Tapir with Akka HTTP file upload - Sending an 2xx 'early' response before end of request was received

Question

I use tapir + akka http for the service. One of the endpoints downloads files.

val load
      : Endpoint[Source[ByteString, Any], Any, Any, AkkaStreams] =
    endpoint
      .post
      .in("load")
      .in(streamBody(AkkaStreams)(
        Schema(Schema.schemaForByteArray.schemaType),
        CodecFormat.OctetStream()
      ))
      .out(???)

Gettin warn

Sending an 2xx 'early' response before end of request was received

How do I handle this using tapir?

Answer 1

This is this issue with akka-http: https://github.com/akka/akka-http/issues/2455

Do you use Source of chunks in your code? Akka-http consumes messages, when LastChunk is consumed, it sends response, not even consuming MessageEnd which comes after LastChunk.

MessageEnd is not consumed, messageEndPending is set to true hence the warning about early response.

I worked around it by filtering the LastChunk and concatenating it to the end of the stream - after MessageEnd and thus forcing akka-http to consume MessageEnd.