Daniele Cammarata

In today’s web development landscape, efficiently managing HTTP redirects is crucial for maintaining SEO rankings, enhancing user experience, and ensuring smooth transitions between different parts of your application. AWS Lambda@Edge provides a powerful way to implement HTTP redirects at the edge, improving performance and scalability by running your code closer to users.

What is Lambda@Edge?

Lambda@Edge allows you to run AWS Lambda functions at AWS Edge locations worldwide in response to Amazon CloudFront events. This capability makes it ideal for implementing logic that needs to execute quickly and near the user, such as generating HTTP redirects.

Why Use Lambda@Edge for Redirects?

Using Lambda@Edge for HTTP redirects offers several benefits:

Low Latency: By running your redirect logic at edge locations, you reduce the latency compared to handling redirects at the origin server.
Scalability: Automatically scales with the volume of requests.
Flexibility: Allows you to implement complex redirect logic based on request headers, cookies, query strings, or other request attributes.

Setting Up Lambda@Edge for HTTP Redirects

Here’s a step-by-step guide to setting up a Lambda@Edge function to handle HTTP redirects:

Step 1: Create the Lambda Function

First, create a new Lambda function in the AWS Management Console:

Navigate to the AWS Lambda console.
Click on Create function.
Choose Author from scratch.
Enter a name for your function (e.g., RedirectFunction).
Choose a runtime (Node.js is commonly used).
Click Create function.

Step 2: Write the Lambda Function Code

Edit the Lambda function code to handle the HTTP redirect. Below is an example in Node.js:

exports.handler = async (event) => {
    const request = event.Records[0].cf.request;
    const response = {
        status: '302',
        statusDescription: 'Found',
        headers: {
            'location': [{
                key: 'Location',
                value: 'https://www.newdomain.com' // The URL to redirect to
            }],
        },
    };
    return response;
};

This code snippet creates a 302 HTTP redirect to https://www.newdomain.com.

Step 3: Add a CloudFront Trigger

To trigger the Lambda function, associate it with a CloudFront distribution:

Go to the Amazon CloudFront console.
Select the distribution you want to associate with the Lambda function.
Choose the Behaviors tab and click Edit on the behavior you want to associate with the function.
Under Lambda Function Associations, choose CloudFront Event (e.g., Viewer Request).
Select your Lambda function and version.
Click Save Changes.

Step 4: Deploy the Lambda Function to Lambda@Edge

Deploy your Lambda function to Lambda@Edge:

Go back to the Lambda function in the AWS Lambda console.
Click on Actions and select Deploy to Lambda@Edge.
Choose the CloudFront distribution and the event you want to trigger the function.
Click Deploy.

Step 5: Test the Redirect

Once deployed, test the redirect by accessing the URL that triggers the CloudFront distribution. You should see the browser redirect to https://www.newdomain.com.

Conclusion

Using Lambda@Edge to generate HTTP redirects provides a powerful way to manage traffic at the edge, reducing latency and improving performance. By following the steps outlined above, you can implement flexible and scalable redirect logic that enhances your application’s user experience and SEO.

Lambda@Edge not only simplifies redirect management but also opens up possibilities for more advanced edge computing use cases. Explore further to see how Lambda@Edge can benefit your web infrastructure!

Using Lambda@Edge to Generate HTTP Redirects