Crate cfgloader_rs 

CFGLoader

A simple, powerful, and ergonomic configuration loading library for Rust applications.

CFGLoader automatically loads configuration from environment variables and .env files with compile-time validation and type safety.

Installation

Add this to your Cargo.toml:

[dependencies]
cfgloader_rs = "1.0"

Quick Start

Basic Usage

use cfgloader_rs::*;

#[derive(FromEnv, Debug)]
struct Config {
    #[env("DATABASE_URL", default = "sqlite://app.db")]
    database_url: String,
     
    #[env("PORT", default = "8080")]
    port: u16,
     
    #[env("API_KEY", required)]
    api_key: String,
     
    #[env("FEATURES", default = "auth,logging", split = ",")]
    features: Vec<String>,
}

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let config = Config::load(std::path::Path::new(".env"))?;
    println!("Config: {:#?}", config);
    Ok(())
}

Nested Configuration

Organize your configuration into logical groups:

use cfgloader_rs::*;

#[derive(FromEnv, Debug)]
struct AppConfig {
    #[env("APP_NAME", required)]
    name: String,
     
    // Nested structs automatically call their own load() method
    server: ServerConfig,
    database: DatabaseConfig,
}

#[derive(FromEnv, Debug)]
struct ServerConfig {
    #[env("SERVER_HOST", default = "127.0.0.1")]
    host: String,
     
    #[env("SERVER_PORT", default = "8080")]
    port: u16,
}

#[derive(FromEnv, Debug)]
struct DatabaseConfig {
    #[env("DB_URL", required)]
    url: String,
     
    #[env("DB_MAX_CONNECTIONS", default = "10")]
    max_connections: u32,
}

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let config = AppConfig::load(std::path::Path::new(".env"))?;
     
    println!("App: {}", config.name);
    println!("Server: {}:{}", config.server.host, config.server.port);
    println!("Database: {}", config.database.url);
     
    Ok(())
}

Enums

CfgError

Traits

FromEnv

Functions

get_env

Utility function for macros: read env and return Option<String>

load_env_file

Utility function for macros: load .env file

load_env_file_iter

Load .env from multiple paths (any iterable), return on first success. If none found, return error.

parse_scalar

Utility function for macros: parse string to T

parse_vec

Split string and parse each part to Vec<T>

Derive Macros

FromEnv