Function bootstrap 

pub fn bootstrap<'a, ConfigExt, S>(sources: S) -> Result<AppConfig<ConfigExt>>
where
    S: IntoIterator<Item = ConfigSource<'a>>,
    ConfigExt: Debug + DeserializeOwned,

Reads AppConfig and calls init_tracing. Return Error if fails to read AppConfig or init_tracing returns error. Return Error if called twice because of internal call to [tracing_subscriber::registry().try_init()].

 use fregate::*;
 use fregate::axum::{Router, routing::get, response::IntoResponse};

 #[tokio::main]
 async fn main() {
    std::env::set_var("TEST_PORT", "3333");
    std::env::set_var("TEST_NUMBER", "1010");

     let config: AppConfig = bootstrap([
         ConfigSource::File("./examples/configuration/app.yaml"),
         ConfigSource::EnvPrefix("TEST"),
     ])
     .unwrap();

     Application::new(config)
         .router(Router::new().route("/", get(|| async { "Hello World"})))
         .serve()
         .await
         .unwrap();
 }