rs-config-loader

Layered configuration from files and environment variables

Installation

[dependencies]
philiprehberger-config-loader = "0.2.0"

Usage

use philiprehberger_config_loader::{ConfigBuilder, ConfigValue};

let config = ConfigBuilder::new()
    .default("port", 8080_i64)
    .default("debug", false)
    .add_file("config.toml")
    .add_env_prefix("APP")
    .set("version", "1.0.0")
    .build()
    .unwrap();

// Typed getters
let port = config.get_int("port");         // Some(8080)
let debug = config.get_bool("debug");      // Some(false)
let ver = config.get_string("version");    // Some("1.0.0")

Configuration file (TOML subset)

# config.toml
host = "localhost"
port = 3000
debug = true

[database]
url = "postgres://localhost/mydb"
pool_size = 5

Environment variables

With prefix APP, environment variables map as follows:

Environment Variable	Config Key
APP_PORT	port
APP_DATABASE__URL	database.url

Double underscore (__) maps to dot-separated nesting.

Layer priority

Later layers override earlier ones:

1. Defaults (lowest)
2. File values
3. Environment variables
4. Manual overrides (highest)

API

Type	Description
ConfigBuilder	Builder for assembling configuration layers
Config	Immutable configuration store
ConfigValue	Enum: String, Integer, Float, Bool, Array
ConfigError	Error: FileNotFound, ParseError, TypeError

ConfigBuilder

Method	Description
ConfigBuilder::new()	Create a new builder
.default(key, value)	Set a default value
.add_file(path)	Add a TOML file source (errors if missing)
.add_file_optional(path)	Add a TOML file source, silently skipped if missing
.add_env_prefix(prefix)	Add env var source with prefix
.set(key, value)	Manual override (highest priority)
.build()	Build the Config

Config

Method	Description
.get(key)	Get a &ConfigValue
.get_string(key)	Get as &str
.get_int(key)	Get as i64
.get_float(key)	Get as f64
.get_bool(key)	Get as bool
.get_array(key)	Get as &[String]
.keys()	Iterate over all keys

Development

cargo test
cargo clippy -- -D warnings

Support

If you find this project useful:

⭐ Star the repo

🐛 Report issues

💡 Suggest features

❤️ Sponsor development

🌐 All Open Source Projects

💻 GitHub Profile

🔗 LinkedIn Profile

License

MIT