CloudFront will miss cache if request is from CURL

This behavior you're experiencing with CloudFront cache hits from browsers but misses from cURL requests is likely due to differences in how browsers and cURL handle requests and caching.

1. Headers: Browsers typically send a consistent set of headers with each request, while cURL may not include the same headers by default. CloudFront's cache key (which determines whether a request is a hit or miss) may include certain headers that browsers send but cURL doesn't.

2. Compression: Browsers usually indicate support for compressed content (e.g., gzip) in their requests. If CloudFront is configured to serve compressed content, it may cache different versions for compressed and uncompressed requests. cURL doesn't request compressed content by default, potentially leading to cache misses.

3. User-Agent: The User-Agent header differs between browsers and cURL. If this header is part of the cache key, it could cause different cache behaviors.

4. Cookies: Browsers often send cookies with requests, while cURL doesn't by default. If the CloudFront distribution is configured to forward certain cookies, this could affect caching behavior.

5. Query strings: Browsers might include query parameters that cURL requests don't, or vice versa, potentially affecting the cache key.

To resolve this issue, you could:

1. Examine and align the headers sent by cURL with those sent by browsers.
2. Check your CloudFront configuration, particularly the cache key settings, to ensure it's not relying on elements that differ between browser and cURL requests.
3. Use CloudFront's logging features to compare the exact requests coming from browsers versus cURL, which can help identify the differences causing the caching discrepancy.

Remember, CloudFront's caching behavior is designed to optimize content delivery for typical web browsing scenarios, which may not always align with command-line tool behaviors like cURL.
Sources
Cloudfront issue | AWS re:Post
Cloudfront caching issue | AWS re:Post
cloudfront . browser caching | AWS re:Post