Rocket/docs/guide/03-getting-started.md

+++ summary = "a gentle introduction to running your first Rocket application" +++

Getting Started

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

Installing Rust

Rocket makes use of the latest Rust features. Because of this, we'll need a recent release of Rust to run Rocket applications. If you already have a working installation of the latest Rust compiler, feel free to skip to the next section.

To install the latest version of Rust, we recommend using rustup. Install rustup by following the instructions on its website. Once rustup is installed, ensure the latest toolchain is installed by running the command:

rustup default stable

! note: You may prefer to develop using the nightly channel.

The nightly Rust toolchain enables certain improved developer experiences, such as better compile-time diagnostics, when developing with Rocket. You may choose to develop on the nightly channel to take advantage of these improved experiences. Note that all Rocket features are available across all Rust channels.

To set the nightly toolchain as your default, run rustup default nightly.

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 as a dependency in your Cargo.toml:

[dependencies]
rocket = "0.5.0"

! warning: Development versions must be git dependencies.

Development versions, tagged with -dev, are not published. To depend on a development version of Rocket, you'll need to point Cargo.toml to a Rocket git repository. For example, with ###### replaced with a git commit hash:

rocket = { git = "https://github.com/rwf2/Rocket", rev = "######" }

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

#[macro_use] extern crate rocket;

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

#[launch]
fn rocket() -> _ {
    rocket::build().mount("/", routes![index])
}

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:

> cargo run
🔧 Configured for debug.
   >> address: 127.0.0.1
   >> port: 8000
   >> workers: [..]
   >> keep-alive: 5s
   >> limits: [..]
   >> tls: disabled
   >> temp dir: /tmp
   >> log level: normal
   >> cli colors: true
🛰  Routes:
   >> (index) GET /
🚀 Rocket has launched from http://127.0.0.1:8000

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

! tip: Don't like colors or emoji?

You can disable colors and emoji by setting the ROCKET_CLI_COLORS environment variable to 0 or false when running a Rocket binary: ROCKET_CLI_COLORS=false cargo run.