Run a Rust Rocket app

This example uses Rocket, a popular Rust web framework. To run this example, follow these steps:

1. Install the kraft CLI tool and a container runtime engine, e.g. Docker.

2. Clone the examples repository and cd into the examples/http-rust1.75-rocket0.5/ directory:

git clone https://github.com/kraftcloud/examples
cd examples/http-rust1.75-rocket0.5

Make sure to log into KraftCloud by setting your token and a metro close to you. We use fra0 (Frankfurt, 🇩🇪) in this guide:

# Set KraftCloud access token
export KRAFTCLOUD_TOKEN=token
# Set metro to Frankfurt, DE
export KRAFTCLOUD_METRO=fra0

When done, invoke the following command to deploy this application on KraftCloud:

kraft cloud deploy -p 443:8080 .

The output shows the instance URL and other details:

[●] Deployed successfully!
 │
 ├────────── name: http-rust175-rocket05-tuwq3
 ├────────── uuid: b6fe13e4-93b7-402b-bdec-1bc4d81bc275
 ├───────── state: running
 ├─────────── url: https://empty-bobo-n3htmpye.fra0.kraft.host
 ├───────── image: http-rust175-rocket05@sha256:23a7a6e155758e6e8f75e9570f0aec5fb744f08c1bad2454d7386367c5ea45d6
 ├───── boot time: 17.41 ms
 ├──────── memory: 128 MiB
 ├─ service group: empty-bobo-n3htmpye
 ├── private fqdn: http-rust175-rocket05-tuwq3.internal
 ├──── private ip: 172.16.6.6
 └────────── args: /server

In this case, the instance name is http-rust175-rocket05-tuwq3 and the URL is https://empty-bobo-n3htmpye.fra0.kraft.host. They are different for each run.

Use curl to query any of the Rocket server’s paths, for example:

curl https://empty-bobo-n3htmpye.fra0.kraft.host/wave/Rocketeer/100

👋 Hello, 100 year old named Rocketeer!

At any point in time, you can list information about the instance:

kraft cloud instance list

NAME                           FQDN                           STATE    CREATED AT     IMAGE                                                                  MEMORY   ARGS     BOOT TIME
http-rust175-rocket05-tuwq3    empty-bobo-n3htmpye.fra0.k...  running  1 minute ago   http-rust175-rocket05@sha256:23a7a6e155758e6e8f75e9570f0aec5fb744...   128 MiB  /server  17412us

When done, you can remove the instance:

kraft cloud instance remove http-rust175-rocket05-tuwq3

Customize your Application

To customize the application, update the files in the repository, listed below:

• src/main.rs: the actual server
• Cargo.toml: the Cargo package manager configuration file
• Kraftfile: the KraftCloud specification
• Dockerfile: the Docker-specified application filesystem

Kraftfile

spec: v0.6

runtime: base:latest

rootfs: ./Dockerfile

cmd: ["/server"]

src/main.rs

#[macro_use] extern crate rocket;

#[cfg(test)] mod tests;

#[derive(FromFormField)]
enum Lang {
#[field(value = "en")]
English,
#[field(value = "ru")]
#[field(value = "ру")]
Russian
}

#[derive(FromForm)]
struct Options<'r> {
emoji: bool,
name: Option<&'r str>,
}

// Try visiting:
//   http://127.0.0.1:8000/hello/world
#[get("/world")]
fn world() -> &'static str {
"Hello, world!"
}

// Try visiting:
//   http://127.0.0.1:8000/hello/мир
#[get("/мир")]
fn mir() -> &'static str {
"Привет, мир!"
}

// Try visiting:
//   http://127.0.0.1:8000/wave/Rocketeer/100
#[get("/<name>/<age>")]
fn wave(name: &str, age: u8) -> String {
format!("👋 Hello, {} year old named {}!", age, name)
}

// Note: without the `..` in `opt..`, we'd need to pass `opt.emoji`, `opt.name`.
//
// Try visiting:
//   http://127.0.0.1:8000/?emoji
//   http://127.0.0.1:8000/?name=Rocketeer
//   http://127.0.0.1:8000/?lang=ру
//   http://127.0.0.1:8000/?lang=ру&emoji
//   http://127.0.0.1:8000/?emoji&lang=en
//   http://127.0.0.1:8000/?name=Rocketeer&lang=en
//   http://127.0.0.1:8000/?emoji&name=Rocketeer
//   http://127.0.0.1:8000/?name=Rocketeer&lang=en&emoji
//   http://127.0.0.1:8000/?lang=ru&emoji&name=Rocketeer
#[get("/?<lang>&<opt..>")]
fn hello(lang: Option<Lang>, opt: Options<'_>) -> String {
let mut greeting = String::new();
if opt.emoji {
    greeting.push_str("👋 ");
}

match lang {
    Some(Lang::Russian) => greeting.push_str("Привет"),
    Some(Lang::English) => greeting.push_str("Hello"),
    None => greeting.push_str("Hi"),
}

if let Some(name) = opt.name {
    greeting.push_str(", ");
    greeting.push_str(name);
}

greeting.push('!');
greeting
}

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

Cargo.toml

[package]
name = "hello"
version = "0.0.0"
edition = "2021"
publish = false

[dependencies]
rocket = "0.5.0"

Dockerfile

FROM rust:1.75.0-bookworm AS build

RUN cargo new --bin app
WORKDIR /app
COPY Cargo.toml ./
COPY Rocket.toml ./
COPY src ./src
RUN cargo build --release

FROM scratch

COPY ./Rocket.toml /Rocket.toml
COPY --from=build /app/target/release/hello /server
COPY --from=build /lib/x86_64-linux-gnu/libc.so.6 /lib/x86_64-linux-gnu/
COPY --from=build /lib/x86_64-linux-gnu/libm.so.6 /lib/x86_64-linux-gnu/
COPY --from=build /lib/x86_64-linux-gnu/libgcc_s.so.1 /lib/x86_64-linux-gnu/
COPY --from=build /lib64/ld-linux-x86-64.so.2 /lib64/

The following options are available for customizing the application:

• If only updating the implementation in the src/main.rs source file, no other change is required.

• If new files are added, these have to be copied in the application filesystem, using the COPY command in the Dockerfile. If new Rust source code files are added, be sure to configure required dependencies in the Cargo.toml file.

• If a new executable is built, update the cmd line in the Kraftfile and replace /server with the path to the new executable.

• More extensive changes may require expanding the Dockerfile with additional Dockerfile commands.

Learn More

Use the --help option for detailed information on using KraftCloud:

kraft cloud --help

Or visit the CLI Reference.