Rocket/site/guide/getting-started.md

Getting Started

Let's create and run our first Rocket application. We'll ensure we have a compatible version of Rust, create a new Cargo project that depends on Rocket, and then run the application.

Installing Rust

Rocket makes abundant use of Rust's syntax extensions and other advanced, unstable features. Because of this, we'll need to use a supported nightly version of Rust.

To install such a version, we recommend using rustup. Install rustup by following the instructions on its website. Once rustup is installed, configure Rust nightly as your default toolchain by running the command:

rustup default nightly-2017-12-21

If you prefer, once we setup a project directory in the following section, you can use per-directory overrides to use the nightly version only for your Rocket project by running the following command in the directory:

rustup override set nightly-2017-12-21

Minimum Nightly

Rocket generally requires the latest version of Rust nightly. At present, however, a Rocket dependency fails to build on the latest nightlies, temporarily grounding Rocket (see #513 for details). As a result, you'll need to use the last known working nightly release while the issue is resolved. The commands above already take this into account by installing the 2017-12-21 nightly.

Once the external issue has been resolved, you can upgrade to the latest nightly with rustup default nightly or rustup override set nightly. If your Rocket application suddenly stops building, it's likely that this issue has been resolved. If Rocket fails to compile in the future, you should also ensure you're using the latest version of Rust nightly and Rocket by updating your toolchain and dependencies with:

rustup update && cargo update

Hello, world!

Let's write our first Rocket application! Start by creating a new binary-based Cargo project and changing into the new directory:

cargo new hello-rocket --bin
cd hello-rocket

Now, add Rocket and its code generation facilities as dependencies of your project by ensuring your Cargo.toml contains the following:

[dependencies]
rocket = "0.3.5"
rocket_codegen = "0.3.5"

Modify src/main.rs so that it contains the code for the Rocket Hello, world! program, reproduced below:

#![feature(plugin)]
#![plugin(rocket_codegen)]

extern crate rocket;

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

fn main() {
    rocket::ignite().mount("/", routes![index]).launch();
}

We won't explain exactly what the program does now; we leave that for the rest of the guide. In short, it creates an index route, mounts the route at the / path, and launches the application. Compile and run the program with cargo run. You should see the following:

🔧  Configured for development.
    => address: localhost
    => port: 8000
    => log: normal
    => workers: [core count * 2]
    => secret key: generated
    => limits: forms = 32KiB
    => tls: disabled
🛰  Mounting '/':
    => GET /
🚀  Rocket has launched from http://localhost:8000

Visit http://localhost:8000 to see your first Rocket application in action!