nurv_config

A Rust wrpper library for config-rs to manage YAML configuration files in a structured way. It provides a simple API to load and merge configuration from multiple YAML files based on environment variables.

Features

• Load configuration from YAML files
• Environment-specific overrides (e.g., local.yaml, production.yaml)
• Type-safe deserialization using Serde
• Convenient macro for quick loading with panic-on-error
• Flexible API for custom error handling

Installation

Add this to your Cargo.toml:

[dependencies]
nurv_config = { git = "https://github.com/bugyboo/nurv_config.git" }
serde = { version = "1.0", features = ["derive"] }

Usage

Basic Setup

1. Create a config/ directory in your project root.
2. Add a base.yaml file with your default configuration.
3. Optionally, add environment-specific files like local.yaml, production.yaml, etc.

Example config/base.yaml:

app:
  name: "My App"
  port: 8080

Example config/local.yaml:

app:
  port: 3000
database:
  url: "localhost:5432"

Loading Configuration

Using the Macro (Recommended for Simple Cases)

The load_config! macro provides a convenient way to load configuration. It panics on failure, so use it when you're confident the config will load.

use nurv_config::load_config;
use serde::Deserialize;

#[derive(Deserialize)]
struct Config {
    app: AppConfig,
    database: DatabaseConfig,
}

#[derive(Deserialize)]
struct AppConfig {
    name: String,
    port: u16,
}

#[derive(Deserialize)]
struct DatabaseConfig {
    url: String,
}

fn main() {
    // Load config, inferring the type
    let config: Config = load_config!();

    // Or specify the type explicitly
    let config = load_config!(Config);

    // Or use the function
    let config: Config = get_configuration()?;

    println!("App name: {}", config.app.name);
    println!("Port: {}", config.app.port);
    println!("Database URL: {}", config.database.url);
}

Environment-Specific Loading

Set the APP_ENV environment variable to load additional config files:

# Loads base.yaml + local.yaml
APP_ENV=local cargo run

# Loads base.yaml + production.yaml
APP_ENV=production cargo run

# Loads only base.yaml
cargo run

API Reference

Macros

• load_config!() - Load configuration, panicking on error. Type inferred.
• load_config!(Type) - Load configuration of specified type, panicking on error.

Functions

• get_configuration<T>() -> Result<T, ConfigError> - Load configuration with error handling.

Types

• ConfigError - Enum representing possible configuration errors (IO or Config parsing).

Testing

Run the tests with:

cargo test

The tests use the example config files in config/.

License

This project is licensed under MIT OR Apache-2.0.