Accessing third-party APIs

[allsey87]

Hi there! I am wondering what is the best way to access third-party APIs from a worker such as sendgrid, gmail, stripe etc. There is a Rust crate for most of these services, however most (if not all) of these crates have a dependency on hyper and/or tokio (which will not compile to wasm).

In your opinion, is it best to modify these existing Rust crates to work with Fetch or would it perhaps be better to create bindings to a Node.js module?

[nilslice]

@allsey87 - That is a bit of an unfortunate side-effect of using a new technology. Many HTTP client crates will use reqwest which does have support for wasm, and its possible that the authors of the client crates for those services have hidden support behind a feature?

Another option is to find a crate that separates the request data from the HTTP transport altogether, such as https://github.com/baschoj/sendgrid-rs

Lastly, you may want to implement the requests yourself using Fetch without any client library. It is a bit more work, but at the end of the day, you will probably have a smaller wasm binary and full control over how things work.

[nilslice]

To add,

or would it perhaps be better to create bindings to a Node.js module?

This is not an option, as the Workers platform is not fully compatible with Node.js, and specifically does not support native Node bindings.

[allsey87]

I agree that for the moment implementing what I need using Fetch is probably the way to go. I am not sure if reqwest will work out-of-the-box though since although it compiles to wasm, it accesses the browser's or Node.js' fetch API which I guess is not available inside of a worker?

[nilslice]

@allsey87 - reqwuest looks for fetch, yes, and it is implemented in the Workers JS runtime. The only difference is that Workers fetch has some extra functionality that isn't accessible via reqwest (like caching, setting up WebSocket connections, and other Cloudflare-specific platform features that differ from the browser-standard Fetch API).

So it should work fine, until you (may or may not) need any of the Cloudflare APIs. For making requests to third-party APIs, I don't think you will have any problems though!

[nilslice]

here's a minimal example of reqwest working within a workers-rs project:

use reqwest::Client;
use worker::*;

#[event(fetch)]
pub async fn main(_req: Request, _env: Env) -> Result<Response> {
    let client = Client::new();
    let resp = client
        .get("https://workers.cloudflare.com")
        .send()
        .await
        .unwrap();

    let bytes = resp.bytes().await.unwrap();

    Response::from_html(String::from_utf8(bytes.as_ref().into()).unwrap())
}