Configuration

Type-safe configuration from environment variables

Environment Variables

Rapina uses environment variables for configuration. Create a .env file for local development:

DATABASE_URL=postgres://localhost/myapp
PORT=3000
JWT_SECRET=your-secret-key

Load the .env file at startup:

use rapina::prelude::*;

#[tokio::main]
async fn main() -> std::io::Result<()> {
    load_dotenv();  // Load .env file

    // ...
}

Config Derive Macro

Use the #[derive(Config)] macro for type-safe configuration:

use rapina::prelude::*;

#[derive(Config, Clone)]
struct AppConfig {
    #[env = "DATABASE_URL"]
    database_url: String,

    #[env = "PORT"]
    #[default = "3000"]
    port: u16,

    #[env = "HOST"]
    #[default = "127.0.0.1"]
    host: String,
}

#[tokio::main]
async fn main() -> std::io::Result<()> {
    load_dotenv();

    let config = AppConfig::from_env().expect("Missing config");

    Rapina::new()
        .state(config.clone())
        .router(router)
        .listen(format!("{}:{}", config.host, config.port))
        .await
}

Attributes

Fail-Fast Validation

If required variables are missing, from_env() returns an error listing all missing variables at once:

Error: Missing environment variables: DATABASE_URL, JWT_SECRET

This prevents the frustrating cycle of fixing one error at a time.

Accessing Config in Handlers

Use the State extractor to access configuration in handlers:

#[get("/config")]
async fn show_config(config: State<AppConfig>) -> String {
    format!("Running on port {}", config.into_inner().port)
}