Trying to implement rocket_cors CorsOptions on a rust api

Question

I'm new to rust and I'm using rocket to create a simple CRUD API that I later would like to put on an AWS EC2 bucket. I've got one or two basic routes and I wanted to start to implement CORS so a react app can call my API. I've tried multiple tutorials and example but I'm still stuck.

Tutorials I've looked at:

• https://www.steadylearner.com/blog/read/How-to-use-CORS-and-OPTIONS-HTTP-request-with-Rust-Rocket
• https://docs.rs/rocket/0.3.6/rocket/fairing/trait.Fairing.html

[dependencies]
rocket = "0.4.6"
rocket_codegen = "0.4.6"
rocket_cors = "0.5.1"
diesel = "1.4.5"
dotenv = "0.15.0"
serde = "1.0.117"
serde_json = "1.0.59"
serde_derive = "1.0.117"
chrono = "0.4.19"

[dependencies.rocket_contrib]
version = "*"
default-features = false
features = ["json"]

My file is attached as a code snippet

#![feature(proc_macro_hygiene, decl_macro)]

#[macro_use]
extern crate rocket;
#[macro_use]
extern crate serde_derive;

use std::error::Error;
use rocket::http::Method;
use rocket_cors::{AllowedHeaders, AllowedOrigins};
use rocket_contrib::json::Json;

mod notes;
mod user_creds;

use notes::Notes;
use user_creds::UserCreds;

#[get("/api/v1/db/read")]
fn read_db() -> &'static str {
    "reading"
}

#[get("/api/v1/govee")]
fn govee() -> &'static str {
    "Hello, govee!"
}

#[post("/api/v1/db/notes", format = "json", data = "<notes>")]
fn get_notes(notes: Json<Notes>) -> Json<Notes> {
    notes
}

#[post("/api/v1/login", format = "json", data = "<user_creds>")]
fn login(user_creds: Json<UserCreds>) -> Json<UserCreds> {
    println!(
        "user creds, {}, {}",
        user_creds.username, user_creds.password
    );
    user_creds
}


fn main() {
    let allowed_origins = AllowedOrigins::some_exact(&["http://localhost:8080"]);

    // You can also deserialize this
    let cors = rocket_cors::CorsOptions {
        allowed_origins,
        allowed_methods: vec![Method::Get].into_iter().map(From::from).collect(),
        allowed_headers: AllowedHeaders::some(&["Authorization", "Accept"]),
        allow_credentials: true,
        ..Default::default()
    }
    .to_cors();

    rocket::ignite()
        .mount("/", routes![read_db])
        .attach(cors)
        .launch();
}

Image of error in the link:

Answer 1

CorsOptions::to_cors returns a Result, meaning that it could potentially return an error. You have to handle that error before you can use it as a Fairing:

let cors = rocket_cors::CorsOptions {
  allowed_origins,
  allowed_methods: vec![Method::Get].into_iter().map(From::from).collect(),
  allowed_headers: AllowedHeaders::some(&["Authorization", "Accept"]),
  allow_credentials: true,
  ..Default::default()
}
.to_cors()
// panic if there was an error
.expect("error creating CORS fairing");

Now you can attach it as a fairing:

rocket::ignite()
  .mount("/", routes![read_db])
  .attach(cors)
  .launch();