Trouble when Hummingbird 2.0.1 used with an Nginx proxy.

[dkyowell]

Discussed in #568

^{Originally posted by dkyowell September 28, 2024}
I have been converting some internal projects from Vapor to Hummingbird. I have run into an issue when using Hummingbird as the protected server behind an Nginx reverse proxy. My Hummingbird based server generates PDF content dynamically. It works perfectly when accessed directly by clients on the LAN. It works across the Nginx proxy when the PDF is very small. When the PDF is larger, I get the following error in my iOS client using URLSession. (It also fails to load from Postman when used with the proxy). The exact same client setup and Nginx reverse proxy worked fine when using Vapor.

Task <8A55EAB5-D2A9-4D3C-A478-F107C107C304>.<29> failed strict content length check - expected: 283409, received: 131629, received (uncompressed): 0

Any thoughts on what could be causing this?

[Joannis]

How do you create the ResponseBody containing the PDF? I think it's related to that

[dkyowell]

let body = ResponseBody.init(byteBuffer: .init(data: pdfData))
var headers = HTTPFields.init()
headers.append(.init(name: .contentType, value: MediaType.applicationPdf.description))
return .init(status: .ok, headers: headers, body: body)

[adam-fowler]

Hi @dkyowell sorry for the delayed reply. This is most likely due to the connection being closed immediately after the response write because the server received a connection: close header. There is a known issue in the swift-nio NIOAsyncChannel where it is not flushing writes before a close. Until this is fixed by swift-nio there isn't much we can do.