Add simple reverse proxy example

[silvioprog]

I found this example useful in understanding how a tide-based server can handle reverse proxy.

[darkdarkfruit]

Good one

[jbr]

I think before merging anything like this, the example should have a large and clear warning not to use this in production. There is more to a correct reverse proxy implementation than this example, and it should be a standalone crate. This is a security-sensitive feature

[silvioprog]

I think before merging anything like this, the example should have a large and clear warning not to use this in production.

Done!

[DavidBM]

I was able to make it work with:

fn bypass_to<State: Send + 'static>(
    method: tide::http::Method,
    url: tide::http::Url,
) -> impl Fn(tide::Request<State>) -> Pin<Box<dyn Future<Output = tide::Result> + Send + 'static>> {
    move |request: tide::Request<State>| {
        let url = url.clone();
        Box::pin(async move {
            let request: &tide::http::Request = request.as_ref();

            let mut request = request.clone();

            *request.url_mut() = url;
            request.set_method(method);

            let request = surf::Request::from(request);

            let response = surf::Client::default().send(request).await?;

            Ok(tide::Response::from_res(response))
        })
    }
}

and then you can just

use tide::http::{Method, Url};

let my_proxied_url = Url::parse("...").unwrap();

let mut app = tide::new();

app.at("/your route")
        .get(bypass_to(Method::Get, my_proxied_url));