Crate rtb_config 

Typed, layered configuration backed by figment.

Design

The Go Tool Base config system exposes a dynamic Containable interface with GetString("foo.bar") accessors. We deliberately do not mimic that. Rust’s strength is in compile-time types, so Config is a generic container over your serde::Deserialize struct:

use rtb_config::Config;
use serde::Deserialize;

#[derive(Deserialize, Default)]
struct MyConfig { host: String, port: u16 }

let cfg = Config::<MyConfig>::builder()
    .embedded_default(concat!(
        "host: localhost\n",
        "port: 8080\n",
    ))
    .env_prefixed("MYTOOL_")
    .build()
    .expect("config layers are consistent");

let current = cfg.get();
assert_eq!(current.host, "localhost");

What ships

• Typed Config<C> with C defaulting to () so rtb-app’s Arc<Config> field keeps working without a type parameter.
• ConfigBuilder layering (embedded default → user file → env).
• Explicit Config::reload re-reading every source and atomically swapping the stored value via arc_swap::ArcSwap.
• Config::subscribe returning a tokio::sync::watch::Receiver that wakes every time a reload succeeds (v0.2).
• Config::watch_files behind the hot-reload feature: a debounced background watcher that calls reload on change and hands back a WatchHandle to stop it (v0.2).

See docs/development/specs/2026-04-22-rtb-config-v0.1.md and docs/development/specs/2026-04-24-rtb-config-hot-reload.md for the authoritative contracts.

Re-exports

pub use config::Config;

pub use config::ConfigBuilder;

pub use error::ConfigError;

Modules

config

The typed, layered Config container.

error

Typed errors for the config subsystem.