S3 CDN URL not being used on non-image uploads

Maybe related to S3 CDN URL ignored when uploading into posts.

At first I thought I had missed some configuration, but it’s reproducible here on meta:
https://meta.discourse.org/uploads/short-url/dw1U4hctATusBlHsUmWQXeme66j.csv (uploaded here) is a 302 redirect to

Shouldn’t it redirect to https://d11a6trkgmumsb.cloudfront.net/original/3X/5/e/5ebb2cfb8cc907e8e8f7c6559a72d2f4a8ba2f8f.csv instead?


Hmmm there may possibly be an issue here @martin can you investigate? We should probably redirect to the CDN if possible.


This is a little bit tricky, I had a look at this just now. Basically we are always downloading from S3 with a presigned URL if we are doing a “force download”, which is what happens when we are clicking on the attachment link or clicking on the Download button on an image. This is so the appropriate content-disposition headers can be added:

attachment; filename="#{upload.original_filename}"; filename*=UTF-8''#{upload.original_filename}

I do not think it is possible to make the CDN URL behave in this way? The CDN URL for images is only used when displaying them inline, not when downloading them. Also in the case of secure images and attachments which have a private ACL the presigned URL must always be used.