Configured

Utility to load configuration from three well defined layers into any type which can be deserialized by Serde.

First, values from the mandatory default configuration file at <CONFIG_DIR>/default.toml are loaded.

Then, if if the environment variable CONFIG_ENVIRONMENT is defined, values from the environment (e.g. "prod") specific configuration file at <CONFIG_DIR>/<CONFIG_ENVIRONMENT>.toml are loaded as an overlay, i.e. adding or overwriting already existing values.

Finally environment variables prefixed with <CONFIG_ENV_PREFIX>__ and separated by __ (double underscores are used as separators because of snake_cased keys) are used as additional overlay.

Example

```rust

[derive(Deserialize)]

struct Config { foo: Foo, qux: Qux, }

[derive(Deserialize)]

struct Foo { bar: String, baz: String, }

[derive(Deserialize)]

struct Qux { quux: String, }

[test]

fn testload() { env::setvar(CONFIGDIR, "test-config"); env::setvar(CONFIGENVIRONMENT, "dev"); env::setvar("APPQUXQUUX", "Quux2");

let config = Config::load();
assert!(config.is_ok());
let config = config.unwrap();

assert_eq!(config.foo.bar.as_str(), "Bar");
assert_eq!(config.foo.baz.as_str(), "Baz2");
assert_eq!(config.qux.quux.as_str(), "Quux2");

} ```

Attribution

This utility is built on top of the fantastic Config library.

License

This code is open source software licensed under the Apache 2.0 License.