeScript compilation, so you don't have to manage separate tsc and Webpack build steps

After making these changes, your Lambda should recognize the handler function without any issues.

内容的提问来源于stack exchange，提问作者eof