Rust envy example2

main.rs

use serde_derive::Deserialize;
use envy;
use std::process;

#[derive(Deserialize, Debug)]
struct Config {
    host: String,
    port: Option<u16>,
    numbers: Vec<u64>,
}

fn main() {
    // APP_HOST=myserver
    // PORT=8080
    // APP_NUMBERS=1,2,3

    let config = match envy::prefixed("APP_").from_env::<Config>() {
        Ok(val) => val,
        Err(err) => {
            println!("{}", err);
            process::exit(1);
        }
    };

    println!("{:#?}", config);

    assert_eq!(config.host, "myserver");
    assert_eq!(config.port, None);
    assert_eq!(config.numbers, vec![1,2,3]);
}