confine-rs

This crate provides both a macro and a builder API for loading configuration files. I would recommend using the macro for most use cases, as it provides a more concise way of loading configuration files. Using either one, you will be provided with a try_load function for your configuration struct. This will instantiate your struct with the configuration values from the following sources in order of precedence:

1. config/application.toml
2. config/application-{environment}.toml
3. Environment variables

The environment is determined by the CONFINE_ENV environment variable, which must be set in order to load the environment-specific configuration file.

You can configure most of these settings, but the general structure is always enforced. Things you can configure include:

• The path to the configuration files (default: config)
• The prefix of the configuration files (default: application)
• The environment variable that determines the environment (default: CONFINE_ENV)

Usage

Default configuration

Macro

use confine::confine;

fn main() {
    let config = MyConfig::try_load().unwrap();
}

#[derive(Deserialize)]
#[confine]
struct MyConfig {
    pub my_int: i64,
    pub my_string: String,
    pub my_bool: bool,
}

Builder

use confine::ConfineConfigBuilder;
use serde::Deserialize;

fn main() {
    let config = ConfineConfigBuilder::default()
        .try_load::<MyConfig>()
        .unwrap();
}

#[derive(Deserialize)]
struct MyConfig {
    pub my_int: i64,
    pub my_string: String,
    pub my_bool: bool,
}

Custom configuration

Macro

use confine::confine;

fn main() {
    let config = MyConfig::try_load().unwrap();
}

#[derive(Deserialize)]
#[confine(
    path = "my_config",
    prefix = "my_prefix",
    env_var = "MY_ENV"
)]
struct MyConfig {
    pub my_int: i64,
    pub my_string: String,
    pub my_bool: bool,
}

Builder

use confine::ConfineConfigBuilder;
use serde::Deserialize;

fn main() {
    let config = ConfineConfigBuilder::default()
        .path("my_config")
        .prefix("my_prefix")
        .env_var("MY_ENV")
        .try_load::<MyConfig>()
        .unwrap();
}

#[derive(Deserialize)]
struct MyConfig {
    pub my_int: i64,
    pub my_string: String,
    pub my_bool: bool,
}

Motivation

I found myself writing the same boilerplate code for loading configuration files in Rust over and over again. Also, while config-rs is a great library, it allows for a lot of flexibility in how exactly you handle configuration. Especially when working on multiple projects, I prefer to have a consistent way of storing and loading configuration files. This crate aims to provide an easy-to-use macro for loading configuration files with sensible defaults.