salak

A layered configuration loader with zero-boilerplate configuration management.

About

salak try to provide an out-of-box configuration loader for creating new apps, such as cli, web, servers.

Multi-Layered source environment.

salak defines following default PropertySources:

1. Command line arguments using clap to parsing -P, --propery KEY=VALUE.
2. System Environment.
3. app.toml(*) in current dir and $HOME dir. Or if you specify APP_CONF_DIR dir, then only load toml in this dir.

* APP_CONF_NAME can be specified to replace app.

Placeholder format

1. ${key:default} means get value of key, if not exists then return default.
2. ${key} means get value of key, if not exists then return PropertyError::NotFound(_).

Key format

1. a.b.c is a normal key separated by dot(.).
2. a.b[0], a.b[1], a.b[2]... is a group of keys with arrays.
3. System environment key will be changed from HELLO_WORLD <=> hello.world, HELLO__WORLD_HOW <=> hello_world.how, hello[1].world => HELLO_1_WORLD <=> hello.1.world.

Auto derived parameters.

attribute default to set default value.

1. #[salak(default="string")]
2. #[salak(default=1)]

attribute disable_placeholder to disable placeholder parsing.

1. #[salak(disable_placeholder)]
2. #[salak(disable_placeholder = true)]

Features

Default features

1. enable_log, enable log record if enabled.
2. enable_toml, enable toml support.
3. enable_derive, enable auto derive [FromEnvironment] for struts.

Optional features

1. enable_clap, enable default command line arguments parsing by clap.

Quick Code

use salak::*;
#[derive(FromEnvironment, Debug)]
pub struct DatabaseConfig {
    url: String,
    #[salak(default = "salak")]
    name: String,
    #[salak(default = "${database.name}")]
    username: String,
    password: Option<String>,
    #[salak(default = "${Hello}", disable_placeholder)]
    description: String,
}

fn main() {
  std::env::set_var("database.url", "localhost:5432");
  let env = SalakBuilder::new()
     .with_default_args(auto_read_sys_args_param!()) // This line need enable feature `enable_clap`.
     .build();
 
  match env.require::<DatabaseConfig>("database") {
      Ok(val) => println!("{:?}", val),
      Err(e) => println!("{}", e),
  }
}
// Output: DatabaseConfig { url: "localhost:5432", name: "salak", username: "salak", password: None, description: "${Hello}" }

Quick Run

git clone https://github.com/leptonyu/salak.rs.git
cd salak.rs
cargo run --example salak --features="default enable_clap" -- -h
# salak 0.4.0
# Daniel Yu <leptonyu@gmail.com>
# A rust configuration loader
# 
# USAGE:
#     salak [OPTIONS]
# 
# FLAGS:
#     -h, --help       Prints help information
#     -V, --version    Prints version information
# 
# OPTIONS:
#     -P, --property <KEY=VALUE>...    Set properties

TODO

1. Support hashmap.
2. Reload configurations.