CloudFront with S3 website as origin is not serving gzipped files

Question

AWS now supports gzipping files through CloudFront

I\'ve followed along with all of the instructions in Serving Compressed Files, and yet gzipping is not working.

Answer 1

My problem was that I uploaded the files specifically with utf-8 encoding. From the documentation:

CloudFront determines whether the file is compressible:

The file must be of a type that CloudFront compresses.

The file size must be between 1,000 and 10,000,000 bytes.

The response must include a Content-Length header so CloudFront can determine whether the size of the file is in the range that CloudFront compresses. If the Content-Length header is missing, CloudFront won't compress the file.

The response must not include a Content-Encoding header.

Answer 2

I hit the same error today and solved it by adding a CORS rule to the S3 bucket. This rule ensures the Content-Length header is sent to Cloudfront so content can be gzipped:

S3 > Bucket > Permissions > CORS Configuration

<?xml version="1.0" encoding="UTF-8"?>
<CORSConfiguration xmlns="http://s3.amazonaws.com/doc/2006-03-01/">
    <CORSRule>
        <AllowedOrigin>*</AllowedOrigin>
        <AllowedMethod>GET</AllowedMethod>
        <MaxAgeSeconds>3000</MaxAgeSeconds>
        <AllowedHeader>Authorization</AllowedHeader>
        <AllowedHeader>Content-Length</AllowedHeader>
    </CORSRule>
</CORSConfiguration>

Credit goes to Robert Ellison: http://ithoughthecamewithyou.com/post/enable-gzip-compression-for-amazon-s3-hosted-website-in-cloudfront

As far I know, this seems to be an undocumented requirement.