What is Gluegun?

Gluegun is a Gleam wrapper around the Erlang Gun HTTP client.

Gun is an asynchronous HTTP client that supports HTTP/1.1, HTTP/2, and WebSocket over HTTP/1.1. Gluegun gives Gleam callers typed connection, request, response, message, and WebSocket helpers while preserving access to Gun's stream-oriented model.

Because Gun is Erlang-only, Gluegun targets the Erlang runtime.

What Gluegun provides

• Typed connection options for transport, protocol preference, and timeouts.
• Low-level request helpers for headers, chunked bodies, cancellation, flow control, and flushing.
• Message decoders for asynchronous Gun stream messages.
• High-level HTTP helpers that send one request on an existing connection and collect the full response (status, headers, body, trailers, and any 1xx informational responses).
• WebSocket helpers for connecting, sending, receiving, and closing.
• Result-based error values instead of exceptions.

What Gluegun does not do

Gluegun does not parse URLs. Open a connection with connection.options() |> connection.open(host: "example.com", port: 443), wait for protocol negotiation with connection.await_up, then pass request paths such as /, /api/items, or /ws to HTTP or WebSocket helpers.

Gluegun also does not hide Gun's streaming model. The high-level client helpers are convenient for regular responses, but streaming bodies, HTTP/2 push, upgrades, WebSocket messages, cancellation, and flow-control updates belong in gluegun/request and gluegun/message.

Module map

Gluegun is organized into focused submodules. Import the ones you need:

Module	Purpose
gluegun/connection	Open, configure, await, close, and shut down Gun connections.
gluegun/request	Low-level HTTP stream API: headers, chunked bodies, cancel, flow control.
gluegun/message	Decode and await asynchronous Gun stream messages.
gluegun/client	One-shot HTTP helpers that collect a full response in memory.
gluegun/response	Inspect collected Response values (status, headers, body, trailers, informational).
gluegun/websocket	WebSocket upgrade, reusable Socket, scoped with_socket, and low-level frame helpers.
gluegun/tls	Typed TLS client options for verification, versions, CAs, SNI, and mTLS.
gluegun/error	The GluegunError type returned by effectful APIs.
gluegun/fin	Fin / NoFin flags for the last chunk in a streamed body.
gluegun	Minimal facade re-exporting the most common helpers.

For complete module, type, and function details, use the API reference.