config-rs

Layered configuration system for Rust applications (with strong support for [12-factor] applications).

• Set defaults
• Set explicit values (to programmatically override)
• Read from [JSON], [TOML], and [YAML] files
• Read from environment
• Loosely typed — Configuration values may be read in any supported type, as long as there exists a reasonable conversion
• Access nested fields using a formatted path — Uses a subset of JSONPath; currently supports the child ( redis.port ) and subscript operators ( databases[0].name )

Install

toml [dependencies] config = "0.2"

• json - Adds support for reading JSON files
• yaml - Adds support for reading YAML files
• toml - Adds support for reading TOML files (included by default)

Usage

Configuration is gathered by building a Source and then merging that source into the current state of the configuration.

```rust fn main() { // Add environment variables that begin with RUST_ config::merge(config::Environment::new("RUST"));

// Add 'Settings.json'
config::merge(config::File::new("Settings", config::FileFormat::Json));

// Add 'Settings.$(RUST_ENV).json`
let name = format!("Settings.{}", config::get_str("env").unwrap());
config::merge(config::File::new(&name, config::FileFormat::Json));

} ```

Note that in the above example the calls to config::merge could have been re-ordered to influence the priority as each successive merge is evaluated on top of the previous.

Configuration values can be retrieved with a call to config::get and then coerced into a type with as_*.

```toml

Settings.toml

debug = 1 ```

```rust fn main() { // Add 'Settings.toml' (from above) config::merge(config::File::new("Settings", config::FileFormat::Toml));

// Get 'debug' and coerce to a boolean
assert_eq!(config::get("debug").unwrap().as_bool(), Some(true));

// You can use a type suffix on `config::get` to simplify
assert_eq!(config::get_bool("debug"), Some(true));
assert_eq!(config::get_str("debug"), Some("true"));

} ```

See the examples for more usage information.

License

config-rs is primarily distributed under the terms of both the MIT license and the Apache License (Version 2.0).

See LICENSE-APACHE and LICENSE-MIT for details.