Crate configure_me

This library aims to help with reading configuration of application from files, environment variables and command line arguments, merging it together and validating. It auto-generates most of the code for you based on configuration (heh) file. It creates a struct for you, which contains all the parsed and validated fields, so you can access the information quickly easily and idiomatically.

Important note: since this is generating code, it’s intended to be used from build script.

Example

Let’s say, your application needs these parametrs to run:

• Port - this is mandatory
• IP address to bind to - defaults to 0.0.0.0
• Path to TLS certificate - optional, the server will be unsecure if not given

First you create Toml configuration file specifying all the parameters:

[[param]]
name = "port"
type = "u16"
optional = false
 
[[param]]
name = "bind_addr"
type = "::std::net::Ipv4Addr" 
default = "::std::net::Ipv4Addr::new(0, 0, 0, 0)" # Rust expression that creates the value
 
[[param]]
name = "tls_cert"
type = "String"

Then, you create a build script like this:

extern crate configure_me;
 
fn main() {
    let mut out: std::path::PathBuf = std::env::var_os("OUT_DIR").unwrap().into();
    out.push("config.rs");
    let config_spec = std::fs::File::open("config.toml").unwrap();
    let config_code = std::fs::File::create(&out).unwrap();
    configure_me::generate_source(config_spec, config_code).unwrap();
    println!("rerun-if-changed=config.toml");
}

Add dependencies to Cargo.toml:

[packge]
# ...
build = "build.rs"
 
[dependencies]
serde = "1"
serde_derive = "1"
toml = "0.4"
 
[build-dependencies]
configure_me = "0.2.2"

Create a module src/config.rs for configuration:

#![allow(unused)]

include!(concat!(env!("OUT_DIR"), "/config.rs"));

And finally add appropriate incantiations into src/main.rs:

extern crate serde;
#[macro_use]
extern crate serde_derive;
extern crate toml;
 
mod config;
 
fn main() {
    use config::prelude::*;
    // This will read configuration from "/etc/my_awesome_server/server.conf" file and
    // the command-line arguments.
    let (server_config, _remaining_args) = Config::including_optional_config_files(&["/etc/my_awesome_server/server.conf]").unwrap_or_exit();
 
    // Your code here
    // E.g.:
    let listener = std::net::TcpListener::bind((server_config.bind_addr, server_config.port)).expect("Failed to bind socket");
 
    Ok(())
}

Structs

Error

Error that occured during code generation

Functions

generate_source

Generates the source code for you from provided toml configuration.