Twelf
Twelf is a configuration solution for Rust including 12-Factor support. It is designed with Layer
s in order to configure different sources and formats to build your configuration. The main goal is to be very simple using the proc macro twelf::config
. For now it supports :
- Default settings (inside your codebase with
#[serde(default = ...)]
coming from serde) - Reading from
TOML
,YAML
,JSON
,DHALL
,INI
files - Reading from environment variables: it supports
HashMap
structure withMY_VARIABLE="mykey=myvalue,mykey2=myvalue2"
and also array likeMY_VARIABLE=first,second
thanks to envy. - All serde attributes can be used in your struct to customize your configuration as you wish
- Reading your configuration from your command line built with clap
Usage
Simple with JSON and environment variables
use config;
// Init configuration with layers, each layers override only existing fields
let config = with_layers.unwrap;
Example with clap support
use config;
// Will generate global arguments for each of your fields inside your configuration struct
let app = new.args;
// Init configuration with layers, each layers override only existing fields
let config = with_layers.unwrap;
// ... your application code
Use features to improve compile time
If you don't want to include useless crates if you just use 2 of all available layers you can use features without default-features, example if you use only yaml and env layer.
[]
= { = "0.1", = false, = ["yaml"] }
TODO:
- Write an example with env + files
- Write an example with default + env
- Write an example with clap
- Write an example with complex structure like hashmap, array, flattened
- Support Vault
- Imagine a good trait/api to extend and let users fetch config from remote
- Refactor to let user extend layers
- Add support of nested struct in envy
- Fix issue with
#[serde(flatten)] when you use other type than
String` in sub types
Alternatives
- config-rs is almost doing the same except the environment layer (for example we support hashmap and array in environment variables). Also
config-rs
don't have clap support and it didn't use any proc-macros if you're not very fan of proc-macros.