Serverless-plugin-include-dependencies Not Working With Esm Modules

MIster jashon

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·

Oct 03, 2024

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Why "serverless-plugin-include-dependencies" Doesn't Work with ESM Modules?

The serverless-plugin-include-dependencies plugin is a popular choice for Serverless Framework users who need to bundle dependencies for their Lambda functions. However, with the rise of ECMAScript Modules (ESM), you might encounter a common issue: the plugin fails to include dependencies when your project is set up for ESM.

Understanding the Problem

The root cause of this issue lies in the fundamental difference between CommonJS (CJS) modules, which are traditionally used in Node.js, and ESM.

• CJS: CJS uses require to import modules, and the module.exports object to export them. This approach creates a global scope for modules, making dependency management relatively straightforward.
• ESM: ESM utilizes import and export keywords, offering features like tree-shaking and static analysis for optimized code. However, this new standard introduces challenges for traditional bundling tools, including serverless-plugin-include-dependencies.

Why Plugin Doesn't Work with ESM

The plugin primarily relies on a process called "bundling" that combines all your project's code and dependencies into a single file. This process often assumes a CJS environment where modules are imported and exported using require and module.exports. When you switch to ESM, the plugin's bundling mechanism struggles to identify and incorporate your ESM dependencies, leading to an incomplete bundle and runtime errors.

Troubleshooting and Solutions

Here's how you can tackle this challenge:

1. Switch to a Suitable ESM Bundler: Instead of relying solely on the serverless-plugin-include-dependencies, consider using a dedicated ESM bundler like Webpack or Rollup. These tools are specifically designed to handle ESM modules and can be integrated into your Serverless Framework workflow.

2. Use Serverless-Webpack: The serverless-webpack plugin offers a seamless integration of Webpack within your Serverless project, providing a comprehensive bundling solution for both CJS and ESM projects.

3. Configure Webpack for ESM: If you choose to use Webpack, make sure you configure it properly to handle ESM. This might involve:

   • Setting the target option to "es2015" or "es2020" to ensure compatibility with the Node.js runtime.
   • Specifying the correct "module" type in your Webpack configuration.

4. Experiment with other ESM-compatible Bundling Options: Consider exploring alternatives like serverless-bundle or serverless-plugin-optimize-bundling.

Example: Using Serverless-Webpack

// serverless.yml
plugins:
  - serverless-webpack
  - serverless-plugin-include-dependencies

custom:
  webpack:
    webpackConfig: ./webpack.config.js

# ... (your serverless functions configuration)

// webpack.config.js
const path = require('path');

module.exports = {
  entry: {
    // Your function names
    'myFunction': './src/myFunction.js',
  },
  output: {
    libraryTarget: 'commonjs2', // Important for Serverless compatibility
    path: path.join(__dirname, '.webpack'),
    filename: '[name].js',
  },
  mode: 'production', // Set to 'development' for debugging
  module: {
    rules: [
      {
        test: /\.js$/,
        exclude: /node_modules/,
        use: {
          loader: 'babel-loader',
          options: {
            presets: ['@babel/preset-env'],
          },
        },
      },
    ],
  },
};

Conclusion

While the serverless-plugin-include-dependencies plugin might not work seamlessly with ESM modules, you have various solutions at your disposal. Employing a dedicated ESM bundler like Webpack provides a robust approach for managing dependencies in your Serverless projects. By making the appropriate changes to your project configuration and utilizing the right tools, you can efficiently handle ESM and achieve a smooth development experience for your Serverless functions.