AWS Lambda is a powerful serverless computing service that allows developers to execute code without the need to provision or manage servers. While its simplicity is appealing, Lambda functions often require external libraries or dependencies, especially when handling complex tasks. This is where Lambda layers come into play, streamlining the inclusion of such dependencies. In this blog post, using a practical example, we’ll explore the significance of Lambda layers, their advantages, and how to integrate them into a Node.js Lambda function.

Introduction to AWS Lambda and the Need for External Libraries

AWS Lambda empowers developers to run code in response to events, enabling them to build scalable and responsive applications. However, real-world applications often rely on external libraries for:

  • Simplifying Code: Leveraging prebuilt modules instead of reinventing the wheel.
  • Enhancing Functionality: Adding features like logging, authentication, or unique identifier generation.
  • Standardizing Development: Using consistent libraries across functions for uniformity.

Traditionally, including these libraries meant bundling them into the deployment package, which could increase its size and complicate updates. This is where Lambda layers prove invaluable.

Understanding Deployment Packages vs. Layers in AWS Lambda

Deployment Packages

  • Contain your function code and all dependencies.
  • They are uploaded as a zip file when deploying the Lambda function.
  • Require re-uploading the entire package for every update, including library changes.

Lambda Layers

  • Allow you to separate common dependencies into reusable components.
  • Are independent of the function’s deployment package.
  • Enable multiple Lambda functions to share the same set of libraries, reducing redundancy and effort.

Advantages of Utilizing Layers in AWS Lambda

  1. Modular Architecture: Separate logic (function code) from dependencies.
  2. Reduced Deployment Time: Update the layer without re-uploading the function code.
  3. Reusability: Share layers across multiple Lambda functions in the same or different accounts.
  4. Smaller Function Size: Keep deployment packages lightweight by excluding external libraries.
  5. Efficient Updates: Modify or upgrade libraries independently.

Step-by-Step Guide to Adding a Layer to a Node.js Lambda Function

Follow these steps to add a layer to your Node.js Lambda function:

Step 1: Prepare the Layer Content

  1. Create a new directory to store the layer’s dependencies:
    mkdir nodejs

cd nodejs

  1. Install the desired library. For example, install the uuid library:

npm install uuid

  1. Ensure the directory structure is correct:
    nodejs/

    node_modules/

        uuid/

Step 2: Package the Layer

  1. Navigate to the directory containing nodejs and create a zip file:
    zip -r layer.zip nodejs

Step 3: Create the Layer in AWS Console

  1. Open the AWS Lambda Console.
  2. Go to the Layers section and click Create layer.
  3. Upload the layer.zip file.
  4. Specify the runtime (e.g., Node.js 14.x, 16.x, etc.).
  5. Click Create.

Step 4: Attach the Layer to Your Lambda Function

  1. Navigate to your Lambda function in the AWS Console.
  2. Under the Function Overview section, click Add a layer.
  3. Select Custom layers, choose your created layer, and click Add.

Step 5: Update Your Function Code

  1. Ensure your function references the external library:

const { v4: uuidv4 } = require(‘uuid’);

exports.handler = async (event) => {

  const id = uuidv4();

  return {

    statusCode: 200,

    body: JSON.stringify({ id }),

  };

};

Step 6: Test the Function

  • Trigger the function and confirm that it generates a unique identifier using the uuid library.

Practical Example: Integrating the UUID Library Using AWS Lambda Layers

Imagine building a service that assigns unique IDs to incoming requests. You’ve integrated the uuid library using the steps above via a Lambda layer. Here’s what you’ve achieved:

  • A modular and reusable design.
  • Simplified updates—future versions of uuid can be applied by updating the layer alone.
  • Optimized Lambda function, reducing deployment package size and complexity.

Conclusion

AWS Lambda layers are a game-changer for managing dependencies in serverless environments. Offloading shared libraries into layers reduces duplication, improves maintainability, and simplifies updates. This guide demonstrated how to leverage Lambda layers in a Node.js function, showcasing their ease of use and efficiency.

References

Working with layers for Node.js Lambda functions

Using Lambda layers to simplify your development process