Migrating to Shuttle

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Setup

For this example, we’ll assume you are migrating an Axum project.

The first step is to add shuttle-runtime and shuttle-axum to your dependencies to be able to use Shuttle’s runtime with the Axum framework.

cargo add shuttle-runtime shuttle-axum

Any secrets you need to use will be kept in a Secrets.toml file (dev secrets in Secrets.dev.toml) which will be placed at the Cargo.toml level.

You can also easily get a provisioned database like so (this example will be for a provisioned PostgreSQL instance specifically):

cargo add shuttle-shared-db --features postgres

If you have any database records you’d like to keep, it would be a good idea to export them so that they can be migrated to the new database. You will not need a secrets file if you only need a provisioned Postgres database - this will be automatically be provisioned and given to you in the form of a connection string or an sqlx pool.

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Migrating your Code

To be able to run your project on Shuttle, you need to make a few changes to your code. Instead of the tokio::main macro, you will use the shuttle_runtime::main macro and swap out dotenvy for Shuttle’s Postgres annotation:

This is what your main.rs file looks like before:

#[tokio::main]
async fn main() {
    dotenvy::dotenv().ok();

    let url = dotenvy::var("DATABASE_URL").expect("No database URL was set!");

    let pool = sqlx::Pool::connect(&url).await.unwrap();

    sqlx::migrate!()
        .run(&pool)
        .await
        .expect("Migrations failed :(");

    let router = create_api_router(pool);
    let addr = SocketAddr::from(([0, 0, 0, 0], 8000));

    Server::bind(&addr)
        .serve(router.into_make_service())
        .await
        .unwrap()
}

And this is what it looks like after:

#[shuttle_runtime::main]
pub async fn axum (
    #[shuttle_shared_db::Postgres] pool: PgPool,
    #[shuttle_runtime::Secrets] secrets: shuttle_runtime::SecretStore,
) -> shuttle_axum::ShuttleAxum {
    sqlx::migrate!()
        .run(&pool)
        .await
        .expect("Migrations failed :(");

    // Use secrets for anything that needs them

    let router = create_api_router(pool);

    Ok(router.into())
}

If you need more than a simple router, you’ll want to create a custom struct that holds all of your required app state information inside and then create an impl for the struct - you can find more about that here. Anything outside of your entry point function (the function that uses the shuttle_runtime::main macro) doesn’t need to be changed. If you are using secrets as well as a database connection, you may wish to create a struct that holds both of these values and then pass it into the function that generates the router.

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Deploying

To ensure that you get a unique project name, create a Shuttle.toml file at the Cargo.toml level to name your project to whatever you like.

name = "my-unique-app-name-here"

Now all you need to do is to run the following commands:

cargo shuttle project start
cargo shuttle deploy

Your project should now be deployed!