Environment Variables

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Environment variable names are declared in the schema with confique:

#![allow(unused)]
fn main() {
#[derive(Debug, Config)]
struct DatabaseConfig {
    #[config(env = "APP_DATABASE_URL")]
    url: String,

    #[config(default = 16)]
    #[config(env = "APP_DATABASE_POOL_SIZE")]
    pool_size: u32,
}
}

rust-config-tree reads those names from confique::Config::META and builds a Figment provider that maps each environment variable to its exact field path.

Do not use delimiter-based Figment environment mapping for this crate:

#![allow(unused)]
fn main() {
// Do not use this pattern for rust-config-tree schemas.
Env::prefixed("APP_").split("_")
Env::prefixed("APP_").split("__")
}

split("_") treats underscores as nested key separators. That makes APP_DATABASE_POOL_SIZE become a path like database.pool.size, which conflicts with Rust field names such as pool_size.

With ConfiqueEnvProvider, this mapping is explicit:

APP_DATABASE_POOL_SIZE -> database.pool_size

Single underscores remain part of the environment variable name. Figment does not guess the nesting rule.

Dotenv Loading

Before runtime providers are evaluated, the loader searches for a .env file by walking upward from the root config file’s directory.

Existing process environment variables are preserved. Values from .env only fill missing environment variables.

Example:

APP_SERVER_PORT=9000
APP_DATABASE_POOL_SIZE=64

These variables override config file values when the schema declares matching #[config(env = "...")] attributes.

Parsing Values

The bridge provider lets Figment parse environment values. It does not call confique’s parse_env hooks. Keep complex values in config files unless the Figment environment value syntax is a good fit for the type.