Attribute Macro http_component

#[http_component]

Exports the procedural macros for writing handlers for Spin components. The entrypoint to a WASI HTTP component written in Rust.

Functions annotated with this attribute can be of two forms:

• Request/Response
• Input/Output Params

When in doubt prefer the Request/Response variant unless streaming response bodies is something you need.

Request/Response

This form takes the form of a function with one request param and one response return value.

Requests are anything that implements spin_sdk::http::conversions::TryFromIncomingRequest which includes spin_sdk::http::Request, spin_sdk::http::IncomingRequest, and even hyperium’s popular http crate’s Request type.

Responses are anything that implements spin_sdk::http::IntoResponse. This includes Result<impl IntoResponse, impl IntoResponse, spin_sdk::http::Response, and even the http crate’s Response type.

For example:

use spin_sdk::http_component;
use spin_sdk::http::{Request, IntoResponse};

#[http_component]
async fn my_handler(request: Request) -> anyhow::Result<impl IntoResponse> {
  // Your logic goes here
}

Input/Output Params

Input/Output functions allow for streaming HTTP bodies. This form is by its very nature harder to use than the request/response form above so it should only be favored when stream response bodies is desired.

The request param can be anything that implements spin_sdk::http::TryFromIncomingRequest. And the response_out param must be a spin_sdk::http::ResponseOutparam. See the docs of ResponseOutparam for how to use this type.

For example:

use spin_sdk::http_component;
use spin_sdk::http::{IncomingRequest, ResponseOutparam};

#[http_component]
async fn my_handler(request: IncomingRequest, response_out: ResponseOutparam) {
  // Your logic goes here
}