Crate confy_rs 

Simple, efficient configuration loading for Rust.

confy-rs loads configuration from multiple file formats, merges layered sources and deserializes the result into your own types via serde. With the watch feature it also hot-reloads the configuration when source files change on disk.

Highlights

• Multi-format: TOML / YAML / JSON, detected from the file extension
• Layered: defaults + any number of files, deep-merged in order
• Hot reload: debounced cross-platform file watching; readers are lock-free and the previous config is kept when a reload fails
• Lean: format parsers and the watcher are feature-gated

Quick start

use serde::Deserialize;

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

let config: AppConfig = confy_rs::load_str(
    r#"
    name = "demo"
    port = 8080
    "#,
    confy_rs::Format::Toml,
)?;
assert_eq!(config.port, 8080);

Loading from files works the same way — the format is detected from the extension, and later sources override earlier ones:

// One-liner for the common case
let config: AppConfig = confy_rs::load("config.toml")?;

// Layered loading
let config: AppConfig = confy_rs::builder()
    .file("config/default.toml")
    .file_optional("config/local.json")
    .build()?;

Hot reloading

let watcher = confy_rs::builder()
    .file("config.toml")
    .watch::<AppConfig>()?;

watcher.on_change(|config| println!("port is now {}", config.port));
let current = watcher.get(); // lock-free snapshot, callable anywhere

Reloads are debounced, editors that save via atomic rename are handled, and when a reload fails the previous configuration stays active while the error is reported through ConfigWatcher::on_error.

Cargo features

Feature	Default	Effect
toml	yes	TOML support via the toml crate
yaml	no	YAML support via serde_yaml_ng
watch	yes	hot reloading via notify + arc-swap

JSON support is always built in.

Structs

ConfigBuilder

A builder that loads configuration from multiple layered sources.

ConfigWatcher

A handle to a configuration that is automatically reloaded when any of its source files change.

Enums

Error

All errors that can occur while loading or watching configuration.

Format

Supported configuration file formats.

Functions

builder

Creates a new empty ConfigBuilder.

load

Loads a single configuration file and deserializes it into T.

load_str

Parses configuration from an in-memory string in the given format.

Type Aliases

Result

Convenience alias for std::result::Result<T, confy_rs::Error>.