How to disable automatic chunked transfer-encoding for responses

Hi :wave:

Have Phoenix application with Cowboy webserver and an endpoint that returns couple of base64 encoded files. Need to implement progress bar for GET request to this endpoint. As soon as body size grows I have an automatic change in response headers and Transfer-Encoding: chunked is set. This makes it impossible to track progress. I want to disable chunked transfer-encoding and have Content-Length header back.

Would appreciate any help on how I can configure (Cowboy as I understand) Content-Length header to be set automatically.