Original Problem domain: Rails/Rack send_data method attempts downloading whole file onto the server in memory, to then send to the client. This would fail with large files because the server ran out of memory. Original Solution: Use Passenger NGINX to create a proxy_pass between the client and the S3 bucket in a secure way (the client never sees the actual S3 bucket URL - opted for thisby stuartweir - Nginx Mailing List - English