env_vars_config/
lib.rs

1//! A simple lib for configuring your applications via environment variables
2
3#[doc(hidden)]
4pub extern crate log;
5
6/// Creates new mod with specified environment variables
7/// # Examples
8///
9/// ```
10/// use env_vars_config::env_vars_config;
11///
12/// env_vars_config! {
13///     SERVER_ADDRESS: String = "0.0.0.0:8080",
14///     WORKERS_COUNT: i32 = 32
15/// }
16///
17/// assert_eq!(config::SERVER_ADDRESS.as_str(), "0.0.0.0:8080");
18/// assert_eq!(config::WORKERS_COUNT.clone(), 32);
19/// ```
20/// # Panics
21///
22/// ```no_compile
23/// use env_vars_config::env_vars_config;
24///
25/// env_vars_config! {
26///     // incompatible type
27///     ENABLE_REGISTRATION: bool = "false"
28/// }
29/// ```
30#[macro_export]
31macro_rules! env_vars_config {
32    ( $( $name:ident: $type:tt = $default_value:expr ),* $(,)? ) => {
33        pub mod config {
34            use std::{
35                sync::LazyLock,
36                env,
37                any::type_name,
38            };
39
40            #[inline]
41            fn get_variable_type<T>(_: &T) -> &'static str {
42                type_name::<T>().split("::").last().unwrap()
43            }
44
45            $(
46                /// Our environment variable. Lazy-evaluated by default
47                pub static $name: LazyLock<$type> = LazyLock::new(|| {
48                    let name = stringify!($name);
49
50                    if let Ok(value) = env::var(name) {
51                        if let Ok(value) = value.parse::<$type>() {
52                            value
53                        } else {
54                            panic!(
55                                "Invalid value type for the variable `{name}`! Expected type `{}`, got `{}`.",
56                                stringify!($type),
57                                get_variable_type(&value)
58                            )
59                        }
60                    } else {
61                        env_vars_config::log::warn!(
62                            "Variable `{}` is missing in the env! Using default value `{}`",
63                            name,
64                            $default_value
65                        );
66                        <$type>::from($default_value)
67                    }
68                });
69            )*
70
71            /// Inits all environment variables
72            pub fn init() {
73                $(
74                    LazyLock::force(&$name);
75                )*
76            }
77        }
78    };
79}
env_vars_config/lib.rs

env_vars_config/
lib.rs
