Sporadic invalid Http response (missing headers) #3395
Description
When serving a simple static file server, occasionally the zio-http server sends invalid HTTP responses that lack all headers.
I've used the command tcpflow -i any -C -g port 8090 to monitor the TCP traffic. Downloading multiple files (regardless of whether sequentially or in parallel), eventually I see the following for a random file:
Request:
GET /files/example.txt HTTP/1.1
User-Agent: my-user-agent
Accept: */*
Host: localhost:8090
Connection: keep-alive
Expected response:
HTTP/1.1 200 Ok
content-type: text/plain; charset=utf-8
date: Wed, 12 Mar 2025 19:19:38 GMT
content-length: 30
text-file-content-lorem-ipsum
Actual response:
text-file-content-lorem-ipsum
which is just the served text file as body. The response headers are missing.
Server code:
import zio.ZIO
import zio.http.*
final class FileServer private (val port: Int)
object FileServer {
def routes(staticDir: java.io.File): Routes[Any, Nothing] = Routes(
Method.GET / trailing -> Handler.fromFunctionHandler[(zio.http.Path, Request)] { case (path: zio.http.Path, _: Request) =>
Handler.fromFileZIO(ZIO.attempt { new java.io.File(staticDir, path.encode) })
.orElse(Handler.notFound).contramap(_._2)
},
).sandbox
def serve(staticDir: java.io.File, port: Int): zio.ZLayer[Any, Nothing, FileServer] =
zio.ZLayer.scoped {
for {
fiber <- Server.install(routes(staticDir))
.zipRight(ZIO.never)
.provideSome(Server.defaultWithPort(port))
.forkScoped
} yield FileServer(port = port)
}
}(I could not find a minimal implementation of a HTTP client that consistently exposes the problem, but the problem seems to be with the server anyway.)
Tested with Scala 3.6.3 & 3.4.2, zio 2.1.16, zio-http 3.0.1, izumi-reflect 3.0.1