Getting configurations in Rust lang

.env

SERVER.PORT=5001

Cargo.toml

[dependencies]
serde = "1.0.113"
serde_derive = "1.0.113"
dotenv = "0.15.0"
config = "0.10.1"

settings.toml

# settings.toml

[server]
    host = "192.168.0.10"
    port = 5000

settings_development.toml

# settings_development.toml

[server]
    host = "127.0.0.1"

src\main.rs

// src/main.rs

mod settings;

use crate::settings::Settings;
use dotenv::dotenv;

fn main() {
    dotenv().ok();

    let config = Settings::new().unwrap();

    println!("Server: {}:{}", config.server.host, config.server.port);
}

src\settings.rs

// src/settings.rs

use config::{Config, ConfigError, Environment, File};
use serde_derive::Deserialize;
use std::env;

#[derive(Deserialize)]
pub struct ServerSettings {
    pub host: String,
    pub port: i32,
}

#[derive(Deserialize)]
pub struct Settings {
    pub server: ServerSettings,
}

impl Settings {
    pub fn new() -> Result<Self, ConfigError> {
        let env = env::var("environment").unwrap_or("development".into());

        let mut cfg = Config::new();
        cfg.merge(File::with_name("settings"))?;
        cfg.merge(File::with_name(&format!("settings_{}", env)).required(false))?;
        cfg.merge(Environment::new())?;
        cfg.try_into()
    }
}