How to Use AWS Lambda@Edge to Enhance Your Web Applications

I want to explain AWS Lambda@Edge services. We’ll dive into Lambda@Edge features, use cases, and even walk through deploying your first Lambda@Edge function from the AWS console.

Lambda@Edge Intro

Lambda@Edge is a remarkable feature of Amazon CloudFront that empowers you to run code at CloudFront edge locations. But what are edge locations? Let’s explore it together.

By configuring CloudFront as a trigger for a Lambda function, that Lambda function will execute each time a request passes through CloudFront. Whether you upload your code directly to Lambda or use Lambda@Edge blueprints, Amazon CloudFront efficiently replicates your Lambda code to all its edge locations worldwide. Consequently, whenever a request is made through CloudFront, the Lambda function is executed, offering unparalleled speed and efficiency.

Edge Locations: AWS Infrastructure Essentials

To comprehend Lambda@Edge fully, we must understand the key components of AWS infrastructure: regions, availability zones, and edge locations. Regions (like US East, US West, Europe) are essentially AWS data centers with multiple availability zones. Availability zones represent unique data centers within a region. Now, the intriguing part is edge locations, represented by blue dots on the map. Edge locations are strategically distributed worldwide, ensuring data centers are as close to users as possible. Even in regions without an AWS presence, you’ll find these edge locations, enhancing global reach.

Lambda@Edge Events and Triggers

Lambda@Edge responds to CloudFront events, and there are four main types of events:

  1. Viewer Request: When an end-user sends a request to CloudFront, this event triggers.
  2. Origin Request: If the request results in a cache miss, CloudFront forwards the request to the origin server (e.g., S3). Lambda@Edge can be triggered here too.
  3. Origin Response: Once CloudFront receives a response from the origin server, Lambda@Edge can intervene before sending the response to the viewer.
  4. Viewer Response: When CloudFront sends the response to the end-user, Lambda@Edge can modify the response further.

Selecting the right event for your use case is crucial. Each event type serves a specific purpose, enabling you to tailor Lambda@Edge functions to your application’s needs.

Lambda@Edge Limitations

While Lambda@Edge offers impressive capabilities, it’s important to be aware of its limitations:

  1. Region Restriction: Lambda@Edge functions must reside in the US East region. Unfortunately, it’s not available in other regions.
  2. Memory and Timeout: Lambda@Edge functions are constrained to 128 MB of memory and a 5-second timeout for viewer request and response events. For origin request and response events, the timeout can extend up to 30 seconds.
  3. Environment Variables: Lambda@Edge functions do not support environment variables, limiting some configuration options.

Lambda@Edge Use Cases

Lambda@Edge is a versatile tool with various use cases, including:

  1. Website Security and Privacy: Lambda@Edge can enhance security by adding extra HTTP security headers to origin responses, bolstering your website’s security.
  2. Dynamic Web Applications: With Lambda@Edge sitting between your users and CloudFront, you can dynamically modify web pages based on headers or data retrieved from DynamoDB. This allows for personalized and efficient content delivery.
  3. Search Optimization: Tailor your web pages based on user agent headers. Serve different pages to real users and web crawlers, optimizing your website’s search engine ranking.

Deploy Your First Lambda@Edge from AWS Console

To conclude our journey, let’s walk through deploying your first Lambda@Edge function from the AWS Console:

  1. Navigate to the Lambda Console in the US East region.
  2. Search for a Lambda@Edge blueprint related to CloudFront (e.g., “CloudFront Modify Response Header”).
  3. Configure your Lambda function, create a role with the necessary permissions, and upload your code.
  4. Set CloudFront as the trigger and specify the CloudFront distribution and cache behavior.
  5. Choose the appropriate CloudFront event (e.g., origin request).
  6. Deploy your function, and monitor the status in the CloudFront console.

With these steps, you can harness the power of Lambda@Edge to optimize your web applications and content delivery.


In this video, we’ve demystified AWS Lambda@Edge, exploring its features, use cases, and deployment process. Armed with this knowledge, you’re now equipped to leverage Lambda@Edge to enhance your web applications and content delivery strategies.

Stay tuned for our next video, where we’ll implement content optimization using Lambda@Edge and CloudFront, providing practical insights into this powerful AWS service. Don’t forget to subscribe to our channel for more exciting content. Thanks for watching, and cheers to serverless innovation!

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