wisp_roadrunner

Run Wisp apps on Roadrunner, the pure-Erlang HTTP/1.1, HTTP/2, HTTP/3 and WebSocket server, through roadrunner_gleam.

Requirements

Requires OTP 27+ and Gleam 1.19+, with rebar3 installed to build Roadrunner.

🚧 Status

wisp_roadrunner is in 0.x. The core is functional and covered by tests, but the API may change between minor versions. Pin an exact version in your deps if you need stability across upgrades.

Installation

gleam add wisp_roadrunner roadrunner_gleam

Usage

Swap wisp_mist for wisp_roadrunner and start a roadrunner_gleam listener; the Wisp app stays the same.

import gleam/erlang/process
import roadrunner_gleam
import wisp
import wisp_roadrunner

pub fn main() {
  let secret_key_base = wisp.random_string(64)
  let assert Ok(_) =
    wisp_roadrunner.handler(handle_request, secret_key_base)
    |> roadrunner_gleam.new
    |> roadrunner_gleam.read_body_on_demand
    |> roadrunner_gleam.port(8000)
    |> roadrunner_gleam.start
  process.sleep_forever()
}

fn handle_request(_request: wisp.Request) -> wisp.Response {
  wisp.ok() |> wisp.string_body("hello, roadrunner!")
}

read_body_on_demand lets Wisp read request bodies in pieces, as it asks for them, so its body size limits hold before a large upload is read. TLS, HTTP/2, HTTP/3 and the other listener options come from roadrunner_gleam.

WebSockets and server-sent events

Wisp has no API for these, but roadrunner_gleam does. Route their paths to its websocket and push modules and hand the rest to Wisp:

let wisp_handler = wisp_roadrunner.handler(handle_request, secret_key_base)

fn(request) {
  case request.path_segments(request) {
    ["ws"] -> websocket.new(on_init:, handler:) |> websocket.upgrade
    _ -> wisp_handler(request)
  }
}
|> roadrunner_gleam.new

Features

• Wisp handlers on HTTP/1.1, HTTP/2 and HTTP/3
• Request bodies read in pieces of Wisp's read_chunk_size, with its max_body_size and max_files_size limits
• Forms, multipart uploads, and Wisp's temporary files deleted after each request
• Text, bytes and file responses, file ranges included, sent by the kernel
• Signed and encrypted cookies, and serve_static
• WebSockets and server-sent events next to a Wisp app, on the same listener

Sponsors

wisp_roadrunner is open source and maintained on personal time. If you or your company find it useful, consider sponsoring.

I also accept coffees ☕

License

Copyright (c) 2026 William Fank Thomé

wisp_roadrunner is open-source under the Apache 2.0 License on GitHub.

See LICENSE.md for more information.