Using Rollup.js for serverless JavaScript applications on platforms like AWS Lambda

18 Sep 2023

In recent years, serverless architecture has gained popularity due to its scalability, cost-effectiveness, and ease of deployment. AWS Lambda, one of the leading serverless platforms, allows developers to run code without provisioning or managing servers. To build efficient and optimized JavaScript applications for AWS Lambda, we can leverage Rollup.js, a popular module bundler.

What is Rollup.js?

Rollup.js is a module bundler for JavaScript applications. It takes your code and its dependencies and bundles them into a single file, optimizing size and performance. Rollup’s tree-shaking feature eliminates unused code, resulting in leaner bundles.

While other bundlers like Webpack are commonly used for front-end development, Rollup is well-suited for serverless applications as it generates smaller bundles, reduces load times, and enhances application performance.

Setting Up Rollup.js for AWS Lambda

To get started with Rollup.js and AWS Lambda, follow these steps:

Create a new project: Start by creating a new directory for your project and navigate to it in your terminal.
Initialize the project: Run npm init to initialize a new Node.js project. Follow the prompts and provide a name, version, and other necessary details.
Install Rollup and necessary plugins: Install Rollup.js and related plugins using the following command:
```
npm install rollup rollup-plugin-commonjs rollup-plugin-node-resolve rollup-plugin-babel @babel/preset-env --save-dev
```
This installs Rollup.js, the CommonJS plugin for handling node_modules, the Node.js resolution plugin, the Babel plugin for transpiling code, and the preset-env package to configure Babel.

Create a Rollup configuration file: Create a rollup.config.js file in the root directory of your project. Configure the necessary plugins and settings within this file. Here’s an example configuration:

import commonjs from 'rollup-plugin-commonjs';
import resolve from 'rollup-plugin-node-resolve';
import babel from 'rollup-plugin-babel';
   
export default {
  input: 'src/index.js',
  output: {
    file: 'dist/bundle.js',
    format: 'cjs',
  },
  plugins: [
    resolve(),
    commonjs(),
    babel({ 
      presets: ['@babel/preset-env']
    }),
  ],
};

In this configuration, we specify the input file (src/index.js), the output file (dist/bundle.js), the module format (cjs for CommonJS), and the necessary plugins.

Create your application files: Inside the src directory, write your application code, including any dependencies you need.
Build the application: To build your application bundle, run the following command:
```
npx rollup --config
```
This will execute Rollup.js using the configuration file we defined earlier.
Deploy to AWS Lambda: Deploy the generated dist/bundle.js file to AWS Lambda along with any other necessary resources such as environment variables or permissions.

Conclusion

Rollup.js is an excellent choice for building serverless JavaScript applications, particularly when targeting platforms like AWS Lambda. Its ability to generate optimized and minimal bundles provides better load times and performance. By following the steps outlined above, you can easily set up Rollup.js for your serverless projects and take advantage of its benefits in your development workflow.

#serverless #AWSLambda