# 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. Because syntax extensions
don't yet have a stable compiler API, we'll need to use a nightly version of
Rust. If you already have a working installation of the latest Rust nightly,
feel free to skip to the next section.

To install a nightly version of Rust, we recommend using `rustup`. Install
`rustup` by following the instructions on [its website](https://rustup.rs/).
Once `rustup` is installed, configure Rust nightly as your default toolchain by
running the command:

```sh
rustup default nightly
```

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:

```sh
rustup override set nightly
```

## Nightly Version

Rocket requires the _latest_ version of Rust nightly to function. If your Rocket
application suddently stops building, ensure you're using the latest version of
Rust nightly and Rocket by updating your toolchain and dependencies with:

```sh
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:

```sh
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 = "0.2.5"
rocket_codegen = "0.2.5"
```

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

```rust
#![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. Run the program with `cargo run`. You
should see the following:

```sh
🔧  Configured for development.
    => address: localhost
    => port: 8000
    => log: normal
    => workers: {logical cores}
🛰  Mounting '/':
    => GET /
🚀  Rocket has launched from http://localhost:8000...
```

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