We have a multisite set up on a load balanced EC2 and have our images pulling from an S3 bucket. Image URLs are correctly being rewritten to point to the correct S3 bucket except in cases where we are using Tim Thumb. For Tim Thumb, we are using wp_get_attachment_image() to get the image URL which is returning the URL from the WordPress install and not the S3 bucket.
Is there a way for to get the S3 URL and pass that to Tim Thumb?
We've thought about using Regex, but we'd have to set up a check for each Blog ID since each site has it's own S3 bucket.