Rouille - Hello World in text/plain

Part of the series about the Rouille micro-web framework in Rust.

Create a new crate

cargo new hello-world-text
cd hello-world-text

Dependencies

Add Rouille as a dependency to the Cargo.toml file:

examples/rouille/hello-world-text/Cargo.toml

[package]
name = "hello-world-text"
version = "0.1.0"
edition = "2021"

# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html

[dependencies]
rouille = "3.6"

The code

examples/rouille/hello-world-text/src/main.rs

#[macro_use]
extern crate rouille;

fn main() {
    let host = "localhost";
    let port = "8000";

    println!("Now listening on {host}:{port}");

    rouille::start_server(format!("{host}:{port}"), move |request| {
        router!(request,
            (GET) (/) => {
                rouille::Response::text("Hello <b>world!</b>")
            },
            _ => rouille::Response::empty_404()
        )
    });
}

• We call rouille::start_server providing it the hostname and port number. Giving "localhost" or "127.0.0.1" will ensure that the web server won't be accessible from outside of your computer. This is a good idea during development.

• The router! macro helps us define the routes.

• (GET) (/) => {} is the mapping that say what to do when an HTTP GET request arrives to the root (/) path on the server.

• The rouille::Response::text method send a response setting the Content-Type to text/plain.

• We also have a default route-handle: _ => rouille::Response::empty_404() calling the empty_404 method.

Running the code

cargo run

Will print Now listening on localhost:8000 on the console and we can visit http://localhost:8000/ with our browser and see

Hello <b>world!</b>

We won't see the text in bold, we'll see the HTML tag.

On Linux and probably also on macOs we can use another terminal to run the following command.

curl -i http://localhost:8000/

The -i flag of curl will make it show the header along the content.

HTTP/1.1 200 OK
Server: tiny-http (Rust)
Date: Mon, 01 Jan 2024 12:40:58 GMT
Content-Type: text/plain; charset=utf-8
Content-Length: 11

Hello <b>world!</b>

Here we can see clearly the Content-Type being text/plain. That's the reason the browser shows us the text and does not try to interpret it as HTML.

404 Not found

If we visit any other URL (e.g. http://localhost:8000/qqrq ) we'll get a blank page.

With curl we can verify that the HTTP response code was 404 as expected.

$ curl -i http://localhost:8000/qqrq

HTTP/1.1 404 Not Found
Server: tiny-http (Rust)
Date: Mon, 01 Jan 2024 12:45:42 GMT
Content-Length: 0