Crate itconfig 

itconfig

Simple configuration with macro for rust application.

Motivation

I began to use rust with web programming experience where environment variables are widely used and often there are more then 50 of them. First I looked at already created libraries. But there it’s necessary to initialise structure that needs to be moved to each function where you need variable. It uses little bit memory, but configuration lifetime is as long as application lifetime. Because of it I decided to create my own library.

Installation

These macros require a Rust compiler version 1.31 or newer.

Add itconfig = { version = "1.0", features = ["macro"] } as a dependency in Cargo.toml.

Cargo.toml example:

[package]
name = "my-crate"
version = "0.1.0"
authors = ["Me <user@rust-lang.org>"]

[dependencies]
itconfig = { version = "1.0", features = ["macro"] }

Basic usage

use itconfig::config;
use std::env;
//use dotenv::dotenv;

config! {
    DEBUG: bool => false,

    #[env_name = "APP_HOST"]
    HOST: String => "127.0.0.1",

    database {
        URL < (
            "postgres://",
            POSTGRES_USERNAME => "user",
            ":",
            POSTGRES_PASSWORD => "pass",
            "@",
            POSTGRES_HOST => "localhost:5432",
            "/",
            POSTGRES_DB => "test",
        ),

        pool {
            MAX_SIZE: usize => 15,
        },
    },

    sentry {
        DSN: Option<&'static str>,
    },

    feature {
        static CORS: bool => false,

        static GRAPHQL_PLAYGROUND: bool => false,
    },
}

fn main () {
    // dotenv().expect("dotenv setup to be successful");
    // or
    env::set_var("FEATURE_CORS", "true");

    config::init();
    assert_eq!(config::HOST(), String::from("127.0.0.1"));
    assert_eq!(config::database::URL(), String::from("postgres://user:pass@localhost:5432/test"));
    assert_eq!(config::database::pool::MAX_SIZE(), 15);
    assert_eq!(config::sentry::DSN(), None);
    assert_eq!(config::feature::CORS(), true);
}

Macro is an optional feature, disabled by default. You can use this library without macro.

use itconfig::*;
use std::env;
// use dotenv::dotenv;

fn main() {
    // dotenv().expect("dotenv setup to be successful");
    // or
    env::set_var("DATABASE_URL", "postgres://127.0.0.1:5432/test");

    let database_url = get_env::<String>("DATABASE_URL").unwrap();
    let new_profile: bool = get_env_or_default("FEATURE_NEW_PROFILE", false);
    let articles_per_page: u32 = get_env_or_set_default("ARTICLES_PER_PAGE", 10);
}

Available features

• default - [“primitives”]
• macro - Activates config! macros for easy configure web application.
• primitives - Group for features: numbers and bool.
• numbers - Group for features: int, uint and float.
• int - Group for features: i8, i16, i32, i64, i128 and isize.
• uint - Group for features: u8, u16, u32, u64, u128 and usize.
• float - Group for features: f32 and f64
• i8 - impl EnvString for i8 type
• i16 - impl EnvString for i16 type
• i32 - impl EnvString for i32 type
• i64 - impl EnvString for i64 type
• i128 - impl EnvString for i128 type
• isize - impl EnvString for isize type
• u8 - impl EnvString for u8 type
• u16 - impl EnvString for u16 type
• u32 - impl EnvString for u32 type
• u64 - impl EnvString for u64 type
• u128 - impl EnvString for u128 type
• usize - impl EnvString for usize type
• f32 - impl EnvString for f32 type
• f64 - impl EnvString for f64 type
• bool - impl EnvString for bool type
• json_array - Add EnvString impl for vector type (uses optional serde_json package). ⚠ DEPRECATED

Macros

config

This API requires the following crate features to be activated: macro

Structs

EnvString

Wrapper under String type.

Enums

ArrayEnvErrorDeprecated

Error type for json array implementation

EnvError

The error type for operations interacting with environment variables

Traits

FromEnvString

Simple and safe type conversions that may fail in a controlled way under some circumstances.

ToEnvString

A trait for converting value to EnvString.

Functions

get_env

Try to read environment variable and parse to expected type. You may to put to argument any type with FromEnvString trait.

get_env_or

This function returns env variable as EnvString structure. You can pass callback for custom default expression. Callback should return EnvString value or EnvError

get_env_or_default

This function is similar as get_env_or_panic, but you can pass default value for environment variable with ToEnvString trait.

get_env_or_panic

This function is similar as get_env, but it unwraps result with panic on error.

get_env_or_set_default

This function is similar as get_env_or_default, but the default value will be set to environment variable, if env variable is missed.

get_vec_env

Try to read environment variable, split by separator and parse each item to expected type.

get_vec_env_or

This function returns env variable as EnvString structure. You can pass callback for custom default expression. Callback should return EnvString value or EnvError

get_vec_env_or_default

This function is similar as get_vec_env_or_panic, but you can pass default value for environment variable with ToEnvString trait.

get_vec_env_or_panic

This function is similar as get_vec_env, but it unwraps result with panic on error.

get_vec_env_or_set_default

This function is similar as get_vec_env_or_default, but the default value will be set to environment variable, if env variable is missed.

maybe_get_env

Same as get_env but returns Option enum instead Result

maybe_get_vec_env

Same as get_vec_env but returns Option enum instead Result