How to Use AWS to Link S3Bucket to Subdomain as CDN

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Setting up your S3 bucket as a Content Delivery Network (CDN) for assets.website.com with HTTPS might seem tricky at first, but with a few clear steps, you can get it working smoothly.

First, make sure your S3 bucket is configured correctly. Your bucket’s name should match your subdomain exactly, so it should be named “assets.website.com”. Enable static website hosting on this bucket and set the permissions to allow public read access. This ensures that anyone can view the assets stored there.

Next, you need to handle the Domain Name System (DNS) settings. Using your DNS provider’s management console (like Route 53), create an alias record that points “assets.website.com” directly to your S3 bucket. Double-check that the record name matches the bucket name perfectly to avoid any issues.

Since you want your assets to be accessible securely over HTTPS, you’ll need to use CloudFront, AWS’s CDN service. Do not delete or bypass CloudFront, as S3’s static website endpoints don’t support HTTPS natively. Instead, follow these steps:

1. Set up a CloudFront distribution with your S3 bucket as the origin.

2. Specify “assets.website.com” as the Alternate Domain Name (CNAME) in your CloudFront settings.

3. Attach an SSL/TLS certificate (from AWS Certificate Manager) to the CloudFront distribution to enable HTTPS.

4. Update your DNS record in Route 53 so that “assets.website.com” points to the CloudFront distribution, not directly to the S3 bucket.

You might run into some common issues if things aren’t set up properly. For example:

– If images aren’t loading, check that your S3 bucket’s CORS policy allows requests from “website.com”.

– Confirm that your application or website is referencing assets with the full URL, like “https://assets.website.com/image.jpg”.

– If you’re experiencing redirects or access errors, it could be due to DNS misconfiguration or a missing CloudFront setup.

Lastly, the security warning you may see is probably because you’re trying to access your S3 bucket directly over HTTPS without CloudFront—that’s not supported with static website endpoints. Using CloudFront with an SSL certificate handles the secure delivery correctly.

Following these steps will help you serve your assets over HTTPS reliably, with good performance and secure connections.